WO2004111180A2 - Procedes et compositions pour enrichir selectivement des microbes - Google Patents

Procedes et compositions pour enrichir selectivement des microbes Download PDF

Info

Publication number
WO2004111180A2
WO2004111180A2 PCT/US2003/040806 US0340806W WO2004111180A2 WO 2004111180 A2 WO2004111180 A2 WO 2004111180A2 US 0340806 W US0340806 W US 0340806W WO 2004111180 A2 WO2004111180 A2 WO 2004111180A2
Authority
WO
WIPO (PCT)
Prior art keywords
medium
sample
kit
acidic medium
acidic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US2003/040806
Other languages
English (en)
Other versions
WO2004111180A3 (fr
Inventor
Michael A. Grant
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
National Institutes of Health NIH
Original Assignee
National Institutes of Health NIH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by National Institutes of Health NIH filed Critical National Institutes of Health NIH
Priority to US10/539,765 priority Critical patent/US20060141603A1/en
Priority to AU2003304215A priority patent/AU2003304215A1/en
Publication of WO2004111180A2 publication Critical patent/WO2004111180A2/fr
Publication of WO2004111180A3 publication Critical patent/WO2004111180A3/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
    • C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
    • C12Q1/02—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving viable microorganisms
    • C12Q1/04—Determining presence or kind of microorganism; Use of selective media for testing antibiotics or bacteriocides; Compositions containing a chemical indicator therefor
    • C12Q1/10—Enterobacteria

Definitions

  • the invention relates generally to methods for enriching the numbers of target microbes in test samples that may contain a mixture of microbial species. More specifically, the invention relates to a selection procedure involving incubating a sample that may contain competitor microbes and target microbes under acidic conditions such that the competitor microbes are growth inhibited or killed, but where the target microbes survive. The surviving target microbes can then be detected using available procedures.
  • Enterohemorrhagic Escherichia coli has emerged in recent years as the predominant cause of hemorrhagic colitis in humans. It may be present in foods of animal-origin or plant- origin, as well as in water, and has been implicated as a cause of food poisoning. Diarrhea, hemorrhagic colitis, hemolytic uremic syndrome, and thrombocytopenic purpura are the principal manifestations of illness.
  • enterohemorrhagic E. coli appears to be associated with a number of virulence factors, including the production of several cytotoxins. These toxins are collectively referred to as verotoxins or Shiga-like toxins because the Shiga-like toxin of E. coli closely resembles the Shiga toxin of Shigella dysenteriae type 1. Although more than sixty E. coli serotypes produce Shiga-like toxins and more are being identified as capable of producing Shiga-like toxins, serotype O157:H7 is the predominant pathogen in the enterohemorrhagic E. coli group and the one associated most frequently with human infections worldwide.
  • the initial symptoms of hemorrhagic colitis generally occur between one and two days after eating contaminated food, although longer periods (3-5 days) have been reported. Symptoms start with mild, non-bloody diarrhea that may be followed by a period of crampy abdominal pain and short-lived fever. The initial diarrhea increases in intensity during the next 24-48 hours to a 4 to 10-day phase of overtly bloody diarrhea accompanied by severe abdominal pain and moderate dehydration.
  • hemolytic uremic syndrome is the most common.
  • the onset of hemolytic uremic syndrome is approximately a week after the onset of gastrointestinal symptoms. Characteristic symptoms are pallor, intravascular destruction of red blood cells (microangiopathic hemolytic anemia), depressed platelet counts (thrombocytopenia), lack of urine formation (oligo-anuria), swelling (edema), and acute renal failure.
  • Hemolytic uremic syndrome occurs most often in children under the age often years. Approximately half of hemolytic uremic syndrome patients require dialysis, and the mortality rate is 3-5%.
  • hemolytic uremic syndrome-associated complications may include seizures, coma, stroke, co Ionic perforation, pancreatitis, and hypertension. Approximately 15% of cases lead to early development of chronic kidney failure. Insulin-dependent diabetes may also persist in hemolytic uremic syndrome patients. A small number of hemolytic uremic syndrome cases may recur.
  • a second complication associated with E. coli 0157 :H7 is thrombotic thrombocytopenic purpura. This condition resembles HUS except that it generally causes less renal damage; has significant neurological involvement, e.g., central nervous system deterioration, seizures, and strokes; and is restricted primarily to adults.
  • Enterohemorrhagic Escherichia coli presents a significant health hazard. Accordingly, improved methods to determine if clinical, food, water, or environmental samples contain enterohemorrhagic bacteria are necessary to ensure the proper diagnosis and treatment of patients, as well as ensuring the safety of food and waters.
  • the present invention provides methods and kits that can be used to produce a test sample in which a target microbe is enriched.
  • the methods used to enrich a target microbe in a test sample involve incubating a first sample that may contain competitive microbes and a target microbe under acidic conditions that inhibit or kill competitor microbes in the first sample and thereby provide a growth advantage to the target microbe.
  • the surviving target microbes can be detected immediately or subjected to conditions permitting additional growth to facilitate detection.
  • the target microbe is a bacterium
  • the target microbe is selected from Escherichia, Salmonella, Staphylococcus, Klebsiella, Listeria, Morganella, Enterobacter, Serratia, Yersinia, Bacillus, Shigella and Hafnia.
  • the methods of the invention can be used with samples suspected of containing target microbes such as pathogemc and non-pathogenic Escherichia coli.
  • the target microbe is Shigella.
  • the target microbe is a pathogenic bacterium.
  • the methods of the invention can be used for enrichment of pathogenic Escherichia coli such as enterohemorrhagic Escherichia coli, enterotoxigenic Escherichia coli (ETEC), enteropathogenic Escherichia coli (EPEC) and the like, i further embodiments, the target microbe is the O157:H7 strain of Escherichia coli.
  • pathogenic Escherichia coli such as enterohemorrhagic Escherichia coli, enterotoxigenic Escherichia coli (ETEC), enteropathogenic Escherichia coli (EPEC) and the like
  • ETEC enterotoxigenic Escherichia coli
  • EPEC enteropathogenic Escherichia coli
  • the acidic condition includes an acidic medium that inhibits the growth of competitor microbes when they are later incubated in growth media.
  • the pH of the acidic medium is between 1 and 6. In other embodiments, the pH of the acid medium is between 1 and 4. h further embodiments, the pH of the acidic medium is between 1 and 2. In still futher embodiments, the pH of the acidic medium is between 2 and 4. In a preferred embodiment, the pH of the acidic medium is between 1.5 and 2.5.
  • the acid condition includes an acidic medium that causes death of the competitor microbes during incubation in the acidic medium.
  • the pH of the acidic medium is between 1 and 6. In other embodiments, the pH of the acid medium is between 1 and 4. h further embodiments, the pH of the acidic medium is between 1 and 2. In still further embodiments, the pH of the acidic medium is between 2 and 4. In a preferred embodiment, the pH of the acidic medium is between 1.5 and 2.5.
  • the first sample is incubated in an acidic medium that inhibits the growth of the competitive microbes when they are later incubated in a growth medium. In some embodiments, the first sample is incubated in the acidic medium for a time period between 0.5 and 10 hours. In other embodiments, the first sample is incubated in the acidic medium for a time period between 1 and 6 hours. In further embodiments, the first sample is incubated in the acidic medium for a time period between 1 and 4 hours. In still further embodiments, the first sample is incubated in the acidic medium for a time period between 1 and 2 hours, many embodiments, the first sample is incubated in the acidic medium for a time period between 1.5 and 3 hours.
  • the microbes are incubated in an acid medium for a period of time that causes death of the competitive microbes.
  • the first sample is incubated in the acidic medium for a time period between 0.5 and 10 hours.
  • the first sample is incubated in the acidic medium for a time period between 1 and 6 hours.
  • the first sample is incubated in the acidic medium for a time period between 1 and 4 hours.
  • the first sample is incubated in the acidic medium for a time period between 1 and 2 hours.
  • the first sample is incubated in the acidic medium for a time period between 1.5 and 3 hours.
  • the first sample is incubated in an acidic medium that inhibits the growth of the competitive microbes when they are later incubated in a growth medium.
  • the temperature is within the range of about 45°C to about 70°C. i other embodiments, the temperature is within the range of about 35°C to about 45°C. In further embodiments, the temperature is within the range of about 25°C to about 35°C. In still further preferred embodiments, the temperature is within the range of about 5°C to about 20°C. In many embodiments, the temperature is within the range of about 20°C to about 25°C.
  • the microbes are incubated in an acidic medium at a temperature that causes death of the competitive microbes.
  • the temperature is within the range of about 45°C to about 70°C.
  • the temperature is within the range of about 35°C to about 45°C.
  • the temperature is within the range of about 25°C to about 35°C.
  • the temperature is within the range of about 5°C to about 20°C. In many embodiments, the temperature is within the range of about 20°C to about 25°C.
  • the microbes are incubated in an acidic medium at a temperature, pH, and for a length of time that inhibits the growth of the competitive microbes when they are later incubated in a growth medium, i one embodiment, the temperature is within the range of about 5°C to about 35°C, the time is within a range of about 1 hour to about 3 hours, and the pH is between about 1.5 and about 3. In another embodiment, the temperature is within the range of about 20°C to about 25°C, the time is within a range of about 1 hour to about 3 hours, and the pH is between about 1.5 and about 2.5. In further embodiments, the temperature is about 22°C, the time about 2 hours, and the pH is about 2.0.
  • the microbes are incubated in an acidic medium at a temperature, pH, and for a length of time that causes death of the competitive microbes when they are later incubated in a growth medium, hi one embodiment, the temperature is within the range of about 5°C to about 35°C, the time is within a range of about 1 hour to about 3 hours, and the pH is between about 1.5 and about 3. hi another embodiment, the temperature is within the range of about 20°C to about 25°C, the time is within a range of about 1 hour to about 3 hours, and the pH is between about 1.5 and about 2.5. In further embodiments, the temperature is about 22°C, the time about 2 hours, and the pH is about 2.0.
  • the acidic medium includes a selective agent.
  • the selective agent is a phage or virus that infects the competitive microbes, h further embodiments, the selective agent is an antibiotic. In still further embodiments, the selective agent is more than one antibiotic. In other embodiments, the selective agent is a nutritional supplement. Examples of non-antibiotic selective agents include organic or inorganic chemicals such as tellurite, selenite, sorbitol, and the like.
  • the acidic medium does not include a selective agent.
  • the growth medium used after selection with the acidic medium includes a selective agent, h some embodiments, the selective agent is a phage or virus that infects the competitive microbes.
  • the selective agent is an antibiotic, h still further embodiments, the selective agent is more than one antibiotic. In other embodiments, the selective agent is a nutritional supplement.
  • non-antibiotic selective agents include organic or inorganic chemicals such as tellurite, selenite, sorbitol, and the like, i another embodiment, the growth medium does not include a selective agent.
  • the acidic medium and the growth medium each include a selective agent.
  • the selective agent is a phage or virus that infects the competitive microbes, h further embodiments, the selective agent is an antibiotic, hi still further embodiments, the selective agent is more than one antibiotic. In other embodiments, the selective agent is a nutritional supplement.
  • non-antibiotic selective agents include organic or inorganic chemicals such as tellurite, selenite, sorbitol, and the like.
  • the acidic medium includes a selective agent and the growth medium does not include a selective agent.
  • the selective agent is a phage or virus that infects the competitive microbes.
  • the selective agent is an antibiotic, h still further embodiments, the selective agent is more than one antibiotic, hi other embodiments, the selective agent is a nutritional supplement.
  • non-antibiotic selective agents include organic or inorganic chemicals such as tellurite, selenite, sorbitol, and the like.
  • the acidic medium does not include a selective agent and the growth medium includes a selective agent.
  • the selective agent is a phage or virus that infects the competitive microbes, hi further embodiments, the selective agent is an antibiotic. In still further embodiments, the selective agent is more than one antibiotic, i other embodiments, the selective agent is a nutritional supplement.
  • non-antibiotic selective agents include organic or inorganic chemicals such as tellurite, selenite, sorbitol, and the like.
  • Kits are also provided by the invention.
  • the invention provides a kit that includes packaging material and an acidic medium.
  • the acidic medium can be a dry medium. In other embodiments, the acidic medium is in liquid form. In some embodiments, the acidic medium has, or upon re-hydration will have, an acidic pH.
  • the invention provides a kit that includes packaging material, acidic medium, and growth medium.
  • the acidic medium and the growth medium can be in dry form. In other embodiments, the acidic medium and the growth medium are in liquid form, hi some embodiments, the acidic medium has, or upon re-hydration will have, an acidic pH.
  • the invention provides a kit that includes packaging material, media, and a pH modifier that can be added to the media to make the media into an acidic medium.
  • the media can be in dry form. In other embodiments, the media is in liquid form.
  • the pH modifier can be an acidic buffer. Alternatively, the pH modifier can be an organic acid, h many embodiments the pH modifier is an inorganic acid.
  • the invention provides a kit that includes packaging material, media, a first pH modifier that causes the media to become an acidic medium, and a second pH modifier that causes the acidic medium to become growth medium.
  • the media can be in dry or liquid form.
  • the first pH modifier can be an acidic buffer, an organic acid or an inorganic acid.
  • the second pH modifier can be a basic buffer, an organic base or an inorganic base.
  • the invention provides a kit that includes an acidic medium, a growth medium, and a means for detecting microbes.
  • the means for detecting microbes can be used to detect bacteria.
  • the means for detecting microbes can be used to detect pathogenic bacteria.
  • the means for detecting microbes can be used to detect Shigella.
  • the means for detecting microbes can be used to detect Escherichia coli.
  • FIG. 1 shows the comparative growth often different cultures of pathogenic enterohemorrhagic E. coli in the standard enrichment procedure (E) versus the enrichment procedure described in Example I (T).
  • the horizontal axis indicates the ten different pathogenic bacterial stains used in the assay, and the vertical axis indicates cell density (xlO 8 per milliliter of medium).
  • FIG. 2 shows the comparative growth often different cultures of pathogenic enterohemorrhagic E. coli in the standard enrichment procedure (E) versus the enrichment procedure described in Example II after the cultures were aged for 44 days (T).
  • the horizontal axis indicates the ten different pathogenic bacterial stains used in the assay, and the vertical axis indicates cell density (xlO 8 per milliliter of medium).
  • FIG. 3 provides a photograph of an agarose gel showing that PCR can be used to facilitate detection of acid enriched microbial samples but use of FDA approved enrichment procedures interferes with PCR detection.
  • Lanes 1 and 2 show that bands typical of the gad gene were generated using two versions of the inventive acid enrichment method.
  • Lane 4 shows no band was generated when enrichment was performed according to FDA accepted procedures.
  • Lanes 3 and 5 are positive controls showing the gad fragment.
  • Lanes 6 and 7 show bands typical of the stxl and stx2 fragments that were generated by PCR amplification of template nucleic acids obtained by the inventive acid enrichment method.
  • Lane 9 shows that no stx 1 or 2 band was generated when FDA enrichment was utilized.
  • Lanes 8 and 10 were positive controls showing the stxl and stx2 fragments.
  • FIG. 4 graphically illustrates that greater numbers ofE. coli O157:H7 cells are recovered by the acid enrichment procedures of the invention than by enrichment procedures commonly used by the Federal Drug Administration (FDA), United States Department of Agriculture (USD A) and Canadian regulatory agencies.
  • the acid enrichment procedure of the invention was also superior to enrichment procedures that employ Buffered Peptone Water
  • E. coli O157:H7 cells were identified by growth on TCSMAC agar. E. coli O157:H7 cells produce sorbitol negative colonies on TCSMAC.
  • FIG. 5 graphically illustrates that greater numbers of E. coli O157:H7 cells are recovered by the acid enricliment procedures of the invention than by enrichment procedures commonly used by the Federal Drug Administration (FDA), United States Department of Agriculture (USD A) and Canadian regulatory agencies.
  • the acid enrichment procedure of the invention was also superior to enrichment procedures that employ Buffered Peptone Water (BPW).
  • BPW Buffered Peptone Water
  • E. coli O157:H7 cells were identified by growth on Rainbow agar.
  • E. coli O157:H7 cells produce black colonies on Rainbow agar.
  • FIG. 6 graphically illustrates that greater numbers of E.
  • coli O157:H7 cells are recovered by the acid enricliment procedures of the invention than by enrichment procedures commonly used by the Federal Drug Administration (FDA), United States Department of Agriculture (USD A) and Canadian regulatory agencies.
  • the acid enricliment procedure of the invention was also superior to enrichment procedures that employ Buffered Peptone Water
  • E. coli O157:H7 cells were identified by growth on Rainbow agar with tellurite and novobiocin. E. coli O157:H7 cells produce black colonies on Rainbow agar plus tellurite and novobiocin.
  • microbes such as pathogenic bacteria
  • Such methods are used to monitor food and water supplies to ensure the safety of food and community drinking water. These methods are also used in clinics for diagnosis and to monitor treatment of infectious diseases.
  • Improved methods to detect microbes that decrease the time necessary to obtain results, or increase the accuracy of the results obtained, can save the lives of persons infected with such microbes.
  • Improved detection methods also allow communities to respond more rapidly to potential outbreaks of microbes that may be pathogenic.
  • Methods used to detect microbes in a sample generally include an enricliment step, where the number of microbes in a sample is increased, and a detection step, where a target microbe is actually detected.
  • the enrichment step involves increasing the number of target microbes being tested for in a sample.
  • the enrichment step may also decrease the number of competing microbes in the sample that are not target microbes. Decreasing the number of competing microbes and increasing the number of target microbes in a sample allows for more accurate detection of target microbes in a sample because the background from the competing microbes is reduced.
  • increasing the number of target microbes during the enrichment step may allow the target microbes to reach a detectable level.
  • the standard assay used by the Food and Drug Administration to detect enterohemorrhagic E. coli uses an enrichment medium that contains components to allow growth of all heterotrophic bacteria, plus a collection of three antibiotics and bile salts to inhibit competing microbes.
  • the present invention provides a method to enrich microbes present in a sample, generally allowing more rapid detection and analysis of such microbes. These microbes include pathogenic bacteria that may present a health hazard to humans and animals exposed to the pathogenic bacteria.
  • the invention involves incubating a first sample under acidic conditions to produce a second sample, and then incubating the second sample in a growth medium to produce a test sample.
  • the acidic medium is selected to allow the target microbe to multiply when incubated in the growth medium, and to cause some or all of the competing microbes to be killed or inhibited from growing when they are incubated in growth medium.
  • this method allows the number of competing microbes to be reduced and the number of target microbes to be enriched in a test sample.
  • This test sample is then used in the detection step to determine if the starting sample contained a target microbe, such as a pathogenic bacterium.
  • An unexpected discovery of the inventive method is that competitive or non-pathogenic microbes may be selected against by incubation in an acidic medium in the absence of additional selective agents, such as antibiotics. Also, target microbes such as pathogenic bacteria, may be positively selected by incubation in an acidic medium. This feature of the inventive method allows the target bacteria to be enriched by incubation in the growth medium in the absence of commonly used antibiotics or other selective agents. In some instances, use of the inventive method allows a target microbe to replicate at a more rapid rate than previously employed enrichment methods because the target microbe is not required to overcome negative selection resulting from the presence of a selective agent.
  • the present invention can offer many advantages over currently available methods for microbe enrichment that include, increased growth rate of a target microbe due to the absence of a selective agent, reduced interference from a selective agent during detection of a target microbe, increased ease of use due to the absence of a selective agent, and decreased expense due to the absence of a selective agent.
  • selective agents may be included in the acidic medium or the growth medium to provide additional selection in addition to acidic pH.
  • EHEC enterohemorrhagic E. coli
  • EPEC enteropatho genie E. coli
  • ETEC enterotoxigenic E. coli
  • ELISA enzyme linked immunosorbant assay
  • Escherichia coli E. coli
  • PCR polymerase chain reaction
  • TTB tryptone soy broth
  • antibiotic media refers to a medium or media having a pH less than 7.0.
  • antibiotic refers to a chemical that kills or inhibits the growth of a microbe that is not resistant to the antibiotic.
  • antibiotics include, but are not limited to, ampicillin, streptomycin, rifampicin, tetracycline, and the like. Numerous antibiotics are known in the art. Merck Index, 13 th edition, Merck & Co., Whitehouse Station, NJ. 2001.
  • basic media or “basic medium” refers to a medium or media having a pH greater than 7.0.
  • bodily sample refers to a sample obtained from an organism. Examples of bodily samples include, but are not limited to, blood, urine, saliva, tears, skin, mucus, bodily secretions, and bodily swabs.
  • competitor microbe refers to microbe that is selected against in a sample through incubation in an acidic medium followed by incubation in a growth medium, i one example, the competitor microbe may be a non-enterohemorrhagic E. coli contained within a sample that is being tested for a target enterohemorrhagic E. coli.
  • environmental sample refers generally to a specimen that is to be tested to determine whether the specimen contains a target microbe.
  • environmental samples include water, food, meat, swabs from instruments or rooms being tested for microbial contamination, soil, fecal matter, cattle feed, plants, animal products, and the like.
  • growth inhibit or “growth inhibited” describes a characteristic of a competitor microbe that is induced by incubating the competitor microbe in an acidic medium, and that causes growth of the competitor microbe to be eliminated or decreased during later incubation in a growth medium.
  • growth media or “growth medium” refers to a medium or media that is selected to promote replication of a microbe. Such a medium may be selected based in the needs of a particular target microbe. Many types of media are well known in the art that allow survival and replication of microbes. Sambrook et al, Molecular Cloning: A Laboratory Manual, 3rd edition, Cold Spring Harbor Press, Cold Spring Harbor, N.Y. (2001).
  • media refers to a support for microbial growth.
  • media include, but are not limited to, nutrient broths, agars, and powdered components that can be used to form nutrient broths and agars.
  • Media may be in liquid form, semi-solid form, or in dry form.
  • Many types of media are known in the art and include, but are not limited to, GYT medium, LB medium, M9 minimal medium, NZCYM medium, NZYM medium, SOB medium, SOC medium, TB medium, TSB medium, 2x YT medium, and agar plates.
  • microbe refers to a biological entity that is able to replicate in a medium.
  • examples of microbes include, but are not limited to, bacteria, mold, fungus, and nematodes.
  • the present invention may be used to selectively enrich a sample for numerous types of target microbes in a sample by incubating the sample in an acidic medium and then in a growth medium to enrich the target microbe in the sample.
  • the conditions required to determine the specific conditions to achieve enrichment of a specific target microbe can readily be determined by one of skill in the art.
  • negative selective agent refers to a chemical or biological agent that inhibits the growth of one microbe over another.
  • neutral media or “neutral medium” refers to a medium or media having pH 7.0.
  • pH modifying agent includes a compound that causes an increase or decrease in the pH of a medium.
  • a pH modifying agent can be an organic acid or base.
  • a pH modifying agent can also be an inorganic acid or base.
  • a pH modifying agent can be a buffer that acts to increase or decrease the pH of a medium to which it is added.
  • buffers include, but are not limited to, acetete buffer, bicine buffer, borate buffer, citrate buffer, phosphate buffer, cysteine buffer, glycine buffer, HEPES buffer, maleate buffer, carbonate buffer, diethanolamine buffer, sulfate buffer, sulfite buffer and the like.
  • buffers are well known in the art and are described.
  • Examples of acids include, but are not limited to, sulfuric, nitric, hydrochloric, formic, phosphoric, and acetic.
  • Examples of bases include, but are not limited to, ammonia, sodium hydroxide, and potassium hydroxide.
  • positive selective agent refers to a chemical or biological agent that promotes the growth of one microbe over another.
  • selective agent refers to a chemical or biological agent other than pH that selectively alters the growth of one microbe over another.
  • selective agents include, but are not limited to, antibiotics, phages, viruses, and nutrients.
  • selective enrichment refers to the process of causing the relative population of a select microbe in a sample to increase relative to the population of competitor (non-target) microbes in the sample.
  • a low relative population of a target microbe may be initially present in a sample when compared to other microbes present in the sample.
  • a target microbe in the sample may be selectively enriched by incubating the sample under conditions in which a competitor (non-target) microbe in the sample is killed or growth inhibited, and then be incubated under conditions where the target microbe multiplies at a higher rate than a competitor (non-target) microbe in the sample. This process will selectively emich the sample for a target microbe by increasing the relative population of the target microbe relative to the competitor microbe.
  • target microbe refers to a microbe that is selectively enriched in a sample tlirough incubation in an acidic medium followed by incubation in a growth medium.
  • the target microbe may be an enterohemorrhagic E. coli (EHEC), enteropatho genie E. coli (EPEC), or enterotoxigenic E. coli (ETEC).
  • EHEC enterohemorrhagic E. coli
  • EPEC enteropatho genie E. coli
  • ETEC enterotoxigenic E. coli
  • the methods of the present invention involve incubating a first sample containing a competitor microbe and a target microbe in an acidic medium to produce an enriched sample.
  • the methods of the invention can also include, incubating the second sample in a growth medium to produce a test sample that is enriched for the target microbe.
  • inventive method may be used to enrich for numerous types of microbes and that enterohemorrhagic E. coli are used as an example to illustrate the invention, but not to limit the invention.
  • the methods and kits of the invention can be used to enrich aerobic and anaerobic microbes, such as bacteria.
  • the acidic medium may be a microbial medium that can be acidified to provide a selective growth advantage to a target microbe as compared to a competitor microbe.
  • microbial medium that can be acidified to provide a selective growth advantage to a target microbe as compared to a competitor microbe.
  • GYT medium LB medium
  • M9 minimal medium NZCYM medium, NZYM medium, SOB medium, SOC medium
  • TB medium 2x YT medium, BHI, and TSB.
  • An acidic medium may be selected to enrich a target microbe that is not a bacterium by determining the medium commonly used to grow the target microbe and
  • the medium may be acidified through addition of numerous types of acids that include, but are not limited to, acetic acid, lactic acid, formic acid, hydrochloric acid, hydrofluoric acid, sulfuric acid, and phosphoric acid. Many types of organic and inorganic acids may be used to formulate the acidic media of the invention. Merck Index, 13 th edition, Merck & Co., Whitehouse Station, NJ. 2001.
  • the pH of the acidic medium maybe adjusted such that a selective advantage is conferred to the target microbe.
  • a suitable pH may be determined for a given microbe by incubating the microbe in acidic media having differing pH, followed by incubation in growth media.
  • the sample produced may be tested to determine conditions under which the population of a target microbe is increased relative to competitor microbes in the original sample.
  • suitable pH ranges include those from about pH 1.5 to about 6, and single unit integers and fractions thereof.
  • Other factors may be taken into account when selecting a suitable pH for the acidic medium. Such factors include, but are not limited to, the microbe being enriched, the time of incubation in the acidic medium, the temperature of incubation, the pressure under which incubation occurs, and the type of medium being used.
  • the amount of time that a sample is incubated in an acidic medium will depend on factors that include, but are not limited to, the pH of the acidic medium, the temperature of incubation, the target microbe being selectively enriched, competitor microbes present in the sample, and the type of medium that is used.
  • Those of skill in the art can determine a time suitable for incubation of a sample containing a target microbe and competitor microbes in an acidic medium by determining the time that will kill or growth inhibit the competitor microbes while allowing the target microbe to replicate in a growth medium. Exemplary times include those from about one-half of an hour to about ten hours, and single unit increments and fractions thereof.
  • a sample can be enriched for E.
  • Such media include, but are not limited to, GYT medium, LB medium, M9 minimal medium, NZCYM medium, NZYM medium, SOB medium, SOC medium, TB medium, 2x YT medium, BHI, and TSB.
  • GYT medium GYT medium
  • LB medium M9 minimal medium
  • NZCYM medium NZYM medium
  • SOB medium SOC medium
  • TB medium 2x YT medium
  • BHI BHI
  • TSB TSB.
  • Growth media may be selected to enrich a target microbe according to the invention that is not a bacterium by determining the media commonly used to replicate the target microbe.
  • the growth media may be different than the acidic media used pursuant to the practice of the invention.
  • the sample and acidic medium may be combined with the growth medium such that the target microbe replicates in the growth medium.
  • the pH of the acidic medium may be adjusted to produce growth medium. This modification may be achieved by adding a pH modifier to the acidic medium.
  • the temperature at which a sample containing target and competitor microbes is incubated will depend on the identity of the target microbe that is being enriched as well as the properties of the incubation medium. Generally, a target microbe may be incubated in an acidic medium at a temperature that is readily determined on one of skill in the art.
  • a target microbe may be incubated in growth medium at a temperature that mimics the temperature that the target microbe is normally found in nature.
  • a sample containing a target microbe that is an enteric bacterium found in association with a mammal may be independently incubated in an acidic medium at a suitable temperature that is dependant on the identity of the bacterium and the pH of the acidic medium, and in a growth medium at about 20 to 22 °C.
  • suitable temperature that is dependant on the identity of the bacterium and the pH of the acidic medium
  • examples of such microbes include, but are not limited to, E. coli, Shigella, and Listeria.
  • a microbe may be incubated at a temperature that is about 37°C or higher.
  • Such a higher temperature may be in a range from about 38°C to about 100°C.
  • therrnophilic microbes have been isolated from hot springs and deep-sea vents where the temperatures approach 100°C.
  • a sample may be incubated at temperatures that range below 37°C, such as about 4°C to about 36°C.
  • Such lowered incubation temperatures may be suitable for enhancing microbes isolated from cold environments, such as arctic waters.
  • Incubation of a sample in an acidic medium or a growth medium may be conducted independently under aerobic or anaerobic conditions.
  • the methods and kits of the invention may be used to enhance or enrich a sample with a target microbe that grows under aerobic and anaerobic conditions.
  • a sample may be incubated in an acidic medium or a growth medium under ambient pressure, or under increased or decreased pressure.
  • Such methods may be particularly useful for enriching microbes that are normally found in environments of high pressure, such as those that are found deep in the ocean.
  • Selective agents may optionally be included in the acidic medium, the growth medium or both. Such selective agents include, but are not limited to, antibiotics, phages, viruses, and nutrients.
  • the methods of the invention may be automated. For example, a first sample can be collected and placed into an acidic medium by a robotic arm. The first sample can be incubated in the acidic medium to produce a second sample. A robotic arm can then be used to transfer all or a portion of the second sample into a growth medium where the second sample can be incubated to enrich a microbe contained therein. All or a portion of the second sample may be transferred to a detector or another vessel where a microbe contained in the second sample can be detected.
  • a first sample may be incubated in an acidic medium to produce a second sample.
  • the pH of the acidic medium can then be increased to produce a growth medium in which a microbe is enriched.
  • An instrument such as an automatic titrator, can be used to raise the pH of the acidic medium. This may be done by positioning the instrument such that the instrument can input a pH modifying agent into the acidic medium to produce a growth medium.
  • the growth medium can then be incubated to enrich any target microbes contained therein.
  • Instruments that can be used to alter the pH of media are commercially available. Analyticon Instruments Corp., Springfield, NJ; PAM Solutions LTD, Helsinki, Finland; Thermo Automation Systems, Beverly, MA.
  • a variety of fermentors may also be used within the methods of the invention to enrich a target microbe.
  • Such fermentors may be programmed to incubate a first sample at an acidic pH to produce a second sample, and then adjust the pH of the medium to produce a growth medium for enrichment of a microbe contained therein.
  • Fermentors are commercially available. New Brunswick Scientific, Edison, NJ. Automated methods are very useful for samples suspected of containing highly pathogenic microbes. Such methods may also be used for high-throughput screening of samples. Kits
  • kits that may be used to enrich a target microbe in a sample.
  • the invention also provides kits that may be used to enrich and detect a target microbe in a sample.
  • a kit of the invention may include packaging material that contains an acidic medium or media in dry form.
  • the acidic medium or media may be sterile or non-sterile.
  • the packaging may or may not be capable of being sterilized. Examples of sterilization methods that may be used include, but are not limited to, baking, autoclaving, and irradiation.
  • the packing material can be constructed to allow fluid to be combined with the dry acidic medium or media in the packaging material.
  • the packaging material is a container containing the dried acidic medium into which fluid may be added to form a liquid medium.
  • the packaging material containing the liquid medium may be sterilized, inoculated with a sample, and incubated.
  • the packing material containing the acidic medium may be sterilized prior to addition of sterile fluid to provide a container that may be inoculated with a sample and incubated.
  • the invention provides a kit that includes packaging material and sterile acidic media or medium in liquid form.
  • the sterile acidic media or medium may be transferred to another container, inoculated with a sample, and incubated.
  • the sterile acidic medium in the packaging material may be inoculated and incubated.
  • a kit of the invention may include packaging material that contains individual packages of acidic media and growth media in dried form.
  • the individual packages containing acidic and growth media may or may not be sterile.
  • the dried acidic and growth media may be combined with fluid in a separate container, or combined with fluid in the packaging material to form liquid media.
  • the packaging material may or may not be able to be sterilized.
  • Packaging material containing liquid media may optionally be inoculated with a sample and incubated.
  • a kit of the invention may include an acidic medium or a growth medium, and one or more pH modifiers.
  • An example of a pH modifier included in the kit may be a basic pH modifier, such as sodium hydroxide, or an acidic pH modifier, such as hydrochloric acid.
  • the acidic medium may be made into a growth medium by addition of a basic pH modifier.
  • the invention provides a kit having packaging material that includes a liquid or a dry medium or media, an acidic pH modifier, and a basic pH modifier.
  • An example of such a kit includes packaging material containing a liquid medium that has been sterilized, a sterile acidic pH modifier, and a sterile basic pH modifier.
  • the acidic pH modifier may be combined with the liquid medium to form acidic medium which is inoculated with a sample and incubated.
  • the basic pH modifier is then added to the incubated acidic medium to form growth medium which is then incubated to enrich a target microbe present in the sample.
  • the kit includes packaging material that contains a sterile liquid acidic medium having a pH of about 2, and a sterile liquid growth medium that has a pH of about 7 after addition of the acidic medium contained within the kit.
  • a kit of the invention may include packaging material that contains an acidic medium, a growth medium, and a means for detecting a target microbe.
  • the acidic medium and the growth medium may optionally be dry or fluid.
  • the acidic medium and the growth medium may be optionally sterile if in dry form.
  • the acidic medium and the growth medium may be packaged in sterile fluid form.
  • Numerous types of detection means may be included in the kit. Examples of such detection methods are described herein and are available to those of skill in the art. These detection methods include, but are not limited to, indicator media, immunological based methods, and nucleic acid detection and amplification assays. Detection Methods (
  • the methods of the invention may be used in combination with numerous detection methods. These detection methods can be tailored to detect the presence of a broad class of microbes in a sample, or used to detect specific microbes in a sample.
  • An advantage of the methods of the present invention is that a microbe may be selected and enriched in the absence of selective agents other than decreased pH. Therefore, the present invention may be used to avoid interference by a selective agent during the detection phase of an assay used to determine the presence of a microbe in a sample.
  • Enzyme linked immunosorbant assays are commonly used to detect microbes in a sample. Such assays generally involve immobilizing a microbe to a solid support and then adding an antibody that is conjugated with an enzyme to the immobilized microbe. The conjugated antibody binds to an antigen on the microbe to form a complex. A substrate is then contacted with the complex such that the enzyme that is conjugated to the antibody converts the substrate into a detectable product. Many such assays are available and known in the art. For example, an ELISA based assay has been used to detect E. coli Ol 57:H7 in raw meat and in stool samples. Johnson et al., Appl. Envir.
  • ELISA based assays have also been used to detect Shigella like toxin- 1 and Shigella like toxin-2 in stool samples. Yamada et al., Microbiol. Immunol., 37:111 (1993). Those of skill in the art will realize that numerous ELISA based assays may be used in combination with the methods and kits of the invention to detect a plethora of microbes in a large variety of samples.
  • Some anti-0157 antibodies have also been coupled to magnetic beads and used to selectively isolate this pathogen from foods or have been incorporated into enzyme immunoassays to directly detect serotype O157:H7 in foods and clinical specimens. Wright et al., Epidemiol. Infect., 113:31 (1994). Nucleic acid amplification can also be used to detect the presence of a target microbe in a sample. Any such amplification procedure can be used, for example, polymerase chain reaction (PCR) assays, strand displacement amplification and other amplification procedures. Strand displacement amplification can be used as described in Walker et al (1992) Nucl. Acids Res. 20, 1691-1696.
  • PCR polymerase chain reaction
  • PCR polymerase chain reaction
  • the steps involve in PCR nucleic acid amplification method are described in more detail below.
  • the nucleic acid to be amplified is described as being double-stranded.
  • the process is equally useful for amplifying a single-stranded nucleic acid, such as an mRNA, although the ultimate product is generally double-stranded DNA.
  • the first step involves the synthesis of a complementary strand so that two complementary target strands are available for amplification.
  • two primers are employed, each primer hybridizing to a different nucleic acid strand at opposite ends of the nucleic acid site to be amplified.
  • the PCR process for amplifying a target nucleic acid consists of introducing a large excess of the two primers to a mixture that may contain a template nucleic acid from a target microbe, followed by a precise sequence of thermal cycling in the presence of a nucleic acid polymerase.
  • each of the two primers is complementary to a distinct region in one of the two strands of the double stranded target sequence.
  • Primers are selected so that they hybridize just outside the region of interest to be amplified and so that, upon primer extension, one primer will be extended towards the hybridization site of a second primer hybridized on the opposite target strand.
  • PCR polymerase chain reaction
  • E. coli O157:H7 has been detected through use of a methylumbelliferyl glucuronide assay that measures glucuronidase activity. Feng et al., Appl. Environ. Microbiol., 43:1320 (1982). Based on the inability of E.
  • E. coli O157:H7 to ferment sorbitol, a number of selective and differential plating media have been developed that indicate the presence of E. coli O157:H7.
  • sorbitol MacConkey agar SMAC; Difco Laboratories
  • SMAC Difco Laboratories
  • E. coli O157:H7 produce near colorless colonies when grown on sorbitol MacConkey agar because they are unable to ferment sorbital, whereas other bacteria that are able to ferment sorbitol produce red colonies.
  • the color changes are not strongly differentiable. Sometimes the red color produced by other bacteria can cover the nearly colorless E. coli O157:H7 colonies, so they can be missed.
  • E. coli produced a yellow color in this greenish blue medium
  • E. coli O157:H7 produced a green color.
  • Another medium was developed that for differentiation between E. coli and E. coli O157:H7. This medium was prepared by comparing several combinations of dyes that can be used to differentiate E. coli from E. coli O157:H7. Some studies indicate that indigo carmine and phenol red are a good combination. These dyes were added to basal agar (SMAC medium excluding neutral red and crystal violet) to produce ⁇ OH medium. On the dark blue ⁇ OH medium, E.
  • SMAC medium basal agar
  • enteric bacteria such as E. hermanii and Hafnia spp.
  • enteric bacteria share similar phenotypes and resemble serotype O157:H7 on sorbitol-containing medium.
  • non-H7 serotype strains of 0157 that are not pathogenic but do not ferment sorbitol have occasionally been isolated from foods. Willshaw et al., J. Appl. Bacteriol., 75:420 (1993). Because of the presence of phenotypically similar species, sorbitol negative isolates should be serologically confirmed with 0157 and H7 antisera.
  • kits of the invention may be used in combination with numerous methods to detect the presence of microbes in many different types of samples.
  • samples include, but are not limited to: environmental samples such as water; foods such as meats, vegetables, fruits, and the like; and bodily samples obtained from the bodies of animals and humans, such as blood, urine, stool, skin, mucus, saliva, tears, and the like.
  • EXAMPLE I Enrichment of enterohemorragic E. coli using standard FDA methods compared to enrichment using methods of the invention with fresh bacterial cultures.
  • samples containing enterohemorragic E. coli were enriched according to one of the methods of the invention.
  • a first sample containing an enterohemorragic E. coli O157:H7 culture, or one of the other nine competitor bacterial cultures were individually added to containers having an acidic medium (pH 2.0) and incubated at 22°C for two hours to produce second samples of each.
  • the components of the acidic medium included Tryptic Soy Broth (TSB, Difco) that was adjusted to pH 2.0.
  • TTB Tryptic Soy Broth
  • each second sample was transferred to a growth medium containing TSB that was adjusted to near neutral pH and incubated at 35°C for 24 hours to produce a test sample.
  • the number of bacteria of each type in the test sample prepared by the standard FDA method and the method of the invention are provided in Tables 1-3. The results indicate that the method of the invention gives better suppression of competitor bacteria than the standard FDA method.
  • Tables 2 and 3 show the number of enterohemorragic E. coli that were present in one milliliter of media following enrichment using one of the methods of the invention (Table 2) and the standard enrichment method used by FDA (Table 3). The results indicate that the methods of the invention enrich enterohemorragic E. coli to higher levels than standard methods currently used by FDA by factors ranging from about 1.6-fold to about 4.3-fold.
  • a sample containing enterohemorragic E. coli was enriched through use of the standard FDA method according to the protocol described in Example I.
  • Another sample containing enterohemorragic E. coli was enriched according to one of the methods of the invention.
  • a first sample containing individual age-stressed enterohemorragic E. coli O157:H7 cultures or nine age-stressed competitor bacterial cultures were individually added to an acidic medium (pH 2.0) and incubated at 22°C for two hours to produce second samples.
  • the components of the acidic medium included TSB adjusted to pH 2.0.
  • the second sample was transferred to non- inhibitory growth medium containing TSB at near neutral pH and incubated at 35°C for 24 hours to produce a test sample.
  • the populations of each of the enterohemorrhagic E. coli and each of the competing bacteria in the test sample was determined as described in Example I.
  • the number of bacteria of each type in the test sample prepared by the standard FDA method and the method of the invention are indicated below.
  • the results indicate that the method of the invention gives better suppression of competitor bacteria than the standard FDA method.
  • Another aspect of the method of the invention is that it provided better results with the age-stressed bacterial culture than with the fresh bacterial culture. This is thought to more closely reflect conditions occurring with a clinical, food, or water sample obtained for testing and analysis.
  • Tables 5 and 6 show the number of enterohemorragic E. coli that were present in one milliliter of medium following enrichment using one of the methods of the invention (Table 5) and the standard enrichment method used by FDA (Table 6). The results indicate that the methods of the invention enrich enterohemorragic E. coli to higher levels than standard methods currently used by FDA by factors ranging from about 2.6-fold to about 5.6-fold.
  • Example III Acid-Selection Treatment.
  • the species used were Salmonella gaminara, Shigella flexneri, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Listeria monocytogenes, nonpathogenic E. coli (EC6268), enterohemorrhagic E. coli (EC6264), Citrobacter freundii, Hafnia alvei, Morganella morganii, Enterobacter aerogenes, and Serratia marcescens.
  • EXAMPLE IV Growth of cells exposed to TSB (pH 2.0) at room temperature
  • TSB noninhibitory growth medium
  • the species used were Citrobacter freundii, Hafnia alvei, Shigella flexneri, Enterobacter aerogenes, Klebsiella pneumoniae, EC6347, EC6396, EC6424 and EC6268.
  • the EC6347, EC6396 and EC6424 strains are all pathogenic strains of E. coli, but EC6268 is a nonpatho genie strain of E. coli.
  • TSB noninhibitory growth medium
  • the species used were Citrobacter freundii, Hafnia alvei, EC6396, EC6424 and EC6268.
  • the EC6396 and EC6424 strains are pathogenic E. coli.
  • EC6268 is non-pathogenic; and Shigella flexneri. Note, the initial cell counts for Shigella flexneri were lower than expected. Thus, the negative growth of Shigella at 5°C and 22°C (#1) may have been due to absence of cells.
  • This Example illustrates another way in which the new acid enrichment method is superior to the current FDA accepted methods for potential rapid detection of E. coli O157:H7 and other enterohemorrhagic E. coli.
  • the current FDA method requires a 24 hr enrichment in enterohemorrhagic E. coli enrichment broth (EEB) as prescribed in the U.S. FDA- Bacteriological Analytical Manual (FDA-BAM), then streaking onto TCSMAC agar and incubation for another 24 hr.
  • EOB enterohemorrhagic E. coli enrichment broth
  • FDA-BAM enterohemorrhagic E. coli enrichment broth
  • TCSMAC MacConkey Sorbitol Agar with Cefixime and Tellurite
  • a sample of wastewater was obtained to provide numerous types of competing bacteria and this wastewater sample was spiked with a known culture of enterohemorrhagic E. coli.
  • the sample was acid-shocked in pH 2.00 TSB for 2 hr, then transferred to TSB at regular pH (7.4) for 24 hr of growth.
  • a similar sample of the wastewater/enterohemorrhagic E. coli was cultured in ⁇ B according to the usual FDA procedure and incubated 24 hr. At the end of the 24 hr period, one ml aliquots were withdrawn from each of the experimental and control cultures. These test aliquots were centrifuged twice to remove contaminants and boiled to provide PCR templates.
  • PCR reactions were set up using primers for three genes characteristic of the presence of enterohemorrhagic E. coli — glutamate decarboxylase (gad), shiga-like toxin 1 (stxl) and shiga-like toxin 2 (stx2).
  • PCR procedures were performed as described in Grant et al. (2001) Applied and Environmental Microbiology 67: 3110-14. The resulting amplicons were run on a 1.5 % agarose gel and visualized with ethidium bromide.
  • Lanes 1 and 2 show that bands typical of the gad gene that is a marker for enterohemorrhagic E. coli were generated using two versions of the inventive acid enrichment method.
  • Lane 4 shows no band for the gad gene - the template for this amplification reaction was generated from FDA accepted enrichment procedures.
  • Lanes 3 and 5 are positive controls showing that the gad fragment is generated under the PCR conditions employed when enterohemorrhagic E. coli DNA is used as template.
  • Lanes 6 and 7 show that bands typical of the stxl/2 genes were generated from samples treated by the inventive acid enrichment method.
  • Lane 9 shows that no PCR band is generated when microbial samples are enriched as specified by FDA procedures (BAM EEB).
  • Lanes 8 and 10 were positive controls showing that the gad fragment is generated under the PCR conditions employed when enterohemorrhagic E. coli DNA is used as template.
  • templates prepared from bacteria cultured using the acid enrichment methods of the invention provided nucleic acid templates that were readily amplified by PCR to generate amplicons indicative of three enterohemorrhagic E. coli template target genes.
  • something in the FDA accepted (EEB) medium interfered with PCR detection of enterohemorrhagic E. coli.
  • the methods of the invention that involve strong acid shock, followed by growth in completely non-inhibitory media such as regular pH TSB generates nothing that inhibits or interferes with PCR analysis.
  • microbiologists can effectively screen for enterohemorrhagic E. coli in only 25-26 hr using PCR, instead of waiting an additional day or more for results on selective agar as is now required under FDA accepted procedures.
  • ETEC enterotoxigenic E. coli
  • EPEC enteropathogenic E. coli
  • a sample of wastewater i.e. untreated sewage was collected to provide a wide variety of competing microorganisms.
  • This sample was spiked with E. coli O157:H7 (strain SEA 6424).
  • Aliquots were then removed from this common mixture and enriched by the acidification method of the invention and by four other methods commonly used by various governmental regulatory agencies — the current FDA method (BAM), the current USDA method, the current Canadian method and Buffered Peptone Water, a commonly used non selective medium.
  • BAM the current FDA method
  • USDA method the current USDA method
  • Canadian method the current Canadian method
  • Buffered Peptone Water a commonly used non selective medium.
  • the acidification method the aliquot sample was placed in pH 2.00 TSB for 2 hr at room temperature then transferred to TSB YE for 24 hr.
  • E. coli O157:H7-spiked wastewater was placed into modified tryptic soy broth (mTSB) with novobiocin and incubated for 24 h at 42°C. Note that the Canadian method also permits use of
  • EHEC enrichment broth (EEB), whose performance was examined as described for the FDA method below.
  • the cultures were plated onto three standard selective agars - TCSMAC, Rainbow agar and Rainbow agar plus tellurite and novobiocin. These three selective agars are the primary selective agars used world wide to see if enricliment has yielded any E. coli O157:H7 from a sample.
  • FIG. 4 provides the numbers of sorbitol negative colonies on TCSMAC plates. As shown, the acid enrichment yielded almost ten-fold more E. coli O157:H7 colonies relative to the other enricliment procedures (FIG. 4).
  • FIG. 5 provides the number of black colonies on Rainbow agar. As shown, the acid enricliment again yielded five- to ten-fold more E. coli O157:H7 colonies relative to the other enrichment procedures (FIG. 5).
  • FIG. 6 provides the number of black colonies on Rainbow agar containing tellurite and novobiocin. As shown, the acid enrichment again yielded five- to ten-fold more E.
  • a reference to "a host cell” includes a plurality (for example, a culture or population) of such host cells, and so forth.
  • the patent be interpreted to be limited to the specific examples or embodiments or methods specifically disclosed herein.
  • the patent be interpreted to be limited by any statement made by any Examiner or any other official or employee of the Patent and Trademark Office unless such statement is specifically and without qualification or reservation expressly adopted in a responsive writing by Applicants.
  • the terms and expressions that have been employed are used as terms of description and not of limitation, and there is no intent in the use of such terms and expressions to exclude any equivalent of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention as claimed.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Zoology (AREA)
  • Wood Science & Technology (AREA)
  • Proteomics, Peptides & Aminoacids (AREA)
  • Analytical Chemistry (AREA)
  • Toxicology (AREA)
  • Immunology (AREA)
  • Microbiology (AREA)
  • Molecular Biology (AREA)
  • Biophysics (AREA)
  • Physics & Mathematics (AREA)
  • Biotechnology (AREA)
  • Biochemistry (AREA)
  • Bioinformatics & Cheminformatics (AREA)
  • General Engineering & Computer Science (AREA)
  • General Health & Medical Sciences (AREA)
  • Genetics & Genomics (AREA)
  • Measuring Or Testing Involving Enzymes Or Micro-Organisms (AREA)
  • Medicines Containing Material From Animals Or Micro-Organisms (AREA)

Abstract

Cette invention se rapporte à des procédés et à des substances servant à enrichir sélectivement des microbes cibles dans un échantillon.
PCT/US2003/040806 2002-12-20 2003-12-19 Procedes et compositions pour enrichir selectivement des microbes Ceased WO2004111180A2 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US10/539,765 US20060141603A1 (en) 2003-12-19 2003-12-19 Methods and compositions for selectively enriching microbes
AU2003304215A AU2003304215A1 (en) 2002-12-20 2003-12-19 Methods and compositions for selectively enriching microbes

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US43563902P 2002-12-20 2002-12-20
US60/435,639 2002-12-20

Publications (2)

Publication Number Publication Date
WO2004111180A2 true WO2004111180A2 (fr) 2004-12-23
WO2004111180A3 WO2004111180A3 (fr) 2005-04-28

Family

ID=33551220

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2003/040806 Ceased WO2004111180A2 (fr) 2002-12-20 2003-12-19 Procedes et compositions pour enrichir selectivement des microbes

Country Status (2)

Country Link
AU (1) AU2003304215A1 (fr)
WO (1) WO2004111180A2 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007124591A1 (fr) * 2006-05-03 2007-11-08 University Of Manitoba Marqueurs microbiens de colopathie fonctionnelle

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996040861A1 (fr) * 1995-06-07 1996-12-19 Biolog, Inc. Milieux de cultures microbiologiques permettant d'isoler et d'identifier des pathogenes enteriques, tels que e. coli et salmonella
DE69939745D1 (de) * 1998-08-14 2008-11-27 Biocontrol Systems Inc Zusammensetzung und verfahren zur freilegung antigener epitope auf gezüchteten mikroorganismen

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007124591A1 (fr) * 2006-05-03 2007-11-08 University Of Manitoba Marqueurs microbiens de colopathie fonctionnelle

Also Published As

Publication number Publication date
AU2003304215A1 (en) 2005-01-04
WO2004111180A3 (fr) 2005-04-28
AU2003304215A8 (en) 2005-01-04

Similar Documents

Publication Publication Date Title
Warren et al. Shigella as a foodborne pathogen and current methods for detection in food
Munshi et al. Detection of virulence potential of diarrhoeagenic Escherichia coli isolated from surface water of rivers surrounding dhaka city
Almeida et al. Detection of Escherichia coli O157 by peptide nucleic acid fluorescence in situ hybridization (PNA-FISH) and comparison to a standard culture method
Simpson et al. Rapid PCR confirmation of E. coli O157: H7 after evanescent wave fiber optic biosensor detection
Chen et al. Detection of verotoxigenic Escherichia coli by magnetic capture-hybridization PCR
Igere et al. Non-serogroup O1/O139 agglutinable Vibrio cholerae: a phylogenetically and genealogically neglected yet emerging potential pathogen of clinical relevance
Gould et al. Update: recommendations for diagnosis of Shiga toxin-producing Escherichia coli infections by clinical laboratories
CN114214443B (zh) 可同时检测多种微生物的多重荧光定量pcr检测方法和多重荧光定量pcr检测试剂盒
WO2014049938A1 (fr) Milieu de culture pour bactéries responsables d'intoxications alimentaires, et méthode de détection de bactéries responsables d'intoxications alimentaires
Beneduce et al. Escherichia coli 0157: H7 general characteristics, isolation and identification techniques
Wang Nucleic acid-based rapid methods for the detection of foodborne pathogens
Zhao et al. Multiple factors trigger the formation and resuscitation of the VBNC state in alcohol-producing Klebsiella pneumoniae
KR100376916B1 (ko) 소화기 감염균들의 검출 방법 및 검출 키트
Özdemir et al. Molecular Characterization and biofilm formation of Escherichia coli from vegetables
Stewart et al. Comparison of assurance gold Salmonella EIA, BAX for screening/Salmonella, and Gene-Trak Salmonella DLP rapid assays for detection of Salmonella in alfalfa sprouts and sprout irrigation water
Datta et al. Detection of Listeria monocytogenes in Food and Environment
US20060141603A1 (en) Methods and compositions for selectively enriching microbes
WO2004111180A2 (fr) Procedes et compositions pour enrichir selectivement des microbes
Notermans et al. Microbiological Contamination of Food: Analytical Aspects
Devi Paper strip based assay for the detection of Salmonella
Balakrishna et al. A novel multiplex polymerase chain reaction for simultaneous detection of Yersinia enterocolitica, Staphylococcus aureus, Aeromonas and Salmonella from chicken meat and milk samples
Arachchillaya Development and evaluation of a paper based biochemical sensor for realtime detection of food pathogen
Michiels et al. Bacteriological analysis
Liwan et al. Monitoring of pollution of Salmonella sp. In raw milk using virulence gen marker
Ameer Isolation of and characterization of E. coli O157/H7 from Common Carp Fish (Cyprinus carpio) in Baghdad governorate

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A2

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NI NO NZ OM PG PH PL PT RO RU SC SD SE SG SK SL SY TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A2

Designated state(s): BW GH GM KE LS MW MZ SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LU MC NL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
ENP Entry into the national phase

Ref document number: 2006141603

Country of ref document: US

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 10539765

Country of ref document: US

WWP Wipo information: published in national office

Ref document number: 10539765

Country of ref document: US

122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: JP

WWW Wipo information: withdrawn in national office

Country of ref document: JP