Chapter 14: Coliforms, Fecal Coliforms and Escherichia coli
Updated: 07/26/07- Potential Food Safety Hazard
- Control Measures
- Guidelines
- Growth
- Heat Resistance
- Analytical Procedures
- Food sampling and preparation of sample homogenate (USFDA)
- Definition of Terms; Collection of Samples; Supplement to all Methods in the HC Compendium (HC)
- Escherichia coli and the coliform bacteria (USFDA)
- Enumeration of coliforms in foods by the hydrophobic grid-membrane filter (HGMF) method (HC)
- Determination of coliforms, faecal coliforms and of E. coli in foods (HC)
- Enumeration of Escherichia coli in foods by the hydrophobic grid-membrane filter (HGMF) method (HC)
- Enumeration of Escherichia coli in foods by the direct plating (DP) method (HC)
- Determination of coliforms in foods using violet red bile agar (HC)
- Enumeration of E. coli and coliforms in food products and food ingredients using 3MTM PetrifilmTM E. coli plates (HC)
- Enumeration of coliforms in food products and food ingredients using 3MTM PetrifilmTM coliform count plates (HC)
- Calculation of the most probable number of growth units for HGMF methods (HC)
- Determination of Enterobacteriaceae (HC)
- Enumeration of faecal coliforms in foods by the hydrophobic grid-membrane filter (HGMF) method (HC)
- Isolation of E. coli O157 in foods (HC)
- Detection of enterohemorrhagic E. coli (EHEC) in food products and food ingredients by the Assurance EHEC enzyme immunoassay (EIA) method (HC)
- Identification of presumptive positive verocytoxigenic Escherichia coli by the polymerase chain reaction (HC)
- Detection of enterohemorrhagic E. coli (EHEC) in food products and food ingredients by the VIP for EHEC method (HC)
- Procedure for the detection of verocytotoxin-producing Escherichia coli in food samples (HC)
- Identification of E. coli O157 by DynaBeadsTM anti-E. coli O157 (HC)
- Detection of E. coli O157 by the TecraTM E. coli O157 visual immunoassay (VIA) method (HC)
- Identification of Escherichia coli verotoxins by the Meridian Premier EHEC KitTM (HC)
- The 20 hour Reveal method for detecting Escherichia coli O157:H7 from foods and environmental samples. (HC)
- Enumeration of coliforms in foods and environmental samples using 3MTM PetrifilmTM high sensitivity coliform count (HSCC) plates (HC)
- Other analytical procedures
- Commercial Test Products
- References
| Potential Food Safety Hazard | Contents |
| Coliforms | Contents |
The coliform group includes species from the genera Escherichia, Klebsiella, Enterobacter, and Citrobacter, and includes E. coli. Coliforms were historically used as indicator microorganisms to serve as a measure of fecal contamination, and thus potentially, of the presence of enteric pathogens in fresh water. Although some coliforms are found in the intestinal tract of man, most are found throughout the environment and have little sanitary significance (Greenberg and Hunt, 1985).
The presence of large numbers of coliforms in foods is highly undesirable, but it would be almost impossible to eliminate all forms (Jay, 1978). Because they are easily killed by heat, coliform counts can be useful when testing for post-processing contamination of cooked fish and fishery products.
| Fecal coliforms | Contents |
| E. coli | Contents |
Some E. coli strains may be only weakly lactose-positive (delayed lactose fermentation) or even lactose-negative (APHA, 1970; Ewing, 1986).
Enterovirulent E. coli (EEC) strains include several major subgroups:
Enterohemorrhagic E. coli (EHEC) causes hemorrhagic colitis and hemolytic uremic syndrome. Six verotoxins have been identified within this group, but only stx-1 and stx-2 seem to be important in human infections. E. coli O157:H7 is the principle serotype of this group (Reed, 1994).
Enteroinvasive E. coli (EIEC) causes a diarrheal illness similar to shigellosis (Reed, 1994).
Enterotoxigenic E. coli (ETEC) is a major cause of travelers' diarrhea and infant diarrhea in developing countries. These strains product a heat-labile toxin (LT) and/or a heat-stable toxin (ST) (Reed, 1994).
Enteropathogenic E. coli (EPEC) is an important cause of infant diarrhea (Reed, 1994).
Enteroadherent E. coli (EAEC) is a newly added category and not fully characterized (Hitchins et al., 1998).
Some properties of enterovirulent E. coli (EEC) subgroups are presented in the table below (Hitchins et al., 1998). For a full discussion, consult one of the recent reviews (DuPont et al., 1971;Levine, 1987).
Some properties of the enterovirulent E. coli (EEC) subgroups (Hitchins et al., 1998)a|
Property |
ETEC |
EPEC |
EHEC |
EIEC |
|
Toxin |
LT/STb |
Verocytotoxin (endogenous) |
Verocytoxin |
- |
|
Invasive |
- |
- |
- |
+ |
|
Stool |
Watery |
Watery, bloody |
Watery, very bloody |
Mucoid, bloody |
|
Fever |
Low |
+ |
- |
+ |
|
Fecal leukocytes |
- |
- |
- |
|
|
Intestine involved |
Small |
Small |
Colon |
Colon, lower small |
|
Serology |
Infantile types |
O157:H7 & a few other serotypes |
||
|
IDc |
High |
High |
Low |
Low |
bLT, labile toxin; ST, stable toxin.
cID, infective dose
| Control Measures | Contents |
| Guidelines | Contents |
| FDA Guidelines | Contents |
| FDA and EPA safety levels in Regulations and Guidance | Contents |
| Compliance Policy Guides | Contents |
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| Crabmeat, fresh and frozen | MPN of at least 3.6 per gram (IMVIC confirmed) in one or more of a minimum of 6 subsamples and inspectional evidence indicating the most probable source of the E. coli. | FDA, 1996b |
| Shrimp, raw breaded | Mean log of 16 units of finished product breaded shrimp collected prior to freezing is greater than 0.56 (i.e., geometric mean greater than 3.6/g) and exceeds the mean log of 16 units of stock shrimp by more than twice the standard error of their difference (2 SED). | FDA, 1996a |
| State Guidelines | Contents |
| State | Products |
Fecal coliforms (MPN) |
E. coli (MPN) |
| Alabama | Oysters, fresh or frozen |
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| Alaska | Oysters, clams, mussels
Oysters, clams, mussels (eviscerated) |
100/100g |
- |
| Arizona | Clams, mussels, oysters |
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| Arkansas | - |
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| California | Oysters, clams, mussels |
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| Colorado | Oysters, clams, mussels, and scallops |
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| Connecticut | Oysters, clams, mussels |
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| Delaware | Clams, mussels, oysters, or other mollusks, fresh or frozen |
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| Florida | Shellfish |
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| Blue crab |
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| Georgia | Clams, mussels, oysters, fresh or frozen |
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| Scallops: fried, frozen; breaded, frozen |
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| Crabmeat, cooked, fresh |
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| Deviled crab: frozen, cooked; fresh, uncooked |
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| Shrimp, peeled, cooked |
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| Shrimp, breaded, frozen, raw |
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| Fish, frozen, breaded, fried |
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| Fish, frozen, breaded, raw |
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| Hawaii | Oysters, clams, mussels, fresh or frozen |
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| Idaho |
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| Illinois |
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| Indiana |
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| Iowa |
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| Kansas |
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| Kentucky | Oysters, clams, scallops, shrimp, fresh or frozen |
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| Louisiana |
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| Maine |
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| Maryland | Oysters, clams, mussels, fresh or frozen |
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| Crabmeat, fresh |
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| |
| Crabmeat, pasteurized |
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| Massachusetts | Oysters, clams, mussels, fresh or frozen |
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| Michigan |
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| Minnesota |
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| Mississippi | Oysters, clams, mussels, fresh or frozen |
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| Missouri | Oysters, clams, mussels, fresh or frozen |
|
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| Foods |
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| |
| Montana |
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| Nebraska | Oysters, clams, mussels, fresh or frozen |
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| Deli foods (shrimp salad, etc.) |
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| |
| Nevada |
- |
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| New Hampshire | Oysters, softshell clams, fresh or frozen |
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| New Jersey | Oysters, clams, mussels, fresh or frozen |
|
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| "Potentially hazardous" (tuna, shrimp salad) |
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| |
| New Mexico |
- |
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| New York |
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| North Carolina | Shellfish |
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| Crustacea, fresh |
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| |
| Crustacea, pasteurized |
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| North Dakota |
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| Ohio |
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| Oklahoma |
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| Oregon | Oysters, clams, mussels, fresh or frozen |
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| Pennsylvania |
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| Rhode Island | Oysters, clams, mussels, fresh or frozen |
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| South Carolina | Blue crab, fresh, cooked |
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| Blue crab, pasteurized |
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| |
| Oysters, clams, mussels, fresh or frozen |
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| South Dakota |
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| Tennessee |
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| Texas | Crabmeat |
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| Oysters, clams, mussels, fresh or frozen |
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| Utah |
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| Vermont |
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| Virginia |
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| Washington | Molluscan shellfish (Oysters, clams, mussels, fresh or frozen) |
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| West Virginia | Deli items (seafood salads) |
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| Wisconsin |
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| Wyoming |
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| ICMSF Recommended Microbial Limits | Contents |
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| Fresh and frozen fish and cold-smoked fish |
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| Precooked breaded fish |
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| Frozen raw crustaceans |
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| Frozen cooked crustaceans |
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| Cooked, chilled, and frozen crabmeat |
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| Fresh and frozen bivalve molluscs |
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2Maximum number of acceptable sample units with bacterial counts between m and M.
3Maximum recommended bacterial counts for good quality products.
4Maximum recommended bacterial counts for marginally acceptable quality products.
Plate counts below "m" are considered good quality. Plate counts between "m" and "M" are considered marginally acceptable quality, but can be accepted if the number of samples does not exceed "c." Plate counts at or above "M" are considered unacceptable quality (ICMSF, 1986).
| Canadian Food Inspection Agency Bacteriological Guidelines for Fish and Fish Products | Contents |
| Growth | Contents |
| Heat Resistance | Contents |
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(min.) |
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Padhye and Doyle, 1992 |
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Padhye and Doyle, 1992 |
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Padhye and Doyle, 1992 |
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Padhye and Doyle, 1992 |
| Analytical Procedures | Contents |
| Food sampling and preparation of sample homogenate (USFDA) | Contents |
| Definition of Terms (HC Appendix A); Collection of samples (HC Appendix B); Supplement to All Methods in the HC Compendium: General Microbiological Guidance (HC Appendix I) HC Supplement to Appendix I) | Contents |
| Escherichia coli and the coliform bacteria (USFDA) | Contents |
| Enumeration of coliforms in foods by the hydrophobic grid-membrane filter (HGMF) method (HC MFHPB-17) | Contents |
| Determination of coliforms, faecal coliforms and of E. coli in foods (HC MFHPB-19) | Contents |
| Enumeration of Escherichia coli in foods by the hydrophobic grid-membrane filter (HGMF) method (HC MFHPB-26) | Contents |
| Enumeration of Escherichia coli in foods by the direct plating (DP) method (HC MFHPB-27) | Contents |
| Determination of coliforms in foods using violet red bile agar (HC MFHPB-31) | Contents |
| Enumeration of E. coli and coliforms in food products and food ingredients using 3MTM PetrifilmTM E. coli plates (HC MFHPB-34) | Contents |
| Enumeration of coliforms in food products and food ingredients using 3MTM PetrifilmTM coliform count plates (HC MFHPB-35) | Contents |
| Calculation of the most probable number of growth units for HGMF methods (HC Appendix C) | Contents |
| Determination of Enterobacteriaceae (HC MFLP-43) | Contents |
| Enumeration of faecal coliforms in foods by the hydrophobic grid-membrane filter (HGMF) method (HC MFLP-55) | Contents |
| Isolation of E. coli O157 in foods (HC MFLP-80) (Supplement to MFLP-80) | Contents |
| Detection of enterohemorrhagic E. coli (EHEC) in food products and food ingredients by the Assurance EHEC enzyme immunoassay (EIA) method (HC MFLP-81) | Contents |
| Identification of presumptive positive verocytoxigenic Escherichia coli by the polymerase chain reaction (HC MFLP-86) | Contents |
| Detection of enterohemorrhagic E. coli (EHEC) in food products and food ingredients by the VIP for EHEC method (HC MFLP-87) | Contents |
| Procedure for the detection of verocytotoxin-producing Escherichia coli in food samples (HC MFLP-89) | Contents |
| Identification of E. coli O157 by DynaBeadsTM anti-E. coli O157 (HC MFLP-90) | Contents |
| Detection of E. coli O157 by the TecraTM E. coli O157 visual immunoassay (VIA) method and Tecra E. coliO156 Immunocapture (HC MFLP-91) | Contents |
| Identification of Escherichia coli verotoxins by the Meridian Premier EHEC KitTM (HC MFLP-93) | Contents |
| The 20 hour Reveal method for detecting Escherichia coli O157:H7 from foods and environmental samples. (HC MFLP-95) | Contents |
| Enumeration of coliforms in foods and environmental samples using 3MTM PetrifilmTM high sensitivity coliform count (HSCC) plates (HC 85) | Contents |
| Other analytical procedures | Contents |
- Bacteria and coliform counts in dairy products: Dry rehydratable film methods (AOAC, 1995a)
- Bacteria and coliform counts in milk: Dry rehydratable film methods (AOAC, 1995b)
- Coliform and Escherichia coli counts in foods: Dry rehydratable film methods (AOAC, 1995c)
- Coliforms in dairy products: Pectin gel method (AOAC, 1995d)
- Confirmed total coliform and E. coli in all foods: Substrate supporting disc method (AOAC, 1995e)
- Detection of Escherichia coli producing heat-labile enterotoxin: DNA colony hybridization method (AOAC, 1995f)
- Enterotoxigenic Escherichia coli: DNA
colony hybridization method using synthetic oligodeoxyribonucleotides and
paper filters (AOAC, 1995g)
- Escherichia coli
enterotoxins: Mouse adrenal cell and suckling mouse assays (AOAC, 1995h)- Escherichia coli
in chilled or frozen foods: Fluorogenic assay for glucuronidase (AOAC, 1995i) - Fecal coliforms in shellfish growing waters: Medium A-1 method (AOAC, 1995j)
- Invasiveness of mammalian cells by Escherichia coli: Microbiological method (AOAC, 1995k)
- Total coliform and Escherichia coli counts in foods: Hydrophobic grid membrane filter/MUG method (AOAC, 1995l)
- Total coliforms and Escherichia coli in water: Defined substrate technology method (AOAC, 1995m)
- Total coliforms, fecal coliforms, and Escherichia coli in foods: Hydrophobic grid membrane filter method (AOAC, 1995n)
| Commercial Test Products | Contents |
|
Test Kit |
Analytical Technique |
Approx. Total Test Time1 |
Supplier |
|
3MTM
PetrifilmTME. coli Count Plate2
|
An indicator of glucuronidase activity
|
24-48 h |
3M Microbiology Products |
|
ColiComplete2 [Confirms total coliforms and E. coli] |
Substrate supporting disc |
48 h for coliforms |
BioControl Systems, Inc.
Web: www.rapidmethods.com |
|
ColiConfirm [Confirms presence of coliforms] |
Substrate supporting disc |
48 h |
BioControl Systems, Inc.
Web: www.rapidmethods.com |
|
Coliforms2 |
Culture |
24 h |
Contamination Sciences LLC
Contact: Robert Steinhauser 4230 East Towne Blvd., Suite 191 Madison, WI 53704 Phone: 608/825-6125 E-mail: bsteinha@contam-sci.com Web: www.contam-sci.com |
|
ColiGel |
Selective media, color indicator for galactosidase production (coliforms), UV fluorescence (E. coli) |
28 h (coliforms) |
Charm Sciences, Inc. Web: www.charm.com |
|
Colilert®2 |
Selective media with color indicator (UV light for E. coli) |
24 h |
IDEXX Laboratories, Inc.
Web: www.idexx.com/fed/home/start.asp |
|
E*Colite |
Selective media, color indicator for galactosidase production (coliforms) UV fluorescence (E. coli) |
28 h (coliforms) |
Charm Sciences, Inc. Web: www.charm.com |
|
ISO-GRID Method for Confirmed Coliform Count using LMG Agar2 |
Membrane filtration with selective and differential culture medium based on lactose fermentation |
24 h |
Neogen Corporation |
|
PathoGelTM |
Selective media, color indicator for galactosidase production (coliforms) UV fluorescence (E. coli), black precipitate (H2S production) |
28 h (coliforms) |
Charm Sciences, Inc. Web: www.charm.com |
|
RCTTM Rapid Coliform Test |
Redox reaction and color change |
14 h |
Applied Research Institute
Web: www.arillc.com |
|
SimPlateTM for Total Coliform and E. coli |
MPN plate with selective media (UV light for E. coli) |
24 h |
IDEXX Laboratories, Inc.
Web: www.idexx.com/fed/home/start.asp |
|
Total coliform/E. coli (estimated) |
Selective media with color indicator that changes based on approximate coliform count (UV light for E. coli) |
30 min for 108 |
Contamination Sciences LLC
Contact: Robert Steinhauser 4230 East Towne Blvd., Suite 191 Madison, WI 53704 Phone: 608/825-6125 E-mail: bsteinha@contam-sci.com Web: www.contam-sci.com |
2AOAC Approved
Commercial test products for E. coli
|
Test Kit |
Analytical Technique |
Approx. Total Test Time1 |
Supplier |
|
3MTM
PetrifilmTME. coli Count Plate2
|
An indicator of glucuronidase activity
|
24-48 h |
3M Microbiology Products |
|
CHECK 3 E. coli |
Chemical, visual detection |
4-18 h |
Contamination Sciences LLC
|
|
Coli ST EIA:ETC STA (Denka Seiken Co. Ltd). |
EIA |
18½ h |
Oxoid, Inc. |
|
ColiComplete2 [Confirms total coliforms and E. coli] |
Substrate supporting disc |
30 h for E. coli 48 h for coliforms |
BioControl Systems, Inc.
Web: www.rapidmethods.com |
|
ColiGel |
Selective media, color indicator for galactosidase production (coliforms), UV fluorescence (E. coli) |
28 h (coliforms) |
Charm Sciences, Inc. Web: www.charm.com |
|
Colilert®2 |
Selective media with color indicator (UV light for E. coli) |
24 h |
IDEXX Laboratories, Inc.
Web: www.idexx.com/fed/home/start.asp |
|
E. coli 2 |
Culture |
24 h |
Contamination Sciences LLC
Web: www.contam-sci.com |
|
E*Colite |
Selective media, color indicator for galactosidase production (coliforms) UV fluorescence (E. coli) |
28 h (coliforms) |
Charm Sciences, Inc. Web: www.charm.com |
|
GENE-TRAK E. coli Assay |
Nucleic acid hybridization |
28 h |
Neogen Corporation |
|
ISO-GRID Method for Confirmed E. coli Count using LMG Agar and BMA Agar2 |
Membrane filtration with selective and differential culture medium based on lactose fermentation and b -glucuronidase |
24 h |
Neogen Corporation |
|
PathoGelTM |
Selective media, color indicator for galactosidase production (coliforms) UV fluorescence (E. coli), black precipitate (H2S production) |
28 h (coliforms) |
Charm Sciences, Inc. Web: www.charm.com |
|
SimPlateTM for Total Coliform and E. coli |
MPN plate with selective media (UV light for E. coli) |
24 h |
IDEXX Laboratories, Inc.
Web: www.idexx.com/fed/home/start.asp |
|
Total coliform/E. coli (estimated) |
Selective media with color indicator that changes based on approximate coliform count (UV light for E. coli) |
30 min for 108 |
Contamination Sciences LLC
Web: www.contam-sci.com |
|
VET-RPLA |
Reversed passive latex agglutination |
|
Oxoid, Inc. |
2AOAC Approved
Commercial test products for E. coli O157:H7
|
Test Kit |
Analytical Technique |
Approx. Total Test Time1 |
Supplier |
|
Assurance EHEC EIA |
Enzyme immunoassay |
19½ h |
BioControl Systems, Inc.
Web: www.rapidmethods.com |
|
BAX® for Screening/E. coli O157:H7 |
Polymerase chain reaction |
21-24 h |
Qualicon, Inc. Web: www.qualicon.com |
| Chromogenic
O157 [A differentiation test for E. coli O157] |
33-48 h | Biomedix Contact: Claver Bundac 1105 #F North Golden Springs Dr. Diamond Bar, CA 91765 Phone: 800/674-8648 #4282; 909/396-0244 E-mail: cb4biomedx@aol.com | |
|
Dynabeads® anti-E. coli O157 |
Immunomagnetic separation |
24 h |
Dynal Inc. Contact: Technical
Service Web: www.dynal.no |
|
E. coli O157:H72 |
Culture |
24 h |
Contamination Sciences LLC
Web: www.contam-sci.com |
|
E. coli O157 Latex Test |
|
|
Oxoid, Inc. |
|
eclipseTM
E. coli O157:H7 Rapid Color Change Test |
Immunoassay |
8.33 or 20.33 h |
Eichrom Technologies, Inc.
Web: www.eichrom.com |
|
EHEC-TekTM |
Magnetic capture and concentration/ELISA |
24 h |
Organon Teknika Corp. |
|
EIAFoss E. coli O157 |
Combination ELISA and Immuno Magnetic Separation |
22-24 h |
Foss North America, Inc.
7682 Executive Dr. Eden Prairie, MN 55344 Phone: 612/974-9892 E-mail: sales@fossnorthamerica.com Web: www.fossnorthamerica.com |
|
ImmunoCard Stat! E. coli O157:H7 |
Immunoassay using colloidal gold |
8-24 h |
Meridian Diagnostics |
|
ISO-GRID Method for E. coli O157:H7 [Enumeration using SD-39 Agar] |
Membrane filtration with selective and differential culture medium based on lysine decarboxylase, sorbitol fermentation and b-glucuronidase |
24-48 h (24 h for presumptive enumeration and 24 h additional to confirm presumptive positive results) |
Neogen Corporation |
|
NOW |
Antibody |
9 h |
Contamination Sciences LLC
Web: www.contam-sci.com |
|
PATH-STICK One Step Rapid E. coli O157 Test |
Immunochromatography |
16-24 h |
Celsis, Inc. Web: www.celsis.com |