Comparison of Methods for Estimation of Coliforms, Fecal Coliforms and Enterococci in Retail Ground Beef

1978 ◽  
Vol 41 (4) ◽  
pp. 263-266 ◽  
Author(s):  
C. J. PIERSON ◽  
B. S. EMSWILER ◽  
A. W. KOTULA
Keyword(s):  
Escherichia Coli ◽  
Brilliant Green ◽  
Agar Medium ◽  
Ground Beef ◽  
Fecal Coliforms ◽  
Most Probable Number ◽  
Type I ◽  
Lauryl Sulfate ◽  
Comparison Of Methods ◽  
Probable Number

Seven recommended methods for estimation of coliforms, three for fecal coliforms and four for enterococci were tested on 30 retail ground beef samples. Lauryl sulfate tryptose broth gave higher coliform counts than did MacConkey's broth or brilliant green lactose bile broth 2% in 3-tube Most Probable Number (MPN) methods. With all MPN broths, coliforms counts were significantly (P ⩽0.05) higher after 48 than after 24 h of incubation. Presumptive coliform counts were higher with surface-overlay plating on violet red bile agar than with pour plating on the same agar or with the MPN broths. However, presence of Escherichia coli Type I was not confirmed as often from the agar medium as the broths. For estimation of fecal coliforms, counts did not differ significantly (P ⩽0.05) between EC broth (45.5 C) and brilliant green lactose bile broth 2% (44 C). Enterococci counts varied significantly (P ⩽0.05) among the four methods.

Efficacy of Petrifilm™ VRB for Enumerating Coliforms and Escherichia coli from Frozen Raw Beef

1987 ◽  
Vol 50 (12) ◽  
pp. 1017-1022 ◽  
Author(s):  
LAWRENCE RESTAINO ◽  
RICHARD H. LYON
Keyword(s):  
Escherichia Coli ◽  
Incubation Temperature ◽  
Ground Beef ◽  
Gas Bubbles ◽  
Most Probable Number ◽  
Type I ◽  
Type Ii ◽  
Probable Number ◽  
E Coli ◽  
Colony Diameter

Petrifilm™ violet red bile (PVRB) compared favorably to the most probable number method (MPN) and violet red bile agar (VRBA) methods for enumerating coliforms from frozen raw ground beef. When comparing PVRB and VRBA incubated at 35°C, coliform enumeration displayed a linear relationship (correlation coefficient of 0.932). However, by analyzing 64 ground beef samples, PVRB enumerated 41% more coliforms/g than did VRBA. Two distinct colony types were observed on PVRB: (a) type I (butterfly in appearence) with a colony diameter equal to or greater than 1 mm and gas bubbles 2–4 mm in diameter touching the associated colony; and (b) type II with a colony diameter less than 1 mm in diameter and gas bubbles of the associated colony not necessarily touching the colony but within a colony diameter. The disparity between PVRB and VRBA for enumerating coliforms was attributed to non-coliforms representing approximately 50% of the type II coliform colonies. At 35°C, 83.7% of the type I colonies were Escherichia coli, whereas only 10.9%, of the type II colonies were E. coli. By elevating the incubation temperature from 35°C to 44.5°C, over 90% of the colonies in the counting dilution were type I of which 99.2% were E. coli. At 44.5°C, 39.4% of the type II colonies were E. coli; however, this colony type represented only 9.5% of the total colonies on PVRB. Therefore, a reliable method for enumerating E. coli from raw meat was developed by counting only the type I colonies on PVRB incubated at 44.5°C.

scholarly journals Lessons from a large outbreak of Escherichia coli O157[ratio ]H7 infections: insights into the infectious dose and method of widespread contamination of hamburger patties

1999 ◽  
Vol 122 (2) ◽  
pp. 185-192 ◽  
Author(s):  
J. TUTTLE ◽  
T. GOMEZ ◽  
M. P. DOYLE ◽  
J. G. WELLS ◽  
T. ZHAO ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Ground Beef ◽  
Most Probable Number ◽  
Strong Argument ◽  
Probable Number ◽  
Infectious Dose ◽  
E Coli ◽  
Beef Patties ◽  
Large Outbreak ◽  
Microbiological Testing

Between November 1992 and February 1993, a large outbreak of Escherichia coli O157[ratio ]H7 infections occurred in the western USA and was associated with eating ground beef patties at restaurants of one fast-food chain. Restaurants that were epidemiologically linked with cases served patties produced on two consecutive dates; cultures of recalled ground beef patties produced on those dates yielded E. coli O157[ratio ]H7 strains indistinguishable from those isolated from patients, confirming the vehicle of illness. Seventy-six ground beef patty samples were cultured quantitatively for E. coli O157[ratio ]H7. The median most probable number of organisms was 1·5 per gram (range, <0·3–15) or 67·5 organisms per patty (range, <13·5–675). Correlation of the presence of E. coli O157[ratio ]H7 with other bacterial indicators yielded a significant association between coliform count and the presence of E. coli O157[ratio ]H7 (P=0·04). A meat traceback to investigate possible sources of contamination revealed cattle were probably initially colonized with E. coli O157[ratio ]H7, and that their slaughter caused surface contamination of meat, which once combined with meat from other sources, resulted in a large number of contaminated ground beef patties. Microbiological testing of meat from lots consumed by persons who became ill was suggestive of an infectious dose for E. coli O157[ratio ]H7 of fewer than 700 organisms. These findings present a strong argument for enforcing zero tolerance for this organism in processed food and for markedly decreasing contamination of raw ground beef. Process controls that incorporate microbiological testing of meat may assist these efforts.

Enterobacteriaceae in ground meats

1978 ◽  
Vol 24 (12) ◽  
pp. 1574-1582 ◽  
Author(s):  
Lai-King Ng ◽  
Michael E. Stiles
Keyword(s):  
Ground Beef ◽  
False Positives ◽  
Coliform Bacteria ◽  
Most Probable Number ◽  
Type I ◽  
Enterobacter Agglomerans ◽  
Frozen Ground ◽  
Probable Number ◽  
E Coli ◽  
Solid Media

Presumptive Escherichia coli counts for 312 samples of non-frozen ground beef were determined and compared with proposed Canadian standards. Results for frozen pork sausages, packaged at manufacturer level, indicated little difference in distribution of presumptive E. coli loads compared with retail ground beef. Use of solid media and direct inoculation of EC broth at 45 °C did not give alternative, rapid methods of estimating E. coli loads in ground beef. Counts on violet red bile agar (VRBA) within 18–24 h incubation at 35 °C gave reliable estimates of coliform bacteria (bile-precipitating colonies) and Enterobacteriaceae (total count), with only 1.3 and 10.7% false positives, respectively. Bile-precipitating isolates from VRBA were primarily E. coli, also Serratia liquefaciens, aerogenic Enterobacter agglomerans, Enterobacter cloacae, Citrobacter freundii, and Klebsiella pneumoniae. Non-bile-precipitating colonies were primarily aerogenic E. agglomerans and S. liquefaciens; however, in the most probable number technique E. agglomerans was screened out. In addition to E. coli, E. agglomerans and S. liquefaciens were the principal types of Enterobacteriaceae in these samples. Enterobacter agglomerans gave a variety of IMViC reactions, including the type I (++−−) reaction, whereas S. liquefaciens were predominantly IMViC type −−++. Incubating EC broth at 45.5 °C, as opposed to 44.5 °C, reduced the number of false positives.

Extended Incubation of LST and BGB Tubes and the MPN Estimates of Coliforms

1994 ◽  
Vol 57 (8) ◽  
pp. 740-742 ◽  
Author(s):  
LAWRENCE A. ROTH ◽  
HAROLD BENGSCH ◽  
CHARLES DAVIDSON ◽  
JAMES S. DICKSON
Keyword(s):  
Incubation Time ◽  
Brilliant Green ◽  
Regulatory Compliance ◽  
Most Probable Number ◽  
Lauryl Sulfate ◽  
Interlaboratory Comparisons ◽  
Confidence Limits ◽  
Probable Number

Extending the incubation time past the standard 48 h for presumptive lauryl sulfate tryptose (LST) broth and confirmed brilliant green bile (BGB) broth tests for coliforms resulted in increases in most probable number (MPN) estimates. Whereas 40% of the samples showed an increase in the presumptive MPN when the incubation was extended from 48 to 72 h, only 5% showed confirmed MPNs, which exceeded the 95% confidence limits established for the 48-h confirmed MPNs. Extending the incubation of BGB tubes to 72 h resulted in less than 5% of the samples exhibiting increased MPNs, which exceeded the 48-h 95% confidence limits. Some loss in viability of coliforms was observed when LST tubes were incubated beyond 72 h. The study demonstrates the importance of adhering to standard incubation times for interlaboratory comparisons and ensuring regulatory compliance.

Rapid Fluorogenic Enumeration of Escherichia coli in Selected, Naturally Contaminated High Moisture Foods

1987 ◽  
Vol 70 (6) ◽  
pp. 991-993
Author(s):  
Paul L Poelma ◽  
Clyde R Wilson ◽  
Wallace H Andrews
Keyword(s):  
Escherichia Coli ◽  
Ultraviolet Light ◽  
Ground Beef ◽  
Most Probable Number ◽  
High Moisture ◽  
Probable Number ◽  
Pork Sausage ◽  
E Coli

Abstract An assay for the enzyme glucuronidase was used to determine the presence of Escherichia coli in selected, naturally contaminated high moisture foods. Raw pork sausage, ground turkey, and ground beef were inoculated into tubes containing the substrate 4-methylumbelliferyl beta-D-glucuronide (MUG) in lauryl tryptose (LT) medium. After incubation at 35°C for 24 h, the inoculated LT-MUG tubes were examined under longwave ultraviolet light for the presence of a fluorogenic glucuronidase end product. A fluorescing tube indicated the presumptive presence of E. coli. The 10 day most probable number method of the AOAC and the LT-MUG procedure gave comparable recoveries of E. coli.

Comparison of a Rapid Plate Count and MPN Methods for Enumeration of Fecal Coliforms and Escherichia coli in Soft-Shell Clams

1995 ◽  
Vol 58 (11) ◽  
pp. 1197-1200 ◽  
Author(s):  
GUADALUPE R. GARCIA ◽  
ROBERT E. HAYMOND ◽  
DIANE M. SPRAGUE ◽  
EMMA R. SINGLETON ◽  
JAMES T. PEELER ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Fecal Coliform ◽  
Mya Arenaria ◽  
Fecal Coliforms ◽  
Plate Count ◽  
Most Probable Number ◽  
Probable Number ◽  
Rapid Procedure ◽  
Soft Shell ◽  
Plate Count Method

A direct elevated temperature plate count method utilizing modified fecal coliform agar with rosolic acid (ETPC/mFC) was compared to 5-tube and 3-tube most probable number (MPN) procedures for its accuracy in enumerating fecal coliforms and Escherichia coli in naturally and artificially contaminated soft-shell clams (Mya arenaria). The results indicated that the extent of overall recovery of fecal coliforms was similar in the two methods tested. Therefore, the ETPC/mFC method may be considered as a rapid procedure for fecal coliform screening during depuration of soft-shell clams.

scholarly journals Two Rapid Methods for Detection of Escherichia coli Exceeding 104/g Action Levels: Precollaborative Study

2006 ◽  
Vol 89 (5) ◽  
pp. 1317-1326
Author(s):  
Michael A Grant ◽  
Jane S Wernberg ◽  
Khanh T Van ◽  
Angelina M Albert
Keyword(s):  
Escherichia Coli ◽  
Membrane Filtration ◽  
Reference Method ◽  
Most Probable Number ◽  
Lauryl Sulfate ◽  
Probable Number ◽  
E Coli ◽  
Potential Alternative ◽  
Aoac Method ◽  
Action Levels

Abstract The current AOAC Method 966.24 for enumeration of Escherichia coli in foods uses a most probable number (MPN) procedure with extensive confirmation steps. Two new methods based on membrane filtration (MF) were compared to the MPN reference method for detection of high levels of E. coli in 5 food types, some of which represent categories for which the U.S. Food and Drug Administration (FDA) mandates additional testing if an action level of 104/g E. coli is exceeded. Ground beef, which is not FDA regulated, was also tested. The 5 food types were all inoculated at 3 levels: 102/g, ≥104/g, and ≥105/g E. coli. An MF protocol using either m-ColiBlue24® (CB) or lauryl sulfate tryptose plus BCIG (LST/BCIG) was an effective potential alternative to the reference method. Sensitivity and specificity for both CB and LST/BCIG were 98 and 100%, respectively. Agreement between MPN and both CB and LST/BCIG was 98%. The 2 proposed methods allow completion of both presumptive and confirmatory steps in 13 days, whereas the reference method requires as many as 11 days. Exclusivity testing with 50 non-E. coli strains indicated 100% were correctly ruled out by the proposed protocols. Inclusivity testing was used to determine whether typical results were obtained after incubation of E. coli cultures on CB or LST/BCIG for 24 h. Of 50 E. coli strains tested, 100% yielded typical results after incubation on CB, and 98% yielded typical results after incubation on LST/BCIG.

Coliforms, Escherichia coli and Salmonella Serovars Associated with a Citrus-Processing Facility Implicated in a Salmonellosis Outbreak†

1998 ◽  
Vol 61 (3) ◽  
pp. 280-284 ◽  
Author(s):  
MICKEY E. PARISH
Keyword(s):  
Escherichia Coli ◽  
Environmental Samples ◽  
Fecal Coliforms ◽  
Most Probable Number ◽  
Probable Number ◽  
Bufo Terrestris ◽  
Processing Facility ◽  
Salmonella Serovars ◽  
Enrichment Techniques ◽  
Fruit Surface

A salmonellosis outbreak occurred during the summer of 1995 among individuals who consumed nonpasteurized orange juice from a Florida citrus-processing facility. Clinical isolates were identified by the Centers for Disease Control as Salmonella serovars Hartford, Gaminara, and Rubislaw. At the processing facility, 70 samples (equipment swabs, fruit surface swabs, juice, and miscellaneous environmental samples) were collected before, during, and after processing runs on two different dates. Bottled juice samples from eight previous extraction dates were also collected. Total plate counts, fecal coliforms, and Escherichia coli were enumerated for each sample. Analyses for Salmonella cells were conducted on all juice samples, fruit surface swabs, environmental samples, and selected equipment swabs using direct enrichment and pre-enrichment techniques. Salmonella serovars Hartford, Rubislaw, Saintpaul, and Newport were detected from either juice, unwashed fruit surfaces, or amphibians (Hyla cinerea and Bufo terrestris) captured outside the processing building. Salmonella cells in juice were associated with population levels of fecal coliforms and E. coli above the upper most probable number (MPN) limits of detection (&gt;110/ml).

Comparison of culturable fecal coliforms and Escherichia coli enumeration in freshwaters

2007 ◽  
Vol 53 (6) ◽  
pp. 798-801 ◽  
Author(s):  
Tamara Garcia-Armisen ◽  
Josué Prats ◽  
Pierre Servais
Keyword(s):  
Escherichia Coli ◽  
Microbiological Quality ◽  
Fecal Coliforms ◽  
Quality Data ◽  
Plate Count ◽  
Most Probable Number ◽  
Tetrazolium Chloride ◽  
Probable Number ◽  
E Coli ◽  
Glucuronidase Activity

Fecal coliforms (FC) counts were compared with Escherichia coli counts in differently contaminated freshwater samples (n = 166). FC were enumerated by plate count on triphenyl 2,3,5-tetrazolium chloride Tergitol medium. Escherichia coli were enumerated by the most probable number microplate method based on the detection of glucuronidase activity. FC and E. coli counts were highly correlated; an average E. coli/FC ratio equal to 0.77 was found, meaning that on average, 77% of FC were E. coli. Knowing the E. coli/FC ratio allows us to convert the historical microbiological quality data expressed in FC counts into E. coli abundance and thus to compare with present and future monitoring data that are (or will be) based on E. coli enumeration.

Sign in / Sign up

Export Citation Format

Share Document