Coliforms and Enterobacteriaceae Isolates from Selected Foods

1979 ◽  
Vol 42 (9) ◽  
pp. 712-714 ◽  
Author(s):  
A. J. MERCURI ◽  
N. A. COX
Keyword(s):  
Ground Beef ◽  
Gas Production ◽  
Fecal Coliforms ◽  
Poultry Meat ◽  
Type I ◽  
Enterobacter Agglomerans ◽  
Pork Sausage ◽  
E Coli ◽  
System A ◽  
Principal Species

We obtained coliform counts and Enterobacteriaceae counts using violet red bile agar (VRB) and VRB + 1% glucose (VRBG), respectively, of samples of five food products. From each set of VRB and VRBG plates, 28 to 40 “typical” colonies were randomly selected and identified by use of the R-B Enteric Differential System. A pure culture of each isolate was also subjected to the sequential tests for gas production in LST and BGLB broths (confirmed coliforms) and in EC broth at 45.5 C (fecal coliforms). IMViC reaction patterns of EC-positive cultures were also determined. Approximately 80% of the VRB isolates from broiler skin and from mechanically deboned poultry meat (MDPM) met all the criteria for fecal coliforms, whereas only 62.5% and 36.5%, respectively, of the VRBG isolates from these two products met these criteria. Fewer than 10% of the VRB and VRBG isolates from chicken pot pie, ground beef, or pork sausage produced gas in LST broth. The percentages of fecal coliforms and Escherichia coli (Type I or II) among the 179 VRB isolates were 34.1 and 33.5, respectively. Corresponding percentages for the 193 VRBG isolates were 20.7 and 19.7. E. coli was the predominant species isolated on both media from broiler skin and MDPM. Enterobacter agglomerans was the principal species isolated from chicken pot pie and pork sausage; Serratia liquefaciens predominated in ground beef.

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.

Enteric Bacteriophages as Potential Fecal Indicators in Ground Beef and Poultry Meat

2002 ◽  
Vol 65 (1) ◽  
pp. 93-99 ◽  
Author(s):  
F.-C. HSU ◽  
Y.-S. CAROL SHIEH ◽  
M. D. SOBSEY
Keyword(s):  
Microbiological Quality ◽  
Ground Beef ◽  
Chicken Meat ◽  
Detection Sensitivity ◽  
Fecal Coliforms ◽  
Poultry Meat ◽  
Chicken Breast ◽  
Fecal Indicators ◽  
Somatic Coliphages ◽  
Critical Control Points

Recovery efficiencies of enteric bacteriophages (F+ RNA coliphages, somatic coliphages, and Salmonella phages) as alternative fecal indicators were determined from ground beef and chicken breast meat using amino acid eluants (glycine and threonine) and a complex eluant (3% beef extract). Levels of F+ RNA coliphages (MS2, GA, Qβ, FI, and SP), the somatic coliphage ΦX174, and three environmental isolates of Salmonella phages (isolated from raw sewage) were assayed using three respective hosts: Escherichia coli Famp, E. coli C, and Salmonella Typhimurium. When 8% polyethylene glycol and 0.1 M NaCl were used to precipitate bacteriophages eluted with five different eluants, the highest recoveries of the three phage groups were with 0.5 M threonine and 0.25 M glycine-threonine. The average recoveries of F+ RNA coliphages, somatic coliphages, and the Salmonella phages from ground beef and chicken meat were 100, 69, and 65%, respectively, with threonine (0.5 M, pH 9.0) as the eluate. Of eight market food samples tested, F+ RNA coliphages were detected in five (63%) and somatic coliphages were detected in seven (88%). The overall detection sensitivity of the method was 3 PFU/100 g of ground beef or chicken meat. Levels of bacteriophages and bacterial indicators on chicken carcass surfaces were determined at identified critical control points at a poultry plant. Through the processing steps of evisceration, washing, and chilling, the levels of F+ RNA coliphages and fecal coliforms were reduced by 1.6 and 1.9 log10 PFU or CFU/100 g, respectively. F+ RNA coliphages and perhaps other enteric bacteriophages may be effective candidate indicators for monitoring the microbiological quality of meat, poultry, and perhaps other foods during processing. The bacteriophage concentration method developed provides a simple, rapid, and practical tool for the evaluation of fecal contamination levels in ground beef and processed chicken meat.

MICROBIOLOGICAL ANALYSIS OF TILAPIA AND WATER IN AQUACULTURE FARMS FROM SINALOA

Biotecnia ◽  
2018 ◽  
Vol 20 (1) ◽  
pp. 20-26
Author(s):  
José Antonio Valenzuela-Armenta ◽  
Sylvia Páz Díaz-Camacho ◽  
Julio Adalberto Cabanillas-Ramos ◽  
Magdalena de Jesus Uribe-Beltrán ◽  
Mária del Carmen De la Cruz-Otero ◽  
...  
Keyword(s):  
Water Samples ◽  
Microbiological Quality ◽  
Fecal Coliforms ◽  
Aerobic Bacteria ◽  
Microbiological Analysis ◽  
Enterobacter Agglomerans ◽  
E Coli ◽  
The World ◽  
Fishery Products

Tilapia is the most cultivated fish around the world. The fish’s environment can harbor bacteria, especially coliforms, which are not normal biota of fish. These microorganisms are contamination indicator groups (IGs) reflecting the possible presence of pathogens, which can compromise the safety of fishery products. The IGs prevalence was estimated in tilapia and water from 29 aquaculture farms. Total and fecal coliforms (TC, FC), mesophilic aerobic bacteria (MAB), S. aureus, E. coli, Salmonella sp., and Streptococcus sp., were investigated. In tilapia, TC and FC were detected in 64% and 48% of the samples, ranging from 4.0 x 101 to 9.8 x 105, and from 1.0 x 101 to 6.4 x 103 CFU/g, respectively; MAB were detected in 90% of the samples. In water, TC and FC were detected in 57% and 35% of the samples, oscillating from 1.0 x 101 to 2.28 x104, and from 1.0 x 101 to 1.2 x 103 CFU/mL, respectively. MAB were detected in 89% of the water samples. Mostly E. coli and Enterobacter agglomerans were detected. Generally, IGs concentrations meet the Mexican regulations; however, the tilapia’s microbiological quality must be continuously monitored.

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.

Comparative Study of Micro-ID, Minitek and Conventional Methods with Enterobacteriaceae Freshly Isolated from Foods

1979 ◽  
Vol 42 (9) ◽  
pp. 735-738 ◽  
Author(s):  
N. A. COX ◽  
A. J. MERCURI ◽  
M. O. CARSON ◽  
D. A. TANNER
Keyword(s):  
Ground Beef ◽  
Enterobacter Cloacae ◽  
Complete Agreement ◽  
Enterobacter Agglomerans ◽  
Biochemical Tests ◽  
Pork Sausage ◽  
Serratia Liquefaciens ◽  
Conventional Tests ◽  
Conventional Systems ◽  
Raw Shrimp

A total of 400 Enterobacteriaceae isolates freshly taken from broiler carcasses, ground beef, pork sausage, raw shrimp, pre-wrapped sandwiches, raw carrots, lettuce and fresh strawberries was inoculated into the 15 biochemical tests of the Micro-ID (4-h) system and into the 15 corresponding tests in the Minitek (24-h) and conventional systems. For each food there were 750 biochemical test comparisons (50 isolates × 15 tests). The overall agreement between Micro-ID and conventional tests was 96.8%, whereas the agreement between Minitek and conventional tests was 93.6%. Three laboratory technicians who independently recorded results of 6000 biochemical tests from each of the three systems were in complete agreement for 99.3%, 98.9% and 99.7% of the Micro-ID. Minitek and conventional tests, respectively. Thus results obtained with the miniaturized systems were as easy to read and interpret as conventional tests in tubes. The most frequently encountered Enterobacteriaceae from these foods were Escherichia coli (broiler carcasses, pork sausage). Enterobacter agglomerans (carrots, lettuce, shrimp, strawberries), Enterobacter cloacae (pre-wrapped sandwiches), and Serratia liquefaciens (ground beef).

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.

Evaluation of a Phosphate To Control Pathogen Growth in Fresh and Processed Meat Products

1996 ◽  
Vol 59 (4) ◽  
pp. 356-359 ◽  
Author(s):  
LISA M. FLORES ◽  
SUSAN S. SUMNER ◽  
DIANNE L. PETERS ◽  
ROGER MANDIGO
Keyword(s):  
Escherichia Coli ◽  
Salmonella Typhimurium ◽  
Foodborne Pathogens ◽  
Meat Products ◽  
Ground Beef ◽  
Processed Meat ◽  
Escherichia Coli O157 ◽  
Pork Sausage ◽  
E Coli

The efficacy of a phosphate blend, Bekaplus MSP, to inhibit the growth of foodborne pathogens in fresh or processed meat products was studied. The following products and challenge microorganisms were tested: ground beef, Escherichia coli O157:H7; linked smoked sausage, Salmonella typhimurium and L. monocytogenes; cured smoked ham, S. typhimurium and L. monocytogenes; and fresh pork sausage, E. coli O157:H7. All the products were prepared with or without 0.5% phosphate, individually inoculated with the challenge microorganism (103CFU/g of meat), and stored at either 4, 12, or 20°C. There was minimal or no effect of the phosphate blend on the growth of L. monocytogenes or S. typhimurium. The temperature of storage had a significant effect (P < 0.05) on the population of E. coli O157:H7 in ground beef and fresh pork sausage with phosphate. However, the presence of phosphate in the ground beef had no effect (P > 0.05) on E. coli O157:H7, but the presence of phosphate in the fresh pork sausage had a significant effect (P < 0.05) on controlling E. coli O157:H7. These results indicate that this phosphate blend could be used in fresh pork sausage to help inhibit the growth of E. coli O157:H7.

Recovery of Fecal Coliforms and of Escherichia coli at 44.5, 45.0 and 45.5°C

1983 ◽  
Vol 46 (3) ◽  
pp. 172-177 ◽  
Author(s):  
K. F. WEISS ◽  
N. CHOPRA ◽  
P. STOTLAND ◽  
G. W. RIEDEL ◽  
S. MALCOLM
Keyword(s):  
Escherichia Coli ◽  
Incubation Time ◽  
Gas Production ◽  
False Positives ◽  
The Other ◽  
Fecal Coliforms ◽  
False Negatives ◽  
E Coli ◽  
Incubation Temperatures ◽  
Valid Criterion

Recovery rates of fecal coliforms and of Escherichia coli were determined at 44.5, 45.0 and 45.5°C in raw milk, ground meat and raw sewage. MPN values based on gas production (Standard MPNs) and on gas production and/or growth only (Total MPNs) were calculated for both fecal coliforms and for E. coli. The expected trend towards lower MPN values with increasing incubation temperature was more pronounced for the Standard MPNs than for the Total MPNs. The temperature effect was also strongly product - specific in that the Total and Standard MPNs for the fecal coliforms and the Standard MPNs for E. coli for sewage only differed significantly from one another within each determination at the three different incubation temperatures. The effect of length of incubation time on the ratios of E. coli to fecal coliforms was most pronounced at 45.5°C. Product specificity was again observed. The greatest increase in the recovery rate of aerogenic E. coli between 24 and 48 h of incubation time occurred in sewage (66%). For meat, the increase was 57% and for milk 46%. In terms of combined (aerogenic and anaerogenic) E. coli (expressed as Total MPNs), the increases were considerably less, but highest for the meat (33%), followed by sewage (29%) and by milk (21%). A breakdown of the E. coli isolates recovered from both gas-positive and gas-negative primary (fecal coliform) EC broth tubes showed that for the three products combined there were eight times as many false-positives at 44.5°C as at the other two incubation temperatures. In contrast, there were 12% false-negatives at 45.5°C compared to 3% at 45.0°C and 2% at 44.5°C. Since the high incidence of false-negatives (loss of E. coil) at 45.5°C is not counter-balanced by an enhanced specificity (fewer false-positives) over 45.0°C, the latter temperature is to be preferred. Meat yielded the lowest rate for false-positives at any of the three incubation temperatures. In contrast, at 45.5°C, it gave 21% false-negatives compared to only 9% for sewage and 10% for milk. On the other hand, milk contributed the most false-positives at 44.5°C (20%), compared to only 1% for meat and 3% for sewage. A potential loss of 21% of E. coli - containing EC broth tubes is hardly tolerable, reinforcing the contention that gas formation at evaluated temperatures is not a valid criterion of fecal origin.

Use of Baird-Parker's Medium to Enumerate Staphylococcus aureus in Meats1

1981 ◽  
Vol 44 (8) ◽  
pp. 583-587 ◽  
Author(s):  
M. E. STILES ◽  
L. -K. NG
Keyword(s):  
Staphylococcus Aureus ◽  
Ground Beef ◽  
Egg Yolk ◽  
Colony Count ◽  
Type I ◽  
Type Ii ◽  
Pork Sausage ◽  
Retail Meat

The Staphylococcus aureus count was determined, using Baird-Parker (BP) medium and coagulase reaction, on 100 samples of ground beef, 23 frozen pork sausage samples and 140 retail meat cuts (beef and pork). S. aureus counts on ground beef ranged from < 100 to 4,500 per g, and 16% had counts of 1,000 per g or greater. Frozen pork sausage samples had similar S. aureus counts to ground beef. Retail meat cuts generally had counts less than 100 per cm2. Typical S. aureus colonies in this study on BP medium were dark grey to grey-black, and not shiny black as generally described. Type II colonies (without egg yolk clearing) did not contribute markedly to the total S. aureus count and egg yolk clearing type I colony count is suggested for routine estimation of the S. aureus count. The S. aureus isolates in this study generally had 3+ coagulase reactions. The coagulase-positive isolates were generally phosphatase-positive (96.8%), Voges-Proskauer test-positive (97.4%), DNase-positive (98.7%) and used glucose and mannitol oxidatively and fermentatively (93.5%). Most non-S. aureus colonies were “other” staphylococci or micrococci. These isolates had variable phosphatase, Voges-Proskauer and DNase reactions, generally with at least one of these three tests negative.

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