scholarly journals Comparison of Fecal Coliform Agar and Violet Red Bile Lactose Agar for Fecal Coliform Enumeration in Foods

2002 ◽  
Vol 68 (4) ◽  
pp. 1631-1638 ◽  
Author(s):  
A. Leclercq ◽  
C. Wanegue ◽  
P. Baylac
Keyword(s):  
Escherichia Coli ◽  
Fecal Coliform ◽  
Food Samples ◽  
Fecal Coliforms ◽  
Predictive Values ◽  
Direct Plating ◽  
Hafnia Alvei ◽  
E Coli ◽  
Plating Method ◽  
Mashed Potatoes

ABSTRACT A 24-h direct plating method for fecal coliform enumeration with a resuscitation step (preincubation for 2 h at 37 ± 1°C and transfer to 44 ± 1°C for 22 h) using fecal coliform agar (FCA) was compared with the 24-h standardized violet red bile lactose agar (VRBL) method. FCA and VRBL have equivalent specificities and sensitivities, except for lactose-positive non-fecal coliforms such as Hafnia alvei, which could form typical colonies on FCA and VRBL. Recovery of cold-stressed Escherichia coli in mashed potatoes on FCA was about 1 log unit lower than that with VRBL. When the FCA method was compared with standard VRBL for enumeration of fecal coliforms, based on counting carried out on 170 different food samples, results were not significantly different (P > 0.05). Based on 203 typical identified colonies selected as found on VRBL and FCA, the latter medium appears to allow the enumeration of more true fecal coliforms and has higher performance in certain ways (specificity, sensitivity, and negative and positive predictive values) than VRBL. Most colonies clearly identified on both media were E. coli and H. alvei, a non-fecal coliform. Therefore, the replacement of fecal coliform enumeration by E. coli enumeration to estimate food sanitary quality should be recommended.

Distribution of Coliphages in Various Foods

1986 ◽  
Vol 49 (12) ◽  
pp. 944-951 ◽  
Author(s):  
J. E. KENNEDY ◽  
C. I. WEI ◽  
J. L. OBLINGER
Keyword(s):  
Escherichia Coli ◽  
Food Samples ◽  
Fecal Coliforms ◽  
Bacterial Indicators ◽  
Processed Meats ◽  
E Coli ◽  
Plate Counts ◽  
The Relationship

The distribution of coliphages in various foods and the relationship between the incidences of coliphages and bacterial indicators were investigated. A total of 120 food samples comprising twelve products and including fresh meats, shellfish, vegetables and processed meats, were analyzed for indigenous coliphages using Escherichia coli hosts C, C-3000 and B. Bacterial analyses included enumeration of E. coli, fecal coliforms and coliforms, as well as aerobic plate counts and Salmonella analyses. Coliphages were detected (≥10 PFU/100 g) in 56% of samples and eleven of twelve products. Coliphages, E. coli, fecal coliforms and coliforms were recovered at a level of at least 30 organisms per 100 g in 43, 43, 68 and 81% of samples, with overall mean recoveries of 13, 19, 93 and 4300 organisms/100 g, respectively. Highest and lowest recoveries of coliphages and E. coli were from fresh meats and vacuum-packaged processed meats, respectively. Significant nonparametric correlations between coliphages, E. coli, fecal coliforms and coliforms were found among all food samples.

Evaluation of the β-Glucuronidase Substrate 5-Bromo-4-Chloro-3-Indolyl-β-D-Glucuronide (X-GLUC) in a 24-Hour Direct Plating Method for Escherichia coli

1988 ◽  
Vol 51 (5) ◽  
pp. 402-404 ◽  
Author(s):  
ELON W. FRAMPTON ◽  
LAWRENCE RESTAINO ◽  
NANCY BLASZKO
Keyword(s):  
Escherichia Coli ◽  
Agar Medium ◽  
Plate Count ◽  
Light Illumination ◽  
Fluorogenic Substrate ◽  
Direct Plating ◽  
E Coli ◽  
Glucuronidase Activity ◽  
Plate Count Agar ◽  
Plating Method

A 24-h direct plating method for Escherichia coli using Peptone-Tergitol agar was used to compare the effectiveness of the chromogenic substrate 5-bromo-4-chloro-3-indolyl-β-D-glucuronide (X-GLUC) with the fluorogenic substrate 4-methylumbelliferyl-β-D-glucuronide (MUG) for β-glucuronidase activity. Values obtained for enumeration of two strains of E. coli recovered from artificially inoculated raw minced chicken (i.e., plating efficiencies on the inoculum, cells per g, and recovery percentages elated to those on Plate Count Agar) indicate that X-GLUC at 50 μg/ml was as effective as MUG in an agar medium. Unlike MUG, X-GLUC does not require ultraviolet light illumination, and the color reaction produced remains localized in the positive colonies.

The Anderson–Baird-Parker direct plating method versus the most probable number procedure for enumerating Escherichia coli in meats

1981 ◽  
Vol 27 (1) ◽  
pp. 147-149 ◽  
Author(s):  
M. K. Rayman ◽  
B. Aris
Keyword(s):  
Escherichia Coli ◽  
North American ◽  
Most Probable Number ◽  
Probable Number ◽  
Direct Plating ◽  
E Coli ◽  
Membrane Filters ◽  
The North ◽  
Plating Method

Comparison of the Anderson–Baird-Parker direct plating method (DP) and the North American most probable number procedure (MPN) for enumerating Escherichia coli in frozen meats revealed that the DP method is more precise and yields higher counts of E. coli than the MPN procedure. Any of three brands of membrane filters tested was suitable for use in the DP method.

Incidence of Fecal Coliforms and Serovars of Enteropathogenic Escherichia Coli in Naturally Contaminated Cheese

1988 ◽  
Vol 51 (5) ◽  
pp. 384-385 ◽  
Author(s):  
F. M. ABBAR
Keyword(s):  
Escherichia Coli ◽  
Fecal Coliform ◽  
Fecal Coliforms ◽  
Enteropathogenic Escherichia Coli ◽  
E Coli

A survey of 60 cheese samples from three different manufacturers and marketed in Mosul were analyzed during the summer of 1987 for fecal coliform counts and also for the presence of enteropathogenic Escherichia coli. Among these samples there was a wide variations in counts, which ranged from <10 to 26000/g while the average ranged from 500 to 14000/g. Only 43 E. coli isolates were recovered from the cheese. Four of them agglutinated with antisera used to screen for classical enteropathogenic sero types.

ICMSF methods studies. XIII. An international comparative study of the MPN procedure and the Anderson–Baird–Parker direct plating method for the enumeration of Escherichia coli biotype I in raw meats

1979 ◽  
Vol 25 (11) ◽  
pp. 1321-1327 ◽  
Author(s):  
M. K. Rayman ◽  
G. A. Jarvis ◽  
C. M. Davidson ◽  
S. Long ◽  
J. M. Allen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Comparative Study ◽  
Most Probable Number ◽  
Probable Number ◽  
Direct Plating ◽  
E Coli ◽  
Plating Method ◽  
International Comparative ◽  
Lower Variability ◽  
Raw Meats

The most probable number (MPN) and a direct membrane-plating (DP) method were compared for enumeration of Escherichia coli biotype I in raw meats by 11 laboratories. The DP method yielded higher counts of E. coli than the MPN method for frozen samples but neither method consistently gave higher counts for non-frozen samples. The DP method was less variable and gave a higher rate of detection of low numbers of E. coli in frozen samples. Despite the inability of the DP method to enumerate E. coli biotype II and intermediate types, which comprise only 3–5% of the Escherichia strains (Ewing 1972), the method is preferable to the MPN method for enumerating E. coli in raw meats because of its lower variability, better recovery from frozen samples, rapidity, decreased requirement for media, and decreased costs for analysts' time.

scholarly journals Marine Bacteria Cause False-Positive Results in the Colilert-18 Rapid Identification Test for Escherichia coli in Florida Waters

2002 ◽  
Vol 68 (2) ◽  
pp. 539-544 ◽  
Author(s):  
John M. Pisciotta ◽  
Damon F. Rath ◽  
Paul A. Stanek ◽  
D. Michael Flanery ◽  
Valerie J. Harwood
Keyword(s):  
Escherichia Coli ◽  
False Positive ◽  
Fecal Coliform ◽  
Membrane Filtration ◽  
False Positives ◽  
Fecal Coliforms ◽  
Marine Waters ◽  
E Coli ◽  
Marine Samples ◽  
Positive Results

ABSTRACT The Colilert-18 system for enumeration of total coliforms and Escherichia coli is approved by the U.S. Environmental Protection Agency for use in drinking water analysis and is also used by various agencies and research studies for enumeration of indicator organisms in fresh and saline waters. During monitoring of Pinellas County, Fla., marine waters, estimates of E. coli numbers (by Colilert-18) frequently exceeded fecal coliform counts (by membrane filtration) by 1 to 3 orders of magnitude. Samples from freshwater sites did not display similar discrepancies. Fecal coliforms, including E. coli, could be cultured from 100% of yellow fluorescent wells (denoting E. coli-positive results) inoculated with freshwater samples but could be cultured from only 17.1% of the “positive” wells inoculated with marine samples. Ortho-nitrophenyl-β-d-galactopyranoside (ONPG)-positive or 4-methylumbelliferyl-β-d-glucuronide (MUG)-positive noncoliform bacteria were readily cultured from Colilert-18 test wells inoculated with marine samples. Filtered cell-free seawater did not cause false positives. Coculture preparations of as few as 5 CFU of Vibrio cholerae (ONPG positive) and Providencia sp. (MUG positive) ml−1 inoculated into Colilert-18 caused false-positive E. coli results. Salinity conditions influenced coculture results, as the concentration of coculture inoculum required to cause false positives in most wells increased from about 5 CFU ml−1 in seawater diluted 1:10 with freshwater to ≈5,000 CFU ml−1 in seawater diluted 1:20 with freshwater. Estimated E. coli numbers in various marine water samples processed at the 1:10 dilution ranged from 10 to 7,270 CFU�100 ml−1, while E. coli numbers in the same samples processed at the 1:20 dilution did not exceed 40 CFU�100 ml−1. The lower estimates of E. coli numbers corresponded well with fecal coliform counts by membrane filtration. This study indicates that assessment of E. coli in subtropical marine waters by Colilert-18 is not accurate when the recommended 1:10 sample dilution is used. The results suggest that greater dilution may diminish the false-positive problem, but further study of this possibility is recommended.

Seasonal Variation in the Fecal Coliform Population of Louisiana Oysters and its Relationship to Microbiological Quality

1987 ◽  
Vol 50 (7) ◽  
pp. 545-549 ◽  
Author(s):  
DIANE PAILLE ◽  
CAMERON HACKNEY ◽  
LAWERENCE REILY ◽  
MARY COLE ◽  
MARILYN KILGEN
Keyword(s):  
Escherichia Coli ◽  
Seasonal Variation ◽  
Antimicrobial Agent ◽  
Significant Relationship ◽  
Fecal Coliform ◽  
Microbiological Quality ◽  
Fecal Coliforms ◽  
Sewage Pollution ◽  
Klebsiella Species ◽  
E Coli

Seasonal variation was observed in the type of bacteria which comprised the fecal coliform population of oysters. Escherichia coli was the principal fecal coliform when water temperatures were below 22°C. Conversely, Klebsiella sp. predominated during the summer months. No significant relationship was observed between levels of E. coli and enterococci and non-E. coli fecal coliforms in oysters. Fecal coliform and E. coli levels were significantly (p >0.001) related in water. Klebsiella sp. isolated from oysters demonstrated considerably less multiple antimicrobial agent resistance than clinical isolates of K. pneumoniae. Fecal coliform-positive Klebsiella species had characteristics of environmental organisms. Results of this study suggest that high levels of non-E coli fecal coliforms in oysters harvested in the summer from beds meeting the fecal coliform water standard are not indicative of sewage pollution. Furthermore, it is suggested that the safety indicator in the guideline for oyster meats should be changed form fecal coliforms to E. coli.

A Direct Plating Method for Estimating Populations of Escherichia coli O157 in Bovine Manure and Manure-Based Materials†

2008 ◽  
Vol 71 (11) ◽  
pp. 2233-2238 ◽  
Author(s):  
ELAINE D. BERRY ◽  
JAMES E. WELLS
Keyword(s):  
Escherichia Coli ◽  
Soil Amendments ◽  
Most Probable Number ◽  
Escherichia Coli O157 ◽  
Surface Material ◽  
Potassium Tellurite ◽  
Probable Number ◽  
Direct Plating ◽  
E Coli ◽  
Plating Method

Escherichia coli O157:H7 outbreaks associated with produce consumption have brought attention to livestock manures and manure-based soil amendments as potential sources of pathogens for the contamination of these crops. Procedures for enumeration of E. coli O157:H7 are needed to assess the risks of transmission from these manures and their by-products. A direct plating method employing spiral plating onto CHROMagar O157 was investigated for enumeration of E. coli O157:H7 in feedlot surface material, aged bovine manure, bovine manure compost, and manure-amended soil. In studies utilizing samples spiked with a five-strain cocktail of E. coli O157:H7 at levels ranging from 102 to 105 CFU/g of sample, there were strong correlations between the observed and predicted levels of this pathogen. Although the addition of 2.5 mg/liter potassium tellurite and 5 mg/liter novobiocin made the medium more restrictive, these amendments enhanced the ability to identify and enumerate E. coli O157:H7 in feedlot surface material, which contained a higher proportion of fresh feces than did the other three sample types and therefore higher levels of interfering bacterial microflora. The spiral plating method was further assessed to determine its ability to enumerate E. coli O157:H7 in naturally contaminated feedlot surface material. Comparison of E. coli O157:H7 counts in feedlot surface material obtained by the spiral plating method and a most probable number technique were well correlated. We conclude that direct spiral plating onto CHROMagar O157 is effective for estimating E. coli O157: H7 levels in a variety of manures and manure-containing sample types to a lower detection limit of 200 CFU/g. The method has application for determining E. coli O157:H7 concentrations in manures and composts before their sale and use as soil amendments and for measuring the effectiveness of manure treatment processes to reduce or inactivate this pathogen.

Microbiological performance and salmonella dynamics in a wastewater depuration pond system of southeastern spain

1995 ◽  
Vol 31 (12) ◽  
pp. 239-248 ◽  
Author(s):  
Ana Emparanza-Knörr ◽  
Francisco Torrella
Keyword(s):  
Fecal Coliform ◽  
No Reduction ◽  
Agar Medium ◽  
Microbiological Quality ◽  
Total Coliform ◽  
Fecal Coliforms ◽  
Selective Media ◽  
E Coli ◽  
The Village ◽  
Final Effluent

The Salmonella presence and the microbiological quality indicators, total and fecal coliforms and coliphages of E. coli C, have been studied in a overloaded wastewater lagoon system treating urban wastewatrers of the village of Guardamar del Segura (Alicante, Spain). Classical microbiological technology to detect salmonellae was used, including pre-enrichment, enrichment, selective media plating and biochemical and serological confirmation. Water was physicochemically characterized according to COD, SS, temperature, pH and dissolved oxygen. The selective migration step through Rappaport-Vassiliadis semisolid agar medium was essential for the consistent detection of Salmonella in the different lagoon effluents. Total and fecal coliform levels of up to 105-106 MPN/100 ml were detected in the final effluent. High coliphage concentrations of 103-104 pfu/ml were also found in the effluent waters. Salmonella was always detected in 100 ml samples and eventually reached an order of value of 103 MPN/100 ml. Total coliform reduction was higher in the anaerobic ponds whereas fecal coliforms were more efficiently eliminated in the facultative (mostly “anoxic”) lagoons. Coliphage reduction was higher in the facultative lagoons when compared to the anaerobic ponds. On many occasions, no reduction or eventual increment of the concentration of salmonellae was detected in the effluents from the anaerobic ponds compared to concentrations of the patohogen in the influent raw wasterwaters. The possibility exists for a capacity of Salmonella to multiply in the anoxic phase of the wastewater treatment, but the presence of microorganisms in raw sewage waters which could maskSalmonella detection with the enrichment methodology employed cannot be ruled out.

Sequence of Colonization Determines the Composition of Mixed Biofilms by Escherichia coli O157:H7 and O111:H8 Strains†

2015 ◽  
Vol 78 (8) ◽  
pp. 1554-1559 ◽  
Author(s):  
RONG WANG ◽  
NORASAK KALCHAYANAND ◽  
JAMES L. BONO
Keyword(s):  
Escherichia Coli ◽  
Foodborne Pathogens ◽  
Early Stage ◽  
Critical Role ◽  
The United States ◽  
Food Samples ◽  
E Coli ◽  
Cell Percentage ◽  
Composition And Structure ◽  
Biofilm Development

Bacterial biofilms are one of the potential sources of cross-contamination in food processing environments. Shiga toxin–producing Escherichia coli (STEC) O157:H7 and O111:H8 are important foodborne pathogens capable of forming biofilms, and the coexistence of these two STEC serotypes has been detected in various food samples and in multiple commercial meat plants throughout the United States. Here, we investigated how the coexistence of these two STEC serotypes and their sequence of colonization could affect bacterial growth competition and mixed biofilm development. Our data showed that E. coli O157:H7 strains were able to maintain a higher cell percentage in mixed biofilms with the co-inoculated O111:H8 companion strains, even though the results of planktonic growth competition were strain dependent. On solid surfaces with preexisting biofilms, the sequence of colonization played a critical role in determining the composition of the mixed biofilms because early stage precolonization significantly affected the competition results between the E. coli O157:H7 and O111:H8 strains. The precolonizer of either serotype was able to outgrow the other serotype in both planktonic and biofilm phases. The competitive interactions among the various STEC serotypes would determine the composition and structure of the mixed biofilms as well as their potential risks to food safety and public health, which is largely influenced by the dominant strains in the mixtures. Thus, the analysis of mixed biofilms under various conditions would be of importance to determine the nature of mixed biofilms composed of multiple microorganisms and to help implement the most effective disinfection operations accordingly.

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