scholarly journals Rapid single-tube confirmatory test forEscherichia coli

1982 ◽  
Vol 89 (1) ◽  
pp. 149-154 ◽  
Author(s):  
J. L. Smith ◽  
S. Rockliff
Keyword(s):  
Membrane Filtration ◽  
Confirmatory Test ◽  
Most Probable Number ◽  
Standing Committee ◽  
Traditional Methods ◽  
Probable Number ◽  
Single Tube ◽  
Laboratory Service ◽  
The Public ◽  
E Coli

SUMMARYA single-tube confirmatory test that allows a result to be obtained in 4 h has been developed from the single-tube confirmatory test recommended by the Joint Committee of the Public Health Laboratory Service and the Standing Committee of Analysts (PHLS/SCA, 1980). A variety of river, lake and reservoir samples were examined for the presence ofE. coliusing either most probable number (MPN) or membrane filtration (MF) technique, and the PHLS/SCA recommended confirmatory medium (LTMB) was evaluated against traditional methods. To improve the performance of LTMB, the medium was modified and this modified medium when used in 0·1 ml volumes and incubated for 4 h at 44°C provided 99% agreement with traditional methods.

scholarly journals Mechanically Ventilated Broiler Sheds: a Possible Source of Aerosolized Salmonella, Campylobacter, and Escherichia coli

2009 ◽  
Vol 75 (23) ◽  
pp. 7417-7425 ◽  
Author(s):  
H. N. Chinivasagam ◽  
T. Tran ◽  
L. Maddock ◽  
A. Gale ◽  
P. J. Blackall
Keyword(s):  
Escherichia Coli ◽  
Most Probable Number ◽  
Production Cycle ◽  
Airborne Bacteria ◽  
Probable Number ◽  
Mechanically Ventilated ◽  
The Public ◽  
E Coli ◽  
Poultry Farms ◽  
Low Levels

ABSTRACT This study assessed the levels of two key pathogens, Salmonella and Campylobacter, along with the indicator organism Escherichia coli in aerosols within and outside poultry sheds. The study ranged over a 3-year period on four poultry farms and consisted of six trials across the boiler production cycle of around 55 days. Weekly testing of litter and aerosols was carried out through the cycle. A key point that emerged is that the levels of airborne bacteria are linked to the levels of these bacteria in litter. This hypothesis was demonstrated by E. coli. The typical levels of E. coli in litter were ∼108 CFU g−1 and, as a consequence, were in the range of 102 to 104 CFU m−3 in aerosols, both inside and outside the shed. The external levels were always lower than the internal levels. Salmonella was only present intermittently in litter and at lower levels (103 to 105 most probable number [MPN] g−1) and consequently present only intermittently and at low levels in air inside (range of 0.65 to 4.4 MPN m−3) and once outside (2.3 MPN m−3). The Salmonella serovars isolated in litter were generally also isolated from aerosols and dust, with the Salmonella serovars Chester and Sofia being the dominant serovars across these interfaces. Campylobacter was detected late in the production cycle, in litter at levels of around 107 MPN g−1. Campylobacter was detected only once inside the shed and then at low levels of 2.2 MPN m−3. Thus, the public health risk from these organisms in poultry environments via the aerosol pathway is minimal.

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.

Effect of Stress and Resuscitation on Recovery of Indicator Bacteria from Foods Using Hydrophobic Grid-Membrane Filtration

1982 ◽  
Vol 45 (14) ◽  
pp. 1326-1331 ◽  
Author(s):  
M. H. BRODSKY ◽  
P. BOLESZCZUK ◽  
P. ENTIS
Keyword(s):  
Membrane Filtration ◽  
Membrane Filter ◽  
Indicator Bacteria ◽  
Poultry Meat ◽  
Most Probable Number ◽  
Indicator Organism ◽  
Plate Method ◽  
Probable Number ◽  
E Coli ◽  
Raw Poultry

The effects of stress and resuscitation on selective enumeration of coliforms, Escherichia coli and enterococci in mechanically deboned raw poultry meat and in dried foods were studied using a hydrophobic grid membrane filter (HGMF) technique. The effects of four different stresses, sublethal heating, freezing, acid pH and drying, were examined on 25 to 30 samples per indicator organism for each type of stress. Counts obtained with resuscitation were compared statistically to direct selective counts for each series of samples. Also, both the direct and resuscitative HGMF results were compared to a 5-tube most probable number method for coliforms and E. coli and to a spread plate method for the enterococci. The use of appropriate resuscitation procedures not only produced a significant increase in counts over the direct HGMF procedure, but also yielded HGMF results that were statistically equivalent to those obtained by conventional methods.

Detection of Escherichia coli in Drinking Water Sources of Filter Units and Supply Water

2016 ◽  
Vol 19 (2) ◽  
pp. 206-210
Author(s):  
Arman Chowdhory ◽  
Nafisa Kabir ◽  
Md Mazharul Islam Chowdhury ◽  
Jakir Ahmed Chowdhury
Keyword(s):  
Drinking Water ◽  
Membrane Filtration ◽  
Tap Water ◽  
Pharmaceutical Journal ◽  
Water Sources ◽  
Most Probable Number ◽  
Probable Number ◽  
E Coli ◽  
Bacteriological Test ◽  
Positive Results

The identification of coliforms has been extensively used as an indicator of drinking water quality. The study was aimed to identify the presence or absence of E. coli from drinking water. Samples were collected from different filtration units and tap water sources of an institution in Dhaka city. All the samples were tested through presumptive, confirmed and completed bacteriological test through MPN (most probable number) using 3 sets of lactose broth (LB) media and MF (membrane filtration) technique using bacteriological filter and nutrient agar media to find out the CFU (colony forming unit). About 10% of samples showed positive results for E. coli in completed test, and also gave positive results in confirmed test and gram staining; having no more than 1100 MPN per 100 ml for samples of filter taps but the source water remained negative.Bangladesh Pharmaceutical Journal 19(2): 206-210, 2016

Enumeration of Indicator Organisms in Foods Using the Automated Hydrophobic Grid-Membrane Filter Technique

1982 ◽  
Vol 45 (4) ◽  
pp. 292-296 ◽  
Author(s):  
M. H. BRODSKY ◽  
P. ENTIS ◽  
A. N. SHARPE ◽  
G. A. JARVIS
Keyword(s):  
Membrane Filtration ◽  
Membrane Filter ◽  
Optimal Recovery ◽  
Most Probable Number ◽  
Indicator Organisms ◽  
Probable Number ◽  
E Coli ◽  
Stressed Cells ◽  
And Staphylococcus Aureus ◽  
Filtration Technique

The automated HGMF technique was compared against accepted traditional methodology for the recovery and enumeration of coliforms, Escherichia coli, enterococci and Staphylococcus aureus from a variety of naturally and artificially contaminated foods. The overall ratios of recovery of the HGMF relative to conventional methods were 0.88 for coliforms, 0.80 for E. coli, 0.81 for enterococci and 0.80 for S. aureus. Our results suggest that the automated HGMF system is a viable alternative to conventional most-probable-number and spread plate techniques for the isolation and enumeration of foodborne microorganisms on selective media; however, consideration must be given to modifying procedures for the optimal recovery of stressed cells by this automated membrane filtration technique.

A Most Probable Number Method for the Enumeration of Legionella Bacteria in Water

1991 ◽  
Vol 24 (2) ◽  
pp. 143-147 ◽  
Author(s):  
N. A. Grabow ◽  
R. Kfir ◽  
W. O. K. Grabow
Keyword(s):  
Water Samples ◽  
Membrane Filtration ◽  
Quantitative Method ◽  
Fluorescent Antibody ◽  
Most Probable Number ◽  
Probable Number ◽  
Comparative Tests ◽  
Antibody Staining ◽  
Direct Fluorescent Antibody ◽  
Yeast Extract Agar

A new quantitative method for the enumeration of Legionella bacteria in water is described. Appropriate tenfold serial dilutions of water samples concentrated by membrane filtration are plated in triplicate on buffered charcoal yeast extract agar. After incubation for 3 days representative smears from individual plates are tested for the presence of Legionella by direct fluorescent antibody staining. The number of positive plates in each dilution is used to calculate the Legionella count by means of conventional most probable number statistics. In comparative tests on a variety of water samples this method yielded significantly higher counts than previously used procedures.

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.

Reduction of Microorganisms on Citrus Fruit Surfaces during Packinghouse Processing

1998 ◽  
Vol 61 (7) ◽  
pp. 903-906 ◽  
Author(s):  
STEVEN PAO ◽  
G. ELDON BROWN
Keyword(s):  
Test Organism ◽  
Citrus Fruit ◽  
Microbial Populations ◽  
Most Probable Number ◽  
Probable Number ◽  
E Coli ◽  
Plate Counts ◽  
High Level ◽  
Inoculation Study ◽  
Fruit Surface

Citrus fruit surface microbial populations were evaluated following various packingline processes of seven Florida commercial packinghouses. At each packinghouse, six fruits (oranges or tangerines) were collected at each of four sampling points. The sampling was conducted in duplicate; thus, 336 fruit were evaluated during this survey. Average aerobic plate counts and yeast and mold counts on fruit surfaces before washing were about 4.0 log CFU/cm2 and 3.3 log CFU/cm2, respectively, and were reduced to 2.1 log CFU/cm2 and 1.3 log CFU/cm2, respectively, by packinghouse processing. Waxing alone reduced the average fruit surface aerobic plate counts and coliform counts from 3.7 log CFU/cm2 and 35.2 most probable number (MPN)/cm2, respectively, to 2.6 log CFU/cm2 and 1.4 MPN/cm2. No Escherichia coli was recovered from fruit at the end of packinghouse processing, and no salmonellae were found on fruit during the entire processing. In an inoculation study to test the effect of packinghouse processes, test organism E. coli was applied to fruit to achieve a high level (4.8 log CFU/cm2) of contamination. The average E. coli count was reduced about 2.4 log cycles by washing and rinsing with potable water (40 psi, 25 °C) for about 30 s. The combination of washing and waxing significantly reduced the inoculated level of E. coli from 4.8 to 1.4 log CFU/cm2.

Comparative study of membrane filtration and enrichment media for the isolation and enumeration of Pseudomonas aeruginosa from sewage, surface water, and swimming pools

1985 ◽  
Vol 31 (8) ◽  
pp. 686-692 ◽  
Author(s):  
A. H. Havelaar ◽  
M. During ◽  
E. H. M. Delfgou-Van Asch
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Membrane Filtration ◽  
Culture Media ◽  
Polluted Water ◽  
Most Probable Number ◽  
Cellulose Ester ◽  
Swimming Pools ◽  
Probable Number ◽  
Membrane Filters ◽  
Swimming Water

The recovery of Pseudomonas aeruginosa on several selective culture media was tested using raw sewage and secondary sewage effluent samples as well as spiked chlorinated imitation swimming water and samples from whirlpools. mPA-medium B gave good recovery of both vital and chlorine-injured P. aeruginosa and selectivity was greater than 90% when analysing whirlpool samples. It is therefore the medium recommended for examination of chlorinated swimming pools. When analysing sewage polluted water with the mPA-B medium, reduced selectivity was noted from low verification rates and from overgrowth by competitive flora. A modified medium (mPA-D; addition of cetrimide, omission of sulphapyridine and actidione) was more selective and sufficiently recovered noninjured cells. Chlorine-injured cells were completely inhibited, however. C-390 (9-chloro-9-(4-diethylaminophenyl)-10-phenylacridan) was confirmed to be highly selective for P. aeruginosa when used in spread plates at a concentration of 30 μg/mL; P. aeruginosa was slightly inhibited. However, the medium could not be used with conventional membrane filtration techniques, because cellulose ester filters interfered with the selective action of C-390. Selectivity could be improved by using Gelman Tuffryn (polysulphone) filters and increasing the C-390 concentration to 120 μg/mL. At this concentration, however, the medium was strongly inhibitory to P. aeruginosa; resuscitation only partially improved recovery. Two other membrane filtration media were tested. Both cetrimide – nalidixic acid agar and Drake's medium No. 19 were inhibitory to chlorine-injured cells. Several types of membrane filters were tested and there was little difference between them. In the most-probable-number technique, recovery of P. aeruginosa was shown to be excellent when using asparagine broth. Malachite green broth was strongly inhibitory to chlorine-injured P. aeruginosa.

The relationship between three potential pathogens and pollution indicator organisms in Nova Scotian coastal waters

1983 ◽  
Vol 29 (10) ◽  
pp. 1261-1269 ◽  
Author(s):  
W. J. Robertson ◽  
R. S. Tobin
Keyword(s):  
Membrane Filtration ◽  
Indicator Bacteria ◽  
Fecal Coliforms ◽  
Most Probable Number ◽  
Indicator Organisms ◽  
Fecal Indicator ◽  
Filtration Method ◽  
Probable Number ◽  
Pollution Indicator ◽  
Nova Scotian

Fifteen stations, in two estuaries, along the Northumberland Strait of Nova Scotia were examined between June and September 1981 for a relationship between the concentrations of commonly monitored fecal indicator bacteria and the potential pathogens Candida albicans, Pseudomonas aeruginosa, and Vibrio parahaemolyticus. Increased densities of these three organisms were usually associated with high densities of indicator bacteria. Whereas C. albicans and P. aeruginosa occur in human fecal wastes, V. parahaemolyticus is indigenous to the marine environment and positively responds to elevated nutrient levels in sewage. There is also some evidence that these bacteria survive as long or longer in marine waters than the common indicator bacteria. While membrane-filtration techniques for the enumeration of C. albicans and P. aeruginosa proved satisfactory, a V. parahaemolyticus membrane-filtration method lacked specificity and was supplemented by a most-probable-number method. In marine recreational and shellfish waters, these three organisms could complement fecal coliforms and fecal streptococci as indicators of human fecal contamination.

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