Evaluation of Four Pea (Pisum sativum) Cultivars in PE-2 Medium for the MPN Enumeration of Anaerobic Spore-Forming Organisms

1997 ◽  
Vol 60 (12) ◽  
pp. 1574-1576 ◽  
Author(s):  
O. A. OGUNRINOLA ◽  
C. G. EDWARDS ◽  
P. M. DAVIDSON
Keyword(s):  
Pisum Sativum ◽  
Anaerobic Bacteria ◽  
False Positives ◽  
Clostridium Butyricum ◽  
The Other ◽  
Most Probable Number ◽  
Clostridium Sporogenes ◽  
Probable Number ◽  
Cooked Meat

Untreated ‘Alaska’ seed peas have traditionally been used to prepare PE-2 medium, a medium used to recover anaerobic bacteria. Three cultivars of seed peas, ‘Columbian’, ‘Yellow’, and ‘Scotch’ were compared to the cultivar ‘Alaska’ peas in PE-2 for recovery of Clostridium butyricum ATCC 860, Clostridium sporogenes ATCC 7955/NCA 3679, and Thermoanerobacterium thermosaccharolyticum ATCC 25773 determined by using the most probable number (MPN) technique. Organisms were grown in cooked meat medium (CMM) and enumerated by the three-tube MPN method in PE-2 media incubated at 37°C for 48 h. Recovery of C. butyricum and T. thermosaccharolyticum grown in homogenates of commercial cream-style corn and vegetable beef soup were also evaluated. Similar recovery of organisms from stock cultures or from foodstuffs were observed in PE-2 prepared with three of the pea cultivars (‘Alaska’, ‘Columbian’, and ‘Yellow’). While the ‘Scotch’ cultivar PE-2 medium yielded recoveries comparable to PE-2 prepared with the other pea cultivars, turbid tubes were occasionally observed from which viable microorganisms could not be recovered. This cultivar is therefore not recommended due to the probability of yielding false positives in the MPN technique.

scholarly journals Chlorine Dioxide Inactivation ofCryptosporidium parvum Oocysts and Bacterial Spore Indicators

2001 ◽  
Vol 67 (7) ◽  
pp. 2993-3001 ◽  
Author(s):  
Christian P. Chauret ◽  
Chris Z. Radziminski ◽  
Michael Lepuil ◽  
Robin Creason ◽  
Robert C. Andrews
Keyword(s):  
Chlorine Dioxide ◽  
Most Probable Number ◽  
Inactivation Kinetics ◽  
Clostridium Sporogenes ◽  
Probable Number ◽  
Waterborne Pathogen ◽  
Viability Assay ◽  
The Relationship ◽  
Different Sources

ABSTRACT Cryptosporidium parvum, which is resistant to chlorine concentrations typically used in water treatment, is recognized as a significant waterborne pathogen. Recent studies have demonstrated that chlorine dioxide is a more efficient disinfectant than free chlorine against Cryptosporidium oocysts. It is not known, however, if oocysts from different suppliers are equally sensitive to chlorine dioxide. This study used both a most-probable-number–cell culture infectivity assay and in vitro excystation to evaluate chlorine dioxide inactivation kinetics in laboratory water at pH 8 and 21�C. The two viability methods produced significantly different results (P < 0.05). Products of disinfectant concentration and contact time (Ct values) of 1,000 mg � min/liter were needed to inactivate approximately 0.5 log10 and 2.0 log10 units (99% inactivation) of C. parvumas measured by in vitro excystation and cell infectivity, respectively, suggesting that excystation is not an adequate viability assay. Purified oocysts originating from three different suppliers were evaluated and showed marked differences with respect to their resistance to inactivation when using chlorine dioxide.Ct values of 75, 550, and 1,000 mg � min/liter were required to achieve approximately 2.0 log10 units of inactivation with oocysts from different sources. Finally, the study compared the relationship between easily measured indicators, includingBacillus subtilis (aerobic) spores andClostridium sporogenes (anaerobic) spores, and C. parvum oocysts. The bacterial spores were found to be more sensitive to chlorine dioxide than C. parvum oocysts and therefore could not be used as direct indicators of C. parvum inactivation for this disinfectant. In conclusion, it is suggested that future studies address issues such as oocyst purification protocols and the genetic diversity of C. parvum, since these factors might affect oocyst disinfection sensitivity.

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.

Differentiation of Clostridium perfringens from Related Clostridia in Iron Milk Medium

1985 ◽  
Vol 48 (2) ◽  
pp. 130-134 ◽  
Author(s):  
CARLOS ABEYTA ◽  
ANITA MICHALOVSKIS ◽  
MARLEEN M. WEKELL
Keyword(s):  
Clostridium Perfringens ◽  
High Selectivity ◽  
Positive Response ◽  
Food Samples ◽  
Gas Production ◽  
The Other ◽  
Plate Count ◽  
Most Probable Number ◽  
Probable Number ◽  
Positive Results

The stormy fermentation reaction of Clostridium perfringens in iron milk medium was compared to that of several C. perfringens-like strains. These clostridia, C. barati, C. perenne, C. absonum, and C. paraperfringens are very similar to C. perfringens on the basis of certain biochemical reactions and, consequently, are often difficult to distinguish from C. perfringens. Furthermore, these related clostridia may also be present in foods. Results of this study demonstrate that after 18 h of incubation at 45°C, only C. perfringens gave a positive reaction in iron milk with inocula as low as 22 cells/g. Some of the other strains began to show only gas production at 18 h. After 24 to 42 h some strains gave positive results and after 72 h all were positive. Enumeration of C. perfringens from food samples in iron milk medium by a 3-tube most probable number (MPN) technique gave similar results to enumeration by plate count using Shahidi-Ferguson Perfringens (SFP) agar. Furthermore, a rapid positive response occurred after only 2 and 3 h incubation of iron milk inoculated with 108 and 107 cells/ml, respectively. The high selectivity, ease of identification and rapid growth of C. perfringens in iron milk make the iron milk MPN procedure a valuable assay for accurate enumeration and differentiation of C. perfringens from related Clostridia in food products.

Microbial Evaluation of Spanish Potato Omelette and Cooked Meat Samples in University Restaurants

2000 ◽  
Vol 63 (9) ◽  
pp. 1273-1276 ◽  
Author(s):  
J. M. SORIANO ◽  
H. RICO ◽  
J. C. MOLTÓ ◽  
J. MAÑES
Keyword(s):  
Control Point ◽  
Most Probable Number ◽  
Probable Number ◽  
Pork Sausage ◽  
E Coli ◽  
Meat Samples ◽  
Cooked Meat ◽  
Group D ◽  
Coagulase Positive Staphylococci ◽  
Lancefield Group

The focus of this study was to evaluate the microbial quality of Spanish potato omelette and cooked meat samples including pork loin, chicken croquettes, long pork sausage, chicken breast, and meatballs from University restaurants. Microbiological analyses of Spanish potato omelette and cooked meat samples resulted in aerobic plate counts from &lt;1.00 to 2.90 and from &lt;1.00 to 6.04 log10 CFU g−1, respectively. Total coliforms ranged from &lt;3 to 43 most probable number (MPN) g−1 and from &lt;3 to &gt;2,400 MPN g−1 for Spanish potato omelette and meat products, respectively. Escherichia coli, coagulase-positive staphylococci, and Lancefield group-D streptococci were detected in 1.7%, 3.5%, and 12.9% of Spanish potato omelette samples, respectively. For cooked meat samples, 8.8%, 7.6%, and 24.6% contained E. coli, coagulase-positive staphylococci, and Lancefield group-D streptococci, respectively. E. coli O157:H7, Salmonella spp., and Shigella spp. were not detected. Klebsiella pneumoniae, Klebsiella oxytoca, Citrobacter freundii, Enterobacter cloacae, and Serratia spp. were isolated from Spanish potato omelette samples. For cooked meat samples, C. freundii, E. cloacae, and Aeromonas hydrophila were detected. The results suggest that some handling practices should require more attention, and as a consequence, a hazard analysis and critical control point program should be developed and implemented.

ICMSF Methods Studies. XI. Collaborative/Comparative Studies on Determination of Coliforms Using the Most Probable Number Procedure1

1979 ◽  
Vol 42 (8) ◽  
pp. 638-644 ◽  
Author(s):  
J. H. SILLIKER ◽  
D. A. GABIS ◽  
A. MAY
Keyword(s):  
Comparative Studies ◽  
Confidence Limit ◽  
Collaborative Study ◽  
The Other ◽  
Most Probable Number ◽  
Probable Number ◽  
Collaborative Studies ◽  
Different Types ◽  
Confirmatory Tests

Results of two international collaborative studies on the MPN technique for determination of coliforms in foods are reported. Three methods involving use of different presumptive and confirmatory media were compared. Results of one collaborative study conducted among 15 laboratories using eight different types of inoculated foods showed differences among the laboratories as great as 3.3 log units. The greatest difference between confirmatory tests using different media was 0.5 log units. Results of the other collaborative study conducted among five laboratories using three types of naturally contaminated foods showed differences among the laboratories as great as 1.4 log units. The greatest difference between tests using different media was 0.2 log unit. Both studies showed that the 95% confidence limit for a single value reported by a given laboratory was ± 1 log unit or ± 0.45 log unit for a mean of five values. The second study showed that a major source of variation within laboratories was between replicate aliquots. The findings are discussed in terms of their significance with respect to the monitoring of microbiological specifications for food.

Enumeration of Enterobacteriaceae in Various Foods with a New Automated Most-Probable-Number Method Compared with Petrifilm and International Organization for Standardization Procedures

2008 ◽  
Vol 71 (2) ◽  
pp. 376-379 ◽  
Author(s):  
P. PAULSEN ◽  
C. BORGETTI ◽  
E. SCHOPF ◽  
F. J. M. SMULDERS
Keyword(s):  
International Organization ◽  
The Other ◽  
Most Probable Number ◽  
Average Difference ◽  
Detection Range ◽  
Probable Number ◽  
International Organization For Standardization ◽  
Glucose Agar ◽  
The Mean ◽  
Mean Differences

An automated most-probable-number (MPN) system (TEMPO, bioMérieux, Marcy l'Etoile, France) for enumeration of Enterobacteriaceae (EB) was compared with methods involving violet red bile glucose agar (VRBG) (International Organization for Standardization [ISO] method 21528-2) (ISO-VRBG) and Petrifilm (PF-EB). The MPN partitioning (three different volumes with 16 replicates of each) is done automatically in a disposable card. Bacterial growth is indicated by acid production from sugars, lowering the pH of the medium, and quenching the fluorescence of 4-methylumbelliferone. After incubation, the number of nonfluorescent wells is read in a separate device, and the MPN is calculated automatically. A total of 411 naturally contaminated foods were tested, and 190 were in the detection range for all methods. For these results, the mean (±standard deviation) counts were 2.540 ± 1.026, 2.547 ± 0.995, and 2.456 ± 1.014 log CFU/g for the ISO-VRBG, PF-EB, and automated MPN methods, respectively. Mean differences were −0.084 ± 0.460 log units for the automated MPN results compared with the ISO-VRBG and 0.007 ± 0.450 for the PF-EB results compared with the ISO-VRBG results. The automated MPN method tends to yield lower numbers and the PF-EB method tends to yield higher numbers than does the ISO-VRBG method (difference not significant; Kruskal-Wallis test, P = 0.102). Thus, the average difference was highest between the automated MPN method and the PF-EB method (−0.091 ± 0.512 log units). Differences between the automated MPN and ISO-VRBG results of &gt;1 log unit were detected in 3.4% of all samples. For 3.9% of the samples, one comparison yielded differences of &lt;1 log CFU/g and the other yielded &gt;1 but &lt;2 log CFU/g, which means that the differences are possibly &gt;1 log CFU/g. For the ISO-VRBG method, confirmation of isolates was necessary to avoid a bias due to the presence of oxidase-positive glucose-fermenting colonies. The automated MPN system yielded results comparable to those of the confirmed Enterobacteriaceae ISO-VRBG method but required only 24 h of analysis time.

A miniaturized counting technique for anaerobic bacteria

1976 ◽  
Vol 22 (12) ◽  
pp. 1728-1733 ◽  
Author(s):  
A. N. Sharpe ◽  
G. L. Pettipher ◽  
G. R. Lloyd
Keyword(s):  
Ascorbic Acid ◽  
Anaerobic Bacteria ◽  
Most Probable Number ◽  
Probable Number ◽  
Counting Technique

A miniaturized counting technique gave results as good as the pour-plate and Most Probable Number (MPN) techniques for enumeration of Clostridia spp. and anaerobic isolates from the gut. Highest counts were obtained when ascorbic acid (1%) and dithiothreitol (0.015%) were added to the reinforced clostridial medium used for counting. This minimized the effect of exposure to air before incubation. The miniature technique allowed up to 40 samples to be plated and incubated in one McIntosh-Filde's-type anaerobic jar, compared with 3 or 4 by the normal pour plate.

scholarly journals Farm Silage Facilities and Their Management for the Prevention of Anaerobic Bacteria Spore Contamination in Raw Milk

Dairy ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 500-514
Author(s):  
Fabio Abeni ◽  
Rosanna Marino ◽  
Francesca Petrera ◽  
Giulia Segati ◽  
Andrea Galli ◽  
...  
Keyword(s):  
Anaerobic Bacteria ◽  
Raw Milk ◽  
Most Probable Number ◽  
Facilities Management ◽  
Probable Number ◽  
Factors Affecting ◽  
Po Valley ◽  
Face Width ◽  
Bulk Milk ◽  
Spore Forming Bacteria

At feed-out, aerobic spoilage of silage enables an increase in anaerobic spore-forming bacteria (ANSB) that may enter the total mixed ration (TMR). The aim of our study was to understand whether in hot summers the silage structures and management may affect the level of ANSB in milk for long-ripening cheese production. A survey of silage facilities, management, and their relationships with silage, TMR, feces, and milk ANSB most probable number (MPN) content was conducted in the Po Valley during summer months. Silo type did not affect the mean ANSB, but only the wideness of their value distributions, with a narrow range for bags and a wider range for bunkers. The unloading equipment affected the ANSB count; the front-end loader with cutter was associated with a lower ANSB count—probably as a result of the reduced surface left after daily silage removal. Silo length and daily removed face width were the main factors affecting contamination of silage by spore-forming bacteria during summer, with longer silos and wider surface removal reducing ANSB contamination—probably as a consequence of reduced aerobic spoilage at the silage surface. The silage contamination by spore-forming bacteria within a log10 2 MPN g−1 allowed a low concentration of spore-forming bacteria at the farm bulk milk tank level. Fecal ANSB levels did not factor into the regression that explains the ANSB in farm milk. It has been found that silage facilities’ features and their management are an important first step to reduce the extent of ANSB contamination at the farm level.

Growth of Salmonella during Sprouting of Alfalfa Seeds Associated with Salmonellosis Outbreaks

2001 ◽  
Vol 64 (5) ◽  
pp. 618-622 ◽  
Author(s):  
D. S. STEWART ◽  
K. F. REINEKE ◽  
J. M. ULASZEK ◽  
M. L. TORTORELLO
Keyword(s):  
Enzyme Immunoassay ◽  
Water Samples ◽  
The Other ◽  
Most Probable Number ◽  
Calcium Hypochlorite ◽  
Probable Number ◽  
Two Samples ◽  
Rinse Water ◽  
Commercial Enzyme Immunoassay ◽  
Alfalfa Seeds

Growth of Salmonella was assessed during sprouting of naturally contaminated alfalfa seeds associated with two outbreaks of salmonellosis. Salmonella was determined daily in sprouts and sprout rinse water samples by a three-tube most probable number (MPN) procedure and a commercial enzyme immunoassay (EIA). Growth of Salmonella in the sprouts was reflected in the rinse water, and the MPNs of the two samples were generally in agreement within approximately 1 log. The results from EIA testing of sprouts and water samples were also in agreement. The pathogen was present in the seed at less than 1 MPN/g, and it increased in number to maximum population levels of 102 to 103 MPN/g in one seed lot and 102 to 104 MPN/g in the other seed lot. Maximum populations of the pathogen were apparent by day 2 of sprouting. These results show the ability of the pathogen to grow to detectable levels during the sprouting process, and they provide support for the recommendation to test the sprout water for the presence of pathogens 48 h after starting seed sprouting. The effectiveness of a 10-min, 20,0000-μg/ml (ppm) calcium hypochlorite treatment of the outbreak-associated seeds was studied. For both seed lots, the hypochlorite treatment caused a reduction, but not elimination, of Salmonella contamination in the finished sprouts. These results confirm the need to test each production batch for the presence of pathogens, even after 20,000 μg/ml (ppm) hypochlorite treatment of seeds, so that contaminated product is not distributed.

Partitioning of External and Internal Bacteria Carried by Broiler Chickens before Processing†

2007 ◽  
Vol 70 (9) ◽  
pp. 2056-2062 ◽  
Author(s):  
J. A. CASON ◽  
A. HINTON ◽  
J. K. NORTHCUTT ◽  
R. J. BUHR ◽  
K. D. INGRAM ◽  
...  
Keyword(s):  
Broiler Chickens ◽  
Pathogenic Bacteria ◽  
The Other ◽  
Most Probable Number ◽  
Processing Plant ◽  
Probable Number ◽  
E Coli ◽  
Sampling Locations ◽  
Peptone Water ◽  
Commercial Processing

Broiler chickens from the loading dock of a commercial processing plant were sampled to determine the incidence and counts of coliforms, Escherichia coli, and pathogenic bacteria. Feathers were removed by hand from ten 6-week-old chickens from each of seven different flocks and rinsed in 400 ml of 0.1% peptone water. Heads and feet were removed and rinsed, and the picked carcass was also rinsed, each in 200 ml. The ceca, colon, and crop were aseptically removed and stomached separately in 100 ml of peptone water. Campylobacter was present in six of the seven flocks. Salmonella was isolated from 50 of the 70 carcasses, with at least 2 positive carcasses in each flock, and five-tube most-probable-number (MPN) assays were performed on positive samples. Significantly (P &lt; 0.05) more coliforms and E. coli were found in the ceca than in the feathers, which in turn carried more than the other samples, but total external and internal counts were roughly equivalent. Counts of Campylobacter were higher in the ceca and colon than in the other samples. Salmonella was isolated in external samples from 46 of the 50 positive carcasses compared with 26 positive internal samples or 17 positives in the ceca alone. The total MPN of Salmonella was approximately equivalent in all samples, indicating that contamination was distributed through all external and internal sampling locations. Salmonella-positive samples did not carry higher counts of coliforms or E. coli, and there were no significant correlations between the indicators and pathogens in any sample. Campylobacter numbers in the ceca were correlated with Campylobacter numbers in the feathers and colon, but Salmonella numbers in those samples were not correlated. The pattern of bacterial contamination before processing is complex and highly variable.

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