Modeling Prevalence and Counts from Most Probable Number in a Bayesian Framework: An Application to Salmonella Typhimurium in Fresh Pork Sausages

2010 ◽  
Vol 73 (8) ◽  
pp. 1416-1422 ◽  
Author(s):  
URSULA GONZALES-BARRON ◽  
GRAINNE REDMOND ◽  
FRANCIS BUTLER
Keyword(s):  
United Kingdom ◽  
Confidence Interval ◽  
Salmonella Typhimurium ◽  
Assessment Model ◽  
Most Probable Number ◽  
Probable Number ◽  
Pork Sausage ◽  
The United Kingdom ◽  
Viable Cells ◽  
Pork Sausages

Prevalence and counts of Salmonella Typhimurium in fresh pork sausage packs at the point of retail were modeled by using Irish and United Kingdom retail surveys' data. A methodology for modeling a second-order distribution for the initial Salmonella concentration (λ0) in pork sausage at retail was presented considering the uncertainty originated from the most-probable-number (MPN) serial dilutions. A conditional probability of observing the tube counts given true Salmonella concentration in a contaminated pack was built from the MPN triplets of every sausage tested. A posterior distribution was then modeled under the assumption that the counts from each of the portions of sausage mix stuffed into casings (and subsequently packed) are Poisson distributed. In order to model the variability of λ0 among contaminated sausage packs, MPN uncertainties were propagated to a predefined lognormal distribution. Because the sausage samples from the Irish survey were frozen prior to MPN analysis (which is expected to cause reduction in viable cells), the resulting distribution for λ0 appeared greatly underestimated (mean: 0.514 CFU/g; 95% confidence interval [CI]: 0.02 to 2.74 CFU/g). The λ0 distribution produced with the United Kingdom survey data (mean: 69.7 CFU/g; 95% CI: 15 to 200 CFU/g) was, however, more conservative, and is to be used along with the fitted distribution for prevalence of Salmonella Typhimurium in pork sausage packs in Ireland (gamma[37.997, 0.0013]; mean: 0.046; 95% CI: 0.032 to 0.064) as the main inputs of a stochastic consumer-phase exposure assessment model.

Prevalence and Number of Salmonella in Irish Retail Pork Sausages†

2004 ◽  
Vol 67 (9) ◽  
pp. 1834-1839 ◽  
Author(s):  
C. BOUGHTON ◽  
F. C. LEONARD ◽  
J. EGAN ◽  
G. KELLY ◽  
P. O'MAHONY ◽  
...  
Keyword(s):  
Phage Type ◽  
Control Program ◽  
Multidrug Resistant ◽  
Most Probable Number ◽  
Probable Number ◽  
Pork Sausage ◽  
Pork Industry ◽  
Phage Types ◽  
Pork Sausages

A national Salmonella control program in the pork industry was enacted in Ireland in August 2002. This study was undertaken as part of a larger project investigating the role of pork as a source of human salmonellosis in Ireland. The objective of this survey was to assess the prevalence of Salmonella in Irish pork sausage at retail level. Samples, comprising branded prepacked sausages and loose sausages from supermarket meat counters and butcher shops, were collected from selected retail sites in four cities from October to December 2001 and from June to August 2002. A three-tube most-probable-number method was used to enumerate Salmonella in a selected number of samples that were positive by enrichment. Salmonella serotypes were detected in 4.4 and 1.7% of samples at each of the respective sampling periods, a level similar to those reported in other U.S. and U.K. studies. Isolates were characterized by serotype, phage type, and antimicrobial susceptibility. Eighteen (70%) were resistant to at least one antimicrobial, and 15 (58%) were resistant to four or more antimicrobials. Most of the isolates exhibited resistance to tetracycline. Five different phage types were detected. DT104 was the predominant phage type among Salmonella Typhimurium isolates. This study revealed that multidrug-resistant salmonellae are present in a proportion of Irish sausages and that further risk analysis work is necessary in order to quantify the risk posed to public health.

scholarly journals VIDAS Salmonella (SLM) Assay Method EasySLM with ChromID Salmonella (SM2) Agar

2009 ◽  
Vol 92 (6) ◽  
pp. 1861-1864 ◽  
Author(s):  
Ronald Johnson ◽  
John Mills ◽  
Judith Coln-Reveles ◽  
Thomas Hammack
Keyword(s):  
Peanut Butter ◽  
Reference Method ◽  
Black Pepper ◽  
Assay Method ◽  
Most Probable Number ◽  
Chicken Breast ◽  
Probable Number ◽  
Pork Sausage ◽  
Selective Enrichment ◽  
Matrix Extension

Abstract A method modification study was conducted for the VIDAS Salmonella (SLM) assay (AOAC Performance Tested MethodSM 020901) using the EasySLM method to validate a matrix extension for peanut butter. The VIDAS EasySLM method is a simple enrichment procedure compared to traditional Salmonella methods, requiring only pre-enrichment and a single selective enrichment media, Salmonella Xpress 2 (SX2) broth. SX2 replaces the two selective broths in traditional methods and eliminates the M broth transfer, incubation, and subsequent pooling of M broths prior to VIDAS assay. The validation study was conducted under the AOAC Research Institute Emergency Response Validation program. VIDAS SLM was compared to the U.S. Food and Drug Administration's Bacteriological Analytical Manual (FDA-BAM) method for detection of S. enterica ser. Typhimurium in peanut butter. All peanut butter samples were prepared, blind-coded, and shipped to the method developers' laboratory by Q Laboratories. In addition, Q Laboratories performed most probable number and reference method analyses on peanut butter samples. The VIDAS EasySLM ChromID Salmonella (SM2) Agar was previously validated in the Performance Tested Methods program for the detection of Salmonella in roast beef, raw ground pork, turkey, pork sausage, raw chicken breast, dry pet food, whole milk, ice cream, bagged spinach, shrimp (raw, peeled), raw cod, spent irrigation water, pecans, peanut butter, dry pasta, cake mix, ground black pepper, nonfat dry milk, liquid eggs, cantaloupe, and orange juice. In the matrix extension study for peanut butter, the VIDAS EasySLM method was shown to be equivalent to the appropriate reference culture procedure using both buffered peptone water pre-enrichment and the FDA-BAM lactose pre-enrichment in the two-step enrichment method with SX2 media. The current study extends the validation to include peanut butter.

scholarly journals Inequity in Access to Transplantation in the United Kingdom

2020 ◽  
Vol 15 (6) ◽  
pp. 830-842 ◽  
Author(s):  
Rishi Pruthi ◽  
Matthew L. Robb ◽  
Gabriel C. Oniscu ◽  
Charles Tomson ◽  
Andrew Bradley ◽  
...  
Keyword(s):  
Health Care ◽  
United Kingdom ◽  
Kidney Transplantation ◽  
Confidence Interval ◽  
Odds Ratio ◽  
Practice Patterns ◽  
Universal Health Care ◽  
The United Kingdom ◽  
Universal Health Care System ◽  
Universal Health

Background and objectivesDespite the presence of a universal health care system, it is unclear if there is intercenter variation in access to kidney transplantation in the United Kingdom. This study aims to assess whether equity exists in access to kidney transplantation in the United Kingdom after adjustment for patient-specific factors and center practice patterns.Design, setting, participants, & measurements In this prospective, observational cohort study including all 71 United Kingdom kidney centers, incident RRT patients recruited between November 2011 and March 2013 as part of the Access to Transplantation and Transplant Outcome Measures study were analyzed to assess preemptive listing (n=2676) and listing within 2 years of starting dialysis (n=1970) by center.ResultsSeven hundred and six participants (26%) were listed preemptively, whereas 585 (30%) were listed within 2 years of commencing dialysis. The interquartile range across centers was 6%–33% for preemptive listing and 25%–40% for listing after starting dialysis. Patient factors, including increasing age, most comorbidities, body mass index >35 kg/m2, and lower socioeconomic status, were associated with a lower likelihood of being listed and accounted for 89% and 97% of measured intercenter variation for preemptive listing and listing within 2 years of starting dialysis, respectively. Asian (odds ratio, 0.49; 95% confidence interval, 0.33 to 0.72) and Black (odds ratio, 0.43; 95% confidence interval, 0.26 to 0.71) participants were both associated with reduced access to preemptive listing; however Asian participants were associated with a higher likelihood of being listed after starting dialysis (odds ratio, 1.42; 95% confidence interval, 1.12 to 1.79). As for center factors, being registered at a transplanting center (odds ratio, 3.1; 95% confidence interval, 2.36 to 4.07) and a universal approach to discussing transplantation (odds ratio, 1.4; 95% confidence interval, 1.08 to 1.78) were associated with higher preemptive listing, whereas using a written protocol was associated negatively with listing within 2 years of starting dialysis (odds ratio, 0.7; 95% confidence interval, 0.58 to 0.9).ConclusionsPatient case mix accounts for most of the intercenter variation seen in access to transplantation in the United Kingdom, with practice patterns also contributing some variation. Socioeconomic inequity exists despite having a universal health care system.

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 <1.00 to 2.90 and from <1.00 to 6.04 log10 CFU g−1, respectively. Total coliforms ranged from <3 to 43 most probable number (MPN) g−1 and from <3 to >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.

Prevalence and Amounts of Salmonella Found on Raw California Inshell Pistachios

2016 ◽  
Vol 79 (8) ◽  
pp. 1304-1315 ◽  
Author(s):  
LINDA J. HARRIS ◽  
VANESSA LIEBERMAN ◽  
RUPINDER P. MASHIANA ◽  
EDWARD ATWILL ◽  
MAI YANG ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Gel Electrophoresis ◽  
Geometric Mean ◽  
Weighted Average ◽  
Pulsed Field Gel Electrophoresis ◽  
Most Probable Number ◽  
Contamination Source ◽  
Probable Number ◽  
Mechanical Abrasion ◽  
Tree Nuts

ABSTRACT After harvest, pistachios are hulled with mechanical abrasion and then separated in a float tank containing water; the nuts that float (~15%; floaters) and those that sink (~85%; sinkers) are dried and stored separately. To determine the prevalence of Salmonella in pistachios, a total of 3,966 samples (1,032 floaters and 2,934 sinkers) were collected within 4 months of the 2010, 2011, and 2012 harvests from storage silos (12 samples from each silo, in most cases) and were stored at 4°C; 100-g subsamples were enriched for the presence of Salmonella. Twenty-one of the floater samples and 11 of the sinker samples were positive for Salmonella: 2.0% prevalence (95% confidence interval [CI], 1.3 to 3.1%) and 0.37% prevalence (95% CI, 0.21 to 0.67%), respectively, for a weighted average prevalence of 0.61%. Levels of Salmonella were determined for positive samples using a most-probable-number (MPN) method with multiple 50-g, three 5.6-g, and three 0.56-g subsamples. Geometric mean levels of Salmonella in floaters and sinkers were 0.66 MPN/100 g (0.14 to 5.3 MPN/100 g) and 0.18 MPN/100 g (0.10 to 0.62 MPN/100 g), respectively. Seven different serovars were identified among the isolates, with nine pulsed-field gel electrophoresis fingerprints; as many as four serovars were isolated from some samples. Salmonella serovars Montevideo (44%), Enteritidis (19%), Senftenberg (16%), Worthington (12%), and Liverpool (9.4%) were most commonly isolated from the initial 100-g samples. The prevalence and levels of Salmonella in pistachios are within those observed for other tree nuts, but the limited number of serovars isolated suggests a narrow and persistent contamination source.

Relative Effectiveness of Selenite Cystine Broth, Tetrathionate Broth, and Rappaport-Vassiliadis Medium for the Recovery of Salmonella from Raw Flesh and Other Highly Contaminated Foods: Precollaborative Study

1995 ◽  
Vol 78 (2) ◽  
pp. 375-380 ◽  
Author(s):  
Geraldine A June ◽  
Patricia S Sherrod ◽  
Thomas S Hammack ◽  
R Miguel Amaguana ◽  
Wallace H Andrews
Keyword(s):  
Relative Effectiveness ◽  
Ground Beef ◽  
Most Probable Number ◽  
Salmonella Spp ◽  
Probable Number ◽  
Pork Sausage ◽  
Selective Enrichment

Abstract The effectiveness of selenite cystine (SC) broth, tetrathionate (TT) broth, and Rappaport-Vassiliadis (RV) medium for recovery of Salmonella spp. from 8 highly contaminated foods was determined. RV medium prepared from individual ingredients and incubated at 42° and 43°C was compared with 2 commercial (Difco and Oxoid) media incubated at 42°C. Naturally and artificially contaminated foods were tested under 2 protocols. For Protocol 1, each food was preenriched in the appropriate medium. After incubation, serial 10 fold dilutions of the preenriched foods were inoculated into selective enrichment media and incubated at 35°, 42°, or 43°C. Effectiveness of these conditions was evaluated by most probable number determination of Salmonella spp. recovered. Productivity of selective enrichments did not differ significantly with this protocol, except that with Oxoid RV medium the number of Salmonella cells recovered from most of the foods was significantly reduced. For Protocol 2, twenty 25 g test portions from artificially inoculated foods were examined qualitatively for Salmonella spp. The effectiveness of the broth/temperature combinations was determined by the number of positive tests under each condition. RV medium prepared from individual ingredients and TT broth incubated at 43°C yielded significantly more Salmonella-positive tests from frog legs and lettuce than did SC and TT broths incubated at 35°C or commercial RV medium incubated at 42°C. With pork sausage and ground beef, significantly fewer Salmonella-positive tests were found with Oxoid RV medium incubated at 42°C and SC incubated at 35°C than from other selective enrichments. With chicken, fewer Salmonella-positive tests were found from SC and TT broths incubated at 35°C and Oxoid RV medium incubated at 42°C than from other selective enrichments. There were no significant differences among selective enrichments in the recovery of Salmonella spp. from the remaining foods. Overall, RV prepared from individual ingredients and incubated at 42°C yielded the highest number of Salmonella-posWive tests.

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.

Recovery of Escherichia coli Biotype I and Enterococcus spp. during Refrigerated Storage of Beef Carcasses Inoculated with a Fecal Slurry

1999 ◽  
Vol 62 (8) ◽  
pp. 944-947 ◽  
Author(s):  
M. CALICIOGLU ◽  
D. R. BUEGE ◽  
S. C. INGHAM ◽  
J. B. LUCHANSKY
Keyword(s):  
Escherichia Coli ◽  
Storage Period ◽  
Most Probable Number ◽  
Probable Number ◽  
E Coli ◽  
Viable Cells ◽  
Beef Carcasses ◽  
Significant Difference ◽  
Enterococcus Spp ◽  
Appreciable Reduction

Three beef front quarters/carcasses were inoculated with a slurry of cattle manure. During storage at 4°C, two sponge samples from each of three sites (i.e., 100 cm2 from each of two fat surfaces and 100 cm2 from a lean surface) were taken from each of the three carcasses on days 0, 1, 3, 7, and 10 after inoculation. The initial numbers of Escherichia coli averaged 2.0 log10 CFU/cm2 (1.21 to 2.47 log10 CFU/cm2) using the Petrifilm method and 2.09 log10 most probable number (MPN)/cm2 (0.88 to 2.96 log10 MPN/cm2) using the MPN method. The initial numbers of enterococci averaged 3.34 log10 CFU/cm2 (3.07 to 3.79 log10 CFU/cm2) using kanamycin esculin azide agar. In general, an appreciable reduction in the numbers of E. coli occurred during the first 24 h of storage; for the Petrifilm method an average reduction of 1.37 log10 CFU/cm2 (0.69 to 1.71 log10 CFU/cm2) was observed, and for the MPN method an average reduction of 1.52 log10 MPN/cm2 (0.47 to 2.08 log10 MPN/cm2) was observed. E. coli were not detected (<−0.12 log10 CFU/cm2) using Petrifilm on day 7 of the storage period on two (initial counts of 1.21 and 2.29 log10 CFU/cm2) of the three carcasses. However, viable E. coli cells were recovered from these two carcasses after a 24-h enrichment at 37°C in EC broth. Viable E. coli cells were detected at levels of −0.10 log10 CFU/cm2 on the third carcass (initial count of 2.47 log10 CFU/cm2) after 7 days at 4°C. No significant difference in recovery of viable cells was observed between the MPN and Petrifilm methods on days 0, 1, and 3 (P > 0.05). However, viable E. coli cells were recovered from all three carcasses by the MPN method on day 7 at an average of −0.29 log10 MPN/cm2 (−0.6 to −0.1 log10 MPN/cm2). On day 10, viable cells were recovered by the MPN method from two of the three carcasses at −0.63 and −0.48 log10 MPN/cm2 but were not recovered from the remaining carcass (<−0.8 log10 MPN/cm2). Similar to E. coli, the greatest reduction (average of 1.26 log10 CFU/cm2, range = 1.06 to 1.45 log10 CFU/cm2) in the numbers of enterococci occurred during the first 24 h of storage. Because of higher initial numbers and a slightly slower rate of decrease, the numbers of Enterococcus spp. were significantly higher (P < 0.017) than the numbers of E. coli Biotype I after 3, 7, and 10 days of storage. These results suggest that enterococci may be useful as an indicator of fecal contamination of beef carcasses.

THE FATE OF SALMONELLA TYPHIMURIUM IN THE MANUFACTURE AND RIPENING OF LOW-ACID CHEDDAR CHEESE1

1970 ◽  
Vol 33 (7) ◽  
pp. 280-284 ◽  
Author(s):  
H. S. Park ◽  
E. H. Marth ◽  
J. M. Goepfert ◽  
N. F. Olson
Keyword(s):  
Salmonella Typhimurium ◽  
Starter Culture ◽  
Most Probable Number ◽  
Initial Increase ◽  
High Moisture ◽  
Gradual Decline ◽  
Probable Number ◽  
Streptococcus Lactis ◽  
Extended Survival ◽  
Made In

Cheddar cheese was made by the stirred-curd procedure from pasteurized milk inoculated with Salmonellea typhimurium and with a slow acid-producing strain of Streptococcus lactis. The Most Probable Number technique was used to enumerate salmonellae in milk and in cheese during its manufacture and ripening. Salmonellae grew rapidly during manufacture and limited additional growth occurred in cheese during the first week of ripening at 13 C after which there was a gradual decline in population. Salmonellae survived during ripening for up to approximately 7 months at 13 C and 10 months at 7 C. Cheese made in 2 of 5 trials exhibited a limited increase in number of salmonellae during the first 2 weeks at 7 C followed by a decline in population of these bacteria. Other cheeses held at 7 C exhibited a reduction in number of viable salmonellae without the initial increase. Growth of salmonellae during the early stages of ripening and subsequent extended survival of these organisms may, in part, be attributable to high moisture (average 43.2%) and high pH (5.75 after overnight pressing) of the cheese which resulted from use of a slow acid-producing starter culture.

scholarly journals The incidence and level of contamination of British fresh sausages and ingredients with salmonellas

1983 ◽  
Vol 90 (2) ◽  
pp. 213-223 ◽  
Author(s):  
J. G. Banks ◽  
R. G. Board
Keyword(s):  
Most Probable Number ◽  
Probable Number ◽  
Routine Production ◽  
Salmonella Serotypes ◽  
Pork Sausages

SUMMARYA five-tube most probable number (MPN) method, with pre-enrichment and enrichment stages, was used in a study of the incidence of salmonella contamination of British fresh sausages and the ingredients used in their manufacture. All samples were taken from a large factory in the course of routine production. There was an incidence of 65 % contamination of pork (n= 20) and 55% (n= 20) in pork and beef sausages. The incidences of contamination of uncooked ingredients varied from 95 % for mechanically recovered meat (n= 20) to 10 % for another type of meat. Cooked and/or dried ingredients were rarely contaminated with these organisms and, when contamination occurred, coliforms were also important.The numbers of salmonellas isolated ranged from 7–40 for pork sausages, from 8–24 for beef and pork sausages and from 0·8–378 organisms/g for ingredients.The following salmonella serotypes were isolated (ranked in descending order of incidence):S. derby, S. dublin, S. newport, S. stanley, S. typhimurium, S. heidelberg, S. infantisandS. agona.

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