Quantitative Detection of Shiga Toxin-Producing and Enteropathogenic Escherichia coli Serotypes O157 and O26 in Bulk Raw Milk

Abstract

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Paediatric HUS Cases Related to the Consumption of Raw Milk Sold by Vending Machines in Italy: Quantitative Risk Assessment Based on Escherichia coli O157 Official Controls over 7 years

“…However, our model inputs show two main sources of uncertainty, namely the level of milk contamination and the probability of boiling milk. Firstly, the STEC O157:H7 concentration is uncertain and few studies are available in the literature, so we used the Italian study by Trevisani et al (2013) to better fit the STEC O157:H7 concentration in milk. Secondly, the probability of boiling milk was used in the model as 'scenario' analysis because this point was considered crucial for risk results and several studies reported very different percentages of consumers boiling milk (Giacometti et al, 2012b(Giacometti et al, , 2013Ricci, 2012;Crotta et al, 2016a, b).…”

“…Assuming that the positive samples resulted contaminated below the quantification limit (LOQ) of MPN‐PCR methods were equal to the value of 0.3 MPN/ml, the limit of quantification of the MPN‐PCR methods used (LOQ), the mean concentration measured by Trevisani et al. () was equal to 0.364 MPN/ml with a SD of 3.056. Considering the few amount of available quantitative data and with an apparent prevalence of 0.15%, no unbiased fitting methods could be applied to any probabilistic distribution, even considering recently proposed Markov chain Monte Carlo fitting methods (Williams et al., ).…”

“…Therefore, we decided to fit two positive distributions (lognormal and gamma) on concentration data obtained by Trevisani et al. () to find biological explanation in microbiological contamination: a lognormal distribution with a mean of 0.364 and a SD of 3.056, and a gamma with α (slope parameter) equal to 0.014 (mean 2 /variance; mean = 0.364 and SD = 3.056) and a scale parameter β (mean/α) of 25.61. No significant difference between the two distributions was observed in chi‐square goodness‐of‐fit (GOF) test, so a gamma distribution was chosen to model the STEC O157:H7 concentration in raw milk because this distribution best fits the data the low range of concentrations observed and admits 95% of the samples below 0.4 MPN/ml, that is similar to what was observed in the Italian study.…”

“…The authors quantified STEC O157:H7 in 34 milk samples in which STEC O157:H7 was demonstrated by the enrichment culture method: all these samples were contaminated below 0.3 MPN/ml (CI 95% 0-0.95) except two samples that had a value equal to 1.4 MPN/ml (CI 95% 0.36-4.2). Assuming that the positive samples resulted contaminated below the quantification limit (LOQ) of MPN-PCR methods were equal to the value of 0.3 MPN/ml, the limit of quantification of the MPN-PCR methods used (LOQ), the mean concentration measured by Trevisani et al (2013) was equal to 0.364 MPN/ml with a SD of 3.056. Considering the few amount of available quantitative data and with an apparent prevalence of 0.15%, no unbiased fitting methods could be applied to any probabilistic distribution, even considering recently proposed Markov chain Monte Carlo fitting methods (Williams et al, 2013).…”

In‐milk inactivation of Escherichia coli O157:H7 by the environmental lytic bacteriophage ECPS‐6

“…The presence of STEC in raw milk is estimated to 13.6% (Douëllou et al, ; Farrokh et al, ). Furthermore, infections can be associated with milk and products made from raw, filtered, and unpasteurized milk, such as cheeses (Álvarez‐Suárez et al, ; A. Gill & Oudit, ; Ivbade, Ojo, & Dipeolu, ; Jackson et al, ; Madic et al, ; Nobili et al, ; M Trevisani et al, ; Trevisani, Mancusi, Riu, & Serraino, ). Transmission route to milk mainly concerns the fecal contamination of unpasteurized milk that is particularly correlated with the fecal excretion of STEC strains.…”