Zero-inflated binomial regressions for modelling low prevalence of pathogens in chicken meat as affected by sampling site

Abstract

Contamination of raw poultry meat with foodborne pathogens could occur because of improper handling at primary production and slaughterhouse levels. Low microbial prevalence data often consists of a high amount of non-detections (zero positives), so a flexible framework is required to characterise the underlying microbial distribution and conduct reliable inferential statistics. Thus, the objective of this work was to evaluate the performance of zero-inflated binomial (ZIB) regression models to describe the effects of sampling site (carcass, thigh, breast, wings) on the measured incidences of Salmonella, Listeria monocytogenes and Staphylococcus aureus on chicken meat. For each pathogen, four regression models based on the zero-inflated binomial ZIB (p, w 0) distribution were fitted to the presence/absence data with sampling site as covariate and random-effects due to sampling occasion either in the binomial probability (p) or in the extra-proportion of non-detections (w 0). For the three pathogens, the sampling site exerted a greater effect on w 0 than on p itself, with breast bearing the lowest prevalence estimates of Salmonella spp. (mean: 0.88%; 95% CI: 0.02-1.95%) and S. aureus (mean 1.48%; 95% CI: 0.01-4.00%). The fitting capacity of the models was further improved when random effects due to sampling occasion were placed in w 0 (deviances decreased from 146.7-156.7 to 140.2-140.6). This would imply that, theoretically, the variability in pathogens' occurrence from batch to batch mainly arises from the variability in non-contaminated zones. At any sampling site, the mean prevalence was estimated as 1.35 (95% CI: 0.15-2.70) for Salmonella, 2.11 (95% CI: 0.04-5.63) for L. monocytogenes and 2.36 (95% CI: 0.04-5.12) for S. aureus. Sampling performance analysis showed that wings were mostly suitable to detect Salmonella and S. aureus with higher probability (0.016 and 0.035 respectively), while for L. monocytogenes, sampling of thigh could be more effective (0.032).

Comparison of Dry and Wet De-Feathering Methods on the Quality Characteristics and Shelf Life of Broiler Carcasses

“…This may cause bacteria contamination, quick growth of bacteria and increased colonization on the carcass surface during the intestines removal and water cooling stages, which affects the shelf life of the meat (Erginkaya & Yurdakul 2010;Var et al 2011). At the same time, there is also cross-contamination risk of other carcasses via contaminated equipments in slaughterhouses (Rivera-Perez et al 2014;Hernandez et al 2018;Perez-Arnedo & Gonzalez-Fandos 2019).…”