One-Day Molecular Detection of Salmonella and Campylobacter in Chicken Meat: A Pilot Study.

Andrea Zendrini,Marina Nadia Losio,Sara Arnaboldi,Niccolò Franceschi,Elena Cosciani-Cunico,Virginia Filipello,Barbara Bertasi,Paolo Ajmone-Marsan,Valentina Carta,Laura Ragni,Dario De Medici

doi:10.3390/foods10051132

Abstract

Salmonella and Campylobacter ssp. are bacterial pathogens responsible for most foodborne infections in EU countries. Poultry serves as a reservoir for these pathogens, and its important role in the meat industry makes it essential to develop a rapid detection assay able to provide results in one day. Indeed, the rapid identification of foodborne pathogens is an important instrument for the monitoring and prevention of epidemic outbreaks. To date, Salmonella and Campylobacter screening is mainly conducted through molecular methods (PCR or real-time PCR) performed after 18–24 h long enrichments. In this study, we evaluated short enrichments (0, 2, 4, and 6 h) combined with a colorimetric loop-mediated isothermal AMPlification (LAMP) or real-time PCR to detect Salmonella and Campylobacter in poultry meat contaminated at different concentration levels (101, 103, and 105 CFU/g). Our results show that real-time PCR allows the detection of Salmonella and Campylobacter, even after shorter enrichment times than prescribed by ISO references; particularly, it detected Salmonella down to 101 CFU/g since T0 and Campylobacter from 103 CFU/g since T0. Detection with LAMP was comparable to real-time PCR without the requirement of a thermal cycler and with shorter execution times. These characteristics make colorimetric LAMP a valid alternative when one-day results are needed, improving the timely identification of positive meat batches, even in the absence of specialized instrumentation.

Highlights

Most of the time required to detect food pathogens is spent in the enrichment of the microorganism of interest (Salmonella enterica and Campylobacter spp. in this specific case)
Concerning Salmonella detection, both methods proved feasible and had comparable performances, despite 300 Loop-mediated isothermal amplification (LAMP) proving to be slightly lower performing than real-time PCR (RT-PCR)
(p < 0.05), since 101 CFU/g of Salmonella were detected after 6 h and 4 h of enrichment in batch 1 and 2, respectively (Figures S2 and S4) in accordance with plate count results, showing an exponential growth already beginning after 2 h of enrichment (Figure 1a,b)

Summary

Introduction

Salmonella enterica and Campylobacter spp. are bacterial pathogens that cause the majority of foodborne infections in EU countries, being the second and first cause of foodborne diseases in 2019, respectively. 87,923 human cases, and Campylobacter spp. was reported in 220,682 clinical cases [1]. The genus Salmonella belongs to two broad species, namely Salmonella enterica and Salmonella bongori. Salmonella enterica represents the most pathogenic species, and includes over 2600 serovars [2,3]. Some serovars are species-specific, while others are highly adapted to a wide range of animal hosts, and are responsible for foodborne infections, causing mild to severe enteric diseases in humans [3]. The serovars more frequently involved in foodborne transmission are

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