Prevalence of Listeria monocytogenes from Chicken and Duck, and Genetic Analysis for the Isolates Using Molecular Typing Methods

Introduction: Listeria monocytogenes has been recognized as high-risk foodborne pathogen. The pathogen can contaminate fresh meat and poultry, and especially, the prevalence of L. monocytogenes in poultry could be higher in wet markets than in grocery stores.

Purpose: The objective of this study was to evaluate the prevalence of L. monocytogenes in poultry carcasses in wet markets, and to analyze pheno- and genotypic characteristics of the isolates.

Methods: During summer from June to August, 160 poultry carcasses (chicken: 80; duck: 80) were purchased from 17 wet markets in Korea. One poultry carcass was washed by 400 ml of 0.1% buffered peptone water, and 0.25 ml aliquots of washings were plated on Palcam agar, followed by incubation at 30^oC for 48 h. Presumptive colony on L. monocytogenes on Palcam agar was further analyzed for identification by 16s rRNA sequencing. The presence of actA, inlA, inlB, plcB, and hlyA were confirmed by PCR, and serotypes were also determined by multiplex-PCR and agglutination test. Genetic correlations among isolates were also evaluated by PFGE patterns formed by ApaI.

Results: Of 160 poultry samples, L. monocytogenes were isolated from 10 samples (6.25%) of poultry carcasses [three chicken samples (3.75%), and 7 duck samples (8.75%)]. Ten L. monocytogenes isolates were from wet markets in Gimhae, Gwangju, Jeonju, Jinju and Wonju. Most isolates had virulence genes such as actA, inlA, inlB, plcB and hlyA, and the presence of high prevalence serotypes were confirmed. Genetic correlations among L. monocytogenes isolates were mostly over 90%.

Significance: This result indicates that food safety to control L. monocytogenes on poultry needs to be improved.