Risk Factors and Level of Listeria monocytogenes Contamination of Raw Pork in Retail Markets in China.

Hua Li,Lijuan Luo,Changyun Ye,Lu Zhang,Ruiting Lan,Yi Wang,Hui Li,Pengfei Wang,Shunshi Ji,Xiaolong Cao,Yan Wang

doi:10.3389/fmicb.2018.01090

Abstract

Listeria monocytogenes can contaminate various foods via food processing environments and contamination of raw materials. There is a limited understanding of L. monocytogenes transmission in retail market and the role of insects in L. monocytogenes transmission in the retail environments. To better understand the risk factors of raw pork contamination, the prevalence of L. monocytogenes was examined in raw pork, retail environments and insects in a retail market over a 6-month period from March to August in 2016 in Beijing, China. A total of 2,789 samples were collected, including 356 raw pork samples, 1,392 meat contact surface swabs (MCS), 712 non-meat contact surface swabs (NMCS) and 329 insect samples. Overall, 424 (15.20%) of the samples were found to be contaminated by L. monocytogenes. Analyzed by serotyping, multilocus sequence typing and pulsed-field gel electrophoresis, the 424 L. monocytogenes isolates were divided into three serotypes (1/2c, 1/2a and 3a), 15 pulsotypes (PTs) and nine sequence types (STs), 1/2c/PT4/ST9 (244/424, 58%) was the most prevalent type of L. monocytogenes strains. The raw pork, MCS of the environments and insects were contaminated with higher levels of L. monocytogenes than NMCS of the environments, which suggested that cross contamination of L. monocytogenes between raw pork and the environment existed in the retail market, and long-term contaminated surfaces and vector insects would act as high risk factors to transmit L. monocytogenes to raw pork. Thus more effective strategies are needed to reduce the risk of retail pork meat contamination by L. monocytogenes and prevent foodborne human listeriosis.

Highlights

We found that prevalence of L. monocytogenes was higher in months with higher temperature in our study, which was different from the patterns of report about that in southwest China (Luo et al, 2017), which possibly attributed to the difference of regional climate and retail environment
This study investigated the risk factors and level of L. monocytogenes contamination in raw pork retail markets in
The results showed that L. monocytogenes contamination was higher in raw pork and meat contact surface swabs (MCS) than in nonmeat contact surface swabs (NMCS), insects in retail market had a high carriage of L. monocytogenes

Summary

Introduction

Listeria monocytogenes is a food-borne pathogen that causes severe infections in humans (Zhou et al, 2010; Galvao et al, 2012; Pagliano et al, 2017; Lowe et al, 2018), especially the elderly, pregnant women, newborns and immunocompromised individuals (Fleming et al, 1985; Gilmour et al, 2010; Lamont et al, 2011). The diseases caused by L. monocytogenes include meningitis, Listeria monocytogenes in Raw Pork Retail Market sepsis, gastroenteritis, neonatal infections and fetal loss (Lamont et al, 2011; Pagliano et al, 2017; Lowe et al, 2018). A wide variety of ready-to-eat food, retail food and related environments have been found to be contaminated by L. monocytogenes in Canada, Italy, China and the United States in recent years (Hoelzer et al, 2011; Kovacevic et al, 2012; Simmons et al, 2014; Wu et al, 2015; Conficoni et al, 2016)

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