Prevalence and Persistence of Listeria monocytogenes in Ready-to-Eat Tilapia Sashimi Processing Plants

Abstract

A 2-year study was performed at two ready-to-eat tilapia sashimi processing plants (A and B) to identify possible routes of contamination with Listeria monocytogenes during processing. Samples were collected from the aquaculture environments, transportation tanks, processing plants, and final products. Seventy-nine L. monocytogenes isolates were found in the processing environments and final products; 3.96% (50 of 1,264 samples) and 3.86% (29 of 752 samples) of the samples from plants A and B, respectively, were positive for L. monocytogenes . No L. monocytogenes was detected in the aquaculture environments or transportation tanks. The predominant L. monocytogenes serotypes were 1/2b (55.70%) and 4b (37.97%); serotypes 3b and 4e were detected at much lower percentages. At both plants, most processing sections were contaminated with L. monocytogenes before the start of processing, which indicated that the cleaning and sanitizing methods did not achieve adequate pathogen removal. Eleven seropulsotypes were revealed by pulsed-field gel electrophoresis and serotyping. Analysis of seropulsotype distribution revealed that the contamination was disseminated by the processing work; the same seropulsotypes were repeatedly found along the work flow line and in the final products. Specific seropulsotypes were persistently found during different sampling periods, which suggests that the sanitation procedures or equipment used at these plants were inadequate. Plant staff should improve the sanitation procedures and equipment to reduce the risk of L. monocytogenes cross-contamination and ensure the safety of ready-to-eat tilapia products.

Contamination sources, serogroups, biofilm-forming ability and biocide resistance of Listeria monocytogenes persistent in tilapia-processing facilities

“…Most of listeriosis cases are caused by the serotypes 1/2a, 1/2b, 1/2c and 4b (Cartwright et al 2013;EFSA 2016), but their distribution in food-related environments is highly variable. Serotypes 1/2a and 1/2b seemed to be the most commonly found in L. monocytogenes isolated from fishery products and fish-processing factories (Abdollahzadeh et al 2016;Chen et al 2016;Jamali et al 2015;Kramarenko et al 2013;Shimojima et al 2016;Wu et al 2015). However, the serogroup II (including the serotype 1/2c) was the most frequently detected in this study, followed by serogroup I (1/2a) and III (1/2b), whereas the serotype 4b was not detected in both tilapia-processing facilities.…”

“…Contamination level of cultivation water and tilapia fillets produced in Brazil was previously investigated (Bartolomeu et al 2011;Boari et al 2008;Carbonera et al 2011;Junior et al 2014), but limited to those foodborne pathogens included in the Brazilian legislation in force (Brazil 2001), being L. monocytogenes excluded. However, the incidence of L. monocytogenes in fish products is a cause of concern to the fishery industry, particularly in raw fish and ready-to-eat fish products (Abdollahzadeh et al 2016;Chen et al 2016;Cruz et al 2008;Kramarenko et al 2013;Shimojima et al 2016).…”

“…Moreover, listeriosis outbreaks reported in Europe (EFSA 2016) and USA (Cartwright et al 2013) showed high rates of mortality, but few of them have been associated to the consumption of fishery products. Nevertheless, L. monocytogenes serotypes 1/2a, 1/2b, 1/2c and 4b, involved in most cases of human listeriosis, have been frequently found in both fishery products and fish-contact surfaces (Abdollahzadeh et al 2016;Chen et al 2016;Jamali et al 2015;Kramarenko et al 2013;Wu et al 2015). The prevalence of L. monocytogenes in fish-related environments seems to be correlated with the degree of human activity, being higher in freshwater fish farms, fish slaughterhouses and fish smokehouses than in freshwater streams (Hansen et al 2006).…”

Clinical and molecular epidemiology of human listeriosis in Taiwan

“…Chenal-Francisque et al showed a worldwide distribution of MLST CC1-3, C7, and CC9, while only a few east Asian isolates were included in their analysis (Chenal-Francisque et al, 2011). In Taiwan, L. monocytogenes has been isolated from various raw materials including seafood, poultry, processed meat, and ready-to-eat food with sporadic human cases reported over the past three decades (Chen et al, 2016;Hsieh et al, 2009;Hung et al, 1995;Wong et al, 1990). An upsurge in human listeriosis occurred since 2004-2005 and three unique ST types of clinical isolates were identified (ST87, ST378, and ST155) (Huang et al, 2010(Huang et al, , 2011Huang et al, 2015).…”

Zoonotic Diseases: Etiology, Impact, and Control

“…In most of the cases, these fish pathogens are endogenous in origin. Cross-contamination with zoonotic pathogens like Listeria monocytogenes in ready-to-eat fish products has recently been reported [ 72 ].…”