Molecular epidemiology and genetic diversity of Listeria monocytogenes isolates from a wide variety of ready-to-eat foods and their relationship to clinical strains from listeriosis outbreaks in Chile

Abstract

Listeria monocytogenes is a pathogen transmitted through food that can cause severe infections in high-risk groups such as pregnant women, elderly, young children and immunocompromised individuals. It is a ubiquitous bacterium that can survive in harsh conditions, such as dry environments, at low temperatures, in brine conditions and at low pH values. It also has the capacity to form biofilms, which makes it particularly successful even in colonizing surfaces within food processing plants. This study analyzed the presence of L. monocytogenes in ready-to-eat food (RTE) such as sausage, cheese, fresh salads, and other types of raw food. 850 samples of refrigerated and packaged food collected in 2008 and 2009 were analyzed. It was found that 25% of these samples were contaminated with L. monocytogenes strains. Serotyping and virulence genes detection by polymerase chain reaction (PCR) identified that strains belonging to serotype 4b, and containing one or more genes encoded by pathogenicity island (LIPI-1), were significantly associated with specific food types. Furthermore, using pulse field gel electrophoresis (PFGE), it was possible to associate isolates from cheese with strains from clinical cases of listeriosis outbreaks that occurred during the same time period within the same geographic regions. In addition, a strong correlation was observed between isolates from frozen seafood and from clinical strains obtained from sporadic cases of listeriosis. In agreement with reports described in other countries, our results shown that Chilean strains of L. monocytogenes from food products include the most virulent serotypes, encoding for the main virulence genes of the LIPI-1, and were clonally related to clinical isolates from sporadic cases and outbreaks of listeriosis. In conclusion, we show that Chilean isolates of L. monocytogenes from RTE and raw food products can cause disease in humans, representing a public health risk that justifies permanent surveillance.

Prevalence of plant beneficial and human pathogenic bacteria isolated from salad vegetables in India

“…A. hydrophila has the potential to grow at 0 °C and the temperature of 4–5 °C supports the growth in foods. L. monocytogenes survives in ready-to-eat fresh salads and causes public health risk [47]. Exiguobacterium acetylicum has been reported as an aetiological agent of bacteraemia in humans [48].…”

Prevalence and molecular characterization of Listeria spp. and Listeria monocytogenes isolated from fish, shrimp, and cooked ready-to-eat (RTE) aquatic products in Iran

“…Many studies have reported the incidence of L. monocytogenes in fruits and vegetables (Hadjilouka, Andritsos, Paramithiotis, Mataragas, & Drosinos, 2014;Montero et al, 2015), dairy products (Dalzini et al, 2015;Karthikeyan, Gunasekaran, & Rajendhran, 2015;Soni, Singh, Singh, & Dubey, 2013), meat (Hadjilouka et al, 2014;Kovacevic, Mesak, & Allen, 2012;Montero et al, 2015), fish (Chou & Wang, 2006;Kovacevic et al, 2012;Wang et al, 2013), seafood products (Boerlin, Boerlin-Petzold, Bannerman, Bille, & Jemmi, 1997;Li et al, 2015;Miya, Takahashi, Ishikawa, Fujii, & Kimura, 2010;Momtaz & Yadollahi, 2013), and food processing environments (Chen, Pyla, Kim, Silva, & Jung, 2010;Li et al, 2015). However, the occurrence of L. monocytogenes in seafood has received less attention in Iran and very limited information is available on the prevalence and contamination levels of Listeria spp.…”

Ready-to-eat meat products as a source of Listeria monocytogenes

“…Listeriosis is one of the most dangerous foodborne zoonoses with a high mortality rate reaching 20%-30% (32,33,39). Although it is a relatively rare illness, with the notification rate of 0.46 cases per 100,000 persons in 2015 in the European Union (EU), most of the infections required hospitalisation (97.4%) (9).…”

“…In highrisk persons, e.g. the elderly, new-borns, or people with weakened immune system, listeriosis may manifest as meningitis, meningoencephalitis, septicaemia, and abortion (29,31,32,36,39). The disease is caused by a ubiquitous microorganism -L. monocytogenes, a Gram-positive and non-spore-forming bacterium which can grow under anaerobic and aerobic conditions and survive even in extreme environmental conditions, a such as high concentration of salts, wide temperature range (−0.4°C-45°C), pH between 4 and 9.6 (40), and water activities ≥0.92 (25).…”