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.
Highlights
Listeria monocytogenes is a pathogen transmitted by food products that may cause listeriosis, a severe infection in humans that has been recognized around the world as a serious public health problem (Farber and Peterkin, 1991; Swaminathan and Gerner-Smidt, 2007)
There are few reports on the prevalence of L. monocytogenes in food consumed in Chile, the real situation of listeriosis remains to be fully characterized in the country
We identified other foods contaminated with strains of L. monocytogenes that are genetically similar to those isolated from listeriosis cases; this information underlines the need to continue monitoring these foods
Summary
Listeria monocytogenes is a pathogen transmitted by food products that may cause listeriosis, a severe infection in humans that has been recognized around the world as a serious public health problem (Farber and Peterkin, 1991; Swaminathan and Gerner-Smidt, 2007). This disease may present either in its invasive form or as febrile gastroenteritis (Vázquez-Boland et al, 2001; Franciosa et al, 2005). Most listeriosis outbreaks are associated with strains of serotype 4b (Swaminathan and Gerner-Smidt, 2007)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
