Genetic diversity of Listeria monocytogenes serotype 1/2a strains collected in Brazil by Multi-Virulence-Locus Sequence Typing.

Listeria monocytogenes is an opportunistic pathogen with the ability to adapt to different environmental conditions, resulting in safety issues for food producers. Foods contaminated by L. monocytogenes can represent a risk if consumed by susceptible individuals such as elderly, pregnant women and the immunocompromised. The aim of this study was to evaluate the genetic diversity of a collection of L. monocytogenes isolated from different matrices in Brazil during the period of 1979-2015. A total of 51 L. monocytogenes serotype 1/2a strains isolated from clinical samples (n = 3) and food samples (n = 48) were characterized by Multi-Virulence-Locus Sequence Typing (MVLST). The strains were assigned to nine virulence types (VT): VT-11 (n = 3, 5·9%), VT-45 (n = 27, 52·9%), VT-59 (n = 11, 21·6%), VT-68 (n = 3, 5·9%), VT-94 (n = 2, 3·9%), VT-107 (n = 2, 3·9%), VT-184 (n = 1, 1·9%), VT-185 (n = 1, 1·9%) and VT-186 (n = 1, 1·9%); and four of them (VT-11, VT-45, VT-59 and VT-68) have already been associated with cases of listeriosis worldwide. The VT-11, VT-59 (Epidemic Clone V) and VT-186 were identified in blood culture samples, as well as in different classes of foods. It is recommended that the epidemiological surveillance agencies evaluate the risk that foods contaminated with L. monocytogenes VTs pose to susceptible populations.