RESUMO
Listeria monocytogenes is a foodborne pathogen that can produce serious, even fatal, infections. Among other foods, it can be found in unpasteurized dairy and ready-to-eat products. Surveillance of L. monocytogenes is of great interest since sources of infection are difficult to determine due to the long incubation period, and because the symptoms of listeriosis are similar to other diseases. We performed a genomic study of L. monocytogenes isolated from fresh cheeses and clinical samples from Ecuador. Sixty-five isolates were evaluated and sequenced, 14 isolates from cheese samples and 20 from clinical listeriosis cases from the National Institute of National Institute of Public Health Research, and 31 isolates from artisanal cheese samples from 8 provinces. All isolates exhibited heterogeneous patterns of the presence of pathogenicity islands. All isolates exhibited at least 4 genes from LIPI-1, but all references (26 L. monocytogenes closed genomes available in the NCBI database) showed the complete island, which encompasses 5 genes but is present in only two Ecuadorian isolates. Most isolates lacked gene actA. Genes from LIPI-2 were absent in all isolates. LIPI-3 and LIPI-4 were present in only a few references and isolates. With respect to the stress survival islets, our samples either presented SSI-1 or SSI-F2365, except for one isolate that presented SSI-F2365 and also one gene from SSI-1. None of the samples presented SSI-2. The predominant ST (sequence type) was ST2 (84.62% 55/65), and the only ST found in food (93.33% 42/45) and clinical samples (65% 13/20). Isolates were not grouped according to their sampling origin, date, or place in a phylogenetic tree obtained from the core alignment. The presence of ST2 in food and clinical samples, with high genomic similarity, suggests a foodborne infection risk linked to the consumption of fresh cheeses in Ecuador.
RESUMO
Listeria monocytogenes is one of the most important bacteria associated with foodborne diseases, soft cheese being an important L. monocytogenes vehicle. In Ecuador, soft cheese is consumed in 84.3% of urban households. We determined the prevalence of L. monocytogenes and serogroups in 260 fresh artisanal soft cheese samples collected in 18 of 24 Ecuadorian provinces. Listeria spp. detection was carried out by culture-dependent and independent methods; 14.23% of samples were positive for L. monocytogenes. Serogroup IVb was found in 83.78% of the food isolates. Serogroups IIb and IIa were present in 8.11% of our isolates. To our knowledge, this is the first report of L. monocytogenes serogroups associated with food in Ecuador; we also found serogroup similarities between cheese isolates and clinical isolates.
