Biodiversidade fenotípica e genotípica de Salmonella spp. isoladas de alimentos envolvidos em surtos de Doenças Transmitidas por Alimentos (DTA), em Minas Gerais/Brasil

Abstract

Salmonella spp. is one of the main pathogens that cause foodborne diseases (DTA) in the world. In this study, we analyzed 70 samples of Salmonella spp., isolated from foods implicated in cases of human salmonellosis in Minas Gerais State / Brazil, to 2003 from 2017, as for bacterial serotyping, antimicrobial susceptibility to 16 antimicrobials (eight therapeutic classes), presence of the virulence genes avrA, flgL, flgK, hilA, invA, iroB, lfpA, sefA, sipA, sipB, sipD, sivH, sopB, sopE, spvB e spvC and the PT4 gene and genetic polymorphism, using the sequences of repetitive elements REP-PCR (Repetitive Extragenic Palindromic). Thirteen serotypes were identified in this study. The frequencies of S. Enteritidis and S. Typhimurium were significantly higher (p ≤ 0.05) than the other serotypes, both corresponding to 74.2% of those. Products of animal origin or with any ingredient of animal origin accounted for 90% of those involved in salmonellosis outbreaks. S. Enteritidis showed a greater association (p ≤ 0.05) with products of animal origin. About 94.3% of the samples of Salmonella spp. demonstrated to be resistant to at least one of the 16 evaluated antimicrobials. Statistically significant percentage (p ≤ 0.05) of antimicrobial resistance was identified for nitrofurantoin (71.4%), nalidixic acid (68.6%) and ciprofloxacin (40%), mainly in the samples of S. Enteritidis. The phenotype of resistance to multiple antimicrobidans varied from 10 to 12.8%, with predominance in the S. Typhimuirum serotype. The presence of virulence genes ranged from 75.7% to 100% in the 70 samples of Salmonella ssp.. Greater association between virulence genes and serotypes, after decomposition of the variables by Principal Component Analysis, was observed in S. Enteritidis. The PT4 phagotype was observed in 90% of S. Enteritidis samples. In the analysis of genetic diversity, S. Enteritidis (n = 40) was subdivided into three clusters that shared more than 80% similarity and 14 electrophoretic patterns (ID = 0.80), the largest consisting of 17 samples (42.5%) indistinguishable originated from different outbreaks of salmonellosis. The cluster formed by S. Typhimurium (n = 12) had two clusters and six distinct profiles (ID = 0.74). The group “Other serotypes”, composed of several serotypes, was characterized by three clusters and 11 profiles with a unique fingerprint (ID = 0.89). In this experiment, REP-PCR showed reproducibility, typability and discriminatory potential. We concluded that the samples of Salmonella ssp., isolated from food in outbreaks of DTA in Minas Gerais/Brazil, from 2003 to 2017, feature a serological pattern similar to that reported by the main centers of Public Health worldwide, are characterized by a high prevalence of resistance to therapeutic classes quinolone and nitrofuran, demonstrate significant pathogenic potential, especially the serotype S. Enteritidis and, although some samples of Samonella spp. have a relatively variable genome, a high genetic similarity between them is common, in some cases, with identical fingerprints. According to this experimente, was also possible to observe the circulation of unique, constant and predominant genetic profiles, in several State mesoregions and in different periods, thus corroborating the hypothesis of clonal circulation of some serotypes in the Minas Gerais/Brazil.