Caracterização genômica e epidemiologia molecular de Campylobacter termofílicos isolados de produtos cárneos de frango comercializados no sul do Brasil

Abstract

Campylobacter spp. is the foodborne pathogen considered to be the most common bacterial cause of human gastroenteritis, and is responsible for as many as 400-500 million cases worldwide each year. This pathogen is a common inhabitant of the broilers gut and often causes human disease through consumption of contaminated poultry meat. The aim of this study was to analize the molecular epidemiology and characterize the thermophilic Campylobacter genome isolated from poultry meat products marketed in Southern Brazil. The genetic relationship among C. jejuni and C. coli isolates was evaluated by the pulsed-field gel electrophoresis (PFGE) technique, the resistance to macrolides, ciprofloxacin and tetracyclines was evaluated by the disk diffusion method, whereas the detection of virulence-associated genes was evaluated by the polymerase chain reaction (PCR). Two C. jejuni isolates were submitted to whole-genome sequence and comparative analysis based on the reference genome C. jejuni NCTC 11168. A high genetic diversity was identified among C. jejuni and C. coli isolates evaluated, although the recurrence of some clones has been observed. High levels of resistance to tetracyclines and ciprofloxacin were observed, while lower levels of resistance to macrolides and multidrug resistance were identified. The isolates also carryed several virulence-associated genes, but no specific gene was related to antimicrobial resistance. The PFGE technique and the virulence-associated genes research had greater discriminatory power, but the antimicrobial resistance analysis provided importante information about the isolates improving the differentiation among them. The first genomic analysis of two C. jejuni isolated in Brazil revelated differences in multilocus sequence typing (MLST). Moreover, the comparative reference analysis revealed differences in genomic structure (SNPs, rearrangements and inversions) in both genomes, as well as the presence of some virulence-associated genes and of mobile genetic elements such as transposons, genomic islands and prophages sequences. Mechanisms of antimicrobial resistance and a new virulence megaplasmid were also identified. In general, it can be concluded that the presence of a diversity of antimicrobial resistant and potentially virulent Campylobacter isolates contaminating the poultry meat products in Brazil represent a potential risk to health of consumers, since this country is the world's largest exporter of chicken meat. This demonstrates the need of more rigorous control measures for Campylobacter in poultry production chain from Brazil.