Emergência de Campylobacter jejuni no setor avícola e na saúde pública do Brasil

Abstract

Campylobacter jejuni is often associated with human gastroenteritis worldwide, being transmitted by the consumption of contaminated foods, mainly those of animal origin, especially chicken. The thesis was divided in four chapters, the first referring to the general considerations of the topics covered in the other chapters. The second chapter aimed to evaluate the changes in the prevalence, virulence characteristics, antimicrobial resistance and genetic similarity of 99 strains of C. jejuni isolated from chicken carcasses from three different units of a Brazilian export poultry company during the periods between 2011-2012 and 2015-2016. The aim of the third chapter was to investigate the potential to produce biofilms separately and in association with other agents in the Mueller Hinton and Chicken juice media, in 30 strains of C. jejuni isolated from chicken carcasses (2015), identify genetic factors related to the formation of biofilms, verify the effectiveness of chemical agents in the removal of sessile structures, analyze the structure and composition of simple and mixed biofilm matrices, and compare the genetic similarity between the strains. The fourth chapter aimed to perform a comparative analysis related to the genes of virulence and adaptive resistance, in addition to the evaluation of the genetic homology in 64 strains of C. jejuni, 44 of poultry origin (2015-2016) and 20 from human patients with symptomatology (2000-2006). The determination of the prevalence restricted to the second chapter was carried out from the traditional analysis of 1070 samples of chicken carcasses. The confirmation of C. jejuni was done by PCR-multiplex. For the evaluation of antimicrobial susceptibility in the 99 strains of poultry origin, the disc diffusion test was performed. The presence of the genes flaA (motility), ciaB (intracellular invasion), cadF (intracellular colonization), pldA (colonization/invasion), cdtABC (cytotoxin), luxS (quorum-sensing mechanism), dnaJ (thermotolerance), htrA (assistance in growth under stress), cbrA (resistance to osmotic shock), sodB (tolerance to oxidative stress), cstII and neuA (Guillain-Barré Sindrom) by the PCR technique. The phylogenetic relationship between the isolates was determined by the RAPD-PCR method in the second chapter and by PFGE in the third and fourth chapters. Biofilm formation analyzes were performed using traditional microbiology techniques using the Mueller Hinton and Chicken Juice media to quantify, classify and determine the biomass composition of single and mixed biofilms of 30 strains of C. jejuni (2015). The morphology of the biofilms was verified by means of scanning electron microscopy. The inhibition tests of the sessile forms of C. jejuni were made with disinfectants commonly used in industry and with zinc oxide nanoparticles. The study allowed concluding that C. jejuni undergoes genotypic and phenotypic modifications over time in order to become more specialized and with greater virulence. Regardless of human or poultry origin, the strains present a high potential to cause GBS. In the industrial environment the problem is aggravated by the persistence of C. jejuni through the formation of highly stable and resistant biofilms. Antibiotic and disinfectant susceptibilitytests in the industry had shown that constant exposure to these agents selects more adapted strains. Therefore, there is a necessity for the implementation of careful monitoring measures within the industry and in public health for the control of C. jejuni.