Descrição de isolado clínico de Bordetella trematum por sequenciamento de genoma total

Abstract

Bordetella trematum is a Gram-negative coccobacillus found in wounds, diabetic foot ulcers, otitis, peritonitis and bacteremia. Usually it does not cause infections in humans. There are few case reports described in the literature, mainly affecting immunocompromised patients. The pathogenicity, life cycle, reservoir and antimicrobial resistance mechanisms of B. trematum are poorly elucidated. Virulence factors are critical to the establishment of the infection. Identificating them is crucial to understand bacterial pathogenesis and interaction with the host. Information about antimicrobial resistance mechanisms plays a key role in the choice of appropriate therapy wich may contribute to a favorable clinical outcome. The aims of this work were to report a rare case of B. trematum in diabetic ulcer and to present the cases already described by other authors; to investigate and describe the function of possible genes encoding virulence factors; to investigate and describe the function of possible antimicrobial resistance genes, as well as to evaluate the antimicrobial resistance phenotype of the clinical isolate, correlating it to the genotype. The isolate was identified by the VITEK 2 system, whose identification was confirmed by Matrix Assisted Laser Desorption Ionization- Time of flight mass spectometry (MALDI-TOF MS) in the VITEK-MS system. Afterwards, it was submitted to whole genome sequencing by the Illumina MiSeq technology, with subsequent bioinformatic analysis. The virulence and antimicrobial resistance genes were investigated using the ABRicate tool in the Virulence Factors Database (VFDB) and Comprehensive Antibiotic Resistance Database (CARD). The antimicrobial susceptibility was evaluated by broth microdilution. Sixteen genes encoding virulence factors were found, cheA, cheW, cheI, fliI, fliN, fliC, bplA, bplA, bplB, bplC, bplD, iroN, mgtA, relA, mtrD and brkB. These genes are involved in several functions in the bacterial cell, such as chemotaxis, motility, lipopolysaccharide biosynthesis, iron and magnesium acquisition, remodeling of bacterial metabolism, expression of efflux pumps and resistance to complement-mediated cell death. Further studies are needed to evaluate the expression and functionality of these genes. In the resistance analysis, the macB, mdsB, mexI and ceoB genes related to efflux pumps were found. In the antimicrobial susceptibility test, only aztreonam had a high inhibitory concentration (>16 μg/mL). The absence of the ftsI gene, which encodes the penicillinbinding protein 3 (PBP3), targeting aztreonam, may be related to this phenotype. The efflux pumps found are not related to beta-lactam resistance. Additional studies will be needed to determine the impact of these efflux pumps on antimicrobial resistance in B. trematum.