Avaliação de aspectos relacionados à virulência de cepas multidroga-resistentes de Corynebacterium amycolatum isoladas de trato urinário de pacientes ambulatoriais

Abstract

Corynebacterium amycolatum has been increasingly reported as an etiologic agent of mild to severe nosocomial infections. studies focused on the virulence potential of C. amycolatum remains scarce. In this study, 38 strains of C. amycolatum isolated from the urinary tract of ambulatorial patients, previously identified by mass spectrometry and classified according to their antimicrobial resistance profile, were evaluated for their epidemiological profile and virulence-related factors. For that, we performed a search for resistance genes to beta-lactams, adherence assays using human pharyngeal epithelial cells, and the model of pathogen-host interaction Caenorhabditis elegans. Most strains of C. amycolatum came from female patients and 86.84% of all samples expressed heterogeneous multidrug-resistant (MDR) profiles, and among these, seven had the bla gene that encodes the beta-lactamase class A. Other BGPIs, such as Brevibacterium ravenspurgense, were also found associated with C. amycolatum, presenting an MDR profile and, together with some C. amycolatum MDR strains, demonstrated the ability to adhere to human epithelial cells, suggesting a colonization mechanism that may aid in the establishment of an infection. Mortality and morphological changes in nematodes infected by twelve strains of C. amycolatum with different MDR and multidrug-sensitive (MDS) profiles were investigated for six days after infection. Death of C. elegans was observed for all tested strains of C. amycolatum, but at different levels. All led to more than 60% mortality of infected worms, and median worm survival (LT50s) ranged between 3 and 5 days. Morphological changes in the anal region and internal hatching of eggs in C. elegans were observed for all tested strains of C. amycolatum. In addition, an unusual mode of infection in the nematode host, cyst-like structures in the vulvar-uterus region were observed for some of the nematodes exposed to the MDR strains of C. amycolatum BR-SW-28 and BR-SW-32, suggesting uterine infection. Corroborating other authors, the most virulent strains showed MDR profiles. These findings may suggest an association between virulence genes and resistance genes, but further studies are needed to confirm this hypothesis. The isolation of coryneforms, such as C. amycolatum, presenting MDR profiles reinforces the importance of correct identification for a better therapeutic approach and constant surveillance of the antimicrobial resistance of these isolates, in addition to the need for further studies in order to elucidate mechanisms involved in the pathogenicity of C amycolatum