Análise fenotípica e molecular da resistência aos antimicrobianos em Pseudomonas aeruginosa provenientes de espécimes clínicos de hospitais privados do estado do Rio de Janeiro e de São Paulo

Abstract

Pseudomonas aeruginosa is a Gram-negative, non-glucose fermenting bacillus that is frequently associated with healthcare-associated infections. Due to the production of multiple virulence factors and multifaceted resistance mechanisms, infections with this bacterium have a high morbidity and mortality rates, constituting a global public health problem. The aim of this study was to determine the susceptibility profile to first-line antimicrobials and new antimicrobials used in clinical practice; asses the occurrence of multidrug-resistant (MDR) P. aeruginosa; analyse the frequency of carbapenem resistance and characterize carbapenemase-encoding genes in samples from patients treated in private hospitals in Rio de Janeiro and São Paulo. The susceptibility profile was assessed by disk diffusion and cabapenemase gene detections was performed by comercial real-time PCR. Among 130 isolates, the antimicrobials with the highest resistance rates were levofloxacin (40%), imipenem (36%) and meropenem (34%). Additionally , 14 (11%) isolates were classified as MDR and 20 (15%) as extensively drug-resistant (XDR). These isolates were further tested against new antimicrobials and polymyxins, with 44% being resistant to ceftazidime/avibactam and 19% resistant to polymyxin. Carbapenemase genes were investigated in 14 isolates, revealing two positive for the bla-KPC gene and one for the bla-VIM gene. Moreover, the bla-CTX-M gene, associated with extended-spectrum beta-lactamases (ESBL), was detected in one isolate. These results indicate that MDR and XDR profiles in some hospitals are associated with resistance to carbapenems, reducing therapeutic options for serious infections. Among the 14 carbapenem-resistant isolates, only three exhibited carbapenemase genes, suggesting the presence of other resistance mechanisms or unstudied carbapenemases. Furthermore, the 44% resistance rate to ceftazidime/avibactam suggests the emergence of resistance mechanisms to this recently antimicrobial introduced into clinical practice, highlighting the need for more in-depth studies on its nature and function.