Tipificação molecular e análise da resistência aos antimicrobianos em Acinetobacter spp. recuperados do período pré-pandêmico e pandêmico da COVID-19

Abstract

Acinetobacter spp. are nosocomial pathogens that present a significant public health challenge due to their ability to resist disinfection and desiccation, primarily attributed to the rising incidence of multidrug-resistant strains, thereby limiting therapeutic options. Throughout the COVID-19 pandemic, Acinetobacter spp. emerged as a prominent pathogen linked to secondary infections, resulting in prolonged stays in the ICU and heightened patient mortality. Therefore, this study aims to evaluate the antimicrobial resistance profile, its correlation with carbapenemase enzyme production, and the phylogenetic relationships among 60 Acinetobacter spp. samples retrieved from patients hospitalized at a university hospital in Rio de Janeiro during both the pre-pandemic and pandemic phases of COVID-19. Antimicrobial susceptibility tests were conducted using agar diffusion and broth microdilution methods. The detection of carbapenemase production was performed using the modified carbapenem inactivation method (mCIM) and the NG-TEST CARBA 5 immunochromatographic assay. The determination of the phylogenetic relationships among isolates was carried out using pulsed-field gel electrophoresis (PFGE). Whole-genome sequencing (WGS) of selected samples was performed to identify the species, determine the sequence type (ST), and detect polymyxin B resistance determinants. Out of the 60 samples tested, 58.3% (n = 35) exhibited resistance to all tested antimicrobials. Only one isolate displayed a multidrug-resistant (MDR) phenotype, and 95% (n = 57) demonstrated extensively drug-resistant (XDR) profiles. Minimum inhibitory concentration values for polymyxin B ranged from 0.25 to 4µg/mL. Through the mCIM, 52 carbapenemase-producing isolates were detected, and through the NG-TEST CARBA 5, 20 isolates were found to produce the IMP carbapenemase. Thirty-six pulsotypes were identified, with pulsotype L being the most prevalent, comprising ten isolates. WGS of isolates 22319 and 22718 was conducted due to polymyxin B resistance and susceptibility to other tested antimicrobials. The analysis of WGS data revealed that both isolates were identified as Acinetobacter nosocomialis, with 22319 associated with ST 395 and 22718 with the new ST 2261, characterized in this study. These isolates did not belong to any clonal complex. Both isolates exhibited mutations in the lpsB, lpxC, and lptD genes, while 22718 also displayed mutations in lpxD and pldA, potentially linked to polymyxin B resistance. The mcr gene was not detected. These results signify a widespread epidemiological profile in Brazil and worldwide, where the high rate of antimicrobial resistance and the presence of carbapenemases are alarming. Further studies are imperative to formulate measures for the control and prevention of healthcare-associated infections caused by these microorganisms. Additionally, polymyxin B resistance may be associated with mutations in the lpsB, lpxC, lpxD, lptD, and pldA genes; however, additional studies are required to comprehend the significance and contribution of these mutations to polymyxin B resistance.