Klebsiella pneumoniae multirresistentes: endemicidade, disseminação, potencial de virulência e diversidade molecular de cepas de origem ambiental e de unidade hospitalar da região metropolitana do Rio de Janeiro

Abstract

Klebsiella pneumoniae has been described as one of the main pathogens related to hospital and community acquired infections due to the increasing mortality. The presence of resistance genes associated with virulence mechanisms, including the ability of biofilm formation, delay the infections treatment. The aim of this present study was to analyze the resistance profile to antimicrobial agents, molecular typing and virulence mechanisms of K. pneumoniae strains isolated from nosocomial infections and river waters. Hospital strains were obtained through LABAC while river isolates strains were collected from four sites of Joana and Maracanã rivers. Multidrug resistance profiles were determined using the disk-diffusion method and polymerase chain reaction (PCR) assays for detection of genes that encode resistance: extended-spectrum beta-lactamase (blaTEM, blaSHV, blaCTX-M e blaTOHO); aminoglycoside-modifying enzymes [aacc2, aacc3 e aacc(6)-Ib-cr]; plasmid mediated quinolones resistance (qnrA, qnrB, qnrD, qnrS e qepA); carbapenemases (blaKpC, blaIMP, blaVIMe blaOXA) and virulence: K1, K2, fimH, mrkD and KfuBc. Additionally, K. pneumoniae MDR strains were subjected to biofilm formation assays on abiotic surfaces, mortality assays using nematode Caenohabiditis elegans as experimental model, investigation of adherence capacity, intracellular viability and persistence using human endothelial CACO-2 cell, in addition to molecular typing by pulsed field gel electrophoresis (PFGE). A total of 45 K. pneumoniae MDR strains were analyzed. Resistance genes were observed in all strains, but three environmental isolates. Hospital strains did not presented resistance gene for carbapenemase while 11 environmental strains harbored at least one resistance genes for different antimicrobial agents classes. Virulence profile demonstrated that all K. pneumoniae MDR strains isolated from nosocomial environment and 21 strains from river environment presented fimH gene. All strains showed biofilm formation capacity at different levels and intensities. PFGE analyzis demonstrated nine different clones, including one pulsotype harbored strains from nosocomial and river environment. Bacterial interaction demonstrated heterogeneity despite none of them ware able to kill Caenorhabditis elegans nematodes after five days infection. All strains were able to adhere on CACO-2 cell at different levels, regardless bacterial concentration and incubation time. The results of the intracellular viability and persistence tests diverge according to execution time and bacterial concentrations. In conclusion, K. pneumoniae strains are heterogeneous and have a high capacity for adaptation. In addition, when associated with different resistance and virulence mechanisms, they are difficulty to treat infections, being necessary to search for new therapeutic options.