Acinetobacter baumannii resistente aos carbapenêmicos em Minas Gerais: epidemiologia hospitalar, multirresistência e disseminação de clones de alto risco

Abstract

Introduction:The spread of Acinetobacter baumannii associated with the emergence of resistance genotypes to carbapenems is of great concern worldwide. Aims: To understand hospital epidemiology as well as the current dissemination of high-risk clones in clinical strains of A. baumannii resistant to carbapenems. Materials and methods: The study was conducted in two stages. First, an epidemiological study was conducted using a cohort of 489 patients with carbapenem-resistant A. baumannii infection from 2013 to 2017 hospitalized at Hospital de Clínicas (HC-UFU), considering the first episode. Secondly, a molecular study of samples recovered from HC-UFU was carried out, along with isolates of A. baumannii recovered from other hospitals in Minas Gerais (MG) state, were selected to be typed by the MLST sequencing technique (Multilocus Sequence Typing, Pasteur scheme) and, of these, the whole-genome of one strain was sequenced using an Illumina Next-Seq 500 paired-end reads (150 bp). Polymerase chain reaction (PCR) were used to detect the oxacillinase genes (blaOXA-51, blaOXA-23, blaOXA-24, blaOXA-58 e blaOXA-143) and other carbapenemases (blaNDM-1, blaKPC, blaIMP-1, blaVIM-1, blaTEM). Results: In the epidemiological study, an incidence of carbapenemresistant A. baumannii infection of 0.7/1000 patient-days were found, with most patients with respiratory tract infections (54.7%), predominantly hospitalized in the intensive care (ICU). In November 2014, the infection rates exceeded the established limits, confirming an outbreak of multi-resistant A. baumannii infection. The frequency of mortality was high (39%) and the multivariate analysis showed that the related risk factors were the presence of sepsis and antimicrobial inappropriate therapy. It was found that 93.9% of the patients had infections with the multidrug resistant microorganism (MDR) and 41.5% with the extensively resistant microorganism (XDR). 94.5% of the 107 strains recovered and tested, recovered from the HC-UFU, were positive for the blaOXA-23 gene. On the molecular stage, 12 clinical strains of A. baumannii, obtained from different hospitals of MG state were selected. Seven strains (58.3%) were positive for the blaOXA-23 gene and one (8.3%) was positive for the blaNDM-1 gene. These 12 strains, along with two selected isolates from the HC-UFU, were typed by MLST, the result showed clonal dissemination of seven STs and four clonal complexes (CC), with predominance of ST/CC79 as well as the identification of two new STs, ST1465/CC216, and ST1466/CC79. Whole-genome sequencing of the positive sample for the blaNDM-1 gene was carried out, which was carried by an unusual plasmid (pAb17), in which some genes of the Tn125 transposon were lost. Besides, on the chromosome, the strain reported here presented blaOXA-106 gene, a variant of blaOXA-51 gene, and blaADC-25 with ISAba1 upstream. Conclusions: The study showed endemicity of A. baumannii MDR at HC-UFU, with a high frequency of the blaOXA-23 gene in recovered isolates, in addition to a higher risk of death in ...