A study on antibiotics resistance and carbapenemase genotype of Acinetobacter baumannii in intensive care unit of Qingdao

Abstract

Objective To investigate antibiotics resistant characteristics and carbapenemases genotype of Acinetobacter baumannii in Intensive Care Unit (ICU), so as to provide theoretical basis for clinical prevention and treatment. Methods Retrospective study was made on 90 non-duplicated clinical isolates of Acinetobacter baumannii, which were collected From January 2013 to January 2014 in three tertiary hospitals of Qingdao. All strains were identified by VITEK2 automated microbiology analyzer; K-B method was used to do drug susceptibility test; polymerase chain reaction (PCR) was used to amplify the OXA-23, OXA-24, OXA-51, OXA-58, KPC-2, VIM, IMP genes, and the positive products of genes were sequenced; the chi-square test was used to compare the difference of the resistance rates. Results The detection rate of multi-drug resistant A. baumannii (MDRAB)and Pan-drug resistant A. baumannii (PDRAB)was 61.11% (55/90) and 17.78% (16/90). In the 32 strains of imipenem-resistant Acinetobacter baumannii, the resistant rates to Cefoperazone/sulbactam, Polymyxin B was lower, while the resistant rates to other drugs tested were more than 85%. The difference of the resistance rates to 9 drugs between imipenem resistant group and Imipenem sensitive group were statistically significant (P≤0.05). PCR result showed: 32 strains detected OXA-51 gene, 28 strains detected OXA-23 gene, and 3 strains detected VIM gene, the detection rates of which were 100%, 87.50% and 9.38% respectively.All strains were not detected OXA-24, OXA-58, KPC-2 and IMP genes. The sequenced results were absolutely homology with the corresponding genes in genbank. Conclusions The resistance of A. baumannii in ICU is serious in this region, especially imipenem-resistant A. baumannii, which were nearly no-sensitive to most of the drugs commonly used in clinical. The gene existence of carbapenemase and carbapenemase producing is one of the main resistance mechanism of Acinetobacter baumannii to carbapenem antibiotics. OXA-23 was the major genotypes in this region.(Chin J Lab Med, 2017, 40: 216-220) Key words: Acinetobacter baumannii; Drug resistance, bacterial; Bacterial proteins; Beta-Lactamases; Genotype; Intensive care units