Investigation of phenotypic and genotypic characteristics of acinetobacter baumannii clinical isolates

Background: In this study, we aimed to investigate the virulence factors (biofilm formation, movement ability, hemolysis) and resistance genes to determine international clones and clonal relationship, plasmid profile by phenotypic-genotypic tests in A. baumannii isolated from various clinical samples in Hitit University-Çorum Erol Olçok Training and Research Hospital between 2018-2019. Materials and Methods: Identification and antibiotic susceptibility of 98 A. baumannii isolates were determined with the Vitek 2 system. Colistin antibiotic susceptibility was determined with the broth microdilution method. Carbapenem resistance genes and biofilm associated genes were investigated. Isolates were typed by molecular methods and international clones identified. The plasmid profiles of the strains were determined by the alkaline lysis method. Colony morphology, type of hemolysis, motility, biofilm formation and metallobetalactamase production were tested by phenotypic methods. Biofilm formation was investigated on ceramic surface, plastic tube, vascular catheter and foley catheter surfaces. Biofilm level was measured by spectrophotometer and visualized by electron microscope. Results: The imipenem-meropenem resistance of A. baumannii isolates was 87% (85/98) and colistin resistance was 8% (8/98). 42% of the isolates were resistant to multiple drugs, 45% to extreme drugs, and 13% to all antibiotics. Metallobetalactamase production was found in 83,5% (71/98) of the strains. The genes of blaOXA-51, blaOXA-23, ISab1 / blaOXA-51, ISAba1 / blaOXA-23 were found in 98,8% (84/85) of carbapenem resistant isolates. The blaOXA-24/40 and blaOXA58 genes were not detected. Hospital epidemic isolate was Genotype D and it has been classified as clon II. Overall, no similarities were observed between susceptible and resistant isolates in terms of plasmid profiles, genotypes and clonality. Different biofilm levels were measured in 88% of the isolates, and biofilm associated genes were detected in most of them. Biofilm formation was most strongly observed on the foley catheter surface. Except for hemolytic activity, no relationship was found between virulence and resistance in the study. Conclusion: Determination of virulence factors and resistance mechanisms of strains and epidemiological follow-up will be beneficial in prevention and treatment of A. baumannii infections. It will also be effective in reducing possible complications and mortality and will help the development of new treatment methods in the future. Keywords: A. baumannii, antibiotic resistance, virulence, REP-PCR, plasmid