Genetic Determinants Supporting The Multi-Drug Resistance Of Acinetobacter Spp. In Georgia

Purpose: Emergence and spread of multidrug- resistant (MDR) bacteria have become a serious challenge for health care workers around the globe. Acinetobacter baumannii represents one of the most widely distributed nosocomial pathogens quickly acquiring resistance to various groups of antibiotics, making treatment a challenging process. Plasmid-encoded genes often contribute to the steadily increasing MDR phenotype. As the molecular mechanisms of antimicrobial resistance of Acinetobacter spp. in Georgia are not yet fully understood, we have examined genes potentially supporting multi drug resistance of Acinetobacter spp. in the Country. Methods & Materials: Bacterial isolates, recovered from the samples of hospitalized patients, were collected at various laboratory sites of Georgia. Identity and resistance patterns were detected by the automated system Vitek 2 and manual methods, such as disc diffusion and E-test. Antimicrobial resistance genes were identified by PCR and sequence analysis. Results: Twenty eight isolates of Acinetobacter baumannii complex were collected between July 2017 and February 2018. It was found that all isolates were resistant to 3rd generation cephalosporins and nitrofurantoin, but sensitive to colistin and minocycline. In addition, 86% (n = 24), 75% (n = 21) and 61% (n = 17) of Acinetobacter strains displayed resistance to carbapenems and fluoroquinolones, aminoglycosides and Trimthroprim/Sulfamethoxazole, respectively. The only gene detected by PCR-based analysis was the New Delhi metallo-beta-lactamase (NDM) presenting in four isolates with intermediate resistance to imipenem and meropenem. In addition, the preliminary whole genome sequence analysis of one MDR isolate revealed the presence beta-lactamase genes blaOXA-72, blaOXA-90, blaOXA-24, as well as blaCTX-M-115 and an ADC-type class C β-lactamase. Point mutations contributing to fluoroquinolone resistance in gyrA and parC were also identified. Conclusion: This is the first sequence-based report describing multiple genetic elements supporting multi-drug resistance of Acinetobacter species in the Country of Georgia. Detection of various transmissible plasmid-associated genes in Acinetobacter is indicative of a potential horizontal spread contributing to the evolvement of extensively drug resistant “superbugs” in Georgia.