Molecular Detection of Aminoglycoside Resistance Genes in Acinetobacter Baumannii Clinical Isolates from Najaf Hospitals, Iraq

Abstract

Background: Acinetobacter baumannii is an opportunistic infection that quickly acquires resistance to frequently administered antimicrobials in hospitalised patients globally. Aminoglycosides are still the preferred treatment for Acinetobacter infections; however, resistance has increased over the past few years. There are several different routes for aminoglycoside resistance, and they almost always interfere with the activity of aminoglycoside-modifying enzymes.Aim of the study: This study studied most of the genes in A. baumannii that code for aminoglycoside-modifying enzymes in clinical samples from hospitals in Najaf, Iraq.Materials and Methods: Twenty-eight samples of A. baumannii were taken from hospitals in Najaf, Iraq. The antimicrobial resistance patterns of of these isolates to different antimicrobial drugs were tried using the disc diffusion method, and the species were determined utilising the automated VITEK-2 system. The genes encoding aminoglycoside modifying enzymes (ACC (6')-lb, aacC1, amrA, and aac(3)-lla) were investigated by the PCR technique.Results: Antimicrobial tests found that all isolates resistant to tetracycline ciprofloxacin, and ceftazidime, whereas colistin (100%) and imipenem (71%) showed the greatest sensitivity. The aminoglycoside resistance rates for gentamicin, amikacin, tobramycin, and neomycin were 93, 86, 82, and 78%, respectively. ACC (6')-lb gene was the most prevalent aminoglycoside-resistance gene among A. baumannii clinical isolates, as identified in 16 isolates (57%) by PCR, followed by aacC1 in 5 isolates (18%) and amrA in 3 isolates (11%) whereas all isolates were negative for aac(3)-lla gene. We identified 4 isolates with 2 AME genes, 3 with ACC (6')-lb and aacC1 and 1 with ACC (6')-lb and amrA. Only seven (25%) A. baumannii isolates were no amplification for every AME resistance gene.Conclusion: This study showed that clinical isolates of A. baumannii in hospitals in Najaf were often very resistant to aminoglycosides, and most of these isolates had the aac (6')-Ib gene.