Analysis of the presence of genes conferring resistance to aminoglycosides in Acinetobacter baumanii isolates belonging to global clone۱ (GC۱) and determination of the location of resistance genes

Background and Aim : A. baumannii (Acinetobacter baumannii) is a nosocomial pathogen known as a global worry because of high levels of resistance to many antibiotics. Aminoglycoside resistance has increased in these bacteria due to the expression of AMEs (Modifying Enzymes Genes). The cause of resistance to the aminoglycosides in A. baumannii isolates belongs to GC۱ (Global Clone۱), and the location of these genes, namely aphA۶, aphA۱b, aadB, aacA۱, aacA۴, and aadA۱, have been determined. Methods : PCR was used to characterize isolates, detect antibiotic resistance genes, and the location of AMEs genes on the mobile genetic elements. Plasmid pRAY* has been isolated and examined by restriction digestion to identify features. The clonal type was determined by Multiplex PCR and MLST (Multilocus sequence typing). Results : Fourteen isolates that belong to GC۱ were found among ۲۵۳ A. baumannii isolated between ۲۰۱۲ and ۲۰۱۸ from ۵ Hospitals in Tehran. Exhibited resistance to gentamicin, kanamycin, and tobramycin have related to AMEs. Present (۱۰۰%) of aadB gene, ۱۱ (۷۸.۵۷%) aadA۱, ۹ (۲۸/۶۴%) aphA۶, ۳ (۴۲/۲۱%) aacA۱, ۳ (۴۲/۲۱%) aphA۱b, ۳ (۴۲ /%) ۲۱) aacC۱ were detected. aacA۴ gene was not found in any of the isolates. These isolates all carried the aadB gene cassette on pRAY*.Conclusion : Substantial diversity was observed among aminoglycoside-resistant genes in GC۱ that increase antibiotic resistance and Lead to phenotypic resistance to the antibiotics amikacin, neomycin, gentamicin, and tobramycin. Therefore, molecular surveillance and providing Appropriate antibiotic prescribing for preventing infections is the most important to control the spread of these genes among GC۱ isolates.

Keywords:

Antibiotic Resistance Genes , Aminoglycosides , Global Clone , Acinetobacter baumannii , pRAY*