Detection of aminoglycoside-modifying enzyme genes in Pseudomonas aeruginosa clinical isolates

Abstract

Pseudomonas aeruginosa is an opportunistic pathogen that frequently causes infections in immunocompromised patients and is involved in outbreaks of hospital-acquired infections with a high mortality rate. Aminoglycosides are a large category of antibiotics that bind specifically to 16S rRNA in 30S ribosomal subunits and disturb protein translation. This antibiotic class plays a significant bactericidal role against a wide range of Gram-negative bacteria such as P. aeruginosa. Among different aminoglycoside resistance mechanisms, inactivation of drugs by plasmid-encoded aminoglycoside-modifying enzymes (AMEs) is a common determinant of aminoglycoside resistance in  P. aeruginosa. These plasmids are spread worldwide, and they are transferred to a wide range of different species. This study aims to detect resistance mechanisms and  identify the most prevalent aminoglycoside resistance genes in P. aeruginosa clinical isolates, collected from the University Clinical Centre Tuzla. This study included a total of 230 clinical P. aeruginosa isolates. Antimicrobial susceptibility tests were performed using the disk diffusion method and the Vitek2 system. Isolates displaying increased MIC values for aminoglycoside antibiotics were included in the multiplex PCR reaction, for the detection of aminoglycoside-modifying enzyme genes. The most prevalent genotype among isolates was aac (6')-I. All aac (6')-I genotyped isolates also displayed a high rate of resistance to other classes of antibiotics, and they were characterized as multidrug-resistant (MDR) or extensively drug-resistant (XDR). Results indicate that the aminoglycoside-resistance genes are highly prevalent and could easily spread among P. aeruginosa strains.