Role of Aminoglycoside‐Modifying Enzymes (AMEs) in Resistance to Aminoglycosides among Clinical Isolates of <i>Pseudomonas aeruginosa</i> in the North of Iran

Abstract

In recent years, the prevalence of resistance to aminoglycosides among clinical isolates of <i>Pseudomonas aeruginosa</i> is increasing. The aim of this study was to investigate the role of aminoglycoside-modifying enzymes (AMEs) in resistance to aminoglycosides in clinical isolates of <i>P. aeruginosa</i>. The clinical isolates were collected from different hospitals. Disk agar diffusion test was used to determine the antimicrobial resistance pattern of the clinical isolates, and the minimum inhibitory concentration of aminoglycosides was detected by microbroth dilution method. The PCR was performed for discovery of aminoglycoside-modifying enzyme-encoding genes. Among 100 screened isolates, 43 (43%) isolates were resistant to at least one tested aminoglycosides. However, 13 (13%) isolates were resistant to all tested aminoglycosides and 37 isolates were detected as multidrug resistant (MDR). The resistance rates of <i>P. aeruginosa</i> isolates against tested antibiotics were as follows: ciprofloxacin (41%), piperacillin-tazobactam (12%), cefepime (32%), piperacillin (26%), and imipenem (31%). However, according to the MIC method, 13%, 32%, 33%, and 37% of the isolates were resistant to amikacin, gentamicin, tobramycin, and netilmicin, respectively. The PCR results showed that <i>AAC(6</i>'<i>)-Ib</i> was the most commonly (26/43, 60.4%) identified AME-encoding gene followed by <i>AAC(6</i>'<i>)-IIa</i> (41.86%), <i>APH(3</i>'<i>)-IIb</i> (34.8%), <i>ANT(3</i> ^″ <i>)-Ia</i> (18.6), <i>ANT(2</i> ^″ <i>)-Ia</i> (13.95%), and <i>APH(3</i> ^″ <i>)-Ib</i> (2.32%). However, <i>APH(3</i>'<i>)-Ib</i> was not found in any of the studied isolates. The high prevalence of AME-encoding genes among aminoglycoside-resistant <i>P. aeruginosa</i> isolates in this area indicated the important role of AMEs in resistance to these antibiotics similar to most studies worldwide. Due to the transmission possibility of these genes between the Gram-negative bacteria, we need to control the prescription of aminoglycosides in hospitals.