Abstract
BACKGROUND AND AIMS: The emergence of Pseudomonas aeruginosa (P. aeruginosa) antibiotic resistance is an important public health problem worldwide that can negatively affect infection control. Therefore, obtaining knowledge about antibiotic resistance mechanisms is necessary for infection control policies. This study aimed to determine the frequency of class C and D β-lactamases in P. aeruginosa strains isolated from patients referred to Ardabil hospitals using phenotypic and genotypic tests. METHODS: Phenotypic detection of β-lactamases including AmpC cephalosporinase, oxacillinase (OXA)-type extended-spectrum β-lactamases (ESBLs), and OXA-type carbapenemases were performed using the disk diffusion-based methods. Amplification of genes encoding classes C (ampC and FOX genes) and D (OXA-1, OXA-2, OXA-10, OXA-23, and OXA-48 genes) β-lactamases was performed using the polymerase chain reaction (PCR) method. A quantitative reverse transcription PCR (qRT-PCR) method was used to determine the expression level of the ampC gene among multiple drug-resistant and imipenem-resistant P. aeruginosa strains. RESULTS: In phenotypic tests, the prevalence of AmpC cephalosporinase, OXA-type ESBLs, and OXA-type carbapenemases were 52.5%, 7.2%, and 95.8%, respectively. In genotypic tests, the prevalence of ampC, FOX, OXA-1, OXA-2, OXA-10, OXA-23, and OXA-48 genes were 100%, 0%, 4.3%, 60.8%, 42%, 29.7%, and 2.9%, respectively. In addition, the ampC gene overexpression was seen in 16 (33.3%) drug-resistant P. aeruginosa clinical isolates. CONCLUSION: Given the presence of class C and D β-lactamases in clinical isolates of P. aeruginosa in Ardabil hospitals, early detection of these strains can help prevent the spread of resistant strains in hospital environments and subsequent treatment failure.