Jerash University, Jordan
Abstract:
Background: Pseudomonas aeruginosa is an important opportunistic pathogen associated with healthcare-associated infections and increasing antimicrobial resistance. This study characterized antimicrobial susceptibility patterns and investigated the occurrence of genes encoding the MexAB-OprM efflux system among clinical P. aeruginosa isolates in Jordan.
Methods: A total of 60 non-duplicate P. aeruginosa isolates were recovered from clinical specimens, including pus, blood and urine, at Medical City, Amman, Jordan. Identification and antimicrobial susceptibility testing were performed using the VITEK 2 system, with interpretation according to CLSI M100 (2023). PCR detection of oprL and the effluxassociated genes mexA, mexB, and oprM was performed on all MDR/XDR isolates and a selected group of susceptible isolates for comparison.
Results: Considerable resistance was observed to several clinically important antibiotics. Resistance to imipenem and meropenem was 38.33% and 32.20%, respectively, while resistance to ciprofloxacin and levofloxacin was 44.06% and 50.00%. In contrast, amikacin retained high activity, with 91.66% susceptibility. MDR and XDR resistance profiles were identified. The mexA, mexB, and oprM genes were detected in all MDR and XDR isolates examined and were also present in the selected susceptible isolates, indicating that gene presence was not restricted to resistant phenotypes.
Conclusion: Clinical P. aeruginosa isolates from Jordan demonstrated substantial resistance, particularly to carbapenems and fluoroquinolones, while amikacin retained comparatively high activity. Detection of mexA, mexB, and oprM in both resistant and selected susceptible isolates indicates that the presence of these structural genes alone cannot account for the observed resistance phenotypes. Further investigation of efflux-gene expression, regulatory mechanisms, and additional resistance determinants is warranted.
Biography:
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