Background: Pseudomonas aeruginosa (P. aeruginosa) is a common causative agent of hospital-acquired infections and exhibits resistance to many antibiotics, including beta-lactams. One of the mechanisms of resistance to beta-lactams is the MexAB-OprM efflux pump. This study investigated the genetic pattern of resistant P. aeruginosa strains concerning the presence of the gene encoding the MexAB-OprM efflux pump
Methods: This descriptive-analytical study was conducted between 2022 and 2023 in Isfahan, and 110 strains of P. aeruginosa isolated from various clinical samples were identified. Antibiotic susceptibility testing of the isolates was conducted using the disk diffusion method, and strains producing extended-spectrum beta-lactamases (ESBLs) were identified using the double disk diffusion method. The gene encoding the MexAB-OprM efflux pump in these strains was investigated using polymerase chain reaction.
Results: A significant proportion of the 101 P. aeruginosa isolates originated from the emergency department and ICU-2, highlighting the clinical significance of this pathogen in these settings. Meropenem demonstrated a high resistance rate (74%), while gentamicin exhibited lower resistance (33.33%). Resistance rates to amikacin, levofloxacin, cefepime, ceftazidime, tazocin, ciprofloxacin, and ceftriaxone were 40.4%, 68%, 65.34%, 66.33%, 57.42%, 71.42%, and 50%, respectively. The prevalence of extended-spectrum beta-lactamases (ESBLs) was 29.7%, and the MexAB-OprM efflux pump gene was identified in 80% of ESBL-producing strains, suggesting a potential role in multidrug resistance.
Conclusion: Our findings reveal a strong association between the presence of the MexAB-OprM efflux pump and extended-spectrum beta-lactamase production in P. aeruginosa. This observation suggests that the MexAB-OprM efflux pump plays a pivotal role in the development of multidrug resistance in this pathogen. Future studies should focus on elucidating the molecular mechanisms underlying the regulation and function of this efflux system to inform the design of novel antimicrobial agents and combination therapies.
