Genotypic Investigation of Antibiotic Resistance: Presence of BlaOXA-۴۸ Gene in Clinical Isolates of Pseudomonas aeruginosa

Background: Identifying antimicrobial resistance patterns and antibiotic resistance genes in clinical isolates of Pseudomonas aeruginosa is an important strategy for effectively combating infections. This study aimed to identify the antimicrobial resistance patterns and the presence of blaOXA-۴۸ beta-lactamase gene in P. aeruginosa isolated from clinical samples. Methods: We collected ۱۰۰ isolates of P. aeruginosa from different clinical samples, including urine, tracheal tube, blood, and burn wounds. The antimicrobial resistance patterns of the isolates were investigated using the disk diffusion method. Extended-spectrum beta-lactamase (ESBL) strains were analyzed phenotypically by the combined disk method. Furthermore, the presence of the blaOXA-۴۸ gene in the isolates was assessed genotypically via molecular techniques. Results: The highest resistance of the isolates was detected for ceftazidime (۸۹%) and ciprofloxacin (۸۳%), whereas the highest sensitivity was detected for colistin (۱۸%). The phenotypic method identified ۶۸ (۶۸%) ESBL-producing isolates among ۱۰۰ isolates. In addition, blaOXA-۴۸ gene was detected genotypically in ۳۳ (۴۸.۵%) isolates among ۶۸ ESBL-producer isolates. Moreover, a significant association was found between the presence of the blaOXA-۴۸ gene and P. aeruginosa isolates’ resistance to cefepime, imipenem, and gentamicin (P<۰.۰۵). Conclusion: The study highlighted the significant prevalence of antimicrobial resistance in P. aeruginosa, particularly against ceftazidime and ciprofloxacin, although colistin remains largely effective. The association between the blaOXA-۴۸ gene and resistance to key antibiotics such as cefepime, imipenem, and gentamicin underscores the need for continuous monitoring and strategic antimicrobial stewardship to mitigate the spread of resistant strains.