ABSTRACT
INTRODUCTION: Pseudomonas aeruginosa has increasingly been associated with the emergence of antibiotic resistance. Antibiotic resistance among P. aeruginosa isolates is an ambiguous and complicated mechanism utilizing several enzymes and structural proteins. This study was conducted to investigate the prevalence of mutations in the chromosomal OprD gene that show resistance to carbapenems among clinical isolates of P. aeruginosa. METHODOLOGY: Sixty-three clinical isolates of P. aeruginosa resistant to meropenem were collected from public hospitals in Irbid city, north of Jordan. Analysis of antimicrobial susceptibility was carried out and their susceptibility was categorized. Molecular analysis of mutations in the OprD gene was performed using restriction fragment length polymorphism (RFLP) and DNA sequencing. RESULTS: Molecular analysis of P. aeruginosa isolates showed 52% of the common molecular modifications among the collected isolates. These alterations could be associated and affect meropenem-susceptibility rather than imipenem. The most frequent molecular changes among the resistant isolates were the F170L substitution mutation. This was detected in 22 (35%) of the isolates with an unusual insertion sequence (IS) of 100 bp within the 590 bp DNA segment downstream of the restriction site. The divergent sequence of 10 amino acids 372(VDSSSSYAGL)383 was detected in 7 (11%) of the isolates. CONCLUSIONS: A significant alteration in the OprD gene in P. aeruginosa clinical isolates was found. Alterations in the OprD gene could be linked to protein permeability of the outer membrane of P. aeruginosa associated with meropenem resistance. Further investigations with a larger number of bacterial isolates are needed to validate the proposed association.
