Characterization of Carbapenem Resistance in Pseudomonas aeruginosa and Involvement of the OprD Gene in Clinical Isolates Isolated in Abidjan

Carbapenem resistance in Pseudomonas aeruginosa (P. aeruginosa) represents a major public health concern, as it drastically limits therapeutic options for severe nosocomial infections. This study investigated carbapenem resistance, multidrug resistance, and the presence of the oprD gene among 31 clinical isolates of P. aeruginosa collected from the National Reference Center for Antibiotics at the Pasteur Institute of C？te d’Ivoire. Isolates were identified using the API 20NE gallery and MALDI-TOF mass spectrometry. Antimicrobial susceptibility testing was performed by the disk diffusion method according to CA-SFM and CLSI recommendations. Results showed that 87.1% and 90.3% of isolates were resistant to imipenem and meropenem, respectively. High levels of cross-resistance were also observed to other β-lactams (cefepime, ceftazidime) and aminoglycosides (gentamicin, tobramycin, amikacin). The oprD gene was detected at a frequency of 83.9% among the isolates. Correlation analysis identified several phenotypic profiles combining carbapenem resistance, multidrug resistance, and oprD positivity. Sequencing of the oprD gene showed substantial polymorphism, including amino acid substitutions and deletions, allowing classification of isolates into five genetic groups. These findings highlight that carbapenem resistance in P. aeruginosa is multifactorial, involving both oprD gene alterations and associated multidrug resistance mechanisms, significantly reducing available therapeutic options.