oprD Genes Detected in Pseudomonas aeruginosa Isolates from a Teaching Hospital but Lost in a Carbapenem-Resistant Strain

Aims: The aims of the study were to evaluate the multidrug resistance profile and mechanisms of carbapenem resistance in Pseudomonas aeruginosa clinical isolates using phenotypic and genotypic methods.

Study Design: A descriptive laboratory based study.

Place and Duration of Study: Microbiology Laboratory, Ondo State University of Science and Technology, Okitipupa, and Biotechnology Laboratory, Ladoke Akintola University of Technology, Osogbo, Nigeria, between June 2017 and November 2018.

Methodology: Ten P. aeruginosa isolates were recovered from patients at Lagos University Teaching Hospital, and susceptibilities to imipenem (10 µg), meropenem (10 µg) and a panel of antibiotics were performed by the disk diffusion method. Genotypic methods including Polymerase Chain Reactions (PCR) and agarose gel electrophoresis were carried out according to established protocols. oprD and blaIMP gene primers were used for the PCR amplification.

Results: Fifty percent (50%) of the isolates showed multiple drug resistance. Four isolates (40%) were carbapenem resistant (CR). oprD gene was detectedin 90% (9/10) of the isolates. 75% (3/4) of CR strains were among the strains showing oprD gene. 25% (1/4) CR strain (PA1421) was oprD negative. Loss or mutation of oprD gene seems to be the mechanism of carbapenem resistance in strain PA1421.

Conclusion: Loss or mutation of oprD gene was identified in this study as a mechanism of carbapenem resistance. oprD gene encodes the outer membrane protein (OprD) porin in P. aeruginosa whose deficiency confers resistance to carbapenems, especially imipenem. Surveillance of the antimicrobial susceptibility patterns of P. aeruginosa is of critical importance in understanding new and emerging resistance trends, reviewing antibiotic policies and informing therapeutic options.