Phenotypic and Genotypic Detection of Efflux Pump in Meropenem-Resistant Pseudomonas aeruginosa Among Burn Patients

Efflux Pump in Meropenem-Resistant P. aeruginosa

Abstract

Background: Multidrug-resistant (MDR) Pseudomonas aeruginosa in burn wounds is becoming a difficult issue worldwide. The recent emergence of meropenem-resistant MDR Pseudomonas aeruginosa poses a serious threat to public health. The activity of the MDR efflux pump is a key mechanism contributing to meropenem resistance.

Objective: The study aims to detect efflux pump phenotypically and genotypically in meropenem-resistant MDR Pseudomonas aeruginosa among burn wound patients.

Methods: A total of 120 laboratory isolates of Pseudomonas species from burn wounds were collected from the patients of National Institute of Burn and Plastic Surgery, Dhaka. The automated VITEK® 2 Compact system in the department of microbiology and immunology at Bangladesh Medical University (BMU) was used to identify Pseudomonas aeruginosa. Antimicrobial susceptibility testing and identification of MDR Pseudomonas aeruginosa were conducted by using the Kirby-Bauer disk diffusion technique. Out of 120 laboratory isolates of Pseudomonas species; Pseudomonas aeruginosa accounted for the majority of these isolates (109, 90.8%), followed by Pseudomonas fluorescens (6, 5%) and Pseudomonas putida (5, 4.17%). Among 109 Pseudomonas aeruginosa, 92 (84.4%) were multidrug resistant (MDR). Among 92 MDR cases, 78 (84.8%) were meropenem-resistant Pseudomonas aeruginosa. Finally, 78 meropenem-resistant Pseudomonas aeruginosa among all MDR were selected as study subjects. Efflux pump that causes meropenem resistance was identified both phenotypically and genotypically. Ethidium bromide cartwheel (EtBr-CW) approach was used for phenotypic identification and efflux pump genes (MexAB-OprM) detection by conventional polymerase chain reaction (PCR) was used for genotypic identification of efflux pump.

Result: Out of 109 Pseudomonas aeruginosa isoates, majority (92, 84.4%) of Pseudomonas aeruginosa were multidrug-resistant (MDR) where majority (78, 84.8%) showed resistance to meropenem. Among meropenem resistant Pseudomonas aeruginosa (78); efflux pump was detected both genotypically and phenotypically in 52 (66.7%) cases and only genotypically in 05 (6.4%) cases. Therefore, in 57 (73.1%) cases efflux pump was detected genotypically through detection of efflux pump gene. Among the different efflux pump gene; Mex A gene was found in 52 cases, Mex B gene in 57 cases, Opr M gene in 19 cases, both Mex A and Mex B gene in 51 cases and Mex A, Mex B, Opr M gene together in 19 cases.

Conclusion: The majority of pseudomonas aeruginosa were multidrug resistant (MDR) and showed resistant to meropenem. Efflux pump genes (MexA, MexB, OprM) were found in good number of the patients.

Bangladesh Medical Res Counc Bull 2025;51(3): 131-138