Detection of IMP and VIM genes and antibacterial activity of some plant extracts in carbapenem-resistant Pseudomonas aeruginosa isolated from burn infections

Carbapenem-resistant Pseudomonas aeruginosa has emerged as a deadly pathogenic agent globally, responsible for the majority of morbidity and fatalities in burn patients. Genes of carbapenemase are considered to be among the most prevalent means of resistance in P. aeruginosa to carbapenem. In the present study, the existence of metallo-beta-lactamase (MBL) genes of the VIM and IMP in carbapenem-resistant P. aeruginosa isolated from burn patients were determined and also the antibacterial effects of five ethanolic plant extracts were investigated. Twenty carbapenem-resistant P. aeruginosa isolates were isolated from burn infections. The disc diffusion test was used for examination of antibacterial susceptibility. Subsequently, MBL were identified by the imipenem-EDTA combined disc test and PCR. This was followed by evaluation of the plant extract and MIC determination by the well-diffusion method. The results revealed that among 20 P. aeruginosa isolates, 17 (85%) were imipenem-resistant. Among them, 11 (64.7%) isolates appeared positive for the IMPEDTA combined disc test. The VIM gene was detected positively in seven (41.2%) isolates. Not a single isolate had the IMP gene. None of the imipenem-sensitive isolates harbored the IMP or VIM genes. Evaluation of ethanolic extract of Rhus coriaria, Punica granatum, Thymus vulgaris, Syzygium aromaticum and Curcuma longa revealed possibly effective though variable efficacy against the tested P. aeruginosa isolates. Rhus coriaria extract was the most efficient and exhibited bactericidal and bacteriostatic activities with MIC's of 3.6 mg/mL while Punica granatum and Syzygium aromaticum showed MIC which reached 4.5 mg/mL. These plant extracts which were demonstrated to be potentially efficient could be utilized as natural alternative treatment to eradicate carbapenem-resistant P. aeruginosa.