Impact of Mint oil and Colistin antibiotic on pilB gene of clinical Pseudomonas aeruginosa Isolates from Baghdad, Iraq

Abstract

Pseudomonas aeruginosa considered as one of the most dangerous bacteria in the world and the studying of its resistant and virulence mechanisms is as important as the elimination of this bacteria. One hundred and fifteen burn and wound samples were collected, from hospitals in Baghdad, diagnosed and identified by routine tests, API 20E and VITEK-2 system. Also the identification of genus was conducted by detection the specific gene rpsl using polymerase chain reaction (PCR) technique. According to cultural and biochemical test results 105 of 115 were showed growth on media, however; only 49 isolates (46.7%) of which were identified as P. aeruginosa as a most causative agent in burn. Sensitivity test was performed for eight antibiotics by Kirby-Bauer standard disk diffusion method, the levels of resistance against, colistin 22.4%,Ticarcillin 59.2% ,Pipracillin tazobactam 28.6%,Amikacin 49%,Cefepime 49%,Ciprofloxacin 28.6%,Ceftazidime 59.2%,Imipenem 42.9% . Minimum inhibitory concentrations (MICs) of Colistin and mint oil were evaluated by well diffusion method (to identify antimicrobial activity) for 5 isolates most resistance to antibiotic, appearance MIC for Colistin was 32 µg/ ml, and MIC for mint oil is 1/16 ml/ ml. At the molecular level of this study, the results of PCR reaction showed the presence of rpsl gene in all isolates (100%) and this confirmed the role of this gene in the identification of P. aerugionsa species and its intrinsic in this species, while the pilB gene presented in 45 isolates (91.8%). The gene expression of pilB gene was conducted by using reverse transcriptase quantitative PCR technique. It was found that the value of gene expression fold was reduced for the burns samples after exposure to mint oil in contrast with the untreated isolates, The rpsl gene expression results, which were used as reference gene, demonstrated that this gene was well suited as housekeeping gene because of the minimal variations of expression of this gene whether in Colistin and mint oil treated or untreated isolates.