Phenotypic and molecular characterization of Multidrug Resistant Pseudomonas aeruginosa from clinical specimens

Abstract

Emergence and global spread of Multi-drug resistant (MDR) Pseudomonas aeruginosa is of great concern in public health care settings. The infections caused by these pathogens are difficult to treat and lead to morbidity and mortality. The aim of the study was to determine the prevalence of crabapenem resistant genes in MDR P. aeruginosa clinical isolates. Total of 200 non-duplicate P. aeruginosa were collected from a tertiary-care hospital, Faisalabad during May 2016 to April 2017. Clinical isolates were sub-cultured on P. aeruginosa selective Cetrimide agar and biochemically confirmed by API 20NE. Antibiogram analysis was performed using Kirby-Bauer disk diffusion method and further confirmed by E test as per CLSI 2016 guidelines. Phenotypic detection of carbapenemase and metallo-β lactamase activity was carried out by Modified Hodge’s test and EDTA disc synergy test. Molecular detection of MBL genes were performed using specific primers by PCR. The antimicrobial activity of silver nanoparticles was determined by Broth micro dilution assay against blaNDM, blaVIM, blaOXA-48 harboring genes. Of 200 P. aeruginosa, 41% were isolated from pus samples. Males (57.5%) were largely infected as compared to females and 46% of the isolates were recovered between 61 to 80 years of age group. Among 55% MDR P. aeruginosa, 63% were carbapenemase and 52% were MBL producers and among these, 25(35.7%) isolates were positive for blaNDM and 23(32.8%) were blaVIM. Antibiogram displayed that 80% of the P. aeruginosa were resistant to both cefotaxime and ceftazidime, and 77% to carbapenems, while least resistance was observed against tigecycline and colistin. MIC of imipenem showed that 57 MDR P. aeruginosa isolates were inhibited at 16μg/mL and 37 at 8μg/mL, however, MIC of meropenem showed that 46 MDR P. aeruginosa isolates were inhibited at 8μg/mL and 39 at 16μg/mL. The MIC and MBC of AgNPs inhibited and killed the MBL producing P. aeruginosa at 1mg/mL and 2mg/mL concentration, respectively. The present study concluded an alarming increase of MBL P. aeruginosa in the clinical settings which displayed resistance to most of the antibiotics therefore, AgNPs can be used as potential antimicrobial agents after their pharmacodynamics and pharmacokinetics.