Resistance profile of genetically distinct clinical Pseudomonas aeruginosa isolates from public hospitals in central Pakistan

Abstract

Introduction: Pseudomonas aeruginosa (member of ESKAPE group) is predominantly responsible for emerging nosocomial infections and poses serious health concern due to ever-increasing drug resistance trends. The current study investigates the prevalence of such highly resistant P. aeruginosa in major hospital settings and further characterizes and compares them for genetic heterogeneity.

Materials and methods: Samples of patients (n=108) with wound infections, bacteremia and burn injuries from major hospitals of Rawalpindi and Islamabad during 2017 to 2018 were collected for the present study. The samples were processed in the COMSATS Microbiology and Public Health lab and screened for the P. aeruginosa by routinely used biochemical tests, drug susceptibility tests and rapid molecular approaches.

Results: The results suggested that most of the isolates (88/108) are indeed P. aeruginosa (81.4%) underpinning the need of its active surveillance in hospital settings. Further analysis suggested that 32 of these 88 microbes are multi-drug resistance (36.3%), 16 (18.1%) are extensively drug resistance and 4 (4.5%) are pan-drug resistance. Moreover, double disc synergistic test suggested that 16 (18.1%) are positive for metallo-β-lactamase production. Molecular screening confirmed that 2 (12.5%) and 3 (18.75%) of these 16 isolates are positive for VIM and NDM gene respectively while all the studied isolates were positive for AmpC β-lactamase. PAP17 isolate harbors both VIM and NDM genes. ERIC PCR profiling showed that majority of MDR bacteria fall in cluster II and III similarly XDR bacteria also fall in cluster II and III while PDR bacteria fall in cluster IV.

Conclusion: This study revealed that majority of the isolates are multi drug resistant MDR and extensively drug resistant (XDR). However, the presence of some pan drug resistant (PDR) isolates among such small sample size screened is of utmost concern. Molecular typing of extremely resistant P. aeruginosa revealed high genetic diversity. Therefore, we suggest that regular monitoring and surveillance of such highly resistant P. aeruginosa in hospital settings will help to control their transmission and hence reduce the disease burden.

Keywords: AmpC-β-lactamase; Metallo-β-lactamase; PDR; Pseudomonas aeruginosa; XDR.