Antibiogram and molecular profiling of non-respiratory isolates of Pseudomonas aeruginosa using ERIC-PCR in a tertiary care hospital

Abstract

Background and Objectives: Pseudomonas aeruginosa is a major nosocomial pathogen implicated in a wide range of hos- pital-acquired infections. Prompt detection and effective control of outbreaks caused by this organism are essential to mini- mize associated morbidity and mortality. Multiple strains may circulate within healthcare settings due to cross-transmission and persistent environmental reservoirs. Various molecular typing techniques have proven valuable in tracing the sources and transmission dynamics of outbreaks. The present study aimed to investigate the antibiogram profiles and enterobacterial repetitive intergenic consensus–polymerase chain reaction (ERIC-PCR) patterns of P. aeruginosa isolates recovered from non-respiratory clinical samples at a tertiary care hospital.

Materials and Methods: A total of 157 clinical isolates phenotypically identified as P. aeruginosa were subjected to 16S rDNA-PCR for species confirmation. Among these, 150 isolates were confirmed as P. aeruginosa and subsequently analysed for antimicrobial susceptibility and molecular typing. Antimicrobial susceptibility testing was performed according to Clini- cal and Laboratory Standards Institute (CLSI) guidelines. Molecular typing was carried out using ERIC-PCR. The resulting ERIC-PCR profiles were analysed using PAST version 4.03 software, and a dendrogram was constructed based on Dice sim- ilarity coefficients to assess genetic relatedness among isolates. Fisher’s exact test was employed to determine associations between specific ERIC types and antibiotic resistance profiles.

Results: Overall, 84% of the P. aeruginosa isolates were identified as multidrug-resistant (MDR), with widespread distri- bution among both inpatients and outpatients. The highest resistance rate was observed against ticarcillin/clavulanic acid, followed by ceftazidime, whereas no resistance was detected against colistin sulphate. A total of 54 distinct antibiotypes were identified, indicating substantial variability in antimicrobial resistance patterns. All 150 isolates were successfully typed using ERIC-PCR, which revealed 41 distinct clusters at an approximate similarity coefficient of 70%, demonstrating considerable genetic diversity among the isolates.

Conclusion: This study enhances the understanding of the epidemiology of P. aeruginosa infections in healthcare settings by characterizing both the molecular diversity and antimicrobial resistance patterns of clinical isolates. The high prevalence of MDR strains and the circulation of multiple genetically diverse strains among hospital patients highlight the ongoing risk of transmission within the healthcare environment. Notably, the findings suggest a comparatively higher rate of cross-infection among burn patients. These observations underscore the urgent need for stringent infection prevention and control measures, particularly in burn units, to limit the spread of MDR P. aeruginosa.