Colistin resistance and the mcr-1 gene of Pseudomonas aeruginosa: Insights from Indian clinical isolates

Abstract

Objective: This study aimed to determine the prevalence of colistin resistance mediated by mcr-1 in Pseudomonas ( P.) aeruginosa isolates from clinical samples.
Methods: P. aeruginosa isolates were collected from various clinical specimens and tested for colistin resistance using the broth microdilution method. Isolates exhibiting resistance underwent polymerase chain reaction (PCR) screening for mcr-1. Antimicrobial susceptibility testing was performed for multiple antibiotics.
Results: Sixty five clinical isolates were obtained; 10 (15.4%) were phenotypically resistant to colistin, with minimum inhibitory concentrations (MIC) values ranging from 4-16 µg/mL. The mcr-1 gene was detected in 4 (40.0%) colistin-resistant isolates, constituting 6.2% of all P. aeruginosa isolates. The highest resistance was observed for ceftazidime (70%), amikacin (60%), and ciprofloxacin (60%). Piperacillin-tazobactam was the most effective antibiotic, with 80% susceptibility.
Conclusions: The presence of mcr-1 in P. aeruginosa isolates highlights the growing risk of colistin resistance beyond Enterobacteriaceae. Routine surveillance, antimicrobial stewardship, and molecular detection strategies are essential to curb further resistance spread.

Keywords

mcr-1 gene / Colistin resistance / Pseudomonas aeruginosa / Antimicrobial resistance / PCR detection

Conflict of interest statement

The authors declare that there is no conflict of interest.

Funding

This study receives no extramural funding.

Data availability statement

The data supporting the findings of this study are available from the corresponding author upon request.

Authors’ contributions

Gautam PK and Prajapati B conceptualized the study. Gautam PK collected the data, and Tiwari ON formatted the manuscript. All the authors agree the content of the manuscript.

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