Genotypic Detection of Colistin Resistant Citrobacter freundii from a Tertiary Care Hospital, Bangladesh

Abstract

Background: The effectiveness of colistin is threatened by its quick growth in resistance, which is a major global public health concern. Effective surveillance, infection management, and evidence-based treatment decisions are hampered by the absence of epidemiological and genotypic data on colistin-resistant Citrobacter freundii in Bangladesh.

Objective: This study was performed to see the genes accountable for colistin resistance in Citrobacter freundii isolates from different microbiological samples.

Methodology: In this cross-sectional study, a total of 27 Citrobacter freundii isolates were obtained from 500 samples collected between July 2019 and June 2020 using standard culture methods, biochemical, and molecular tests. Their colistin susceptibility was determined using the Minimum Inhibitory Concentration (MIC) agar dilution method. Specific primers were used to detect the colistin-resistant pmrA, pmrB, pmrC, phoP, phoQ, mcr-1, and mcr-2 genes by PCR.

Results: Amongst the isolated Citrobacter freundii, 29.63% were resistant to colistin. Among these resistant bacteria, 50%, 75%, 87.5%, 100%, 12.5% were phoP, phoQ, pmrA, pmrB, and mcr-1, respectively. pmrC and mcr-2 were not found in any colistin-resistant isolates.

Conclusion: Citrobacter freundii is showing increasing resistance to colistin highlighting the utmost importance for continuous surveillance, rational antibiotic use, and strengthened disease prevention tactics to limit the further spread of colistin resistance.

Bangladesh Journal of Medical Microbiology, January 2026;20 (1):31-38