Quantitative Polymerase Chain Reaction Identified a Multitude of mcr-1 to mcr-5 Genes in Fresh Cow Dung in Bangladesh: An Urgent Public Health Concern

Introduction: The emergence of antimicrobial resistance (AMR) in the food industry is a serious global public health threat. Colistin is frequently used as a growth promoter in livestock, which is a concern. The widespread use of colistin in the food industry is linked to the emergence of mobilised colistin resistance ( mcr ) genes. This must be avoided with colistin, an important Reserve antibiotic in humans. Consequently, there is an urgent need to investigate current variants of mcr gene in cattle faeces in Bangladesh. Methods: Cross-sectional study analysing mcr-1 to mcr-5 in fresh cow dung samples from 20 commercial farms and 6 individual houses. DNA was extracted from cow dung samples using commercial kits. Real-time quantitative polymerase chain reaction was used to assess the five mcr genes in the extracted DNA. Results: 40.8% (49/120) of the samples revealed the existence of at least one mcr gene, with mcr-1, mcr-2, mcr-3, mcr-4 and mcr-5 identified in 27.5% (33/120), 2.5% (3/120), 4.2% (5/120), 14.2% (17/120) and 8.3% (10/120) of samples, respectively. Co-occurrence of two or more genes was documented in 8.3% samples, with co-carriage of three genes in 1.7% of samples. No significantly higher numbers of mcr genes were identified between commercial farms and individual households. Conclusion: Excess use of antibiotics in cattle may result in increased prevalence of antibiotic-resistant genes. A comprehensive One Health approach is urgently needed in Bangladesh to reduce the spread of colistin resistance and meet the United Nation’s targets for Access to antibiotics and AMR.