Tehran University of Medical Sciences Journal of Medical Bacteriology 2251-8649 13 4 2025 12 12 56 66 EN Komal Parashar Institute of Applied Medicine and Research, Duhai, 9th Km. Stone, Delhi-Meerut Road, Ghaziabad-201206, UP, India. Anil Kumar Teotia Indian Pharmacopoeia Commission, Ministry of Health & Family Welfare, Government of India, Sector-23, Raj Nagar, Ghaziabad, Uttar Pradesh, India-201002 Prasad Thota Indian Pharmacopoeia Commission, Ministry of Health & Family Welfare, Government of India, Sector-23, Raj Nagar, Ghaziabad, Uttar Pradesh, India-201002 Ajay Lagashetti Indian Pharmacopoeia Commission, Ministry of Health & Family Welfare, Government of India, Sector-23, Raj Nagar, Ghaziabad, Uttar Pradesh, India-201002 Manoj Pandey Indian Pharmacopoeia Commission, Ministry of Health & Family Welfare, Government of India, Sector-23, Raj Nagar, Ghaziabad, Uttar Pradesh, India-201002 Ajayendra Keshari Indian Pharmacopoeia Commission, Ministry of Health & Family Welfare, Government of India, Sector-23, Raj Nagar, Ghaziabad, Uttar Pradesh, India-201002 Meenakshi Dahiya Indian Pharmacopoeia Commission, Ministry of Health & Family Welfare, Government of India, Sector-23, Raj Nagar, Ghaziabad, Uttar Pradesh, India-201002 Vivekanandan Kalaiselvan Indian Pharmacopoeia Commission, Ministry of Health & Family Welfare, Government of India, Sector-23, Raj Nagar, Ghaziabad, Uttar Pradesh, India-201002 2025 08 12 2025 08 28 Background:   The increasing application of Escherichia coli as a model organism in microbiological quality control highlights importance of E. coli due to their wide range of applications. However, rising antimicrobial resistance in E. coli produced a serious concern with respect to public health globally which eventually generated the need of screening of pathogens for their sensitivity and resistance profile against different antibiotics. Methods:   The present study isolated a bacterial strain of E. coli, SA-01 from Ghaziabad, Uttar Pradhesh, India which was then characterized based on morphology, microscopy, biochemical testing in comparison with standard reference strains of E. coli (ATCC 8739, ATCC 10536 and MTCC 448). The identity of the isolated strain was further confirmed by MALDI-TOF analysis. The antibiotic susceptibility of the isolated strain of E. coli (SA-01) was then assessed in comparison with E. coli ATCC 10536 by cup plate method using different antibiotic doses of colistimethate sodium (1, 5, 10, 20, 30, 40, 50, 100 and 461 µg/mL). Results:    Based on phenotypic and biochemical characteristics, isolated bacterial strain, SA-01 was identified as E. coli and was further authenticated by MALDI-TOF analysis. In the antibiotic susceptibility testing, the indigenous strain of E. coli (SA-01) has shown zone of inhibition similar to E. coli ATCC 10536. Conclusion: Similar zone of inhibition compared to E. coli ATCC 10536 in the antibiotic susceptibility testing, revealed sensitivity profile of the indigenous strain of E. coli (SA-01) to Colistimethate sodium suggesting its potential use in microbiological quality control methods. https://jmb.tums.ac.ir/index.php/jmb/article/view/599