Dynamics of Antimicrobial Susceptibility and Risk Factors Associated with Infections Caused by Colistin-Resistant Bacteria: A Study from the Northern Region of Haryana, India.

Antimicrobial resistance poses a significant threat to global health, with colistin as a last-resort antibiotic against multidrug-resistant (MDR) microorganisms. The present study aimed to investigate the dynamics of antimicrobial susceptibility patterns and risk factors associated with infections caused by colistin-resistant bacteria in the Northern region of Haryana, India. Clinical samples (n = 12,652) collected from a single hospital in Haryana were subjected to microbiological analysis for five months. Among the total samples (n = 12,652) processed, 24% (n = 3,061) showed growth of pathogenic bacteria. Within the Gram-negative isolates, 56% (n = 1,242) were non-MDR, while 44% (n = 995) were MDR. Among MDR isolates (n = 995), 6% (n = 57) showed resistance to colistin. Notably, Pseudomonas spp. (12%, n = 19) and Acinetobacter spp. (11%, n = 8) demonstrated the highest resistance to colistin, followed by Klebsiella spp. (5%, n = 13), Escherichia coli (3%, n = 16), and Citrobacter freundii (1%, n = 1), respectively. The study revealed significant associations between the level of education (demographic variable) and the occurrence of colistin resistance. Prolonged hospital stays (> 5 days) and specific comorbidities, including diabetes (p < 0.01) and chronic obstructive pulmonary disease (p < 0.01), were identified as risk factors for colistin-resistant infections. Importantly, none of the colistin-resistant bacteria harbored mcr genes, suggesting alternative resistance mechanisms. Antibiotic sensitivity analysis indicated promising efficacy of antibiotics such as amikacin and gentamicin against colistin-resistant strains, though with variations across bacterial species. In summary, the study emphasizes the urgent need for enhanced surveillance, infection control protocols, and antimicrobial stewardship programs in healthcare settings to minimize the dissemination of MDR and colistin-resistant bacteria.