Journal of Bioscience and Biotechnology Discovery

The presence of resistant plasmids (R-plasmids) in microorganisms allows them to evade antibiotics, complicating infection treatment. Disinfectants, though essential in infection control, can become contaminated, contributing to antimicrobial resistance in hospital environments. This study investigated plasmid-mediated antibiotic resistance in bacteria isolated from used disinfectants across four hospitals by evaluating their susceptibility before and after plasmid curing. A total of 100 disinfectant samples (both used and unused diluted forms) were collected, with 21% found contaminated, 86% of which were Gram-negative bacteria. The most frequent isolates included Pseudomonas aeruginosa (24%), Klebsiella pneumoniae (19%), Escherichia coli (14%), Proteus vulgaris (14%), Salmonella typhi (14%), and Staphylococcus aureus (14%). Antibiotic susceptibility tests showed that 81% of isolates were sensitive to all 17 antibiotics tested, while 19% exhibited multidrug resistance, particularly Pseudomonas, Klebsiella, Salmonella, and E. coli. Ampicillin showed the highest resistance, while ciprofloxacin and levofloxacin retained effectiveness. Plasmid curing revealed partial plasmid-mediated resistance in key bacteria. Before curing, Salmonella typhi, Klebsiella pneumoniae, Pseudomonas aeruginosa, and E. coli resisted 15, 9, 8, and 7 antibiotics, respectively (100%). After curing, resistance reduced to 67% in Salmonella, 78% in Klebsiella, 88% in Pseudomonas, and 57% in E. coli, indicating loss of resistance to specific antibiotics. This suggests that resistance to erythromycin, amoxicillin, norfloxacin, and septrin in Salmonella; norfloxacin and septrin in Klebsiella; septrin in Pseudomonas; and norfloxacin, chloramphenicol, and septrin in E. coli was plasmid mediated.