TIBACTERIAL EFFICACY OF COMMONLY USED DISINFECTANTS AGAINST STAPHYLOCOCCUS AUREUS AND ESCHERICHIA COLI

ABSTRACT The aim of this study is to determine the antimicrobial efficiency of commonly used disinfectants against Escherichia coli and Staphylococcus aureus. The persistent threat of healthcare-associated infections (HAIs), largely driven by bacterial pathogens such as Staphylococcus aureus and Escherichia coli, underscores the critical need for effective surface disinfection in clinical environments. This study evaluated the antimicrobial efficacy of three commonly used disinfectants—Dettol, Iodine, and Izal—against S. aureus and E. coli isolated from clinical samples. Isolation and identification of the bacteria were performed using standard cultural, morphological, and biochemical techniques. The bactericidal activities of the disinfectants were assessed via disc diffusion and minimum inhibitory concentration (MIC) methods. Results showed that Izal exhibited the highest antibacterial activity, with inhibition zones ranging from 35–43 mm and MIC values as low as 3.75 mg/ml. Dettol demonstrated moderate efficacy (13–18 mm zones; MIC of 6.25 mg/ml), while Iodine showed the least activity, requiring higher concentrations (MIC of 50 mg/ml) to inhibit growth. The differential responses of the isolates were linked to their structural and biochemical characteristics, with Gram-negative E. coli showing variable susceptibility due to its outer membrane, and Gram-positive S. aureus exhibiting relative resistance possibly due to its thick peptidoglycan layer. The study concludes that disinfectant selection should be guided by empirical efficacy data, as commonly used agents vary widely in potency. Izal was found to be the most effective disinfectant and is recommended for high-risk hospital environments, while Iodine may require supplementary use for reliable disinfection outcomes. These findings support informed disinfection practices and highlight the need for periodic review of antimicrobial products in healthcare settings.