The Influence of Antimicrobial Disinfectants on the Survival of Food Borne Pathogens

Abstract

These was carried out to evaluate the effectiveness of a selection of domestic products marketed as household disinfectants such as Sodium hypochlorite (NaOCl); 0.25%, 0.5%, 1%, 2%, 12% v/v & Chlorhexidine (CHX); 0.25%, 0.5%, 1%, 2% w/v], against some potential bacterial contaminantsEscherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The research evaluated the effectiveness in relation to microbial susceptibility of target microbes and the effects of ionic strength and organic load. Disinfectant effectiveness was assessed by Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC), using Broth Dilution Method. It was found that 1% CHX was effective on both the organisms, 1% NaOCl did not inhibit the growth, but repeated experiments with increased concentration (12% NaOCl) inhibited the growth. The S. aureus appeared with high MIC of 0.03125%, was more resistant than E. coli (low MIC of 0.01563%). Manipulation of ionic strength [using sodium chloride (NaCl) w/v concentrations of varying percentages) and organic load [by addition of Bovine Serum Albumin (BSA) 1%, 2%, 4%, 5% and 10% w/v] was evaluated using Agar Diffusion tests in duplicate. The resistance ability of the organisms against the disinfectants had increased when grown in NaCl, where E. coli became more resistant than S. aureus. However, Agar Diffusion Method, by using zones of inhibition; the results showed that 0.25% CHX was effective against both test organisms, while NaOCl was only effective against E. coli at the concentration of 0.5-1%. But, contrary to the Broth Dilution Method, S. aureus was more sensitive to the disinfectants than E. coli. When the disinfectants were used with BSA/NaCl, the antimicrobial activities were reduced. The BSA had more influence on the disinfectants than NaCl, and E. coli was more resistant than S. aureus.