In-Vitro Investigation on the Antiseptic Efficacy of Commonly Used Disinfectants in Dairy Farms Against Methicillin-Resistant Staphylococcus Aureus

Concern has been rising with the respect to the capability of clinically important bacteria to acquire resistance against antibiotics and disinfectants. This investigation was undertaken to provide information on the sensitivity of methicillin-resistant Staphylococcus aureus (MRSA) to some disinfectants. The isolated PCR genotyped MRSA strains were collected from milk and its surrounding animal milking environment of 4 dairy cattle farms. Five commonly used disinfectants (quaternary ammonium compounds, iodine (Povidone-iodine), Sodium hypochlorite (Chlorine), ethyl alcohol and Chloroxylenol (Dettol) were evaluated at different contact times (5, 10, 15 minutes) and variable concentrations using suspension test for measuring their minimal inhibitory concentrations (MICs) against each isolate. The obtained results of MICs of the five tested disinfectants indicated high sensitivity of MRSA to both QACs and iodine, with MICs of 0.25% within 5 minutes(QACs), and 1.37% within 5 minutes (Iodine) at three tested concentrations and exposure times. Nonetheless, these strains exhibited a significant resistance to both ethyl alcohol and chlorine at different concentrations and contact times. Meanwhile, Dettol inhibited MRSA growth at dilutions (5% & 2.5%) within (5, 15, 20 minutes), however, 1.25% at 5 and 15 minutes was unable to potentiate the antibacterial activities of Dettol against strains tested. The findings of the present study reinforce the importance of disinfection as an integral part of the control policies of MRSA prevention and eradication in dairy farms.