In vitro susceptibility of Staphylococcus aureus including MRSA to four disinfectants

The spread of nosocomial infections caused by pathogenic organisms such as methicillin-resistant S. aureus (MRSA) has prompted the dental community to focus more attention on certain control strategies. In the present study, we tested the abilities of the four skin disinfectants (povidone iodine, benzalkonium chloride, chlorhexidine gluconate, and ethanol) to prevent horizontal transmission of MRSA in the dental office. The bactericidal activities of the disinfectants were evaluated by the decrement over time of viable cell numbers of four clinical isolated strains of S. aureus: two MRSA strains and two methicillin-sensitive S. aureus (MSSA) strains. The most effective disinfectant was 70 percent ethanol, which eradicated both MRSA and MSSA in less than three minutes. The 0.1 percent chlorhexidine gluconate proved the least effective of four disinfectants. More than 10(2) bacteria survived despite exposure to it for thirty minutes.