An assessment of triclosan susceptibility in methicillin-resistant and methicillin-sensitive Staphylococcus aureus

Triclosan is widely used to reduce skin colonization with staphylococci and is incorporated into methicillin-resistant Staphylococcus aureus (MRSA) eradication regimes. Using an agar dilution method, the minimum inhibitory concentration (MIC) to triclosan was determined for 186 isolates of MRSA and methicillin sensitive Staphylococcus aureus (MSSA). Fourteen isolates (7.5%) were detected with a MIC greater than or equal to 1.0 part per million (ppm). There was no significant difference between the incidence of triclosan resistance in strains of MSSA and MRSA. None of 16 strains of MRSA which exhibited low-level mupirocin resistance had MIC's greater than or equal to 1.0 ppm. Increased MIC's of staphylococci to triclosan may contribute to treatment failure when used to eradicate staphylococcal carriage. We suggest that routine susceptibility testing of staphylococci against triclosan might now be indicated.