Susceptibility of Staphylococcus Aureus to Fusidic Acid: Canadian Data

Background: Ongoing antimicrobial surveillance is important to ensure proper management of infectious diseases. There are inherent issues in estimating the relevant incidence of antimicrobial resistance from surveillance data and special issues for topical preparations.

Objective: To perform semiannual surveillance of fusidic acid susceptibility of Staphylococcus aureus strains in a Canadian tertiary care hospital.

Methods: S. aureus strains were collected twice yearly from routine cultures. Routine antimicrobial susceptibility testing was performed by an automated method. Fusidic acid susceptibility testing was performed by disk diffusion.

Results: Between 1999 and 2005, 2,302 S. aureus strains were tested, of which 240 were methicillin resistant (MRSA). Among all strains tested, 65 (2.8%) were resistant to fusidic acid. Ten of the MRSA strains (4.2%) were resistant to fusidic acid. Although from different patients, these were shown to be part of a hospital outbreak and were epidemiologically linked.

Conclusions: There has been no trend toward increasing fusidic acid resistance in our hospital over this period.