Evaluation of the activity of fusidic acid tested against contemporary Gram-positive clinical isolates from the USA and Canada.

We evaluated the antimicrobial activity of fusidic acid (CEM-102) against 1140 clinical strains of Gram-positive bacteria obtained from patients with bacteraemia or skin and skin-structure infections collected in more than 30 medical centres in the USA and Canada over a 10-year period (1997-2006). Fusidic acid was very active against meticillin-susceptible Staphylococcus aureus (MSSA), meticillin-resistant S. aureus (MRSA) and coagulase-negative staphylococci (CoNS), with MIC(90) values (minimum inhibitory concentration encompassing 90% of isolates tested) at 0.12mug/mL for US strains of MSSA, MRSA and CoNS and 0.25mug/mL for Canadian strains of MSSA and MRSA. A progressive increase in fusidic acid resistance was observed among Canadian strains of S. aureus (12.2% in 2005-2006) and among Canadian strains of CoNS. In contrast, no fusidic acid resistance was detected among US S. aureus strains and only 1.5% among CoNS. Fusidic acid was equally active against community-acquired MRSA and linezolid-resistant staphylococci. Fusidic acid exhibited equal or greater potency against staphylococci compared with vancomycin, daptomycin and linezolid.