Outbreak of methicillin-resistant Staphylococcus aureus with reduced susceptibility to glycopeptides in a Parisian hospital

Epidemiological relationships were investigated between 40 methicillin-resi stant Staphylococcus aureus (MRSA) strains with decreased glycopeptide susc eptibility isolated from November 1998 to March 1999 from 39 patients (17 i nfected and 22 colonized patients) in nine wards of the Broussais Hospital, Paris, France. Reduced glycopeptide susceptibility was readily detected on brain heart infusion (BHI) agar containing 6 mu g of teicoplanin per mi an d on gradient plates, but not by the standard disk diffusion method. The MI Cs of vancomycin and teicoplanin, determined on BHI agar, were 4 and 8 to 3 2 mu g/ml, respectively (standard antibiotic dilution), and 4 to 8 and 8 to 32 mu g/ml, respectively (E-test). All strains were resistant to macrolide s, aminoglycosides, tetracycline, rifampin, sulfonamides, and pefloxacin, s howed reduced susceptibility to fusidic acid and fosfomycin, and were susce ptible to trimethoprim and chloramphenicol, Pulsed-field gel electrophoresi s and lysotyping revealed that a multidrug-resistant MRSA clone with decrea sed susceptibility to glycopeptides has been discretely endemic since at le ast 1996 in our institution, where it was responsible for an outbreak in No vember and December 1998.