Glycopeptide and oxacillin activity against Staphylococcus aureus isolates at a tertiary care center in Lebanon
Kanj, S.S.; Ghaleb, P.A.; Araj, G.F.
Le Journal Medical Libanais. Lebanese Medical Journal 52(1): 8-12
2004
ISSN/ISBN: 0023-9852 PMID: 15881695 Document Number: 566980
Worldwide reports have noted the emergence of glycopeptide-intermediate Staphylococcus aureus (GISA). However, data from Lebanon is lacking. We conducted a study to determine the minimum inhibitory concentrations (MICs) for oxacillin (OXA), vancomycin (VAN) and teicoplanin (TEC) against consecutive clinical isolates of S. aureus at a tertiary care center in Lebanon. The categorization of isolates as susceptible, intermediately-resistant, or resistant was based on the OXA agar screen plate (OS) and the 1 microg OXA disk diffusion (OD) according to the National Committee for Clinical Laboratory Standards (NCCLS) guidelines. The MICs of OXA, VAN and TEC against these isolates were determined using the E-test. We tested 147 S. aureus isolates, 108 of which were methicillin-resistant (MRSA) and 39 methicillin-susceptible (MSSA). The rar ges of MICs (microg/ml) among MRSA and MSSA isolates respectively were : OXA 1.5- > or = 256 and 0.19-3; VAN 1-3 and 1.5-3; TEC 0.094-3 and 0.19-2. The MIC50/90 (microg/ml) for MRSA versus MSSA isolates were, respectively: 24/ > or = 256 vs. 1/2 for OXA; 2/3 vs. 2/2 for VAN; 1/1.5 vs. 0.75/1.5 for TEC. This data indicates that despite the presence of high rates of MRSA (around 38%), these strains remain fully susceptible to VAN and TEC. We did not detect any GISA at this tertiary care referral medical center in Lebanon.