Glycopeptide and oxacillin activity against Staphylococcus aureus isolates at a tertiary care center in Lebanon.
BACKGROUND
Worldwide reports have noted the emergence of glycopeptide-intermediate Staphylococcus aureus (GISA). However, data from Lebanon is lacking.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Kanj
Souha S
SS
Department of Internal Medicine, American University of Beirut Medical Center, Beirut.
Ghaleb
Patricia A
PA
Araj
George F
GF
D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001431:Bacteriological Techniques; D002648:Child; D002675:Child, Preschool; D004352:Drug Resistance, Microbial; D006785:Hospitals, University; D006801:Humans; D007861:Lebanon; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests / Q000379:methods; D008875:Middle Aged; D010068:Oxacillin / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification; D017334:Teicoplanin / Q000494:pharmacology*; D014640:Vancomycin / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D017334:Teicoplanin; D014640:Vancomycin; D010068:Oxacillin