erm(C) is the predominant genetic determinant for the expression of resistance to macrolides among methicillin-resistant Staphylococcus aureus clinical isolates in Greece.
OBJECTIVE
Macrolide, lincosamide and streptogramin type B (MLS(B)) resistance was determined in Staphylococcus aureus clinical isolates from two University Hospitals.


METHODS
Antibiotic resistance was investigated by double disc diffusion and MIC determination. Resistance determinants were detected by PCR and DNA hybridization, while clonal types were identified by pulsed-field gel electrophoresis (PFGE) analysis of SmaI DNA fragments.


RESULTS
Among methicillin-susceptible S. aureus (MSSA) isolates, inducible and MS phenotypes were detected, with the predominance of the erm(A) gene, followed by the msr(A) and erm(C) genes. The majority of methicillin-resistant S. aureus (MRSA) isolates expressed the constitutive phenotype and carried the erm(C) gene. PFGE revealed the dissemination of two major clones among the MRSA in both hospitals.


CONCLUSIONS
erm(C) is the predominant genetic determinant for the expression of MLS(B) resistance among S. aureus isolates, especially MRSA, in Greece. This is due to the spread of two major clones in the country.
Spiliopoulou
I
I
Department of Microbiology, School of Medicine, University of Patras, Rion 26500, Patras, Greece. spiliopl@med.upatras.gr
Petinaki
E
E
Papandreou
P
P
Dimitracopoulos
G
G
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003001:Cloning, Molecular; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D005838:Genotype; D006115:Greece / Q000453:epidemiology; D018942:Macrolides / Q000494:pharmacology*; D016106:Methicillin Resistance / Q000235:genetics*; D008780:Methyltransferases / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D010641:Phenotype; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics*
D000900:Anti-Bacterial Agents; D018942:Macrolides; D008780:Methyltransferases; C035181:rRNA (adenosine-O-2'-)methyltransferase