Molecular and epidemiological evidence for spread of multiresistant methicillin-susceptible Staphylococcus aureus strains in hospitals.

The excision of the staphylococcal chromosomal cassette mec (SCCmec) from methicillin-resistant Staphylococcus aureus (MRSA) strains results in methicillin-susceptible S. aureus (MSSA) strains. In order to determine the proportion and diversity of multidrug-resistant MSSA (MR-MSSA) strains derived from MRSA strains, 247 mecA-negative isolates recovered in 60 French hospitals between 2002 and 2004 were characterized.

Changes in staphylococcal cassette chromosome type and antibiotic resistance profile in methicillin-resistant Staphylococcus aureus isolates from a French hospital over an 11 year period.

Background: In this study, we investigated the relationship between changes in antibiotic resistance and distribution of staphylococcal cassette chromosome (SCC) types amongst methicillin-resistant Staphylococcus aureus (MRSA) isolates expressing the most frequently encountered profiles of antibiotic resistance over an 11 year period in the University Hospital of Rennes, France.

Methods: Antibiotic susceptibilities were determined by agar diffusion. SCC typing was performed using PCR.