The SLCH microbiology laboratory routinely banks MRSA isolates recovered from the airways of patients with CF. These isolates were retrieved for the purposes of this study. Antibiotic susceptibility data were retrieved from the medical record. High-level mupirocin resistance was detected using a 200-µg mupirocin disk (Oxoid Microbiology Products, Hampshire, UK) in accordance with Clinical and Laboratory Standards Institute guidelines (19 ).
RepPCR was performed on all MRSA isolates to determine relatedness of strains within individual patients using the Diversilab Bacterial Barcodes system (bioMerieux, Durham, NC) as previously described (20 (link), 21 (link)). A pair of isolates were considered to be identical if their similarity index (SI) was ≥95%. SCCmec characterization was performed using a multiplex PCR assay that detects and differentiates SCCmec types I–V as previously described (5 (link)).
RepPCR was performed on all MRSA isolates to determine relatedness of strains within individual patients using the Diversilab Bacterial Barcodes system (bioMerieux, Durham, NC) as previously described (20 (link), 21 (link)). A pair of isolates were considered to be identical if their similarity index (SI) was ≥95%. SCCmec characterization was performed using a multiplex PCR assay that detects and differentiates SCCmec types I–V as previously described (5 (link)).