Strain types of Staphylococcus aureus nasal isolates from persons undergoing joint replacement surgery

Document Type

Letter to the Editor

Publication Date


Publication Source

Journal of Hospital Infection


In this study, 953 patients scheduled for either knee or hip replacement surgery from June 2nd, 2014 to August 5th, 2014 were tested for nasal colonization several weeks prior to their surgery. A pre-admission swab (PAS) was tested by a commercial polymerase chain reaction (PCR) assay for MSSA and MRSA (Xpert SA Nasal Complete assay; Cepheid, Sunnyvale, CA, USA) as described by the manufacturer. A second nasal swab was stored at 4°C for bacterial culture. PCR-positive individuals underwent decolonization with twice-daily 2% intranasal mupirocin ointment and daily chlorhexidine baths for five days. On the day of surgery (DOS), or occasionally a few days prior to surgery, a second set of nasal swabs was obtained from all subjects who had consented to participate. One swab was tested using PCR and the second stored for bacterial culture. The second swab from sets that were positive for S. aureus or MRSA by PCR were sent to a central laboratory for culture and spa typing. Pulsed-field gel electrophoresis typing was performed on selected isolates. The swabs were enriched in Tryptic Soy Broth with 6.5% sodium chloride and incubated at 35°C for 18–20 h. The broth was inoculated on to HardyCHROM S. aureus and HardyCHROM MRSA agar plates (Hardy Diagnostics, Santa Maria, CA, USA) to isolate MSSA and MRSA, respectively. Organisms were confirmed as S. aureus by Gram stain, catalase, and coagulase testing, and as MRSA by disc diffusion testing with cefoxitin and oxacillin discs. S. aureus strains were tested for susceptibility to mupirocin using Etest (bioMérieux, Raleigh, NC, USA) according to the manufacturer's instructions. Results were interpreted using the EUCAST epidemiological cut-off value of

Inclusive pages