Optimizing screening procedures for Staphylococcus aureus nasal carriage in patients on haemodialysis.

BACKGROUND So far it remains unclear what the optimal screening method for detection of S. aureus nasal carriage in patients on haemodialysis is with regard to number of cultures performed, culture interval, and necessity of a broth-enrichment procedure. METHODS A prospective, uncontrolled study was performed at the renal unit of a tertiary care centre, including all haemodialysis patients (n=91) attending the unit during the study period. The purpose was to determine the optimal screening method for S. aureus nasal carriage in patients on haemodialysis. RESULTS When compared to the conventional culture method, inclusion of a broth-enrichment procedure increased the number of cultures positive for S. aureus significantly (31 vs 24%, P<0.0001). Of 91 patients 37% were S. aureus carriers (defined as at least 1 of 5 cultures positive), 33% were stable carriers (defined as at least 2 of 5 cultures positive). Fourth and 5th cultures, taken at subsequent dialysis sessions, captured only two additional carriers (6% of all carriers). With respect to culture results and identification of carrier status a short (1-h) and a long (>24-h) sampling procedure showed no significantly different results. CONCLUSIONS S. aureus nasal carriage in haemodialysis patients can be conveniently established with three nasal cultures taken with 1-h intervals, and the inclusion of a broth-enrichment procedure.