Staphylococcus aureus carriage in adult peritoneal dialysis patients and their spouses

Objective: We hypothesized that carriage of Staphylococcus aureus among continuous ambulatory peritoneal dialysis (CAPD) patients was influenced by their spouses. Furthermore, this carrier status was compared to previous Staph. aureus peritonitis episodes in order to identify the influence of Staph. aureus carriage on peritonitis rate. Design: A combined prospective surveillance study (Staph. aureus carriage) and retrospective chart review (Staph. aureus peritonitis). Setting: A single peritoneal dialysis unit in a county hospital. Patients and methods: Cultures from patients (n = 32) and spouses (n = 16) were obtained twice, with a 1-month interval, from the anterior nares, the umbilical, and one groin area. All positive cultures were phage typed. Retrospective chart review of all episodes of Staph. aureus peritonitis among the patients was carried out. Results: Twelve of 32 patients (37.5%) and 5 of 16 spouses (31%) evaluated were carriers. Half of the spouses of patients who were Staph. aureus carriers, were also carriers, as opposed to 20% of spouses of noncarrier patients (p = 0.30). Patients and spouses always shared the same phage type. Among patients, Staph. aureus was found in the nose only (n = 9), in all three regions (n = 2), and extranasally only (n = 1). If only one nasal culture was used to establish carriage, the sensitivity and negative predictive value would be 92% and 95%, respectively. A trend toward a higher incidence (p = 0.062) of Staph. aureus peritonitis was found among carriers (patients), 0.37 versus 0.28 peritonitis episode/dialysis-year. Conclusions: Only one positive nasal culture was necessary when carriage of Staph. aureus was to be established. Staph. aureus carriage was found more often in patients who had previously suffered from Staph. aureus peritonitis. The phage types isolated remained fairly constant, and the patients and spouses often had the same carrier state and shared the same phage types, although transmission does not always take place.