Incidence and clinical significance of nasal and pericatheter colonization by Gram-negative bacteria among patients undergoing chronic peritoneal dialysis

Background. Nasal and pericatheter colonization by Staphylococcus aureus portends an increased risk of peritonitis and exit-site infection for peritoneal dialysis (PD) patients. The aim of the present study was to examine the incidence of colonization by other peritoneal pathogens, and more specifically by Gram-negative bacteria (GNB), among PD patients, and to disclose its potential correlation with PD-related infections. Method. Over a 3-year period, we prospectively screened 152 PD patients and 99 partners every other month for nasal and pericatheter bacterial colonization (total follow-up for patients 3182 months). We performed 1089 studies in patients and 561 in partners. Results. Although S. aureus and coagulase-negative Staphylococcus spp. predominated both in patients and partners, we recovered GNB from 15.8% (nares) and 22.4% (pericatheter) of the patients and from 29.3% of the partners. Most isolations of GNB were transient and only 7.2% of the patients and 7.1% of the partners had the same GNB isolated in at least two controls from the same sampling site. Older age, male gender, longer follow-up on PD, previous immunosuppressive therapy, low socioeconomic conditions, and a high global incidence of peritonitis were predictive of colonization by GNB. Previous pericatheter mupirocin therapy was also associated with later colonization by GNB. Nasal or pericatheter colonization by bacteria other than S. aureus, particularly GNB, had a poor predictive power for PD-related infections. Conclusion. Nasal and pericatheter bacterial colonization is protean in PD patients and their partners, and includes the significant presence of potentially pathogenic GNB. Colonization by GNB was not clearly associated with an increased risk or peritonitis or exit-site infection in these patients.