SP511PERITONEAL DIALYSIS: INFECTIOUS AGENTS OR NORMAL MICROBIOTA

Abstract

Introduction and Aims: Infection-related morbidity remains one of the major complications in peritoneal dialysis (PD) patients. In our center there is a low but persistent number of PD related peritonitis every year, mainly attributed to Staphylococcus and Pseudomonas species (spp.). This work aimed to characterize possible sources of peritonitis agents focusing on normal microbiota. Methods: Microbiological analysis of saliva, nose and catheter exit-site (CES) samples of 27 PD patients, were evaluated regarding: Staphylococcus spp. (by Mannitol-salt medium, gram-staining, catalase-test followed by sequencing analysis of DnaJ or Multi-test system API 32 STAPH (Biomerieux®)); and Pseudomonas spp. (by Cetrimide selective agar, gram-staining and oxidase-test). Staphylococcus and Pseudomonas normal colonization of PD patients were correlated to previous peritonitis episodes and CES infections. Results: PD patients had an average age of 47±12 years and the mean duration of PD was 12.8±15.6 months. About 26% of the patients had a previous peritonitis episode and 55.5% had a previous CES infection; Staphylococcus spp. were responsible for 37.5% of peritonitis and 34.4% of CES infections, whereas Pseudomonas spp. were identified only in CES infections (37.5% of the episodes). Concerning normal microbiota characterization, Staphylococcus spp. were detected in 91.7% of saliva samples, 100% of nasal samples and 51.8% of CES samples of our population. Thirteen different Staphylococcus spp. were documented. Interestingly, 60% of the saliva samples presented simultaneously 2 or more Staphylococcus spp. and in 7.4% of these patients the same microorganism was identified in the 3 body locations examined. The Staphylococcus spp. responsible for a previous infectious episode was identified in the normal microbiota of 25.9% of saliva samples, in 29.6% of nasal cavity samples and in 11.1% of CES samples. Pseudomonas colonization was detected in the saliva of only one PD patient and was not related to a previous Pseudomonas infection. Conclusions: Our results suggest that Staphylococci PD-related infections may be strongly related to normal human microbiota, since the Staphylococcus spp. most commonly found in the saliva, nasal cavity or CES of our population corresponded to the most prevalent spp. associated with infections. No correlation was found between PD-related infection and normal Pseudomonas colonization, suggesting that Pseudomonas infections may occur through other routes of infection.