A 15 year-review of peritoneal dialysis-related peritonitis: microbiological trends and patterns of infection in a teaching hospital in Argentina.

This study reports the infectious peritonitis rates in 44 patients on peritoneal dialysis in three different systems over the last 15 years, covering clinical outcomes, exit-site infections, tunnel infections, causative microorganisms, and the history of susceptibility of organisms causing peritonitis, in order to establish our center-specific selection of empiric therapy. Two microbiological procedures were herein used: method A, where 100 ml of dialysate were centrifuged and cultured in standard media and into blood-culture bottles; and method B, where 10 ml were directly injected into blood-culture bottles. Swabs from the exit-site or tunnel were taken when purulent drainage was observed. There were 96 episodes of peritonitis during 110.43 patient-years (0.87 episodes/patient-year). Sensitivity of method A was 96.88% (93/96 episodes) versus 81.25% (78/96) of method B (p=0.001). Gram stain sensitivity was 36.46%. The etiologic agents were 64 (56.64%) gram-positive cocci, 22 (19.47%) gram-negative fermentative rods, 20 (17.7%) gram-negative non fermentative rods, 5 (4.43%) yeasts, 1 (0.88%) micelial fungus, and 1 (0.88%) anaerobic rod. Fifty-five exit-site infections were documented (0.5 episodes/patient-year). Ceftazidime and imipenem showed excellent activity on gram-negative rods. There were 92.3% of methicillin-susceptible Staphylococcus aureus but only 33.3% of methicillin-susceptible coagulase-negative staphylococci; vancomycin was active against 100% of the gram-positive cocci. The clinical outcomes of peritonitis were 73 initial cure, 19 catheter removal and four related deaths. The empiric therapy in our center should be vancomycin plus ceftazidime or imipenem. Once the etiological agent and its susceptibility pattern are known, the deescalating therapy must be applied to avoid the emergence and spread of vancomycin-resistant microorganisms.