Microbiological aspects of peritonitis associated with peritoneal dialysis

Peritonitis is one of the most common and serious infectious complications in patients undergoing peritoneal dialysis (PD). Its microbiological etiology is diverse and directly influences the choice of antimicrobial therapy, clinical prognosis, and the feasibility of dialysis treatment. This article reviews the main etiologic agents, mechanisms of infection, and antimicrobial resistance patterns associated with peritonitis in PD. Peritoneal dialysis is an effective form of renal replacement therapy, but its success can be compromised by recurrent episodes of peritonitis. This complication represents a frequent cause of hospitalization, techniquefailure, and mortality in patients with chronic kidney disease (CKD) on PD.1 Up-to-date knowledge of microbiological aspects is essential to optimize the prevention and treatment of peritonitis in this setting. Approximately 60-80% of PD peritonitis cases are caused by gram-positive bacteria, with coagulase-negative staphylococci (such as Staphylococcus epidermidis) and Staphylococcus aureus being the main culprits.2 These microorganisms usually originate from the skin flora of the patient or healthcare personnel, and their transmission is related to catheter manipulation or errors in aseptic technique. Gram-negative bacteria, primarily Escherichia coli, Klebsiella spp., and Pseudomonas aeruginosa, are responsible for 15-30% of cases and are commonly associated with enteric infections or retrograde catheter contamination.3 Gram-negative peritonitis tends to have a more aggressive course and a worse prognosis. To a lesser extent, fungal infections (usually Candida spp.), non-tuberculous mycobacteria, and other unusual pathogens have been identified, particularly in immunocompromised patients or after multiple courses of antibiotics.4