What is the purpose of topical antibiotic prophylaxis at the nasal carriage site of S. aureus in PD patients?

• A. To prevent systemic infections by strengthening nasal immune defenses.
• B. To treat active nasal infection before PD sessions.
• C. To reduce the risk of exit-site and catheter-related infections by decolonizing nostrils with mupirocin as per protocol.
• D. To prevent skin dryness around the catheter site.

Answer: (C)

The important idea here is that Staphylococcus aureus often lives harmlessly in the nose, but in peritoneal dialysis patients that nasal reservoir can seed infections at the catheter exit site or along the catheter tract, potentially leading to exit-site infections or peritonitis. Using a topical antibiotic like mupirocin in the nares aims to remove or reduce this nasal carriage, so the bacteria are less likely to be transmitted during catheter care or handling. This prophylactic decolonization lowers the risk of catheter-related infections, which is why it’s done as part of the protocol. It’s not about treating an active nasal infection, nor about boosting nasal immune defenses or preventing skin dryness around the catheter. The focus is on preventing infections by reducing the nasal source of bacteria.