For suspected peritonitis in a PD patient, what is the essential diagnostic step?

• A. Start antibiotics immediately after observing cloudy effluent.
• B. Obtain effluent for Gram stain and culture before starting antibiotics.
• C. Check blood pressure.
• D. Schedule follow-up in two weeks.

Answer: (B)

When suspected peritonitis in a PD patient, the essential diagnostic move is to obtain the peritoneal effluent for Gram stain and culture before starting antibiotics. This step preserves the ability to identify the causative organism and its antibiotic sensitivities, which is crucial for guiding targeted therapy and detecting organisms that might be missed or misidentified if antibiotics are given first. In practice, while clinicians often start empiric antibiotics promptly to control the infection, collecting the effluent first ensures the diagnostic information isn’t compromised. Checking blood pressure or scheduling a later follow-up doesn’t address the infection’s cause or guide appropriate therapy.