A neutropenic patient receiving empirical broad-spectrum antibiotics has serial serum galactomannan testing. Two consecutive indices are 0.9 and 1.1, but CT chest shows no nodules or halo sign and blood cultures are sterile. Review of the drug chart reveals one agent capable of producing this pattern without invasive aspergillosis. Which agent is it?

• A Vancomycin
• B Meropenem
• C Linezolid
• D Piperacillin-tazobactam ✓

Explanation

Semisynthetic penicillin derivatives manufactured by fermentation, particularly piperacillin-tazobactam and amoxicillin-clavulanate, contain fungal cell wall components and are a classic cause of false-positive serum galactomannan results. Meropenem is produced synthetically and does not share this property. Vancomycin and linezolid have never been implicated. Recognising this confounder prevents unnecessary escalation to empiric voriconazole, which carries hepatotoxicity and QT prolongation risks in an already vulnerable host.

Reference: Mandell, Douglas and Bennett's Principles and Practice of Infectious Diseases, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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