Table 2.

Infections for which PCT may not be an effective marker

May be raised but inconsistent results: Atypical bacteria – Legionella species, Mycoplasma and Chlamydia species

Non-bacterial infections associated with positive PCT: Scrub typhus, Plasmodium spp., Candidiasis, Clostridium difficile-associated disease

Procalcitonin negative in bacterial infection – localized infections such as tonsillitis, sinusitis, cystitis, uncomplicated skin/soft tissue infections, abscesses, or empyema

Procalcitonin negative in infections – Viral infections, Borrelia spp., Chlamydia pneumoniae, Mycoplasma pneumoniae, Aspergillosis, Coccidioidomycosis, and Mucormycosis