Quantitative PCR for Differentiating Between Pneumocystis Colonization and Infection

Pneumocystis jirovecii pneumonia (PCP) is a common opportunistic infection in immunocompromised patients. The illness is typically more severe and more deadly in HIV-negative individuals than in HIV-positive ones, despite a lower fungal load. Conventional polymerase chain reaction (PCR) can detect low levels of P. jirovecii DNA in bronchoalveolar lavage fluid or induced sputum but cannot differentiate between colonization and infection.

Researchers in France developed a real-time quantitative PCR (qPCR) strategy for making this distinction and recently evaluated it in 278 respiratory specimens from 238 immunocompromised patients (69 HIV positive, 169 HIV negative) with suspected PCP. According to clinical criteria, 16 of the patients had a h…