Recent advances in the diagnosis of Pneumocystis jirovecii pneumonia in HIV-infected adults.

Introduction: Pneumocystis jirovecii pneumonia (PCP) is one of the most common opportunistic infections in HIV-infected adults. Although the microscopic demonstration of the organisms in respiratory specimens is still the golden standard of its diagnosis, recent advances in the diagnostic tools have been changing the situation.

Areas covered: Colonization of Pneumocystis is highly prevalent among the general population and could be associated with the transmission and development of PCP in immunocompromised individuals. Nested or conventional polymerase chain reaction (PCR) has a high sensitivity, detecting Pneumocystis DNA in induced sputum or oropharyngeal wash, but often produces false positives. Although quantitative real-time PCR is promising for discriminating colonization from PCP, the targeted DNA sequences and the cut-off values remain to be standardized. Serum β-D-glucan is useful as an adjunctive tool for the diagnosis of PCP. High-resolution computed tomography, which typically shows diffuse ground-glass opacities, is informative for evaluation of immunocompromised patients with suspected PCP and normal chest radiography.

Expert opinion: Although these new tools have been making the diagnosis of PCP less invasive and more accurate, any one of them can not make a definitive diagnosis by itself. The diagnostic criteria based on the combination of the testing ought to be established.