Pneumocystis polymerase chain reaction and blood (1→3)-β-d-glucan assays to predict survival with suspected Pneumocystis jirovecii pneumonia

Pneumocystis polymerase chain reaction (PCR) and blood (1→3)-β-d-glucan assays are known to be useful for the diagnosis of Pneumocystis pneumonia (PCP). However, their impact on the outcome of clinically suspected PCP patients has not yet been elucidated. Between January 2008 and July 2011, we prospectively observed 190 immunocompromised patients who had ground-glass opacity on chest computed tomography scans and were suspected to have PCP. The blood β-d-glucan levels of these patients were measured, and PCR was used to detect Pneumocystis jirovecii in the respiratory samples. The 30-day mortality rates and related factors were assessed. The 30-day mortality rate of all included patients was 21.6%. Both β-d-glucan-positive (10.1%) and PCR-positive patients (15.0%) had significantly lower mortality rates than β-d-glucan-negative (28.1%) or PCR-negative patients (30.1%). All of the 13 definite PCP patients had positive PCR and β-d-glucan results, received anti-PCP treatments, and survived. Among the 72 patients who were negative for microscopic detection of P. jirovecii but received anti-PCP treatments, positive PCR results (odds ratio [OR], 0.14; 95% confidence interval [CI], 0.02–0.74), a high Sequential Organ Failure Assessment score (OR, 1.42; CI, 1.08–1.88), and positive β-d-glucan levels (OR 0.25, CI 0.06–1.02) were associated with mortality rates using stepwise logistic regression analyses. A positive Pneumocystis PCR or β-d-glucan test was a candidate predictor of survival in patients who were suspected of having PCP, even though negative for visual detection by microscopy.