Detection of Pneumocystis Jirovecii by Nested PCR in HIV-negative Patients with Pulmonary Disease

Background: Nested PCR can be used to determine the status of Pneumocystis jirovecii infection in other lung diseases.

Aims: This study sought to detect a target DNA fragment (mitochondrial large subunit rRNA or mtL SUrRNA) of P. jirovecii in patients with lung disease who underwent bronchoscopy with collection of bronchoalveolar lavage (BAL).

Methods: The results from toluidine blue staining were compared with those obtained using molecular methods that included an "in house" DNA extraction procedure, PCR and nested PCR.

Results: Fifty-five BAL samples from patients with atypical chest X-rays were screened for P. jirovecii. None of the samples was positive for P. jirovecii using toluidine blue staining. In contrast, P. jirovecii DNA was detected by nested PCR in BAL samples from 36 of 55 patients (65.5%). The lung diseases in the patients included cancer, pneumonia, tuberculosis, and chronic obstructive pulmonary disease (COPD). Other chronic problems in the patients included hypertension, diabetes, smoking, and alcoholism.

Conclusions: Nested PCR showed high sensitivity for detecting P. jirovecii, especially when compared with toluidine blue staining. Using this method, P. jirovecii infection was detected in HIV-negative patients with lung disease.