Sensitive detection of Pneumocystis jirovecii DNA in gastric wash using nested polymerase chain reaction.

One hundred and five samples of gastric washes were obtained from 52 pediatric patients. Eleven of the 105 samples (10%) gave positive results using immunofluorescence antibody test (IFA) for Pneumocystis jirovecii. Single-step polymerase chain reaction (PCR) produced 13% (14 samples), whereas detection by nested PCR was increased to 65 samples (62%). Moderate agreement (kappa = 0.5) was found between test results of IFA and single-step PCR, but no agreement was found between the results of IFA and nested PCR (kappa = 0.1).