Detection of Pneumocystis carinii sequences in serum by polymerase chain reaction.

The clinical significance of the detection of Pneumocystis carinii DNA was evaluated, as well as the detection of circulating P. carinii antigen from serum using previously collected samples. Fourteen serum samples from 13 patients were diagnosed positively for P. carinii DNA by polymerase chain reaction (PCR). Ten of 14 episodes (71.4%) of pulmonary complications were compatible with P. carinii pneumonia. Two patients were definitely diagnosed as having had P. carinii pneumonia at autopsy. All patients positive for circulating antigens were also positive for P. carinii DNA, suggesting that the detection of P. carinii DNA by PCR is more sensitive compared to the detection of circulating antigens by the Ouchterlony method. It is concluded that the detection of P. carinii DNA in serum by PCR provides useful information for identifying P. carinii pneumonia.