Detection of Pneumocystis carinii with DNA amplification.

Oligonucleotide primers and probes were used in the polymerase chain reaction to amplify Pneumocystis carinii specific DNA sequences from alveolar lavage samples from 47 diagnostic bronchoscopies. No P carinii DNA was found in lavage from 10 immunocompetent patients; only low levels were found in 3 of 13 samples from immunosuppressed individuals without P carinii pneumonia (PCP), and the highest levels, readily demonstrated by simple ethidium bromide staining, were found in all of 16 samples from immunosuppressed patients with PCP confirmed by means of standard silver staining and in 4 from patients with clinical PCP but negative silver staining. DNA amplification provides a highly sensitive and specific technique for the identification of P carinii that should be valuable in epidemiological studies on this parasitic infection and in diagnosis.