Pulmonary colonisation with Pneumocystis carinii in an immunosuppressed HIV-negative patient: detection and typing of the fungus by PCR

Mostly Pneumocystis carinii isolates from patients with acute pneumocystosi s (PCP) have been typed until now This report describes the typing of P. ca rinii organisms obtained from an HIV-negative patient without PCP. The pati ent underwent a broncho-alveolar lavage (BAL) to investigate an abnormal ch est X-ray. He was diagnosed with sarcoidosis, However, a low level of P. ca rinii organisms undetectable by microscopy was detected in BAL quid by two subsequent nested PCR assays: one assay amplifying a portion of the mitocho ndrial large subunit RNA gene and a second one amplifying the internal tran scribed spacers (ITS) 1 and ITS 2 of the nuclear rRNA operon, This low leve l of the fungus did not reflect acute PCP, Indeed, the clinical outcome was improvement despite the absence of specific treatment. The patient was con sidered to be only colonised by the fungus. Analysis of sequences of ITS PC R products led to identification of genotype Gg, This information constitut es the first data concerning P. carinii ITS genotype from a patient without acute PCP and HIV, This type has been described previously in AIDS patient s diagnosed with PCP, These results show that PCR and ITS genotyping could represent efficient tools for the further investigation of the role played by HIV-negative patients with pulmonary colonisation in the human reservoir of P. carinii.