Molecular Biological Study on Hospital-Acquired Infections and Drug-Resistance of Pneumocystis carinii

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I.Genotyping of Pneumocystis carinii (Pc) isolated from 24 BALF in Japan was examined based on nucleotide sequence variations in internal transcribed spacer regions 1 and 2 (ITS1 and ITS2, respectively) of rRNA genes. We found 11 ITS1 genotypes including 2 novel ones and 11 ITS2 genotypes including 3 new ones. Combination of ITS1 and ITS2 genotypes resulted in 30 ITS genotypes, of which 10 were newly described in this report. Two or more genotypes in ITS regions in a specimen were observed in 16 of 24 patients. Our results will be of help for the epidemiological investigation of Pc infection. II.We examined mutations in dihydropteroate synthase (DHPS) gene of Pc isolated from 24 patients with Pc pneumonia (PCP) in Japan. DHPS mutations were identified at amino acid positions 55 and/or 57 in isolates from 6 (25.0 %) of 24 patients. Co-trimoxazole treatment failed more frequently in patients whose isolates had DHPS mutations than in those whose isolates had wild-type DHPS (n=4 [100%] versus n=2 [11.1%] ; P=0.002). Our results thus suggest that DHPS mutations may contribute to failures of co-trimoxazole treatment for PCP.