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

I.根据rRNA基因内转录间隔区1和2（分别为ITS 1和ITS 2）的核苷酸序列变异，对从日本24个BALF中分离的卡氏肺孢子虫（Pc）进行基因分型。共发现11种ITS 1基因型，其中2种为新基因型; 11种ITS 2基因型，其中3种为新基因型。ITS 1和ITS 2基因型组合得到30种ITS基因型，其中10种为新发现。在24例患者中，16例在一个标本中的ITS区域观察到两种或两种以上的基因型。本研究结果将有助于Pc感染的流行病学调查。我们检测了日本24例Pc肺炎（PCP）患者分离的Pc的二氢蝶酸合酶（DHPS）基因突变。在来自24名患者中的6名（25.0%）的分离物中，在氨基酸位置55和/或57处鉴定出DHPS突变。复方新诺明治疗失败的患者中，分离株有DHPS突变的患者比分离株有野生型DHPS的患者更频繁（n=4 [100%] vs n=2 [11.1%] ; P=0.002）。因此，我们的研究结果表明，DHPS突变可能有助于失败的复方新诺明治疗PCP。

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.