van Hal Sebastiaan J, Gilgado Felix, Doyle Tom, Barratt Joel, Stark Damien, Meyer Wieland, Harkness Jock
Department of Microbiology and Infectious Diseases, St. Vincent's Hospital, Darlinghurst 2010, NSW Australia.
J Clin Microbiol. 2009 Jun;47(6):1818-23. doi: 10.1128/JCM.02102-08. Epub 2009 Apr 15.
Pneumocystis jirovecii is an important opportunistic pathogen in immunocompromised patients. Molecular typing is employed to study this pathogen, as no culture system exists. No Australian P. jirovecii strains have been previously studied. Direct sequencing, targeting the internal transcribed spacer (ITS) regions of the nuclear rRNA operon, the mitochondrial large-subunit rRNA (mt LSU rRNA), and the dihydropteroate synthase (DHPS) gene, was performed on 68 Australian samples, collected between 2001 and 2007. Seven novel Australian ITS haplotypes (a composite of the ITS1 and ITS2 regions) were identified (SYD1m, SYD1g, Isyd2, Esyd3, Osyd4, Ag, and Hc). A dendrogram of published ITS haplotypes revealed that of the seven novel haplotypes, three (SYD1m, SYD1g, and Osyd4) are closely related to the haplotype Eg. Applying statistical parsimony, an Australian haplotype network was constructed which identified Eg as the ancestral haplotype, with two unresolved loops encountered. This suggests that the ITS lacks the resolution required for evolutionary analysis. Only two mt LSU rRNA genotypes were detected, with genotype 1 predominating. Mutant DHPS genotypes were present in 13% (8/60) of the samples. The novel haplotype Isyd2 was associated with less severe disease than the other Australian haplotypes. In contrast, patients with mutant DHPS genotypes were more likely to have severe disease, require invasive ventilation, and have a poor outcome than patients with wild-type DHPS genotypes. In conclusion, genetic clinical correlates continue to be found for Pneumocystis pneumonia; however, they remain controversial and warrant further study.
耶氏肺孢子菌是免疫功能低下患者重要的机会致病菌。由于不存在培养系统,因此采用分子分型来研究这种病原体。此前尚未对澳大利亚的耶氏肺孢子菌菌株进行过研究。对2001年至2007年间收集的68份澳大利亚样本进行了直接测序,靶向核核糖体RNA操纵子的内转录间隔区(ITS)区域、线粒体大亚基rRNA(mt LSU rRNA)和二氢蝶酸合酶(DHPS)基因。鉴定出7种新的澳大利亚ITS单倍型(ITS1和ITS2区域的组合)(SYD1m、SYD1g、Isyd2、Esyd3、Osyd4、Ag和Hc)。已发表的ITS单倍型的系统发育树显示,在这7种新单倍型中,有3种(SYD1m、SYD1g和Osyd4)与单倍型Eg密切相关。应用统计简约法构建了澳大利亚单倍型网络,确定Eg为祖先单倍型,遇到两个未解析的环。这表明ITS缺乏进化分析所需的分辨率。仅检测到两种mt LSU rRNA基因型,其中基因型1占主导。13%(8/60)的样本中存在突变型DHPS基因型。新的单倍型Isyd2与比其他澳大利亚单倍型病情较轻相关。相比之下,与野生型DHPS基因型的患者相比,突变型DHPS基因型的患者更有可能患有严重疾病,并需要有创通气,且预后较差。总之,仍不断发现耶氏肺孢子菌肺炎的遗传临床相关性;然而,它们仍然存在争议,值得进一步研究。