Genotypes of Klebsiella oxytoca Isolates from Patients with Nosocomial Pneumonia Are Distinct from Those of Isolates from Patients with Antibiotic-Associated Hemorrhagic Colitis
Genotypes of Klebsiella oxytoca Isolates from Patients with Nosocomial Pneumonia Are Distinct from Those of Isolates from Patients with Antibiotic-Associated Hemorrhagic Colitis
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DOI：
10.1128/jcm.03373-13
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发表时间：
2014-05-01
影响因子：
9.4
通讯作者：
Hoegenauer, Christoph
中科院分区：
文献类型：
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作者：
Herzog, Kathrin A. T.;Schneditz, Georg;Hoegenauer, Christoph
产酸克雷伯氏菌在生态失调的人类肠道微生物群中作为致病菌，引起腹泻相关出血性结肠炎（AAHC），但它也感染其他器官，导致肺炎、尿路和皮肤感染。K.催产素仍然知之甚少。一种特异性细胞毒素的产生与AAHC的发病机制有关。研究了K.根据产酸克雷伯氏菌的临床来源和毒力特点，建立了多位点序列分型方法，并对74株临床产酸克雷伯氏菌进行了分析。产酸菌分离自无症状携带者和AAHC、呼吸道感染和其他感染患者。根据7个管家基因的序列对分离株进行表型表征、分型和遗传学比较。MLST分析产生了60个序列类型，其中12个由一个以上的分离物代表。系统发育树将K. AAHC患者和呼吸道感染患者之间的催产素分离株。毒素阳性和阴性菌株内观察到一个序列类型。我们的研究结果表明AAHC分离株具有共同的遗传背景。有趣的是，K。来自医院获得性肺炎的催产素分离株显示出不同的遗传聚类，这表明这些菌株不是源自肠，或者它们是专门用于呼吸道定殖的。我们的研究结果进一步表明了K.催产素细胞毒素产生。这项工作提供了证据，K。定殖于人类宿主的两个主要临床相关生境（下胃肠道和呼吸道）的催产素分离物在遗传上是不同的。MLST分析的应用有助于阐明医院感染的来源。
Klebsiella oxytoca acts as a pathobiont in the dysbiotic human intestinal microbiota, causing antibiotic-associated hemorrhagic colitis (AAHC), but it also infects other organs, resulting in pneumonia and urinary tract and skin infections. The virulence of K. oxytoca is still poorly understood. The production of a specific cytotoxin has been linked to AAHC pathogenesis. To investigate the clonal relationships of K. oxytoca with regard to clinical origin and virulence attributes, we established a multilocus sequence typing (MLST) method and analyzed 74 clinical K. oxytoca isolates from asymptomatic carriers and patients with AAHC, respiratory infections, and other infections. The isolates were phenotypically characterized, typed, and compared phylogenetically based on the sequences of seven housekeeping genes. MLST analysis yielded 60 sequence types, 12 of which were represented by more than one isolate. The phylogenetic tree distinguished clusters of K. oxytoca isolates between patients with AAHC and those with respiratory infections. Toxin-positive and -negative strains were observed within one sequence type. Our findings indicate that AAHC isolates share a genetic background. Interestingly, K. oxytoca isolates from nosocomial pneumonia showed a different genetic clustering, suggesting that these strains do not originate from the intestines or that they are specialized for respiratory tract colonization. Our results further indicate a polyphyletic origin and possible horizontal transfer of the genes involved in K. oxytoca cytotoxin production. This work provides evidence that K. oxytoca isolates colonizing the two main clinically relevant habitats (lower gastrointestinal [GI] tract and respiratory tract) of the human host are genetically distinct. Applications of this MLST analysis should help clarify the sources of nosocomial infections.