We obtained nine Klebsiella pneumoniae isolates successively isolated from a single patient. Four pairs (M1–M4 and NM1–NM4) obtained simultaneously from the same site showed different colony types, mucoid and non-mucoid, while the final isolate (M5) was isolated alone from the blood and showed a mucoid phenotype. The whole genome of isolate M5 was sequenced de novo using the PacBio RSII system, while the others were sequenced with an Illumina Hiseq4000 and mapped to the genome sequences of M5. To identify insertions or deletions in the cps locus, we amplified and sequenced cps locus genes. We identified insertion sequence (IS) elements in several genes of the cps locus or one amino acid substitution in WcaJ in all non-mucoid isolates. Five additional amino acid alterations in RpsJ, LolE, Lon-2, PpsE, and a hypothetical protein were detected in some mucoid and non-mucoid isolates. Based on the genome data and cps locus sequences, the mucoid phenotype may have been lost or converted into the non-mucoid phenotype because of the insertion of IS elements or amino acid alterations at this locus. We inferred a within-host evolutionary scenario, in which non-mucoid variants emerged repeatedly from mucoid isolates, but may be short-lived because of their low fitness.

我们获得了9株肺炎克雷伯菌的分离株，这些分离株是从一名患者中连续分离出来的。从同一位点同时获得的四对菌丝（M1-M4和NM1-NM4）显示出不同的菌落类型（粘液样和非粘液样），而最终分离株（M5）是从血液中单独分离出来的，并显示出粘液表型。使用PacBio RSII系统从头对分离株M5的整个基因组进行了测序，而其他序列则使用Illumina Hiseq4000进行了测序，并定位到M5的基因组序列。为了识别cps基因座中的插入或缺失，我们扩增了cps基因座基因并对其进行了测序。我们确定了cps的几个基因中的插入序列（IS）元素所有非粘液分离物中WcaJ中的一个基因座或一个氨基酸取代。在一些粘液样和非粘液样分离物中还检测到RpsJ，LolE，Lon-2，PpsE和一种假设蛋白中的五个其他氨基酸改变。根据基因组数据和cps基因座序列，由于在该基因座上插入了IS元素或氨基酸改变，可能已经失去了粘液表型或将其转变为非粘液表型。我们推断出宿主内部的进化情况，其中非粘液变体从粘液分离物中反复出现，但由于适应性低而可能短暂。