Characterization of the flexible genome complement of the commensal Escherichia coli strain AO 34/86 (O83:K24: H31)
Characterization of the flexible genome complement of the commensal Escherichia coli strain AO 34/86 (O83:K24: H31)
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DOI：
10.1099/mic.0.27469-0
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发表时间：
2005-02-01
期刊：
影响因子：
2.8
通讯作者：
Buchrieser, C
中科院分区：
文献类型：
--
作者：
Hejnova, J;Dobrindt, U;Buchrieser, C
在过去的三十年中，在捷克儿科诊所中，由共生大肠杆菌菌株AO 34/86 （083: K24: H31）定殖已被证明在预防和治疗早产儿和新生儿的医院感染和腹泻方面是安全有效的。为了寻找与该菌株肠道定植能力相关的有益作用的特征，作者通过DNA-DNA杂交与大肠杆菌K-12 （MG1655）基因组DNA阵列和“病理阵列”，以及多重PCR，细菌人工染色体（BAC）文库克隆和霰枪测序分析了其基因组。在AO 34/86中缺失410个大肠杆菌K-12 orf，而在AO 34/86中检出了与大肠杆菌和志贺氏菌致病性岛相关的456个基因中的72个。利用多重PCR技术检测肠外致病性大肠杆菌铁摄取和粘附相关基因，通过分析AO 34/86 DNA的2304个shotgun和1344个BAC克隆序列，鉴定出尿路致病性大肠杆菌536致病性岛11的HlyA和细胞毒性坏死因子毒素编码基因和21个基因。多个序列比较鉴定出31 kb的大肠杆菌AO 34/86特异性DNA；这种DNA携带的一些基因可能与菌株的定植能力有关，使其能够战胜病原体。在所检测的100个大致覆盖AO 34/86基因组的BAC克隆中，一个克隆可重复地赋予实验室菌株DH10B在新生仔猪肠道中持续存在的能力增强。测序结果显示，该BAC克隆携带编码葡萄糖酸盐和甘露糖酸盐代谢、粘附（膜）、侵袭（膜）和限制性修饰功能的基因簇。因此，这种临床安全且高效的定植菌株的基因组似乎包含许多“毒力相关”基因。这些结果突出了细菌“毒力”和“适应性”或“定植”因素之间的细微差别，并对肠杆菌毒力因素的定义提出了质疑。
Colonization by the commensal Escherichia coli strain AO 34/86 (083: K24: H31) has proved to be safe and efficient in the prophylaxis and treatment of nosocomial infections and diarrhoea of preterm and newborn infants in Czech paediatric clinics over the past three decades. In searching for traits contributing to this beneficial effect related to the gut colonization capacity of the strain, the authors have analysed its genome by DNA-DNA hybridization to E. coli K-12 (MG1655) genomic DNA arrays and to 'Pathoarrays', as well as by multiplex PCR, bacterial artificial chromosome (BAC) library cloning and shotgun sequencing. Four hundred and ten E. coli K-12 ORFs were absent from AO 34/86, while 72 out of 456 genes associated with pathogenicity islands of E. coli and Shigella were also detected in E. coli AO 34/86. Furthermore, extraintestinal pathogenic E. coli-related genes involved in iron uptake and adhesion were detected by multiplex PCR, and genes encoding the HlyA and cytotoxic necrotizing factor toxins, together with 21 genes of the uropathogenic E. coli 536 pathogenicity island 11, were identified by analysis of 2304 shotgun and 1344 BAC clone sequences of AO 34/86 DNA. Multiple sequence comparisons identified 31 kb of DNA specific for E. coli AO 34/86; some of the genes carried by this DNA may prove to be implicated in the colonization capacity of the strain, enabling it to outcompete pathogens. Among 100 examined BAC clones roughly covering the AO 34/86 genome, one reproducibly conferred on the laboratory strain DH10B an enhanced capacity to persist in the intestine of newborn piglets. Sequencing revealed that this BAC clone carried gene clusters encoding gluconate and mannonate metabolism, adhesion (fim), invasion (ibe) and restriction/modification functions. Hence, the genome of this clinically safe and highly efficient colonizer strain appears to harbour many 'virulence-associated' genes. These results highlight the thin line between bacterial 'virulence' and 'fitness' or 'colonization' factors, and question the definition of enterobacterial virulence factors.