Owrangi B, Masters N, Vollmerhausen T L, O'Dea C, Kuballa A, Katouli M
School of Health and Sport Sciences, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland 4558, Australia.
School of Health and Sport Sciences, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland 4558, Australia.
Microb Pathog. 2017 Apr;105:171-176. doi: 10.1016/j.micpath.2017.02.032. Epub 2017 Feb 22.
Escherichia coli strains are normal inhabitants of the gut and are normally found in the faeces of the host at different population sizes. We characterised faecal E. coli of 45 healthy male (n = 17) and female (n = 28) volunteers by testing 28 isolates from each individual. These isolates were typed and divided into dominant (if constituted >50% of the population tested) and non-dominant types in each individual. Representative strains of each dominant and non-dominant type were tested for their virulence gene profiles, their ability to form biofilm, adhere to, invade and translocate through a gut epithelial cell line (Caco-2 cells). Strains belonging to dominant types adhered significantly more to Caco-2 cells than non-dominant strains (5.7 ± 0.3 versus 4.3.± 0.13 CFU/cell mean ± SEM, P = 0.0003). They also invaded (135 ± 6 versus 63 ± 13 CFU) and translocated through Caco-2 cells (84 ± 5 versus 32 ± 9 CFU) significantly more than non-dominant strains (P < 0.0001 and P = 0.0002, respectively). Moreover, dominant strains showed the ability to form significantly more biofilm than non-dominant strains (1.1 ± 0.01 versus 0.5 ± 0.1 OD, P < 0.0001). Majority (51%) of the strains belonged to phylogroup D followed by B2 (23%). Furthermore, out of 25 virulence genes tested, kpsMTII, papC and papG allele III were found to be significantly higher among dominant than non-dominant strains. Our results suggest that E. coli strains dominating the gut may have virulence properties that enable them to efficiently interact with the gut epithelium and translocate under predisposing conditions of the host.
大肠杆菌菌株是肠道的正常寄居菌，通常在宿主粪便中以不同的数量存在。我们通过检测45名健康男性（n = 17）和女性（n = 28）志愿者粪便中的大肠杆菌来进行特征分析，每位志愿者检测28株分离菌。对这些分离菌进行分型，并在每个个体中分为优势型（如果占检测菌群的>50%）和非优势型。对每种优势型和非优势型的代表性菌株进行毒力基因谱、形成生物膜、黏附、侵袭以及穿过肠道上皮细胞系（Caco-2细胞）转运能力的检测。与非优势菌株相比，优势型菌株对Caco-2细胞的黏附显著更多（平均5.7±0.3对4.3±0.13 CFU/细胞，均值±标准误，P = 0.0003）。它们对Caco-2细胞的侵袭（135±6对63±13 CFU）和转运（84±5对32±9 CFU）也显著多于非优势菌株（分别为P < 0.0001和P = 0.0002）。此外，优势菌株形成生物膜的能力显著强于非优势菌株（1.1±0.01对0.5±0.1 OD，P < 0.0001）。大多数（51%）菌株属于D系统发育群，其次是B2（23%）。此外，在检测的25个毒力基因中，发现优势菌株中的kpsMTII、papC和papG等位基因III显著高于非优势菌株。我们的结果表明，在肠道中占主导地位的大肠杆菌菌株可能具有毒力特性，使其能够在宿主的易感条件下与肠道上皮细胞有效相互作用并转运。
