Basic Medical Sciences Department, College of Medicine, Prince Sattam Bin Abdulaziz University, Al-Kharj, Saudi Arabia.
Mahaveer Hospital and Research Centre, Hyderabad, India.
Microb Pathog. 2018 Jul;120:1-7. doi: 10.1016/j.micpath.2018.04.013. Epub 2018 Apr 21.
There are reports of non-toxigenic C. difficile strains from asymptomatic carriers are increasing source of transmission. Asymptomatic carriage transmission in the hospital or community settings might have changed over the years. Therefore, we initiated a prospective epidemiological study to define the risk factors and pathogenicity of asymptomatic C. difficile carriage.
Stools sample from 188 subjects with diarrhoea due to C. difficile toxin and colonization without diarrhoea was subjected to routine microbial culture, molecular characterization for identification of toxin genes and mechanisms of resistance in C.difficile. Demographic data were recorded. Fifty five were positive for C. difficile includes thirty nine toxigenic C. difficile (TCD) and sixteen non toxigenic C. difficile (NTCD) isolates. Pathogenecity of toxic and nontoxic strains were analysed using AO/EB staining, Annexin V staining using flow cytometer and Galleria mellonella survival analyses.
Among 188, fifty five were positive for C.difficile. Infected or colonized individual with TCD or NTCD were more frequently exposed to hemodialysis compared with uncolonized patients. Isolates showed more resistant to clindamycin and levofloxacin. All TCD and eight of NTCD were tcdA-positive. Only four of TCD were positive for cdtA, tcdA, and tcdB (7%, n = 55). In thirty isolates erm (B) gene was found to be prevelant gene. High virulence was found with TCD strain and it was validated using in Galleria mellonella infection model which supported in vitro experiments. The strain with cdtA, tcdA, and tcdB, seen to have elevated virulence to increased resistance and virulence subsequently led to raised virulence in this pathogen.
Asymptomatic TCD colonization was relatively high, however, with a small number of enrolled subjects the significant of results might have limitations and the occurrence of CDI among different age group still remains unclear.
有报道称，无毒素的艰难梭菌（C. difficile）菌株来自无症状携带者，这是传播的主要来源。近年来，医院或社区环境中无症状携带者的传播情况可能已经发生了变化。因此，我们开展了一项前瞻性的流行病学研究，以确定无症状艰难梭菌定植的危险因素和致病性。
对 188 例因艰难梭菌毒素和定植而腹泻但无腹泻的患者的粪便样本进行常规微生物培养、分子特征鉴定，以确定艰难梭菌的毒素基因和耐药机制。记录人口统计学数据。55 例艰难梭菌阳性，包括 39 例产毒艰难梭菌（TCD）和 16 例非产毒艰难梭菌（NTCD）分离株。采用 AO/EB 染色、流式细胞术 Annexin V 染色和金龟子幼虫存活分析对有毒和无毒菌株的致病性进行分析。
在 188 例患者中，55 例艰难梭菌阳性。与未定植患者相比，感染或定植 TCD 或 NTCD 的个体更频繁地接受血液透析。分离株对克林霉素和左氧氟沙星的耐药性更高。所有 TCD 和 8 例 NTCD 均为 tcdA 阳性。只有 4 例 TCD 对 cdtA、tcdA 和 tcdB 呈阳性（7%，n=55）。在 30 株分离株中，erm（B）基因是普遍存在的基因。TCD 菌株的毒力较高，并在金龟子幼虫感染模型中得到验证，这支持了体外实验的结果。携带 cdtA、tcdA 和 tcdB 的菌株表现出更高的毒力，这与更高的耐药性和随后增加的毒力有关。
无症状 TCD 定植相对较高，但由于纳入的研究对象数量较少，结果的意义可能存在局限性，不同年龄组艰难梭菌感染的发生情况仍不清楚。
