从英国社区居住的老年人群体中分离出的艰难梭菌菌株的特征和携带率。
Characterisation and carriage ratio of Clostridium difficile strains isolated from a community-dwelling elderly population in the United Kingdom.
机构信息
National Institute for Health Research Biomedical Research Centre, Royal Liverpool and Broadgreen University Hospitals National Health Service Trust, Liverpool, United Kingdom.
出版信息
PLoS One. 2011;6(8):e22804. doi: 10.1371/journal.pone.0022804. Epub 2011 Aug 23.
BACKGROUND
Community-associated Clostridium difficile infection (CDI) appears to be an increasing problem. Reported carriage rates by C. difficile are debatable with suggestions that primary asymptomatic carriage is associated with decreased risk of subsequent diarrhoea. However, knowledge of potential reservoirs and intestinal carriage rates in the community, particularly in the elderly, the most susceptible group, is limited. We have determined the presence of C. difficile in the faeces of a healthy elderly cohort living outside of long-term care facilities (LCFs) in the United Kingdom.
METHODS
Faecal samples from 149 community-based healthy elderly volunteers (median age 81 years) were screened for C. difficile using direct (Brazier's CCEY) and enrichment (Cooked Meat broth) culture methods and a glutamate dehydrogenase (GDH) immunoassay. Isolates were PCR-ribotyped and analysed for toxin production and the presence of toxin genes.
RESULTS
Of 149 faecal samples submitted, six (4%) were found to contain C. difficile. One particular sample was positive by both the GDH immunoassay and direct culture, and concurrently produced two distinct strain types: one toxigenic and the other non-toxigenic. The other five samples were only positive by enrichment culture method. Overall, four C. difficile isolates were non-toxigenic (PCR-ribotypes 009, 026 (n = 2) and 039), while three were toxigenic (PCR-ribotypes 003, 005 and 106). All individuals who had a positive culture were symptom-free and none of them had a history of CDI and/or antibiotics use in the 3 month period preceding recruitment.
CONCLUSIONS
To our knowledge, this is the first study of the presence of C. difficile in healthy elderly community-dwelling individuals residing outside of LCFs. The observed carriage rate is lower than that reported for individuals in LCFs and interestingly no individual carried the common epidemic strain PCR-ribotype 027 (NAP1/BI). Further follow-up of asymptomatic carriers in the community, is required to evaluate host susceptibility to CDI and identify dynamic changes in the host and microbial environment that are associated with pathogenicity.
背景
社区相关性艰难梭菌感染（CDI）似乎是一个日益严重的问题。艰难梭菌的带菌率存在争议，有研究表明原发性无症状带菌与随后腹泻风险降低有关。然而，对于社区中潜在的储菌库和肠道带菌率，特别是在最易感染的老年人中，相关知识有限。我们已经确定了居住在英国长期护理机构（LCF）之外的健康老年人群中粪便中艰难梭菌的存在。
方法
使用直接（Brazier 的 CCEY）和富集（熟肉肉汤）培养方法以及谷氨酸脱氢酶（GDH）免疫测定法，对 149 名来自社区的健康老年志愿者（中位年龄 81 岁）的粪便样本进行了艰难梭菌筛查。对分离株进行 PCR-核糖体分型，并分析其毒素产生和毒素基因的存在。
结果
在提交的 149 份粪便样本中，有 6 份（4%）被发现含有艰难梭菌。有一个特定的样本通过 GDH 免疫测定和直接培养均为阳性，同时产生了两种不同的菌株类型：一种产毒，另一种不产毒。其他 5 个样本仅通过富集培养法为阳性。总的来说，有 4 个艰难梭菌分离株为非产毒株（PCR-核糖体型 009、026（n=2）和 039），而 3 个为产毒株（PCR-核糖体型 003、005 和 106）。所有培养阳性的个体均无症状，且在招募前 3 个月内均无 CDI 和/或抗生素使用史。
结论
据我们所知，这是第一项关于居住在 LCF 之外的健康老年社区居民中艰难梭菌存在情况的研究。观察到的带菌率低于 LCF 中个体的报道，有趣的是，没有个体携带常见的流行株 PCR-核糖体型 027（NAP1/BI）。需要对社区中的无症状携带者进行进一步随访，以评估宿主对 CDI 的易感性，并确定与致病性相关的宿主和微生物环境的动态变化。
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