Karmanos Cancer Institute, Detroit, MI, USA.
Med Sci Monit. 2010 Jan;16(1):CR1-7.
Intestinal microbes have been postulated to play an important role in the development of colorectal cancer. Recently developed methods for preserving and delivering fecal samples at ambient temperature to the laboratory for molecular analysis of bacterial constituents were used to test associations of bacterial populations with epidemiologic risk factors for colorectal cancer.
MATERIAL/METHODS: Real-time PCR targeting 16S rRNA gene sequences was used to quantify three intestinal bacterial groups relative to total DNA in stool samples preserved with RNAlater from 62 subjects. Subjects' medical and family history, race, diet, weight, height, and personal habits including smoking were obtained through structured questionnaires.
Bacteroides DNA proportions were relatively stable among individuals and relatively independent of dietary intake or other personal factors. Clostridium (coccoides group) DNA was positively associated with total fat and vitamin C intake. Desulfovibrio DNA amount tended to be higher in African Americans than in other races. Furthermore, Desulfovibrio DNA increased progressively with pack-years of cigarette smoking. The relative DNA quantity (%) was more than 17 times higher in the subjects who smoked at least 15 pack-years compared with never-smokers (P-value for a linear trend =0.001). In addition, Desulfovibrio DNA (%) decreased with increased calcium, vitamin E, and dietary fiber intake. However, only smoking remained significant in multivariable analysis.
Although the study was limited by its sample size, these results suggest that smoking (or possibly unmeasured dietary confounders) may exert modulatory effects on the bacterial populations of the gastrointestinal tract. The study also demonstrates collection, preservation, and sample delivery procedures suitable for large epidemiological studies.
肠道微生物被认为在结直肠癌的发展中起重要作用。最近开发的在环境温度下保存和输送粪便样本到实验室进行细菌成分分子分析的方法，被用于检测细菌种群与结直肠癌的流行病学风险因素之间的关联。
材料/方法：使用针对 16S rRNA 基因序列的实时 PCR 技术，定量粪便样本中三种肠道细菌群相对于总 DNA 的含量。通过结构化问卷获取研究对象的医疗和家族史、种族、饮食、体重、身高以及包括吸烟在内的个人习惯等信息。
个体间拟杆菌 DNA 比例相对稳定，且与饮食摄入或其他个人因素相对独立。梭状芽胞杆菌（梭菌群）DNA 与总脂肪和维生素 C 摄入呈正相关。与其他种族相比，脱硫弧菌 DNA 含量在非裔美国人中较高。此外，随着吸烟包年数的增加，脱硫弧菌 DNA 呈递增趋势。与从不吸烟者相比，吸烟至少 15 包年的研究对象的相对 DNA 量（%）高出 17 倍以上（线性趋势检验 P 值=0.001）。此外，脱硫弧菌 DNA（%）随钙、维生素 E 和膳食纤维摄入的增加而减少。然而，在多变量分析中只有吸烟仍然具有显著意义。
尽管该研究受到样本量的限制，但这些结果表明吸烟（或可能是未测量的饮食混杂因素）可能对胃肠道细菌种群产生调节作用。该研究还展示了适合大型流行病学研究的采集、保存和样本输送程序。
