Abstract：
World Health Organization (2019) has declared colorectal cancer (CRC) as the second most common cancer in females and third in males, where the incidence seems to rise year by year. One of the very few potential pathogens specifically associated with malignant colonic diseases is Streptococcus gallolyticus (Sg). Sg is a part of the intestinal flora which formerly known as biotype I of Streptococcus bovis, belongs to Group D streptococci. Owing to only a few researches done in determining evidence to support Sg as a determinant of CRC, a systematic review is constructed.
Full-text articles on case-control and cohort studies published from 1st January 2010 to 1st October 2020 were searched using Google Scholar, PubMed and JSTOR. People of all age groups and Sg bacteraemia or colonisation were the type of participant and exposure used for the search strategy, respectively. Data collection was done by three reviewers and checked by two reviewers for discrepancies. All the papers were critically appraised using the STROBE statement. Qualitative synthesis was done by descriptive comparison, distribution of Sg according to stage comparison, method used for Sg detection comparison and risk of bias comparison.
Seven out of 11 articles that fulfil the eligibility criteria were selected. Four papers have low overall risk of bias due to low confounding or selection bias. Sg is found to be a risk factor for CRC from three papers studied, whereas the other four papers did not include the strength of association. Only two papers studied the association between the distribution of Sg and stages of CRC, where the results were contradictory from each other, making it to be inconclusive. The most common method used for Sg detection is a culturing technique, followed by molecular and biochemical techniques.
There is insufficient evidence to prove the association between Sg bacteraemia as the risk factor for CRC as well as the association between the Sg distribution and stages of CRC. Culturing technique is the most common method used for the detection of bacteria, but it requires subsequent investigations to confirm the presence of Sg. Thus, it is recommended that more studies need to be done using strong statistical analysis to control for most of the confounders with comprehensive explanation and use of more methods in the detection of Sg.
Full-text articles on case-control and cohort studies published from 1st January 2010 to 1st October 2020 were searched using Google Scholar, PubMed and JSTOR. People of all age groups and Sg bacteraemia or colonisation were the type of participant and exposure used for the search strategy, respectively. Data collection was done by three reviewers and checked by two reviewers for discrepancies. All the papers were critically appraised using the STROBE statement. Qualitative synthesis was done by descriptive comparison, distribution of Sg according to stage comparison, method used for Sg detection comparison and risk of bias comparison.
Seven out of 11 articles that fulfil the eligibility criteria were selected. Four papers have low overall risk of bias due to low confounding or selection bias. Sg is found to be a risk factor for CRC from three papers studied, whereas the other four papers did not include the strength of association. Only two papers studied the association between the distribution of Sg and stages of CRC, where the results were contradictory from each other, making it to be inconclusive. The most common method used for Sg detection is a culturing technique, followed by molecular and biochemical techniques.
There is insufficient evidence to prove the association between Sg bacteraemia as the risk factor for CRC as well as the association between the Sg distribution and stages of CRC. Culturing technique is the most common method used for the detection of bacteria, but it requires subsequent investigations to confirm the presence of Sg. Thus, it is recommended that more studies need to be done using strong statistical analysis to control for most of the confounders with comprehensive explanation and use of more methods in the detection of Sg.
摘要：
背景：世界卫生组织（2019）宣布结直肠癌（CRC）是女性中第二常见的癌症，男性中第三常见的癌症，发病率似乎逐年上升。与恶性结肠疾病相关的极少数潜在病原体之一是溶胆囊链球菌(Sg)。Sg是肠道菌群的一部分，以前称为牛链球菌的生物型I，属于D组链球菌。由于在确定支持Sg作为CRC决定因素的证据方面仅进行了一些研究，构建了系统的回顾。
方法：使用GoogleScholar搜索了2010年1月1日至2020年10月1日发表的有关病例对照和队列研究的全文文章，PubMed和JSTOR。所有年龄组的人和Sg菌血症或定植是用于搜索策略的参与者和暴露类型，分别。数据收集由三名审查人员完成，并由两名审查人员检查是否有差异。所有论文都使用STROBE声明进行了严格评估。定性综合是通过描述性比较，根据阶段比较，Sg的分布，方法用于Sg检测比较和风险偏差比较。
结果：选择了符合资格标准的11篇文章中的7篇。由于混淆或选择偏差较低，四篇论文的总体偏差风险较低。从研究的三篇论文中发现Sg是CRC的危险因素，而其他四篇论文不包括关联强度。只有两篇论文研究了Sg的分布与CRC分期之间的关系，结果相互矛盾，使它不确定。用于Sg检测的最常用方法是培养技术，其次是分子和生化技术。
结论：没有足够的证据证明Sg菌血症作为CRC的危险因素以及Sg分布与CRC分期之间的关联。培养技术是最常用的细菌检测方法，但它需要随后的调查来确认Sg的存在。因此，建议需要进行更多的研究,使用强有力的统计分析来控制大多数混杂因素,并在Sg检测中全面解释和使用更多方法.
方法：使用GoogleScholar搜索了2010年1月1日至2020年10月1日发表的有关病例对照和队列研究的全文文章，PubMed和JSTOR。所有年龄组的人和Sg菌血症或定植是用于搜索策略的参与者和暴露类型，分别。数据收集由三名审查人员完成，并由两名审查人员检查是否有差异。所有论文都使用STROBE声明进行了严格评估。定性综合是通过描述性比较，根据阶段比较，Sg的分布，方法用于Sg检测比较和风险偏差比较。
结果：选择了符合资格标准的11篇文章中的7篇。由于混淆或选择偏差较低，四篇论文的总体偏差风险较低。从研究的三篇论文中发现Sg是CRC的危险因素，而其他四篇论文不包括关联强度。只有两篇论文研究了Sg的分布与CRC分期之间的关系，结果相互矛盾，使它不确定。用于Sg检测的最常用方法是培养技术，其次是分子和生化技术。
结论：没有足够的证据证明Sg菌血症作为CRC的危险因素以及Sg分布与CRC分期之间的关联。培养技术是最常用的细菌检测方法，但它需要随后的调查来确认Sg的存在。因此，建议需要进行更多的研究,使用强有力的统计分析来控制大多数混杂因素,并在Sg检测中全面解释和使用更多方法.
