B 群链球菌定植与奶牛接触的关联：一项前瞻性横断面队列研究。
Association of Group B Streptococcus colonization and bovine exposure: a prospective cross-sectional cohort study.
机构信息
Microbial Evolution Laboratory, Michigan State University, East Lansing, Michigan, United States of America.
出版信息
PLoS One. 2010 Jan 20;5(1):e8795. doi: 10.1371/journal.pone.0008795.
BACKGROUND
While Group B Streptococcus (GBS) human colonization and infection has long been suspected as originating from cows, several investigators have suggested that ongoing interspecies GBS transmission is unlikely due to genotyping data demonstrating that human and bovine-derived GBS strains represent mostly distinct populations. The possibility of ongoing transmission between humans and their livestock has not been systematically examined.
METHODOLOGY/PRINCIPAL FINDINGS: To examine ongoing interspecies transmission, we conducted a prospective cross-sectional cohort study of 68 families and their livestock. Stool specimens were collected from 154 people and 115 livestock; GBS was detected in 19 (12.3%) humans and 2 (1.7%) animals (bovine and sheep). Application of multilocus sequence typing (MLST) identified 8 sequence types (STs or clones), with STs 1 and 23 predominating. There were 11 families in which two members submitted stools and at least one had GBS colonization. In 3 of these families, both members (consisting of couples) were colonized, yielding a co-colonization rate of 27% (95% CI: 7%-61%). Two of these couples had strains with identical MLST, capsule (cps) genotype, susceptibility, and RAPD profiles. One couple co-colonized with ST-1 (cps5) strains also had a bovine colonized with the identical strain type. On multivariate analysis of questionnaire data, cattle exposure was a predictor of GBS colonization, with each unit increase in days of cattle exposure increasing the odds of colonization by 20% (P = 0.02). These results support interspecies transmission with additional evidence for transmission provided by the epidemiological association with cattle exposure.
CONCLUSIONS/SIGNIFICANCE: Although GBS uncommonly colonizes livestock stools, increased frequency of cattle exposure was significantly associated with human colonization and one couple shared the same GBS strains as their bovine suggesting intraspecies transmission. These results set the framework for GBS as a possible zoonotic infection, which has significant public health implications.
背景
长期以来，人们一直怀疑乙型链球菌（GBS）在人体中的定植和感染源自奶牛，但一些研究人员认为，由于基因分型数据表明，人类和牛源 GBS 菌株主要代表不同的种群，因此种间 GBS 传播不太可能持续发生。人类与其家畜之间持续传播的可能性尚未得到系统研究。
方法/主要发现：为了研究种间持续传播，我们对 68 个家庭及其家畜进行了前瞻性横断面队列研究。从 154 人和 115 家畜中采集了粪便标本；19 名（12.3%）人类和 2 名（1.7%）动物（牛和羊）中检测到 GBS。应用多位点序列分型（MLST）鉴定出 8 种序列类型（ST 或克隆），以 ST1 和 ST23 为主。有 11 个家庭中，两个成员提交了粪便，至少有一个成员定植了 GBS。在这些家庭中有 3 个，两个成员（由夫妻组成）都定植了，定植率为 27%（95%CI：7%-61%）。这两对夫妻的菌株具有相同的 MLST、荚膜（cps）基因型、药敏性和 RAPD 谱。一对夫妻共同定植了 ST-1（cps5）菌株，其牛也定植了相同的菌株类型。在对问卷调查数据的多变量分析中，牛的暴露是 GBS 定植的预测因子，牛的暴露天数每增加一个单位，定植的几率就增加 20%（P = 0.02）。这些结果支持种间传播，并通过与牛暴露的流行病学关联提供了进一步的传播证据。
结论/意义：虽然 GBS 很少定植于家畜粪便，但牛的暴露频率增加与人类定植明显相关，一对夫妻与他们的牛共享相同的 GBS 菌株，提示种内传播。这些结果为 GBS 作为一种可能的人畜共患病感染奠定了基础，具有重要的公共卫生意义。
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