Research Unit in Biology of Microorganisms (URBM), University of Namur, 5000, Namur, Belgium.
Culture Collection University of Gothenburg (CCUG), Department of Clinical Microbiology, Sahlgrenska University Hospital, 41346, Gothenburg, Sweden.
Emerg Microbes Infect. 2018 Jul 4;7(1):124. doi: 10.1038/s41426-018-0126-x.
Capnocytophaga canimorsus is a dog oral commensal bacterium that causes rare but life-threatening generalized infections in humans who have been in contact with its animal hosts. Two other dog commensals, Capnocytophaga canis and Capnocytophaga cynodegmi, cause rare, mild local infections. To date, nine capsular serovars have been described in C. canimorsus. Here, we serotyped 112 strains of Capnocytophaga spp. isolated from human infections. The C. canimorsus strains (86 of 96, 89.6%) belonged to serovars A, B, or C with relative frequencies of approximately 30% for each serovar. The high prevalence of the A, B, and C serovars in strains isolated from humans, compared to the previously described low prevalence of these serovars among dog isolates (7.6%), confirms that these three serovars are more virulent to humans than other serovars and suggests that the low incidence of disease may be linked to the low prevalence of the A, B, and C serovars in dogs. We serotyped six strains of C. canis and ten strains of C. cynodegmi and, surprisingly, found one C. canis and three C. cynodegmi strains to be of capsular serovar B. This observation prompted us to test 34 dog-isolated C. canis and 16 dog-isolated C. cynodegmi strains. We found four C. canis strains belonging to serovar A and one belonging to serovar F. In contrast, no dog-isolated C. cynodegmi strain could be typed with the available antisera. This work demonstrates that virulence-associated capsular polysaccharides (A, B, and C) are not specific to the C. canimorsus species.
贪噬二氧化碳噬纤维菌是一种犬口腔共生菌，会导致与人接触过其动物宿主的人发生罕见但危及生命的全身性感染。另外两种犬共生菌贪噬二氧化碳噬纤维菌犬亚种和贪噬二氧化碳噬纤维菌 Cynodegmi 亚种则引起罕见的轻度局部感染。迄今为止，贪噬二氧化碳噬纤维菌已描述了 9 种荚膜血清型。在此，我们对从人类感染中分离出的 112 株贪噬二氧化碳噬纤维菌属进行了血清分型。贪噬二氧化碳噬纤维菌菌株（96 株中的 86 株，89.6%）属于血清型 A、B 或 C，每个血清型的相对频率约为 30%。与之前描述的犬分离株中这些血清型的低流行率（7.6%）相比，从人类分离株中分离出的 A、B 和 C 血清型的高流行率证实了这三种血清型对人类的毒力强于其他血清型，并表明疾病的低发病率可能与 A、B 和 C 血清型在犬中的低流行率有关。我们对 6 株贪噬二氧化碳噬纤维菌犬亚种和 10 株贪噬二氧化碳噬纤维菌 Cynodegmi 进行了血清分型，令人惊讶的是，发现一株贪噬二氧化碳噬纤维菌犬亚种和三株贪噬二氧化碳噬纤维菌 Cynodegmi 为荚膜血清型 B。这一观察结果促使我们测试了 34 株犬分离的贪噬二氧化碳噬纤维菌犬亚种和 16 株犬分离的贪噬二氧化碳噬纤维菌 Cynodegmi。我们发现 4 株贪噬二氧化碳噬纤维菌犬亚种属于血清型 A，1 株属于血清型 F。相比之下，没有犬分离株贪噬二氧化碳噬纤维菌 Cynodegmi 可以用现有的抗血清进行分型。这项工作表明，与毒力相关的荚膜多糖（A、B 和 C）并非贪噬二氧化碳噬纤维菌特有。
