Draft Genome Sequences of Three Capnocytophaga canimorsus Strains Isolated from Healthy Canine Oral Cavities

Whole genome sequencing identifies a novel species of the genus Capnocytophaga isolated from dog and cat bite wounds in humans

C. canimorsus and C. cynodegmi are dog and cat commensals which can be transmitted to humans via bites or scratches and can cause sepsis, meningitis, endocarditis, and eye- or wound infections. Recently an additional Capnocytophaga species was identified as part of the oral flora of healthy dogs and was given the name “C. canis”. We previously identified a Capnocytophaga isolate that could not be typed with available diagnostic tests including MALDI-TOF, 16S rRNA sequencing or species-specific PCR. This strain and 21 other Capnocytophaga spp isolated in Sweden from clinical blood- or wound-cultures were subjected to whole genome sequencing using the Illumina platform. Phylogenetic analysis revealed that the previously non-typable isolate belongs to the putative new species “C. canis”. Since this strain was isolated from a wound it also shows that members of “C. canis” have the potential to be pathogenic. In addition, our phylogenetic analysis uncovered an additional species of Capnocytophaga, which can be transmitted from dogs and cats to humans, suggesting a speciation within the Capnocytophaga family that has not been observed before. We propose the name of “C. stomatis” for this putative novel species.

Only a subset of C. canimorsus strains is dangerous for humans

Capnocytophaga canimorsus are gram-negative bacteria living as commensals in the mouth of dogs and cats. C. canimorsus cause rare but life-threatening generalized infections in humans that have been in contact with a dog or a cat. Over the last years we collected 105 C. canimorsus strains from different geographical origins and from severe human infections or healthy dogs. All these strains were analyzed by 16S rDNA sequencing and a phylogenetic tree revealed two main groups of bacteria instead of one with no relation to the geographical origin. This branching was confirmed by the whole-genome sequencing of 10 strains, supporting the evidence of a new Capnocytophaga species in dogs. Interestingly, 19 out of 19 C. canimorsus strains isolated from human infections belonged to the same species. Furthermore, most strains from this species could grow in heat-inactivated human serum (HIHS) (40/46 tested), deglycosylate IgM (48/66) and were cytochrome-oxidase positive (60/66) while most strains from the other species could not grow in HIHS (22/23 tested), could not deglycosylate IgM (33/34) and were cytochrome-oxidase negative (33/34). Here, we propose to call Capnocytophaga canis (Latin: dog) the novel, presumably less virulent dog-hosted Capnocytophaga species and to keep the name C. canimorsus for the species including human pathogens.

Draft Genome Sequences of Three Capnocytophaga cynodegmi Strains Isolated from the Oral Cavity of Healthy Dogs

Here, we present the draft genome sequences of three strains of Capnocytophaga cynodegmi. In contrast to the very close relationship among them, C. cynodegmi and Capnocytophaga canimorsus differ dramatically in terms of virulence in humans. Comparative genomics provided some understanding on how Capnocytophaga species may switch from being dog commensals to human pathogens.

Draft Genome Sequences of Three Capnocytophaga canimorsus Strains Isolated from Septic Patients

Capnocytophaga canimorsus is a bacterium from the normal oral flora of dogs and cats that causes rare generalized infections in humans. In an attempt to determine whether infections could be caused by a subset of strains and to identify pathogenicity factors, we sequenced the genomes of three strains isolated from human infections.