Capnocytophaga species and perinatal infections: case report and review of the literature

Isolation and Characterization of Capnocytophaga bilenii sp. nov., a Novel Capnocytophaga Species Detected in a Gingivitis Subject

Capnocytophaga species are commensal gliding bacteria that are found in human and animal oral microbiota and are involved in several inflammatory diseases, both in immunocompromised and immunocompetent subjects. This study contributes to increased knowledge of this genus by characterizing a novel species isolated from a dental plaque sample in a male with gingivitis. We investigated morphological and chemotaxonomic characteristics using different growth conditions, temperature, and pH. Cellular fatty acid methyl ester (FAME) analysis was employed with gas chromatography/mass spectrometry (GC/MS). Phylogenetic analysis based on 16S rRNA, orthologous average nucleotide identity (OrthoANI), and digital DNA–DNA hybridization (dDDH) relatedness were performed. The Marseille-Q4570^T strain was found to be a facultative aerobic, Gram-negative, elongated, round-tipped bacterium that grew at 25–56 °C and tolerated a pH of 5.5 to 8.5 and an NaCl content ranging from 5 to 15 g/L. The most abundant fatty acid was the branched structure 13-methyl-tetradecanoic acid (76%), followed by hexadecanoic acid (6%) and 3-hydroxy-15-methyl-hexadecanoic acid (4%). A 16S rDNA-based similarity analysis showed that the Marseille-Q4570^T strain was closely related to Capnocytophaga leadbetteri strain AHN8855^T (97.24% sequence identity). The OrthoANI and dDDH values between these two strains were, respectively, 76.81% and 25.6%. Therefore, we conclude that the Marseille-Q4570^T strain represents a novel species of the genus Capnocytophaga, for which the name Capnocytophaga bilenii sp. nov. is proposed (=CSUR Q4570).

Capnocytophaga bacteremia precipitating severe thrombocytopenia and preterm labor in an asplenic host

Capnocytophaga species are gram-negative bacilli that inhabit mammalian oral surfaces and can cause opportunistic infection, especially in asplenic patients. The species Capnocytophaga canimorsus is particularly associated with dog bites and is known to cause endocarditis, meningitis, and sepsis in the general population. In pregnant patients, infections tied to Capnocytophaga species from human flora have been associated with preterm labor, chorioamnionitis, and neonatal septicemia. There is little known about the effects of zoonotically-acquired Capnocytophaga infection in pregnant patients. In this case report, we present a patient with Capnocytophaga bacteremia acquired after a dog bite associated with profound thrombocytopenia and preterm labor. Dog bites are common in the United States, and we present basic recommendations for management of dog bites in pregnant patients in order to avoid morbidity associated with delay in time to antibiotic treatment of infection as described in this case.

A practical guide to the diagnosis, treatment, and prevention of neonatal infections

Neonatal infections continue to cause morbidity and mortality in infants. Among approximately 400,000 infants followed nationally, the incidence rates of early-onset sepsis infection within 3 days of life are 0.98 cases per 1000 live births. Newborn infants are at increased risk for infections because they have relative immunodeficiency. This article provides evidence-based practical approaches to the diagnosis, management, and prevention of neonatal infections.

'Bobo-Newton syndrome': An unwanted gift from man's best friend

Capnocytophaga canimorsus is a facultative Gram-negative bacillus that is typically a constituent of the oral flora of dogs and cats. It was first isolated by Bobo and Newton in 1976 from a man presenting with meningitis following a dog bite. Transmission to humans follows various animal-related injuries, which may be gross or subtle. C canimorsus can cause a spectrum of syndromes ranging from skin and soft tissue infection to invasive disease such as meningitis or endocarditis. The present article reports a case of C canimorsus meningitis in a patient with the classic risk factor of alcoholic liver cirrhosis. Clinical suspicion was confirmed by culture and genetic identification of the blood isolate. The present article reviews the Capnocytophaga genus, the clinical syndromes most commonly associated with this zoonotic organism, its laboratory identification and treatment.

T cell epitope mimicry between Sjögren's syndrome Antigen A (SSA)/Ro60 and oral, gut, skin and vaginal bacteria

This study was undertaken to test the hypothesis that Sjogren's syndrome Antigen A (SSA)/Ro60-reactive T cells are activated by peptides originating from oral and gut bacteria. T cell hybridomas generated from HLA-DR3 transgenic mice recognized 3 regions on Ro60, with core epitopes mapped to amino acids 228-238, 246-256 and 371-381. BLAST analysis identified several mimicry peptides, originating from human oral, intestinal, skin and vaginal bacteria, as well as environmental bacteria. Amongst these, a peptide from the von Willebrand factor type A domain protein (vWFA) from the oral microbe Capnocytophaga ochracea was the most potent activator. Further, Ro60-reactive T cells were activated by recombinant vWFA protein and whole Escherichia coli expressing this protein. These results demonstrate that peptides derived from normal human microbiota can activate Ro60-reactive T cells. Thus, immune responses to commensal microbiota and opportunistic pathogens should be explored as potential triggers for initiating autoimmunity in SLE and Sjögren's syndrome.