A Previously Undescribed Gram-negative Bacillus Causing Septicemia and Meningitis

Bobo, Raymond A.; Newton, Eleanor J.

doi:10.1093/ajcp/65.4.564

Cited by 157 publications

(79 citation statements)

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“…C apnocytophaga canimorsus is a commensal bacterium from the oral cavity of dogs that is regularly isolated, since its description in 1989, from extremely severe human infections worldwide (1,2). Following contact with a dog, these infections generally start with vague influenza symptoms, and patients enter the hospital with fulminant septicemia often associated with peripheral gangrene.…”

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“…Following contact with a dog, these infections generally start with vague influenza symptoms, and patients enter the hospital with fulminant septicemia often associated with peripheral gangrene. Mortality is as high as 40% in spite of adequate antibiotherapy and frequent amputations (1,(3)(4)(5)(6)(7). Infections do not necessarily occur after severe injuries, which generally are followed by a preventive antibiotic treatment, but rather after small bites, scratches, or even licks (8).…”

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New Iron Acquisition System in Bacteroidetes

et al. 2015

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b Capnocytophaga canimorsus, a dog mouth commensal and a member of the Bacteroidetes phylum, causes rare but often fatal septicemia in humans that have been in contact with a dog. Here, we show that C. canimorsus strains isolated from human infections grow readily in heat-inactivated human serum and that this property depends on a typical polysaccharide utilization locus (PUL), namely, PUL3 in strain Cc5. PUL are a hallmark of Bacteroidetes, and they encode various products, including surface protein complexes that capture and process polysaccharides or glycoproteins. The archetype system is the Bacteroides thetaiotaomicron Sus system, devoted to starch utilization. Unexpectedly, PUL3 conferred the capacity to acquire iron from serotransferrin (STF), and this capacity required each of the seven encoded proteins, indicating that a whole Sus-like machinery is acting as an iron capture system (ICS), a new and unexpected function for Sus-like machinery. No siderophore could be detected in the culture supernatant of C. canimorsus, suggesting that the Sus-like machinery captures iron directly from transferrin, but this could not be formally demonstrated. The seven genes of the ICS were found in the genomes of several opportunistic pathogens from the Capnocytophaga and Prevotella genera, in different isolates of the severe poultry pathogen Riemerella anatipestifer, and in strains of Bacteroides fragilis and Odoribacter splanchnicus isolated from human infections. Thus, this study describes a new type of ICS that evolved in Bacteroidetes from a polysaccharide utilization system and most likely represents an important virulence factor in this group.

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New Iron Acquisition System in Bacteroidetes

et al. 2015

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“…In a single report, the isolation of C. canimorsus (DF-2) from sheep and 46 cattle (25-30% of the animals tested) but not from pigs was reported (Westwell et al, 1989 (Lion et al, 1996:). Consequently human to human transmission of C. canimorsus has not been 52 reported apart from one case where it could not be excluded 100% (Risi and Sprangler 2006 In 1976 a patient with meningitis and sepsis, caused by an unidentified Gram-negative 64 bacillus, after a recent dog bite was first described (Bobo and Newton, 1976). At that time, the 65 phenotypic as well as the biochemical characteristics of the agent also became known.…”

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Capnocytophaga canimorsus

Gaastra

Lipman

2010

Veterinary Microbiology

101

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“…Since its discovery in 1976, Capnocytophaga canimorsus has been regularly isolated from severe human infections transmitted by dogs or cats (3). The genus Capnocytophaga belongs to the family Flavobacteriaceae and the phylum Bacteroidetes.…”

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Resistance ofCapnocytophaga canimorsusto Killing by Human Complement and Polymorphonuclear Leukocytes

et al. 2009

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Capnocytophaga canimorsus is a bacterium of the canine oral flora known since 1976 to cause rare but severe septicemia and peripheral gangrene in patients that have been in contact with a dog. It was recently shown that these bacteria do not elicit an inflammatory response (H. Shin, M. Mally, M. Kuhn, C. Paroz, and G. R. Cornelis, J. Infect. Dis. 195:375-386, 2007). Here, we analyze their sensitivity to the innate immune system. Bacteria from the archetype strain Cc5 were highly resistant to killing by complement. There was little membrane attack complex (MAC) deposition in spite of C3b deposition. Cc5 bacteria were as resistant to phagocytosis by human polymorphonuclear leukocytes (PMNs) as Yersinia enterocolitica MRS40, endowed with an antiphagocytic type III secretion system. We isolated Y1C12, a transposon mutant that is hypersensitive to killing by complement via the antibody-dependent classical pathway. The mutation inactivated a putative glycosyltransferase gene, suggesting that the Y1C12 mutant was affected at the level of a capsular polysaccharide or lipopolysaccharide (LPS) structure. Cc5 appeared to have several polysaccharidic structures, one being altered in Y1C12. The structure missing in Y1C12 could be purified by classical LPS purification procedures and labeled by tritiated palmitate, indicating that it is more likely to be an LPS structure than a capsule. Y1C12 bacteria were also more sensitive to phagocytosis by PMNs than wild-type bacteria. In conclusion, a polysaccharide structure, likely an LPS, protects C. canimorsus from deposition of the complement MAC and from efficient phagocytosis by PMNs.

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A Previously Undescribed Gram-negative Bacillus Causing Septicemia and Meningitis

Cited by 157 publications

References 2 publications

New Iron Acquisition System in Bacteroidetes

New Iron Acquisition System in Bacteroidetes

Capnocytophaga canimorsus

Resistance ofCapnocytophaga canimorsusto Killing by Human Complement and Polymorphonuclear Leukocytes

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