Capnocytophaga ochracea Septicemia

A case report describing Capnocytophaga ochracea (Bacteroides ochraceus) septicemia in a 21-year-old male patient receiving chemotherapy for acute lymphocytic leukemia is presented. The unusual features of this organism are discussed together with a review of the literature.     

Septic arthritis involving Capnocytophaga ochracea

Septic arthritis of the knee developed in a 21-month-old child. The causative organism, isolated from two separate arthrocenteses, was identified as Capnocytophaga ochracea morphologically and by biochemical reactions. Previous human infections (bacteremias) have occurred in granulocytopenic hosts with concomitant oral pathology including periodontitis and gingivitis. No abnormalities of oral hygiene were present in this patient, and granulocyte numbers were normal or elevated. Eradication of the infection was accomplished with 8 weeks of antibiotic therapy combined with surgical drainage. Septic arthritis expands the spectrum of infections reported to be caused by Capnocytophaga spp.     

Energy Metabolism in Capnocytophaga ochracea

Among the microflora of the gingival sulcus are members of the genus Capnocytophaga which have been implicated as possible etiological agents of juvenile periodontitis and systemic infectious diseases. In this study, the pathway used by C. ochracea strain 25 for generating energy from glucose was investigated. When grown in a complex medium supplemented with glucose and NaHCO₃, the major end products formed were acetate (4.6 mmol), succinate (11.0 mmol), pyruvate (4.3 mmol), and oxalacetate (3.6 mmol), and the molar growth yield was 58. Addition of yeast extract to the growth medium caused (i) an increase in acetate (9.2 mmol) and succinate (14.3 mmol), (ii) a decrease in pyruvate (0 mmol) and oxalacetate (1.1 mmol), and (iii) the molar growth yield increased to 75. Glucose was transported by a phosphoenolpyruvate:phosphotransferase system and then catabolized to phosphoenolpyruvate by enzymes of the Embden-Meyerhof-Parnas pathway. No activities were detected for the key enzymes of the Warburg-Dickens, Entner-Douderoff, or hexose phosphoketolase pathways. During growth in the yeast extract-supplemented medium, approximately 37% of the phosphoenolpyruvate carbon was converted to acetate by pyruvate kinase, a pyruvate-decarboxylating enzyme activity, and acetate kinase; the remaining 63% was converted to succinate via phosphoenolpyruvate carboxykinase, malate dehydrogenase, fumarate hydratase, and fumarate reductase.     

Suppression of Murine Lymphocyte Mitogen Responses by Exopolysaccharide from Capnocytophaga ochracea

An extracellular polysaccharide was purified from culture supernatants of Capnocytophaga ochracea 25, a gram-negative bacillus associated with human periodontal disease. The extracellular polysaccharide suppressed in vitro mitogenic responses of murine splenic lymphocytes to concanavalin A and lipopolysaccharide. This suppression wad dose dependent, persisted up to 120 h, and was not caused by direct toxicity of the extracellular polysaccharide.     

Ultrastructure of gliding bacteria: scanning electron microscopy of Capnocytophaga sputigena, Capnocytophaga gingivalis, and Capnocytophaga ochracea.

When examined by both light and scanning electron microscopy, Capnocytophaga gingivalis, C. sputigena, and C. ochracea displayed three distinct growth zones: the original streak, an intermediate zone, and the advancing edge, or halo zone. On Trypticase (BBL Microbiology Systems)-soy-blood agar, the cells translocated by gliding. C. gingivalis and C. sputigena formed large, irregular isolated colonies, while C. ochracea formed a more confluent cell mass. The cells within the streak zone and in most of the intermediate zone were heaped into mounds, with the individual cells displaying a definite flow pattern, the latter characteristic of C. sputigena and C. gingivalis. The halo zone consisted of tracks of cells which appeared to have translocated back upon themselves, or were restricted in their outward movements by adjacent cells. Also present within the halo zone were small aggregates of cells, referred to as pioneer colonies. The cell surfaces of C. gingivalis and C. ochracea were smooth and free of any apparent extracellular material, whereas C. sputigena was covered with a thick amorphous material, as well as long, thick, cell surface-associated fibrils.     

Serological cross-reaction between Legionella spp. and Capnocytophaga ochracea by using latex agglutination test.

Cross-reactivity between Legionella spp. and Capnocytophaga ochracea was noted by latex agglutination tests (Serobact Legionella; Disposable Products, Adelaide, Australia). Four of 11 (36%) C. ochracea isolates agglutinated with latex reagents designed to identify Legionella pneumophila serogroups. C. ochracea isolated on buffered charcoal yeast extract media may give false-positive results in this Legionella latex agglutination assay.     

Brain abscess associated with multidrug-resistant Capnocytophaga ochracea infection

Brain abscesses are occasionally associated with a dental source of infection. An unusual case of frontal lobe abscess in a nonimmunocompromised child infected with multidrug-resistant Capnocytophaga ochracea is described and confirms the pathogenic potential of this organism to cause human disease in the central nervous system.     

Endocarditis caused by M6.

M6 is a Moraxella-like organism which is usually of pharyngeal origin and is generally nonpathogenic. Endocarditis caused by M6 occurred in a 31-year-old female with known mitral valve prolapse. The infection quickly responded to ampicillin, but valve replacement was required because of progressive left ventricular failure.     

Endocarditis caused by Actinobacillus actinomycetemcomitans.

Actinobacillus actinomycetemcomitans is a gram-negative coccobacillus which is a very rare cause of bacterial endocarditis. Preexisting cardiac lesions are a main contributing factor, and antibiotic prophylaxis has long been felt necessary before dental or other manipulation to prevent endocarditis. Penicillin in combination with an aminoglycoside has been the most often used treatment regimen. We present a case of endocarditis caused by this organism which developed after antibiotic prophylaxis for dental cleaning. Streptomycin and rifampin therapy resulted in the cure of the infection. The treatment and epidemiology of Actinobacillus endocarditis are reviewed.     

Endocarditis caused by Rothia dentocariosa.

A case of infective endocarditis caused by Rothia dentocariosa is described in a 53 year old man with a history of rheumatic fever. R dentocariosa is a component of the oral microbiota and has only rarely and recently been recognised as a human pathogen. In this patient the oral flora was the probable source of infection, with a broken molar tooth providing the probable avenue for infection.     

Capnocytophaga ochracea infection: two cases and a review of the published work.

Bacteria of the genus Capnocytophaga are recently recognised pathogens which may cause oral disease and subsequent septicaemia in the immunocompromised host. We present two cases of infection caused by Capnocytophaga ochracea; a soft tissue infection in an immunologically normal patient and an episode of septicaemia in a child with leukaemia. The microbiology, pathogenicity, and antimicrobial susceptibility of the genus capnocytophaga are reviewed.     

Endocarditis caused by nonhemolytic group B streptococcus.

We report a case of bacterial endocarditis caused by nonhemolytic group B streptococcus (GBS) in a 67-year-old man with no predisposing risk factors. Nonhemolytic GBS strains rarely cause illness and are usually detected in perinatal infections. We believe this to be the first reported case of endocarditis caused by a nonhemolytic strain of GBS.     

Endocarditis caused by Cardiobacterium valvarum

A fastidious, gram-negative bacterium was isolated from the blood of a 51-year-old man who had acute infectious endocarditis (IE). Characterization of the organism through phenotypic and genotypic analyses revealed the causative role of Cardiobacterium valvarum. This is the third reported case of IE caused by C. valvarum.     

Endocarditis caused by relatively penicillin-resistant Stomatococcus mucilaginosus.

We report a case of Stomatococcus mucilaginosus endocarditis in which the isolate was relatively resistant to penicillins and cephalothin. The patient was treated successfully with vancomycin and valve replacement.     

Endocarditis caused by Torulopsis glabrata

A case of Torulopsis glabrata endocarditis involving the mitral valve is reported. Endocarditis developed during convalescence from severe abdominal trauma and was associated with fungemia. Morphologically characteristic organisms were present in the mitral valve.     

Genetic analysis of an ambler class A extended-spectrum beta-lactamase from Capnocytophaga ochracea

A beta-lactamase gene (cfxA3, 966 bp) was isolated from a beta-lactam-resistant Capnocytophaga ochracea clinical isolate and amplified using primers from the cfxA gene of Bacteroides vulgatus. The MICs of third-generation cephalosporins were much higher than those of the transconjugant Escherichia coli strain. The deduced protein sequence, by comparison with CfxA2 of Prevotella intermedia, had a Y239D substitution and possessed the characteristics of a class A, group 2e beta-lactamase.     

Carbon dioxide metabolism by Capnocytophaga ochracea: identification, characterization, and regulation of a phosphoenolpyruvate carboxykinase.

Cell suspensions of Capnocytophaga ochracea incorporated [14C]NaHCO3 into a major four-carbon fermentation product, succinate, and cell-free extracts from this organism contained high levels of phosphoenolpyruvate carboxykinase (PEPCK). PEPCK is the major, if not the only, CO2(HCO-3)-fixing enzyme in C. ochracea since cell-free extracts were devoid of pyruvate-dependent and other phosphoenolpyruvate (PEP)-dependent CO2(HCO-3)-fixing enzymes. The reaction products of the enzyme, which was partially purified by diethylaminoethylcellulose column chromatography, were identified as adenosine 5'-triphosphate (ATP) and oxalacetate. The enzyme showed maximum activity when manganese (Mn2+) was the divalent cation in the incubation mixture, and it had an absolute requirement for the nucleoside 5-'diphosphate adenosine 5'-diphosphate (ADP). PEPCK showed a sigmoidal kinetic response to the Mn2+ concentration and homotropic interactions in its kinetic responses to each of its three substrates PEP, ADP, and CO2(HCO-3). The (S)0.5v values for Mn2+, PEP, ADP, and CO2(CHO-3) were approximately 0.08, 0.3, 0.1, and 10 mM, respectively, and Hill coefficients for these same ligands were 2.60, 1.7, 1.9, and 3.0, respectively. In addition, C. ochracea PEPCK is under metabolic control by the nucleoside -5'-triphosphate ATP, and it also showed a sigmoidal kinetic response to this allosteric effector. The Hill coefficient for ATP was 2.70.