Capnocytophaga Canimorsus Research Articles

Rapid killing of Capnocytophaga canimorsus and Capnocytophaga cynodegmi by human whole blood and serum is mediated via the complement system.

PurposeCapnocytophaga canimorsus (Cani) and Capnocytophaga cynodegmi (Cyno) are found in the oral cavities of dogs and cats. They can be transmitted to humans via licks or bites and cause wound infections as well as severe systemic infections. Cani is considered to be more pathogenic than Cyno, but the pathophysiological mechanisms are not elucidated. Cani has been suggested to be resistant to serum bactericidal effects. Thus, we hypothesized that the more invasive Cani would exhibit a higher degree of serum-resistance than the less pathogenic Cyno.MethodsWhole blood and serum bactericidal assays were performed against Cani- (n = 8) and Cyno-strains (n = 15) isolated from blood and wound-specimens, respectively. Analysis of complement-function was performed by heat-inactivation, EGTA-treatment and by using C1q-depleted serum. Serum and whole blood were collected from healthy individuals and from patients (n = 3) with a history of sepsis caused by Cani.ResultsBoth Cani and Cyno were equally susceptible to human whole blood and serum. Cani was preferentially killed by the classical pathway of the complement-system whereas Cyno was killed by a partly different mechanism. Serum from 2/3 Cani-infected patients were deficient in MBL-activity but still exhibited the same killing effect as control sera.ConclusionBoth Cani and Cyno were readily killed by human whole blood and serum in a complement-dependent way. Thus, it is not likely that serum bactericidal capacity is the key determinant for the clinical outcome in Cani or Cyno-infections.

Answer to October 2015 Photo Quiz

Answer: Streptococcus pyogenes. Figure 1 in the photo quiz demonstrates hypergranular, vacuolated neutrophils with intracellular cocci forming chains, resembling the genus Streptococcus. In light of the clinical features and blood film, a presumptive diagnosis of Streptococcus pyogenes toxic shock syndrome was made. Six hours following the blood film observation, growth of Gram-positive cocci in chains was detected in blood culture, which was subsequently confirmed to be S. pyogenes. As a result of the blood film findings, intravenous clindamycin was added; however, 19 h after presentation, the patient died of multiorgan failure. The published literature suggests that observation of bacteria on routine blood film is rare; case reports involving Capnocytophaga canimorsus (1), Citrobacter koseri (2), and Streptococcus pneumoniae (3) have been described, plus a case series of four neonates involving Staphylococcus aureus and coagulase-negative staphylococci (4). A larger case series, published in 1966, reported 26 bacteremic patients with bacteria observed within leukocytes on routine blood films (S. aureus, S. pneumoniae, Escherichia coli, Klebsiella pneumoniae, Neisseria meningitidis, Proteus species, viridans group Streptococcus, beta-hemolytic Streptococcus, and “paracolon bacillus”) (5). To the best of our knowledge, this is the first case of S. pyogenes observed in a routine blood film. The high fatality rate among these published cases (24 of 33 patients died) (1,–5) likely reflects the poor diagnostic sensitivity of blood films except in patients with very high bacterial loads observed during overwhelming septicemia, such as in our case. The use of buffy-coat smears may improve sensitivity (to a limit of detection of 104 CFU/ml) but is labor- and time-consuming, prohibiting its routine use (6). Bacteria observed during routine blood film examination should be discussed immediately with the treating physician, as the result may be used to predict a microbiological diagnosis and assist with choice of empirical antimicrobial and adjunctive therapy and portends a poor patient outcome. (See page 3109 in this issue [doi:10.1128/JCM.02824-13] for photo quiz case presentation.)

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.

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

Here, we present the draft genome sequences of three strains of Capnocytophaga canimorsus, each isolated from a different dog's mouth. Genome analysis provided evidence that these organisms may belong to a different nonpathogenic subtype of C. canimorsus.

Capnocytophaga canimorsus: an emerging cause of sepsis, meningitis, and post-splenectomy infection after dog bites.

Newly named in 1989, Capnocytophaga canimorsus is a bacterial pathogen found in the saliva of healthy dogs and cats, and is transmitted to humans principally by dog bites. This review compiled all laboratory-confirmed cases, animal sources, and virulence attributes to describe its epidemiology, clinical features, and pathogenesis. An estimated 484 patients with a median age of 55 years were reported, two-thirds of which were male. The case-fatality rate was about 26%. Its clinical presentations included severe sepsis and fatal septic shock, gangrene of the digits or extremities, high-grade bacteremia, meningitis, endocarditis, and eye infections. Predispositions were prior splenectomy in 59 patients and alcoholism in 58 patients. Dog bites before illness occurred in 60%; additionally, in 27%, there were scratches, licking, or other contact with dogs or cats. Patients with meningitis showed more advanced ages, higher male preponderance, lower mortality, and longer incubation periods after dog bites than patients with sepsis (p < 0.05). Patients with prior splenectomy presented more frequently with high-grade bacteremia than patients with intact spleens (p < 0.05). The organism possesses virulence attributes of catalase and sialidase production, gliding motility, cytotoxin production, and resistance to killing by serum complement due to its unique lipopolysaccharide. Penicillin is the drug of choice, but some practitioners prefer third-generation cephalosporins or beta-lactamase inhibitor combinations. C. canimorsus has emerged as a leading cause of sepsis, particularly post-splenectomy sepsis, and meningitis after dog bites.

Capnocytophaga canimorsus: Rare cause of Fatal Septic Shock. Case report

Introduction: Capnocytophaga canimorsus is a common bacterium in oral cavity of dogs and cats. Severe sepsis can develop following a dog or cat bite or scratch in susceptible individuals. Main risk factor for severe infections is immune deficit. Case presentation: We describe a case of eighty-one-years old woman with significant comorbidities admitted to the hospital with fever and non-specific symptoms following a fall at home. She was bitten by her dog 3 days prior to admission with a small wound on her hand. She had cardiac arrest with cardiopulmonary resuscitation eleven hours after admission and died ten hours later in ICU from refractory septic shock. PCR confirmed C. canimorsus as a causative organism. Conclusions: Severe infections caused by C. canimorsus can develop following a bite or a scratch by dog or cat. Fulminant sepsis with fatal outcome can rapidly evolve and the main risk factor among patient population is present immune deficiency. Clinicians should be aware of this fact and any person at risk presenting to the hospital with recent bite or scratch injury by dog or cat should be given adequate antibiotic treatment.

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.

New iron acquisition system in Bacteroidetes.

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.

Antibiotic treatment following a dog bite in an immunocompromized patient in order to prevent Capnocytophaga canimorsus infection: a case report

BackgroundCapnocytophaga canimorsus is a commensal bacterium found in the saliva of dogs and cats. Clinically significant infections in humans after a bite are often associated with the presence of immune deficiency. Early recognition and appropriate treatment are crucial for patient survival. In addition, patients with immune deficiency are susceptible to serious life-threatening nosocomial infections, which may also influence the prognosis of patients with Capnocytophaga canimorsus infection.Case presentationA 62-year-old Caucasian female was admitted with septic shock, acute respiratory distress syndrome, acute renal failure, metabolic acidosis and disseminated intravascular coagulation after suffering two small bites from her dog. She had received a splenectomy during childhood. The patient survived after early empiric treatment with antibiotics and intensive supportive care, including ventilation support, a high dose of noradrenalin, and continuous venovenous hemodialysis applied prior to the definitive diagnosis of Capnocytophaga canimorsus sepsis. She improved within 2 weeks but, despite all efforts to prevent nosocomial infection, her hospital course was complicated by Enterococcus species and Candida albicans pleuropneumonia that prolonged her stay in the intensive care unit, and necessitated ventilation support for 2 months.ConclusionSevere Capnocytophaga canimorsus sepsis may be complicated by life-threatening nosocomial infection in immunocompromized patients. The prophylactic application of antibiotics after a dog bite should be considered in high-risk individuals with immune deficiency in order to prevent both Capnocytophyga canimorsus sepsis and serious nosocomial complications.

Delayed Treatment of a Dog Bite Resulting in Devastating Capnocytophaga Sepsis in an Alcoholic Patient With Functional Asplenia

Capnocytophaga canimorsus is a slow-growing gram-negative rod found in the normal oral flora of 20% to 25% of dogs. It is usually transmitted to humans by dog bite or exposure, causing symptoms ranging from local wound irritation to sepsis, meningitis, and death. Asplenia, alcohol abuse, and steroid use are risk factors for invasive disease, but this infection also occurs in the normal host.

Hypertensive emergency and type 2 myocardial infarction resulting from pheochromocytoma and concurrent capnocytophaga canimorsus infection.

A diagnosis of myocardial infarction is made using a combination of clinical presentation, electrocardiogram and cardiac biomarkers. However, myocardial infarction can be caused by factors other than coronary artery plaque rupture and thrombosis. We describe an interesting case presenting with hypertensive emergency and type 2 myocardial infarction resulting from Pheochromocytoma associated with Capnocytophaga canimorsus infection from a dog bite. We also review current literature on the management of hypertensive emergency and Pheochromocytoma.

Renal Failure Due to Capnocytophaga Canimorsus Generalized Shwartzman Reaction from a Dog Bite (Df-2 Nephropathy)

We report a case of a 54-year-old man who developed gram-negative sepsis with multiorgan failure and generalized Shwartzman reaction after sustaining a dog bite. The causative organism was the fastidious gram-negative rod Capnocytophaga canimorsus, which is a commensal organism found in the oral flora of dogs and cats. More than 30 years after it was first described and despite technological advances in identification techniques, proper identification of this organism remains a challenge. In light of the increase in pet ownership as well as the increase in the different immunocompromised populations of the 21st century, we decided to revisit the case and reignite awareness of physicians caring for patients with recent dog or cat bites presenting with fulminant sepsis.

Distribution of Capnocytophaga canimorsus in dogs and cats with genetic characterization of isolates

Capnocytophaga canimorsus, which is often found in the oral cavities of dogs and cats, is sometimes transmitted to humans, causing severe infection. To elucidate the risk of C. canimorsus in humans and animals, this study was undertaken to characterize this bacterium epidemiologically and genetically. We examined the distribution of C. canimorsus in dogs and cats, and analyzed the correlation between the presence of bacteria and individual factors statistically. We also compared C. canimorsus isolates genetically using 16S rRNA gene sequence analysis and pulsed-field gel electrophoresis (PFGE). C. canimorsus was detected in 76 of 109 dogs (69.7%) and 57 of 104 cats (54.8%). A relation between C. canimorsus presence and some individual factors was detected both in dogs and cats, but the predictive factors of carrying the bacterium differed between dogs and cats. 16S rRNA gene sequences from C. canimorsus isolates in this study were combined with previously published sequences to assess their intra-specific phylogeny. Results show that C. canimorsus is classifiable into two main groups (I and II) with differing γ-glutamyl aminopeptidase activity. Strains from human patients belonged unevenly to group I, possibility suggesting that group I can be transmitted to humans and group II is indigenous only to the oral cavities of dogs and cats. PFGE genotyping showed high discriminatory power, and the dendrogram accorded with genetic segregation between isolates of group I and II. Sma I-digest PFGE developed for this study is useful as a molecular typing method for additional epidemiological and phylogenetic studies of C. canimorsus.

Capnocytophaga canimorsus sepsis following BMT in a patient with AML: possible association with functional asplenia

Capnocytophaga canimorsus sepsis following BMT in a patient with AML: possible association with functional asplenia

Capnocytophaga canimorsus infection in cats: ABCD guidelines on prevention and management.

Capnocytophaga canimorsus and Capnocytophaga cynodegmi are part of the normal bacterial flora of the oral cavity of dogs and cats. C canimorsus is more pathogenic and causes more severe infections in humans. Disease is less frequently seen after a cat bite, scratch or close contact than after dog contacts. Serious disease has been reported in people, especially associated with immunocompromise and alcoholism. Disease in cats is not well documented; two cases of respiratory infection have been associated with the presence of these bacteria. Diagnosis is based on culture in specific media, but these are slow growing bacteria; polymerase chain reaction and sequencing may aid in diagnosis and species identification. Penicillin or beta-lactams are the treatment options of choice. ZOONOTIC POTENTIAL: Based on incidence surveys, the zoonotic potential is low. The risk may be higher for immunocompromised persons, where dog and cat ownership must be discussed.

Sequence Analysis of the Cas2 Gene in &lt;i&gt;Riemerella anatipestifer&lt;/i&gt;

Objective: By analyzing the Cas2gene of Riemerella anatipestifer (RA), the aim was to acquire more useful information as a guide of further study. Methods: Using bioinformatics method, sequence analysis of RA Cas2 gene was performed with some databases and software, including homology search, sequence alignment, phylogenetic tree analysis, composition analysis and physicochemical property analysis. Results: Homology search suggested that Cas2 protein sequence of R. anatipestifer showed high similarity to those of strains within Bergeyella zoohelcum and Capnocytophaga canimorsus, consistent with the result of multiple sequence alignment and phylogenetic tree analysis. The rare codon analysis revealed that there was no rare codon string in RA Cas2 gene. Conclusion: Cas2 gene of R. anatipestifer was evolutionally closely related to those strains of Bergeyella zoohelcum and Capnocytophaga canimorsus, and can be over-expressed in E.coli without considering the impact of rare codons on translation.

‘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.

Capnocytophaga canimorsus ‐ A rare cause of severe sepsis and multi‐organ system failure

SummaryA 70‐year‐old man was admitted with rapidly progressive sepsis characterised by respiratory failure, acute renal injury, disseminated intravascular coagulopathy and endocarditis. He was treated with empirical antibiotics for a Gram‐negative anaerobe that was difficult to characterise. He had a protracted clinical course during which he developed ischaemic gangrene of his toes. After 5 weeks, the organism was identified at a reference laboratory as Capnocytophaga canimorsus (C. canimorsus), a normal inhabitant of the oral flora of dogs and cats. This infection had never been encountered amongst the mostly rural population served by the hospital. He recovered from his illness but was left with mobility issues. He had a significant alcohol history which was an important factor for developing severe sepsis from C. canimorsus.

Capnocytophaga canimorsus infection presenting with complete splenic infarction and thrombotic thrombocytopenic purpura: a case report

BackgroundAnimal bites are typically harmless, but in rare cases infections introduced by such bites can be fatal. Capnocytophaga canimorsus, found in the normal oral flora of dogs, has the potential to cause conditions ranging from minor cellulitis to fatal sepsis. The tendency of C. canimorsus infections to present with varied symptoms, the organism’s fastidious nature, and difficulty of culturing make this a challenging diagnosis. Rarely, bacterial cytotoxins such as those produced by C. canimorsus may act as causative agents of TTP, further complicating the diagnosis. Early recognition is crucial for survival, and the variability of presentation must be appreciated. We present the first known case of C. canimorsus infection resulting in TTP that initially presented as splenic infarction.Case presentation72-year-old Caucasian male presented with a four-day history of abdominal pain, nausea, vomiting, diarrhea, and intermittent confusion. On presentation, vital signs were stable and the patient was afebrile. Physical examination was unremarkable apart from petechiae on the inner left thigh, and extreme diffuse abdominal pain to palpation and percussion along with positive rebound tenderness. Initial investigations revealed leukocytosis with left shift and thrombocytopenia, but normal liver enzymes, cardiac enzymes, lipase, INR and PTT. Abdominal CT demonstrated a non-enhancing spleen and hemoperitoneum, suggesting complete splenic infarction. Although the patient remained afebrile, he continued deteriorating over the next two days with worsening thrombocytopenia. After becoming febrile, he developed microangiopathic hemolytic anemia and hemodynamic instability, and soon after was intubated due to hypoxic respiratory failure and decreased consciousness. Plasma exchange was initiated but subsequently stopped when positive blood cultures grew a gram-negative organism. The patient progressively improved following therapy with piperacillin-tazobactam, which was switched to imipenem, then meropenem when Capnocytophaga was identified.ConclusionsThere is a common misconception amongst practitioners that the presence of systemic infection excludes the possibility of TTP and vice versa. This case emphasizes that TTP may occur secondary to a systemic infection, thereby allowing the two processes to coexist. It is important to maintain a wide differential when considering the diagnosis of either TTP or C. canimorsus infection since delays in treatment may have fatal consequences.

The Lipopolysaccharide from Capnocytophaga canimorsus Reveals an Unexpected Role of the Core-Oligosaccharide in MD-2 Binding

Capnocytophaga canimorsus is a usual member of dog's mouths flora that causes rare but dramatic human infections after dog bites. We determined the structure of C. canimorsus lipid A. The main features are that it is penta-acylated and composed of a “hybrid backbone” lacking the 4′ phosphate and having a 1 phosphoethanolamine (P-Etn) at 2-amino-2-deoxy-d-glucose (GlcN). C. canimorsus LPS was 100 fold less endotoxic than Escherichia coli LPS. Surprisingly, C. canimorsus lipid A was 20,000 fold less endotoxic than the C. canimorsus lipid A-core. This represents the first example in which the core-oligosaccharide dramatically increases endotoxicity of a low endotoxic lipid A. The binding to human myeloid differentiation factor 2 (MD-2) was dramatically increased upon presence of the LPS core on the lipid A, explaining the difference in endotoxicity. Interaction of MD-2, cluster of differentiation antigen 14 (CD14) or LPS-binding protein (LBP) with the negative charge in the 3-deoxy-d-manno-oct-2-ulosonic acid (Kdo) of the core might be needed to form the MD-2 – lipid A complex in case the 4′ phosphate is not present.