The dangers of dog bites

The dog, valves' best friend: infective endocarditis due to Capnocytophaga canimorsus-a case report

Background

Capnocytophaga canimorsus is a Gram-negative bacillus found in the oral microbiota of dogs. It is a very rare cause of endocarditis. We hereby present a case of aortic valve endocarditis due to this microorganism.

Case Summary

A 39-year-old male was admitted to hospital with a history of intermittent fever and exertion dyspnoea and showed signs of heart failure on physical examination. Transthoracic and transoesophageal echocardiography confirmed the presence of a vegetation in the non-coronary cusp of the aortic valve, aortic root pseudoaneurysm, and left ventricle-to-right atrium fistula (Gerbode defect). The patient underwent aortic valve replacement with a biological prosthesis. The fistula was closed with a pericardial patch, although a dehiscence of the patch was detected in post-operative echocardiogram. The post-operative period was complicated by acute mediastinitis and cardiac tamponade secondary to a pericardial abscess, requiring emergent surgery. The patient made a good recovery afterwards and was discharged 2 weeks later.

Discussion

Capnocytophaga canimorsus is a very rare cause of endocarditis, although it can be very aggressive, with high degree of valve damage, necessity of surgery, and high mortality. It mainly affects young men with no previous structural heart disease. Due to its slow growth, blood cultures can be negative, so other microbiological techniques such as 16S RNA sequencing or matrix-assisted laser desorption/ionization and time-of-flight (MALDI-TOF) can be helpful for diagnosis.

Capnocytophaga tricuspid valve endocarditis: a case report and literature review

Capnocytophaga canimorsus is a Gram-negative zoonotic pathogen capable of causing serious infection following dog or cat bite. Infections often manifest as sepsis, fatal septic shock, gangrene, bacteraemia, meningitis and endocarditis. Here we report a case of C. canimorsus bacteraemia complicated by tricuspid valve infective endocarditis and septic pulmonary emboli.

Capnocytophaga canimorsus tricuspid valve endocarditis

Capnocytophaga canimorsus is an uncommon cause of infective endocarditis (IE) and mainly affects persons with compromised immune-systems who have been in contact with dogs. We describe a case of C. canimorsus tricuspid valve IE in a 70 year-old dog-owner where diagnosis and treatment were delayed. The reason for the delayed diagnosis in this case was likely due to that initial blood cultures were negative due to preceding antibiotic treatment, discrepancies between echocardiographic investigations, and a thymoma and colonic polyps which were thought to explain the symptoms. A multi-diciplinary approach in cases with suspected IE might help to avoid diagnostic delays.

Capnocytophaga canimorsus - a potent pathogen in immunocompetent humans - systematic review and retrospective observational study of case reports

Purpose: Severe and fatal Capnocytophaga canimorsus infection has been described in immunocompromised patients. Data of C. canimorsus infection in immunocompetent and risk factors of severe courses are missing. Our aims were to describe the epidemiology of C. canimorsus infection and to identify potential risk factors of sepsis and fatal outcome.Methods: Observational study and systematic review of all cases reported in immunocompetent subjects between 2002 and 2019.Results: A total of 128 cases of C. canimorsus infection in immunocompetent individuals were reported. Male gender comprised 74.2%, the median age was 58 years and 47.7% were admitted with sepsis. Case-fatality rate was 29.7% and especially high in septic patients (55.7%). Transmission by bite (OR = 2.37, 95% CI: 1.05-6.52) and incubation time ≤3 d (OR = 7.98; 95% CI: 2.33-27.34) were identified as risk factors of sepsis on admission, and early wound cleansing as protective (OR = 0.42; 95% CI: 0.14-0.96). Sepsis (OR = 23.67; 95% CI: 2.85-197.89) and septic shock (OR = 45.50; 95% CI: 3.08-676.55) were risk factors of fatal outcome, whereas early wound cleansing (OR = 0.05; 95% CI: 0.01-0.72), initial penicillin therapy with beta-lactamase inhibitors (OR = 0.48; 95% CI: 0.16-0.92) and surgical removal of infectious focus (OR = 0.38; 95% CI: 0.06-0.95) were protective factors.Conclusions: Immunocompetent patients with C. canimorsus infection frequently develop sepsis. A shorter incubation period in cases of sepsis might be related to higher infectious dose. Fatal outcome may be prevented by early wound cleansing, initial use of penicillins in combination with beta-lactamase inhibitors and surgical removal of an infectious focus.

Infective endocarditis caused by Capnocytophaga canimorsus; a case report

Background

Capnocytophaga canimorsus is a gram-negative bacterium and an oral commensal in dogs and cats, but occasionally causes serious infections in humans. Septicemia is one of the most fulminant forms, but diagnosis of C. canimorsus infection is often difficult mainly because of its very slow growth. C. canimorsus infective endocarditis (IE) is rare and is poorly understood. Since quite a few strains produce β-lactamase, antimicrobial susceptibility is pivotal information for adequate treatment. We herein report a case with C. canimorsus IE and the results of drug susceptibility test.

Case presentation

A 46-year-old man had a dog bite in his left hand 3 months previously. The patient was referred to our hospital for fever (body temperature > 38 °C), visual disturbance, and dyspnea. Echocardiography showed aortic valve regurgitation and vegetation on the leaflets. IE was diagnosed, and we initially administered cefazolin and gentamycin assuming frequently encountered microorganisms and the patient underwent aortic valve replacement. C. canimorsus was detected in the aortic valve lesion and blood cultures. It was also identified by 16S ribosome DNA sequencing. Ceftriaxone were started and continued because disk diffusion test revealed the isolate was negative for β-lactamase and this case had cerebral symptoms. The patient successfully completed antibiotic treatment following surgery.

Conclusions

We diagnosed C. canimorsus sepsis and IE by extended-period blood cultures and 16S ribosome DNA sequencing by polymerase chain reaction, and successfully identified its drug susceptibility.

Mycotic Aneurysm following a Dog Bite: The Value of the Clinical History and Molecular Diagnostics

A 63-year-old Caucasian taxi driver presented with a 3-week history of malaise, night sweats, 7 kg weight loss, generalized arthralgia, and persistent mid-lower abdominal pain. Blood inflammatory markers were raised, and a computed tomography scan demonstrated an irregular degeneration of the infrarenal aorta, with a differential diagnosis including aortic infection. An urgent type IV thoracoabdominal aneurysm repair was performed with a rifampicin-soaked aortic tube graft during an open procedure. No organisms were grown from multiple peripheral blood cultures or culture of the affected aorta. However, subsequent 16S ribosomal polymerase chain reaction analysis of the resected aorta identified Capnocytophaga canimorsus as the causative organism-a commensal that lives in the mouth of dogs and cats. The patient subsequently gave a history of multiple bites from his pet dog over recent months-the likely source of infection. He was treated with 8 weeks of intravenous antibiotics before switching to oral antibiotics for an additional 6 weeks.

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 a novel pathogen for joint arthroplasty

We report the case of a 59-year-old man with Waldenstrom's macroglobulinemia and active alcohol use who presented with bilateral knee pain 5 years after a bilateral staged TKA. Cultures of synovial fluid and periprosthetic tissue specimens from both knees yielded, after prolonged anaerobic incubation, a catalase- and oxidase-positive gram-negative bacillus, which was identified as Capnocytophaga canimorsus by 16S ribosomal RNA PCR analysis. C. canimorsus, an organism that is commonly found in dog and cat saliva, is a rare cause of various infections in immunocompromised and healthy individuals. However, a review of the medical literature indicates C. canimorsus has not been reported previously to cause infection after joint arthroplasty. The patient was immunocompromised by cytotoxic chemotherapy, corticosteroids, and alcohol use. The patient was managed successfully with bilateral two-stage exchange and 6 weeks of intravenous ertapenem therapy. Because of its fastidious and slow-growing characteristics, C. canimorsus may be an unrecognized cause of culture-negative joint arthroplasty infections, especially in cases when dog and cat exposure is evident in the clinical history.

Man's best friend? Infective endocarditis due to Capnocytophaga canimorsus

Infective endocarditis caused by zoonotic microorganisms is an uncommon clinical entity. A 55-year-old man was diagnosed with endocarditis due to Capnocytophaga canimorsus, a commensal bacterium contained in the saliva of dogs, that involved the aortic and tricuspid valves and was complicated by a para-aortic valve abscess and aorta-to-right atrial fistula. The patient was successfully treated with antibiotic therapy and surgical intervention. C canimorsus endocarditis should be considered in patients with culture-negative endocarditis, particularly in immunosuppressed, asplenic or alcoholic individuals who have recently suffered a dog bite or have had close contact with dogs.

A 42-year-old woman with septic shock: an unexpected source

BACKGROUND

Dog bites are the most common animal bite injuries occurring in the United States. Estimated infection rates range between 15% and 20%. Polymicrobial infections are most common. Capnocytophaga canimorsus (C. canimorsus) is a Gram-negative rod strongly associated with dog bites, and is known to cause life-threatening infection in humans.

OBJECTIVES

1) Outline epidemiology of dog bites in the United States; 2) Identify host factors associated with infection, and common pathogens; 3) Discuss microbiology of C. canimorsus; 4) Discuss common clinical manifestations of C. canimorsus infection; 5) Outline treatment options.

CASE REPORT

A 42-year-old woman with a remote history of Hodgkin's lymphoma (treated with irradiation) and thyroid carcinoma, both of which were in remission, presented to the Emergency Department with fever, abdominal pain, and diarrhea. She was found to be in septic shock. She was aggressively resuscitated and administered broad-spectrum antibiotics. Blood cultures grew C. canimorsus in 2/4 bottles. The patient recalled being bitten by the family dog 48 h before her initial presentation. She made an uneventful recovery. She was felt to be "functionally hyposplenic" due to her prior irradiation.

CONCLUSIONS

C. canimorsus is a rare pathogen strongly associated with dog bites. By eliciting a history of animal bite, clinicians may be able to alert the laboratory of suspected C. canimorsus infection. Prolonged laboratory incubation times may be necessary as the organism is fastidious. Predisposing conditions include, among others, prior splenectomy and alcoholism. The mortality rate from C. canimorsus sepsis is high, so treatment should be promptly initiated.

Meningitis caused by Capnocytophaga canimorsus: When to expect the unexpected

In this article we review the available data concerning meningitis caused by Capnocytophaga canimorsus. The clinical presentation of this rare condition is described with the emphasis on associated conditions and management issues. Two additional cases, illustrating the difficulties in recognizing this rare disease, are presented. Reviewing a total of 28 reported cases, a preceding bite-incident by a cat or dog, or close contact with these animals, was described in the majority of cases (89%). Patients had a median age of 58 years; splenectomy and alcohol abuse were noted in, respectively, 18% and 25% of patients. Only in one case immune suppressive drug use was reported. The diagnosis C. canimorsus meningitis should be considered in healthy and immunocompromised adults, especially after splenectomy, who present with symptoms attributable to meningitis and a history of recent exposure to dogs or cats. The possibility of this condition has implications for both the diagnostic work-up and the treatment of the patient.