Community-acquired Capnocytophaga canimorsus meningitis in adults: report of one case with a subacute course and deafness, and literature review

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.

A case of Capnocytophaga canimorsus meningitis and bacteraemia

Capnocytophaga canimorsus is a commonly detectable commensal in the oral flora of dogs and cats, found in 25.5% and 15%, respectively, by culture and 70% and 55%, respectively, by molecular methods [1]. Formerly known as dysgonic fermenter 2 (DF-2), it was first reported in 1976 as a Gram-negative bacillus causing septicaemia and meningitis following dog bites [2]. It causes a spectrum of clinical syndromes from wound infections to bacteraemia and meningitis, especially in those with hyposplenism and alcoholism. We report a case of C. canimorsus meningitis and bacteraemia, and give a review of the relevant literature.

Capnocytophaga canimorsus-associated sepsis presenting as acute abdomen: do we need to think outside the box?

Capnocytophaga canimorsus is a commensal bacterium commonly found in the oral cavity of dogs and cats. Although this organism rarely causes infection, prompt diagnosis is crucial for survival of these patients. Several unusual clinical presentations of this infection have been reported in the published medical literature. The present report represents the first case of C. canimorsus-related sepsis presenting with symptoms of acute abdomen in a patient with no known history of immunodeficiency. Prompt aggressive care and appropriate antibiotic therapy resulted in a successful clinical outcome with no long-term morbidity. This paper illustrates that clinicians should include this infectious aetiology among the differentials of patients presenting with acute abdomen, regardless of their immune status. Additionally, this paper outlines our current understanding of the epidemiology of and risk factors for C. canimorsus-associated sepsis, the pathophysiology of this disorder, and currently available approaches to diagnosis and management.

Capnocytophaga canimorsus Meningitis: Diagnosis Using Polymerase Chain Reaction Testing and Systematic Review of the Literature

INTRODUCTION

Capnocytophaga canimorsus infections are associated with dog bites, especially in asplenic or immunocompromised patients, and typically manifest as sepsis and/or bacteremia. Meningitis has been rarely described, and its diagnosis may be delayed due to poor or slow growth using traditional culture techniques. We provide our experience using polymerase chain reaction (PCR) to establish the diagnosis and perform a comprehensive review of C. canimorsus meningitis cases to provide summary data on the clinical manifestations, diagnosis, and outcomes of this unusual infection.

METHODS

A systematic review of the peer-reviewed English literature (PubMed, Embase, Ovid Medline) from January 1966 to March 2018 was conducted to identify cases of C. canimorsus meningitis. Data collected included demographics, risk factors, cerebrospinal fluid (CSF) findings, PCR results, treatments, and outcomes. Descriptive statistics are presented as numbers (percentages) and medians (ranges).

RESULTS

A total of 37 patients were reviewed with a median age of 63 years (12 days to 83 years) with a male predominance (76%). A relatively low proportion had an immunocompromised state (16% splenectomy and 5% steroid use); the most common risk factor was alcoholism (19%). Fifty-nine percent reported a dog bite (all within ≤ 14 days prior to presentation), while 22% reported a non-bite dog exposure, 3% reported cat bite, and 3% reported both dog and cat exposures; 11% reported no animal contact. CSF parameters included a median white count of 1024 cells/mm3, 81% had neutrophilic predominance, median protein of 190 mg/dl, and median glucose CSF/serum ratio 0.23. In 54% of cases, blood cultures were positive for C. canimorsus (median, 4 days) and 70% had positive CSF cultures (median, 5 days). PCR established the diagnosis in eight (22%) cases. Antibiotic therapy was given for a median of 15 days (range, 7 to 42 days). Prognosis was overall favorable with only one (3%) death reported and adverse neurologic and/or physical sequelae in 19% of the survivors.

CONCLUSION

C. canimorsus meningitis is a rare but increasingly important clinical entity occurring in patients of all ages, typically after dog exposure. While classically considered an infection among immunocompromised patients, most cases have occurred in previously healthy, immunocompetent persons. Diagnosis may be rapidly established by PCR, and this test should be considered in culture-negative cases with associated exposures. Outcome was generally favorable after a median antibiotic duration of 15 days.

Capnocytophaga canimorsus Meningitis: Three Cases and a Review of the Literature

Bacterial meningitis is a disease with a high morbidity and mortality. It may be caused by the zoonotic pathogen Capnocytophaga canimorsus, which is part of the commensal oral flora in dogs and cats. We report three cases of C. canimorsus meningitis in a nationwide cohort study of bacterial meningitis patients and performed a review of the literature. Three episodes of C. canimorsus meningitis were identified in three patients included in a nationwide cohort study from 2006 through 2014. The calculated annual incidence was 0.03 per million adults. When combined with the literature, 33 patients were identified of which 28 were male (85%). The median age was 63 years, and 13 (42%) were immunocompromised, which consisted of alcoholism in 7 (21%). Animal contact could be established in 29 of 30 patients (93%) and consisted of dog bites in 22 of 29 (76%). One patient died (3%) and 8 had neurological sequelae upon discharge (25%), most often hearing loss (n = 6, 19%). Capnocytophaga canimorsus meningitis is associated with dog bites. Although mortality is relatively low, survivors often have neurological sequelae.

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

PURPOSE

Capnocytophaga 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.

METHODS

Whole 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.

RESULTS

Both 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.

CONCLUSION

Both 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.

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.

'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.

Three cases of Capnocytophaga canimorsus meningitis seen at a regional hospital in one year

Three cases of meningitis caused by the fastidious Gram-negative rod Capnocytophaga canimorsus have been observed at a regional hospital in 1 y. The difficulties connected with the correct diagnosis by classical culturing methods in contrast to molecular methods, as well as possible reasons for the accumulation of cases, are discussed.

Animal bite-associated infections: microbiology and treatment

Human and animal bites may lead to serious infection. The organisms involved tend to originate from the oral cavity of the offending biter, as well as the environment where the injury occurred. A variety of aerobic as well as anaerobic organisms have been isolated from bite wounds, with infection ranging from localized cellulitis to systemic dissemination, leading to severe disease ranging from abscess to bone and joint infection, to endocarditis and brain abscess. Immediate wound management, including recognition of the most commonly associated infectious pathogens, and judicious use of empiric antibiotics are crucial in providing the best care after a bite. Here, we discuss the common animal bite associated infections, and provide the most up to date information regarding their management.

Capnocytophaga canimorsus infections in The Netherlands: a nationwide survey

A retrospective nationwide survey on the occurrence of Capnocytophaga canimorsus and Capnocytopaga cynodegmi infections in The Netherlands over 3 years showed 32 cases, of which 31 were caused by C. canimorsus and one by an unspecified oxidase-positive Capnocytophaga strain. Twenty-eight patients had been diagnosed by blood culture, one by culture from both blood and cerebrospinal fluid (CSF), one by culture from a conjunctival swab, and two patients by 16S rRNA gene amplification by PCR directly from a blood or CSF specimen. The incidence rate was 0.67 infections per million population. Bacteraemia was found in 94% of the cases. The age range of patients was 38-80 years; 72% of them were male. Among 26 patients from whom clinical data were available, splenectomy was not reported, but alcoholism was reported in five. Nine patients (35%) had been admitted to the intensive-care unit, and three patients (13%) died. The mortality rate was much lower than observed in previous studies.

[Fatal sepsis due to capnocytophaga canimorsus after dog bite]

A 56-year-old man was bitten by a dog. 8 days later he was admitted to a hospital because of severe deterioration of his clinical situation. He developed the clinical picture of fulminant sepsis. In spite of aggressive intensive care therapy the patient died 24 hours later. Capnocytophaga canimorsus was identified from initial blood cultures. This gram-negative rod is part of the normal oral flora of dogs and cats. It can be spread to humans by bites, licking or scratches and causes severe infections, especially in persons with special risk factors (splenectomy, alcoholism). The mortality rate in the published cases is 25-30%.