Fatal sepsis with peripheral necrosis due to Capnocytophagus canimorsus infection after dog bite: a case report

Introduction and Importance:

Capnocytophaga canimorsus is a commensal bacterium in dogs and cats’ saliva that can be transmitted to humans by licking, biting, or scratching. Although rare, an infection with C. canimorsus can have lethal consequences. Based on this case, the authors want to emphasize the importance of adequate wound care, close monitoring, and the use of prophylactic antibiotics after a dog bite or cat bite

Case Presentation:

The authors present the case of a healthy 52-year-old patient with severe sepsis, disseminated intravascular coagulation, multiorgan failure, and peripheral necrosis of the lower arms, lower legs, nose, and genitals due to an infection with C. canimorsus after a dog bite. The patient eventually died on the ICU.

Clinical Discussion:

Due to the severeness of the sepsis, the patient was admitted to the ICU for maximum supportive care. As a last resort to save his life, an amputation of his nose, genitals, lower arms, and a transtibial amputation was proposed. In good consultation with the family, the decision was made not to perform this very mutilating surgery. The therapy was stopped because the loss in quality of life was too severe to justify continuation. The patient died soon after stopping supportive therapy.

Conclusion:

Based on this case, the authors would like to point out that, although rare, an infection with C. canimorsus can have devastating consequences with a high mortality and morbidity rate. It is important to know about this complication and to be aware of the importance of adequate wound care, close monitoring, and the use of prophylactic antibiotics after a dog bite or cat bite.

Introduction and importance

Highlights

• Capnocytophaga canimorsus is a commensal bacterium in dogs and cats’ saliva that can be transmitted to humans by licking, biting, or scratching.

• The nature of the infection varies from cellulitis to meningitis, endocarditis to organ failure and fatal sepsis.

• A fatal outcome may be prevented by early wound cleansing, the initial use of penicillin in combination with beta-lactamase inhibitors, and surgical removal of an infectious focus.

Capnocytophaga canimorsus, formerly designated dysgonic fermenter 2, is a fastidious, gram-negative rod that was first described in 1976. It is a commensal bacterium of dogs and cats’ saliva, which can be transmitted to humans by licking, biting, or scratching1. The organism was given its current name based on its CO₂ requirement and usual mode of transmission. The nature of the infection varied from cellulitis to meningitis, endocarditis to organ failure, and fatal sepsis2. We present the case of a healthy 52-year-old patient with severe sepsis, disseminated intravascular coagulation (DIC), multiorgan failure, and peripheral necrosis of the lower arms, lower legs, nose, and genitals who eventually died. The case is presented following the SCARE 2020 Guideline3.

Case presentation

A 52-year-old male presented to the emergency department of a large regional hospital in the Netherlands. He was the owner of a grooming salon for dogs. Four days prior to admission, he was bitten by a dog in his index finger of the left hand. One day before admission, he started experiencing pain throughout his body, vomiting, diarrhea, coldness, shortness of breath, and a rash. He did not develop a fever. He has no medical history and takes no medication. He had a known allergy to bee stings. The patient smoked cigarettes and marihuana. On arrival of the ambulance, the patient was alert, tachypneic (47/min), pale, and cyanotic, with hematomas over his whole body. Blood pressure was 130/81 mm Hg, pulse 105/min, temperature 36.1°C. Oxygen saturation was not measurable due to insufficient peripheral circulation. Clemastine was administered on suspicion of anaphylaxis. On arrival at the emergency department, the blood pressure was 140/70 mm Hg, pulse 140/min, capillary refill time was greater than 5 se, temperature 34.7°C. The patient had generalized petechia. Laboratory results showed acidosis (pH: 7.28), hypocarbia (3.1 kPa), low bicarbonate (10.7 mmol/l), high lactate (8.3 mmol/l), renal failure (blood urea nitrogen 14.9 mmol/l, creatinine 379 µmol/l), C-reactive protein 169 mg/l, leukocytosis 15,6.10⁹/l, rhabdomyolysis (CK 4746 U/l), diffuse intravascular coagulation (activated partial thromboplastin time >100 s, international normalized ratio 2.9, thrombocytes 8.10⁹/l, D-dimer >35 000 µg/l) and later liver cell decay. The chest radiography showed no abnormalities. The patient received tetanus toxoid, amoxicillin/clavulanic acid associated with gentamycin intravenously and was admitted to the ICU with a systemic sepsis of unknown cause as a working diagnosis. Antibiotics were continued, and meropenem associated with clindamycin was added. There was no diuresis despite the liberal fluid infusion. Respiration gradually started failing, resulting in hypercarbia and increased oxygen dependency. The circulation further deteriorated, for which noradrenaline and, later, for a short period, adrenaline were administered. The patient received hydrocortisone in the context of therapy-resistant sepsis. Twelve hours after admission to the ICU, renal replacement therapy was started. Eighteen hours after admission, the patient was intubated and ventilated. On day 5, the blood cultures obtained at admission became positive with a strong suspicion for C. canimorsus. During his stay in the ICU, the patient developed necrosis of the hands, feet, genitals, face, and later the forearms and lower legs (Fig. 1 and 2). The senior vascular and plastic surgeons were consulted. The exact origin of the necrosis could be due to vasopressors, DIC, or a combination of those two. Despite maximal supportive therapy, the condition of the patient further deteriorated. On day 11, it was decided that multiple amputations, including all four extremities, the nose, and the genitals, seemed mandatory to improve the patient’s chance of survival.

Figure 1.

Extensive peripheral necrosis of the foot.

Figure 2.

Mummified, dry necrosis of all fingers.

After careful consultation with his relatives, we concluded that performing these amputations would have a detrimental and unjustifiable effect on the quality of life.

Therefore, supportive therapy was stopped, after which the patient died on day 11. Definitive conformation for C. canimorsus from the blood cultures was obtained on day 13.

The antibiogram showed it was sensitive to amoxicillin/clavulanic acid and clindamycin and resistant to metronidazole.

Clinical discussion

From the review of Pers et al. 4, the incidence of this condition in Denmark is estimated to be 0.5 case per 1 million people per year, although this might be an underestimation. The yearly incidence in the Netherlands was 0.67 cases per 1 million people per year and in the same range as the incidence reported in Denmark5.

Some activities predispose to a higher risk of infection, like being an animal keeper, veterinarian, breeder, pet owner, or dog groomer, as in this case. Predisposing medical conditions for a fulminant course are splenectomy, alcohol abuse, use of immunosuppressive medication, diabetes, hematopoietic stem cell transplantation, active hematologic or solid organ malignancy, and end-stage renal disease6. However, up to 40% of the cases occurred in previously healthy adults7.

In the study of Mader et al. 8, there were 128 cases described in immunocompetent patients between 2002 and 2019.

More than 60% of patients from whom C. canimorsus was found, initially had sepsis, a combination of septicemia and meningitis, or a fever of unknown origin. In a study by Janda et al. 9, DIC or septic shock developed in 13% of the patients during hospitalization. Butler’s comprehensive review, which was published in 2014, included all 484 cases of C. canimorsus infections with a lethality rate of 26%. There were 222 cases of sepsis with positive blood cultures, 30 cases of septic shock, and 18 cases of digital or limb gangrene in the period. Sepsis was the most common presentation. The second most common presentation was meningitis in 32 cases. Other, less frequent presentations were endocarditis or mycotic aneurysms in 12 cases. Although almost all cases were caused by animal bites, severe wound infections were only present in five cases10. The diagnosis is most of the time initially based on a high index of suspicion and confirmed usually on the bacterial culture of blood in 88% of the cases9. The treatment of sepsis caused by C. canimorsus is not different from the treatment of sepsis of other origins. Currently, there is no standard antimicrobial susceptibility guide for Capnocytophaga species. The rate of β-lactamase production was almost 30% in a study by Chesdachai and colleagues and it was solely found in the human-oral-associated Capnocytophaga group. Owing to the higher prevalence of β-lactamase production among the human-oral Capnocytophaga group, stable agents against β-lactamases should be utilized for definitive therapy. This includes a combination of β-lactam/β-lactamase inhibitors, advanced-generation cephalosporins (third or fourth generation), or carbapenems6.

This patient was a healthy adult man. The patient was presented to the AD and admitted to the ICU 4 days after a dog bite. He did not receive any antibiotics prior to his hospital presentation. At this moment, there is still no European consensus or guideline on the systematic use of antibiotics after dog bites. A group of surgeons working in the Netherlands (the Dutch Society for Surgery NVVH) published a guideline regarding the treatment of wounds caused by dog bites. The recommendation for dog bites of the hand, like in this specific case, was to administer amoxicillin/clavulanic acid 500/125 mg three times a day for 5 consecutive days11.

A fatal outcome may be prevented by early wound cleansing, the initial use of penicillin in combination with beta-lactamase inhibitors, and surgical removal of the infectious focus8.

However, C. canimorsus infection can still develop despite prophylactic antibiotics12.

Conclusion

Infections with C. canimorsus are mostly due to dog or cat bites. Systemic infections with sepsis have a high mortality and morbidity rate. Based on this case, we want to emphasize the importance of adequate wound care, close monitoring, and the use of prophylactic antibiotics after a dog bite or cat bite.

Ethical approval

The authors declare that ethical approval was not required for this study as it is a descriptive, nonexperimental case report.

Consent

Written informed consent was obtained from the family of the patient for the publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Sources of funding

No funding.

Author contribution

All authors wrote an equal contribution.

Conflicts of interest disclosure

No conflicts of interest.

Research registration unique identifying number (UIN)

1. Name of the registry: NA.

2. Unique identifying number or registration ID: NA.

3. Hyperlink to your specific registration (must be publicly accessible and will be checked): Not necessary as stated on the website ‘we do not register case reports that are not first-in-man or animal studies’.

Guarantor

Maxim Peeters, Surgery Resident, Zuyderland MC, Heerlen, The Netherlands. max.peeters@zuyderland.nl

Provenance and peer review

Not commissioned, externally peer-reviewed