Capnocytophaga infections
Capnocytophaga infections are caused by the Capnocytophaga bacterium, which is a slender, gram-negative rod that thrives in carbon-dioxide-enriched environments. This opportunistic pathogen includes species that are part of the normal oral flora in both humans and pets, particularly dogs and cats. Infections can occur through bites or oral contact, particularly in individuals who are immunocompromised or have other risk factors, such as poor dental hygiene, chronic illnesses, or advanced age. Symptoms of Capnocytophaga infections vary widely and can range from fever and cellulitis to more severe conditions like sepsis and renal failure, depending on the infection site.
Diagnosis typically involves isolating the bacterium from clinical specimens, with advanced methods like PCR and gene sequencing used if initial cultures are inconclusive. Treatment often requires prompt empiric antibiotic therapy, with specific drugs chosen based on the species involved and potential resistance patterns. Preventive measures include maintaining good dental hygiene, managing underlying health issues, and practicing careful hygiene after contact with animals. Awareness of these infections and their risk factors can aid in prevention and early intervention.
Capnocytophaga infections
- ANATOMY OR SYSTEM AFFECTED: All
Definition
Capnocytophaga infections are caused by the bacterium Capnocytophaga, a slender, fusiform-shaped, gram-negative rod that requires a carbon-dioxide-enriched environment to grow. Capnocytophaga is an opportunistic pathogen.
There are nine species of Capnocytophaga: canimorsus, canis, and cynodegmi are part of the oropharyngeal flora of dogs and cats; ochracea, sputigena, gingivalis, granulosa, leadbetteri, and haemolytica are part of the oropharyngeal flora in humans.
Causes
Capnocytophaga possesses virulence factors that degrade tissue, inhibit macrophage activity, and increase inflammation. Capnocytophaga species can enter the bloodstream in the immunocompromised person through ulcers in the mouth, leading to sepsis and endocarditis.
An infection caused by a human, dog, or cat Capnocytophaga bite can develop into cellulitis. Capnocytophaga species has been isolated from dental plaque and is a cause of juvenile gingivitis and periodontal disease.
Risk Factors
The following factors increase the risk of developing a Capnocytophaga infection: poor dental hygiene, leukemia, multiple myeloma, cirrhosis of the liver caused by alcoholism, splenectomy, use of corticosteroids, and chemotherapy. Another risk factor is contact with dogs and cats. Additional risk factors include being over forty years old or having a chronic illness like diabetes.
Symptoms
Symptoms are not specific to Capnocytophaga infection and will vary depending on the site of infection. The symptoms range from fever, cellulitis, and sinusitis to abscesses, skin lesions, and renal failure.
Screening and Diagnosis
A physician will consider Capnocytophaga infection in immunocompromised persons and in persons who have been bitten by a dog, a cat, or another person. Diagnosis involves isolating one of the Capnocytophaga species from clinical specimens. The type of specimens submitted for culture depends on the site of the infection and include blood, an aspirate from an infected wound, sputum if pneumonia is present, and spinal fluid if meningitis is suspected. If traditional culture methods prove unsuccessful in identifying Capnocytophaga, Polymerase Chain Reaction (PCR) tests and gene sequencing may be necessary to obtain a diagnosis. Capnocytophaga species are all slow-growing; they require a minimum of forty-eight hours of incubation to develop their characteristic morphology.
Treatment and Therapy
In serious infections, one should start empiric therapy based on the clinical findings and the patient’s history. Capnocytophaga species are susceptible to the antibiotics erythromycin, clindamycin, tetracycline, and imipenem/cilastatin. Penicillin-resistant strains are being isolated, so testing for beta-lactamase using the nitrocefin test can help direct therapy. For beta-lactamase-positive strains, the use of amoxicillin/clavulanate is effective. The fluoroquinolones (ciprofloxacin) have also shown resistance. When choosing an antibiotic, several factors including patient demographics, specific species, and resistance factors need to be considered. Abscesses need to be drained, and the patient needs treatment with antibiotics.
Prevention and Outcomes
Preventing Capnocytophaga infections requires treatment of any underlying diseases, maintaining good dental health, administering prophylactic antibiotics before dental work for persons at risk, and thorough handwashing after contact with cats and dogs.
Bibliography
Chesdachai, Supavit, et al. "The Characteristics of Capnocytophaga Infection: 10 Years of Experience." Open Forum Infectious Diseases, vol. 8, no. 7, 2021, doi.org/10.1093/ofid/ofab175. Accessed 4 Nov. 2024.
"Clinical Overview of Capnocytophaga." CDC, 9 May 2024, www.cdc.gov/capnocytophaga/hcp/clinical-overview/index.html. Accessed 4 Nov. 2024.
Engelkirk, Paul G., and Janet Duben-Engelkirk. Laboratory Diagnosis of Infectious Diseases: Essentials of Diagnostic Microbiology. Lippincott Williams & Wilkins 2008.
Gomez-Garces, Jose-Luis, et al. "Bacteremia by Multidrug-Resistant Capnocytophaga sputigena." Journal of Clinical Microbiology, vol. 32, no. 4, Apr. 1994, pp. 1067-1069.
Ritzert, Chantelle, and Dany Paul Baby. "What To Know About Capnocytophaga." WebMD, 18 Oct. 2022, www.webmd.com/a-to-z-guides/what-to-know-capnocytophaga. Accessed 4 Nov. 2024.
Winn, Washington C., Jr., et al. Koneman’s Color Atlas and Textbook of Diagnostic Microbiology. 6th ed., Lippincott Williams & Wilkins, 2006.