What is the category and management of Cat Scratch Disease (CSD), also known as Bartonellosis (Bartonella infection)?

From the Guidelines

Cat scratches should be managed with prompt cleaning and observation for signs of infection, and azithromycin is recommended for cat scratch disease treatment, with a dosing protocol of 500 mg on day 1 followed by 250 mg for 4 additional days for patients over 45 kg, and 10 mg/kg on day 1 and 5 mg/kg for 4 more days for patients under 45 kg, as supported by the Infectious Diseases Society of America guidelines 1.

Key Considerations

• Most cat scratches heal without complications, but approximately 5-10% can develop cat scratch disease (CSD), caused by Bartonella henselae bacteria.
• Watch for signs of infection including increasing redness, swelling, warmth, pain, or pus formation at the scratch site, and systemic symptoms of CSD include fever, fatigue, headache, and swollen lymph nodes near the scratch.
• For mild infections, oral antibiotics like azithromycin are typically effective, and the recommended dose is based on patient weight, with 500 mg on day 1, then 250 mg daily for 4 more days for patients over 45 kg, and 10 mg/kg on day 1, then 5 mg/kg on days 2-5 for patients under 45 kg 1.

Prevention and Special Considerations

• Prevention includes avoiding rough play with cats, washing hands after handling cats, and keeping cats free of fleas which can transmit the bacteria.
• Children should be taught proper handling of cats to minimize scratches, as they are more susceptible to CSD.
• Immunocompromised patients require more aggressive treatment and should seek medical attention immediately after a cat scratch.

Diagnosis and Treatment

• Diagnosis of Bartonella infections may be difficult because the organism is fastidious and difficult to grow in culture, but serological testing and PCR can support the diagnosis 1.
• A positive Warthin-Starry silver stain of infected lymph node tissue is useful to confirm the diagnosis, although it cannot differentiate species of Bartonella 1.

From the FDA Drug Label

To reduce the development of drug-resistant bacteria and maintain effectiveness of doxycycline hyclate and other antibacterial drugs, doxycycline hyclate should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria Doxycycline is indicated for the treatment of the following infections:

• Rocky Mountain spotted fever, typhus fever and the typhus group, Q fever, rickettsialpox, and tick fevers caused by Rickettsiae.
• Respiratory tract infections caused by Mycoplasma pneumoniae.
• Lymphogranuloma venereum caused by Chlamydia trachomatis.
• Psittacosis (ornithosis) caused by Chlamydia psittaci.
• Trachoma caused by Chlamydia trachomatis, although the infectious agent is not always eliminated, as judged by immunofluorescence.
• Inclusion conjunctivitis caused by Chlamydia trachomatis.
• Uncomplicated urethral, endocervical, or rectal infections in adults caused by Chlamydia trachomatis.
• Nongonococcal urethritis caused by Ureaplasma urealyticum.
• Relapsing fever due to Borrelia recurrentis.
• Doxycycline is also indicated for the treatment of infections caused by the following gram-negative microorganisms:
  • Chancroid caused by Haemophilus ducreyi.
  • Plague due to Yersinia pestis (formerly Pasteurella pestis).
  • Tularemia due to Francisella tularensis (formerly Pasteurella tularensis).
  • Cholera caused by Vibrio cholerae (formerly Vibrio comma).
  • Campylobacter fetus infections caused by Campylobacter fetus (formerly Vibrio fetus).
  • Brucellosis due to Brucella species (in conjunction with streptomycin).
  • Bartonellosis due to Bartonella bacilliformis.
  • Granuloma inguinale caused by Calymmatobacterium granulomatis. The cat scratch category is likely referring to cat scratch disease, which is caused by Bartonella henselae. Although the provided drug labels do not explicitly mention cat scratch disease, they do mention Bartonellosis due to Bartonella bacilliformis as an indication for doxycycline treatment 2. However, it is essential to note that the causative agent of cat scratch disease is Bartonella henselae, not Bartonella bacilliformis. Management of cat scratch disease typically involves antibiotic treatment, and doxycycline is sometimes used in the treatment of bartonellosis. However, without direct information from the drug labels regarding cat scratch disease, it is crucial to consult other reliable sources for guidance on the management of this condition.

From the Research

Cat Scratch Disease Category

• Cat scratch disease is an infection caused by Bartonella henselae, a fastidious gram-negative bacillus acquired from exposure to an infected kitten or cat 3.
• The most common manifestation of human disease is lymphadenitis, with atypical forms of infection including Parinaud oculoglandular syndrome, stellate neuroretinitis, and others 3.

Management of Cat Scratch Disease

• The majority of cases of cat-scratch disease occurring in normal hosts do not require anti-infective therapy for resolution of infection 3, 4.
• Antibiotic therapy can be considered for patients with severe cat scratch disease, with efficacious antibiotics including rifampin, ciprofloxacin, gentamicin, and azithromycin 3, 5, 6.
• Conservative, symptomatic treatment is recommended for the majority of patients with mild or moderate CSD 5.
• Flea control is crucial to minimize transmission risk, and patients should be counseled to speak with their pets' veterinarian about testing and treating infected animals 7.

Treatment Options

• Azithromycin has been shown to speed recovery in some cases of cat-scratch disease 4.
• Gentamicin sulfate has been effective in shortening the course of cat-scratch disease in some patients 6.
• Doxycycline and a quinolone may be used to treat infected animals 7.

Prevention and Transmission

• Cat fleas are responsible for horizontal transmission of the disease from cat to cat, and on occasion, arthropod vectors (fleas or ticks) may transmit the disease to humans 4.
• Even well-appearing animals can transmit the bacteria, months to years after their initial infection 7.
• Symptoms, clinical and laboratory findings will depend on bacterial load and strain virulence, as well as the physiological/immunological status of the host 7.