From the Guidelines
Cat scratch fever manifesting as a swollen arm should be treated with azithromycin 500mg on day 1, followed by 250mg once daily for 4 additional days, as it has been shown to reduce lymph node size by 80% at 30 days in patients with cat scratch disease 1. The infection is caused by the bacteria Bartonella henselae, which is typically transmitted through cat scratches or bites, and usually causes swollen lymph nodes near the injury site. Some key points to consider when treating cat scratch fever include:
- The disease course varies, but lymphadenopathy generally resolves within 1–6 months, even without treatment 1.
- In about 10% of cases, the nodes suppurate, and extranodal disease develops in ≤2% of cases 1.
- Diagnosis of Bartonella infections may be difficult because the organism is fastidious and difficult to grow in culture, but serological testing, PCR, and a positive Warthin-Starry silver stain of infected lymph node tissue can support the diagnosis 1.
- While waiting for medical care, applying warm compresses to the swollen area and taking over-the-counter pain relievers like acetaminophen or ibuprofen as needed can help manage symptoms.
- It is essential to seek immediate medical attention if you develop fever over 102°F, severe pain, spreading redness, or the swelling doesn't improve after 48 hours of antibiotics, as these may indicate a worsening infection requiring more aggressive treatment.
From the Research
Cat Scratch Fever Manifesting as Swollen Arm
- Cat scratch disease (CSD) is a common infection that usually presents as tender lymphadenopathy, and it should be included in the differential diagnosis of fever of unknown origin and any lymphadenopathy syndrome 2.
- The causative microorganism, B. henselae, is difficult to culture, and diagnosis is most often arrived at by obtaining a history of exposure to cats and a serologic test with high titers of immunoglobulin G antibody to B. henselae 2.
- Most cases of cat-scratch disease are self-limited and do not require antibiotic treatment, but if an antibiotic is chosen, azithromycin has been shown in one small study to speed recovery 2.
Treatment Options
- Severe or persistent cases of CSD respond well to several antibiotics, including erythromycin and doxycycline 3.
- Gentamicin sulfate has been used to treat CSD in some cases, with patients responding within 48 hours to intravenous gentamicin 4.
- Azithromycin antibiotic therapy has been used to treat CSD in patients with advanced immunosuppression, with resolution of lymphadenopathy 5.
Clinical Considerations
- CSD should be included in the differential diagnosis of serious neurologic disease, particularly when regional lymphadenopathy develops suddenly in a previously healthy patient who owns a cat 3.
- Treatment of uncomplicated central nervous system disease is generally supportive, with antibiotic therapy reserved for patients with atypical or severe involvement 3.
- Clinicians' experience and knowledge of CSD vary, with some choosing antibiotic treatment over recommended treatment options of analgesics and monitoring 6.