By Jonas Wilson, Ing. Med.
Transmitted by the bite or scratch of a cat and occasionally by fleas or ticks, cat scratch disease (CSD) is a common bacterial infection. It is caused by Bartonella henselae and has a high prevalence in humid and warm climates.
Children and adolescents are more likely than adults to have a higher risk of exposure. People who become infected present within 1 – 2 weeks with mild infection at the site of inoculation, which is followed by proximal lymphadenopathy and possible systemic symptoms such as fever, anorexia, and malaise.
Diagnosis is made on the grounds of clinical history and symptoms in addition to serology (best initial test) and is supported by other investigations, such as hematology and lymph node biopsy, if necessary.
CSD is usually a self-limiting disease and as such generally only requires symptomatic and conservative treatment in patients with a mild or moderate presentation.
Analgesics and antipyretics may be administered as necessary and applying localized heat to the affected lymph nodes may also be done.
Patients with more severe presentations of CSD and atypical symptoms such as encephalopathy and neuroretinitis may be treated with corticosteroids.
Although the use of corticosteroids is a bit controversial, they have shown promising results when used in combination with the appropriate antibiotics.
In the majority of cases, antibiotic therapy is not indicated for CSD. However, they may be a vital part of therapy for patients that present with severe clinical complications from CSD.
In particular, immunocompromised patients should be treated with antimicrobial therapy, because they are very susceptible to bacteremia and associated systemic consequences.
Studies have shown that the antibiotics are most effective in severe cases of CSD are rifampicin, ciprofloxacin, gentamicin, and trimethoprim / sulfamethoxazole.
Severe cases of CSD were considered as those with persistently high fever as well as systemic signs, such as headache, fatigue, and blindness.
The four antibiotics were regarded as highly effective, because they lead to a reduction and/or resolution of the CSD-associated lymphadenopathy, reduction in erythrocyte sedimentation rate (ESR), and constitutional and inflammatory symptoms all within 3 – 10 days.
Current literature suggests antimicrobial therapy for 10–14 days although those who have existing immunocompromised systems may require longer courses of treatment.
Lymph Node Aspiration
Patients who present with suppuration of the lymph node may require aspiration. This procedure can have both therapeutic and diagnostic value. Moreover, repeating the procedure may be indicated if there is a recurrence of pus in the node. Cases where the diagnosis is uncertain and/or aspiration fails to relieve pain associated with the lymphadenopathy may require surgical excision of the node.
Follow-up and Prevention
Immunocompromised patients and/or those with severe atypical CSD symptoms may require hospitalization. Those who are immunocompetent with any signs of systemic disease may be followed up in an outpatient clinic with a scheduled appointment several weeks later to ensure that resolution of CSD lymphadenopathy has been achieved.
However, a patient should seek medical attention if neurological complications occur or if the lymphadenitis progressively enlarges.
The latter could be a sign of something more sinister, such as a neoplasm. To prevent CSD, parents should instruct children to always exercise caution to avoid scratches and bites.
Proper pet hygiene is also recommended to prevent flea and tick infestations. Treating cats with antibiotics may also be done, but has not been shown to reduce the risk of transmission to humans.
Reviewed by Susha Cheriyedath, MSc
Last Updated: Sep 26, 2016