Clinical Care of Rat-bite Fever

Key points

  • RBF should be suspected in patients with fever, nausea, vomiting, joint pain, and rash who have been around rodents
  • Without early diagnosis and appropriate treatment, RBF can cause severe infections and death.
Medicine bottles and colorful pills

Medication options

There is limited research on the effectiveness of specific antibiotics to treat RBF. However, several antibiotics prove effective against S. moniliformis. These include:

  • penicillins
  • cephalosporins
  • carbapenems
  • aztreonam
  • clindamycin
  • erythromycin
  • nitrofurantoin
  • bacitracin
  • doxycycline
  • tetracycline
  • teicoplanin
  • vancomycin

Intravenous (IV) penicillin G given for 7 or more days, then oral penicillin, is usually recommended for the treatment of RBF. Patients can develop reactions to penicillin treatment, but usually improve quickly once they're on antibiotics.

Treatment precautions

In patients allergic to penicillin, doxycycline or streptomycin are alternative choices.

RBF can present similarly to other febrile rash illnesses, such as Rocky Mountain Spotted Fever (RMSF). If RBF and RMSF are both in differential diagnosis, doxycycline should be considered as first-line treatment. This is because there is a need for rapid treatment and limited diagnostics for both diseases. In patients under the age of eight, dental staining is not a risk when using doxycycline for less than 14 days.

Endocarditis is a rare complication and may require combination therapy with both intravenous penicillin G and streptomycin or gentamicin. Note, this is based on older studies and no recent studies have been done to evaluate the effectiveness of combination treatment.