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.
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.
- Rat-Bite Fever in the United States: An Analysis Using Multiple National Data Sources, 2001–2015 | Open Forum Infectious Diseases | Oxford Academic (oup.com)
- Elliott SP. Rat bite fever and Streptobacillus moniliformis. Clin Microbiol Rev. 2007;20(1):13-22.
- Dendle C, Woolley IJ, Korman TM. Rat-bite fever septic arthritis: illustrative case and literature review. Eur J Clin Microbiol Infect Dis. 2006;25(12):791-797.
- Gaastra W, Boot R, Ho HT, Lipman LJ. Rat bite fever. Vet Microbiol. 2009;133(3):211-228.
- Todd SR, Dahlgren FS, Traeger MS, et al. No visible dental staining in children treated with doxycycline for suspected Rocky Mountain Spotted Fever [PDF – 311KB]External. J Pediatr. 2015;166(5):1246-1251.
- Washburn RG. Rat-Bite Fever. In: Bennett, Dolin, Blaser, editors. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 8th ed. Philadelphia, Pennsylvania: Elsevier, Inc.; 2015. p. 2629-32.