Rat-bite fever
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Synonyms and keywords: Spirillum minus rat bite fever; spirochaeta morsus minus; spirochaeta muris; sokosho; sodoku.
Overview
Historical Perspective
Pathophysiology
Epidemiology and Demographics
Risk Factors
Causes
Normal commensal of rodent oropharynx also in ferrets, weasels, gerbils. Risk factors for acquisition: crowded urban dwellings (especially kids), lab workers. Transmission: bite/scratch from rat, mice, squirrels—also cats, dogs, pigs.
Differentiating Rat-bite fever from other Diseases
Differential diagnosis: rash on palms/soles consider RMSF, syphilis. Arthritis: disseminated gonorrhea, Lyme, brucella, endocarditis, rheumatological dz, and rheumatic fever.
Natural History, Complications and Prognosis
Diagnosis
History and Symptoms | Physical Examination | Laboratory Findings | Imaging Findings | Other Diagnostic Studies
Symptoms: incubation for 10-day fever, chills, HA, N/V, migratory arthralgias, leukocytosis. Days 2-4 days: nonpruritic maculopapular, petechial, or pustular rash (palms soles, extremities). May be purpuric/confluent. In 50% pts, polyarthritis (even septic arthritis) with or after onset rash (knees>ankles>elbows>hips). Most symptoms resolve within 2 weeks (even if no abx). Arthritis can persist for 2 years. Nonzoonotic transmission (orally): aka Haverhill Fever (similar manifestations as RBF). Rodent excrement contaminating water, milk, turkey meat. Milk contamination associated w/ epidemics.
Diagnosis: Gram or Giemsa stain blood, joint fluid, pus. Perform culture using TSA or blood agar. ELISA or agglutinins (sero-negative within 5 months-2 yrs); PCR.
Treatment
Medical Therapy | Prevention | Cost-effectiveness of Therapy | Future or Investigational Therapies
Antimicrobial therapy
- (1) Migratory arthropathy and arthritis (joints)
- Preferred regimen: Penicillin G IV uncomplicated disease—2.4-4.8 MU/day IV divided q6h. If better after 1 wk, switch to oral Amoxicillin OR Penicillin Vk complete 14 days.
- (2) Diarrhea, especially kids. Liver or spleen abscess (gastrointestinal)
- Preferred regimen: Penicillin G IV uncomplicated disease—2.4-4.8 MU/day IV divided q6h. If better after 1 wk, switch to oral Amoxicillin OR Penicillin Vk complete 14 days.
- (3) Undifferentiated fever
- Preferred regimen: Penicillin G IV uncomplicated disease—2.4-4.8 MU/day IV divided q6h. If better after 1 wk, switch to oral Amoxicillin OR Penicillin Vk complete 14 days.
- (4) Endocarditis, myocarditis, pericarditis (cardiac)
- Preferred regimen: Penicillin 20 mU/day IV divided q4h. Optimal duration recommendation for IE is 4 wks.
- Alternative regimen: Cephalosporins-Ceftriaxone OR Clindamycin OR Erythromycin OR Chloramphenicol AND Streptomycin.
- (5) Meningitis, brain abscess
- Preferred regimen: Penicillin 20 mU/day IV divided q4h. Optimal duration recommendation for IE is 4 wks.
- Alternative regimen: Cephalosporins-Ceftriaxone OR Clindamycin OR Erythromycin OR Chloramphenicol AND Streptomycin.
- (6) Anemia
- Preferred regimen: Penicillin G IV uncomplicated disease—2.4-4.8 MU/day IV divided q6h. If better after 1 wk, switch to oral Amoxicillin OR Penicillin Vk complete 14 days.
- (7) Pneumonia
- Preferred regimen: Penicillin G IV uncomplicated disease—2.4-4.8 MU/day IV divided q6h. If better after 1 wk, switch to oral Amoxicillin OR Penicillin Vk complete 14 days.
- (8) Amnionitis (pregnancy)
- Preferred regimen: Penicillin G IV uncomplicated disease—2.4-4.8 MU/day IV divided q6h. If better after 1 wk, switch to oral Amoxicillin OR Penicillin Vk complete 14 days.
- (9) Renal abscess
- Preferred regimen: Penicillin G IV uncomplicated disease—2.4-4.8 MU/day IV divided q6h. If better after 1 wk, switch to oral Amoxicillin OR Penicillin Vk complete 14 days.
- Prevention
- Eradication of rats.
- Pasteurize milk.
- Avoid contaminated water.
- Use gloves when handling rodents in lab (can also be carried by hamsters and other laboratory rodents).
- If bitten: oral PCN (2 gs) × 3 days may be beneficial. No clinical data available.
External Links
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