Introduction

Rat-bite fever consists of two similar febrile zoonoses caused by the treponeme Spirillum minus (Asia), or the bacteria Streptobacillus moniliformis (North America)

-Streptobacillus moniliformis is a pleomorphic Gram-negative rod

-Spirillum minus is a Gram-negative spirochete

-it is transmitted to humans by the bites from rats, mice, squirrels or gerbils 

-it can also result from exposure to rat feces or urine and ingestion of infected food or drink 

Symptoms & Signs 

-A flu-like illness: Fever, chills, headache, stiff neck, myalgia, nausea and vomiting 

-A rash: macular, morbilliform or petechial rash resembling measles 

-A desquamation: over the palms and soles 

-Arthritis: mostly involving large joints 

Diagnosis 

Gram stains of S. moniliformis:  Gram-negative filamentous branching chains, interspersed with bead-like swellings giving “necklace-shaped” colonies 

Dark field examination reveals Gram-negative spirochete Spirillum minus 

Treatment 

Treatment of choice: Penicillins; amoxicillin-clavulanic acid, Penicillin G

Alternative: Doxycycline