A case of septic arthritis from rat-bite fever in Hawai'i

Infection associated with a rat bite has been known for centuries. Streptobacillus moniliformis is a zoonotic organism identified in the 20th century as the causative agent of most cases of rat bite fever outside of mainland Asia. There are no previously published cases of this pathogen in Hawai'i.

The authors present a case of Streptobacillus moniliformis causing septic polyarthritis in a 59-year-old Hawaiian man with a history of alcohol abuse and recurrent exposure to rodents in his apartment. Blood cultures from the patient were negative. The organism was isolated after three days only in thioglycolate broth from a synovial fluid culture. 16S rRNA sequencing of extracted and purified DNA confirmed the organism as Streptobacillus moniliformis.

Diagnosis of infection from Streptobacillus moniliformis is difficult to make because of the fastidious nature of the organism's growth, as well as inhibitors present in standard blood culture bottles. The use of bacterial 16S rRNA sequencing may aid in an earlier diagnosis for this disease. More research is required to identify host and virulence risk factors for involvement of specific organ systems.