Infectious Disease Compendium

Streptobacillus moniliformis


Highly pleomorphic, filamentous, gram negative rod.

S. moniliformis is the classic organism. There is also S. hongkongensis isolated from 2 human patients, S. felis from the lung of a cat, S. ratti from black rats, and S. notomytis from a spinifex hopping mouse and a human case in Japan from rats (PubMed).


Rat bites (a cause of rat bite fever along with Spirillum minus). Also known as Haverhill fever, named after a 1926 outbreak in Haverhill Ma (PubMed) from po exposure.

At least 30% can't recall a rat exposure.

Can also get infection after drinking rat contaminated water or milk.


Incubation is 3-10 days

Fever (often relapsing), rash (mostly on the hands and feet) and polyarticular arthritis. The arthritis may exist without the symptoms of classic rat bite fever: "Asymmetrical polyarticular involvement of the peripheral joints is typical for streptobacillary arthritis. In contrary to streptobacillary rat-bite fever, skin rash and bacteremia is uncommon (PubMed)."

The odd endocarditis.


Penicillin G.

For penicillin allergic patients streptomycin or tetracycline.


It is part of the normal respiratory flora of rats and up to 100% of wild and pet rats can carry it.

Curious Cases

Relevant links to my Medscape blog

Another unconfirmed great diagnosis.

Last Update: 07/05/18.