Streptobacillus moniliformis is a Gram-negative bacterium found in various 
laboratory animal species and is the cause of rat bite fever and Haverhill fever 
in man. In order to evaluate a polymerase chain reaction (PCR) for the detection 
of this zoonotic bacterium in animal tissues a set of primers was designed based 
on the DNA base sequence of part of the 16S rRNA gene from 11 S. moniliformis 
strains. The PCR detected as few as 2-6 copies of S. moniliformis DNA. A 296 bp 
DNA fragment was amplified from S. moniliformis strains from rodents, humans and 
turkeys. Amplicons of about the same size were obtained from Fusobacterium 
necrogenes and Sebaldella (Bacteroides) termitidis but Bfa I treatment of these 
amplicons did not result in the S. moniliformis specific 130 bp DNA fragment. 
The in silico evaluation of 14 additional Fusobacterium spp. and 12 unculturable 
phytoplasmas indicated that none is likely to give rise to confusing amplicons 
or DNA fragments. The PCR detected S. moniliformis infection in all four orally- 
and four intravenously-infected C57BL/6 mice and the bacterium was cultured from 
all but one mouse. The PCR detected S. moniliformis infection in all 12 
orally-infected WU rats, and in five of eight rats exposed to natural infection. 
Enzyme linked immunosorbent assay (ELISA) and PCR were equally successful in 
detecting infection in rats but S. moniliformis was not detected by using 
culture.