PCR for the detection of Streptobacillus moniliformis

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.