BACKGROUND: The Leptotrichiaceae are a family of fairly unnoticed bacteria 
containing both microbiota on mucous membranes as well as significant pathogens 
such as Streptobacillus moniliformis, the causative organism of streptobacillary 
rat bite fever. Comprehensive genomic studies in members of this family have so 
far not been carried out. We aimed to analyze 47 genomes from 20 different 
member species to illuminate phylogenetic aspects, as well as genomic and 
discriminatory properties.
RESULTS: Our data provide a novel and reliable basis of support for previously 
established phylogeny from this group and give a deeper insight into 
characteristics of genome structure and gene functions. Full genome analyses 
revealed that most S. moniliformis strains under study form a heterogeneous 
population without any significant clustering. Analysis of infra-species 
variability for this highly pathogenic rat bite fever organism led to the 
detection of three specific variable number tandem analysis loci with high 
discriminatory power.
CONCLUSIONS: This highly useful and economical tool can be directly employed in 
clinical samples without laborious prior cultivation. Our and prospective 
case-specific data can now easily be compared by using a newly established MLVA 
database in order to gain a better insight into the epidemiology of this 
presumably under-reported zoonosis.