Why Is the Current Monitoring of Rodentibacter spp. Exclusively by Molecular Methods Insufficient?

The former [Pasteurella] pneumotropica complex has rendered until now 12 Rodentibacter species, which has implications in the monitoring of these highly prevalent laboratory rodent microorganisms. Rodentibacter spp. are known as classic opportunistic pathogens of laboratory rodents and represent noteworthy members of the oral and genital microbiome, with potential pathophysiological interferences in colonized animals. Laboratory mice and rats are predominantly colonized by host-specific Rodentibacter spp., with R. pneumotropicus and R. heylii as mouse-specific species and R. ratti, R. heidelbergensis, R. rarus, and R. trehalosifermentans as rat-specific species; however, host specificity of R. haemolyticus, currently prevalent in both species, remains to be elucidated. Nevertheless, cross contaminations with the taxa from the opposite host occurs between mice and rats. The monitoring occurs by classic culture and/or by molecular techniques, although the latter are currently available only for a few Rodentibacter taxa. Unfortunately, many current health monitoring strategies do not take into consideration the host specificities of these taxa and are often focused nearly exclusively on the molecular diagnostics of R. pneumotropicus and R. heylii, thus neglecting the remaining taxa. Until future research addresses the lack of molecular tests available for all relevant Rodentibacter spp. and a host-specific monitoring is implemented, we consider that monitoring exclusively by current molecular methods risks missing opportunistic members of this genus. Importing laboratory rodents based on health reports relying solely on molecular assays is currently associated with an increased risk of accepting Rodentibacter-positive animals.