Novel bacterium Candidatus Sarcina troglodytae

The bacterial genus Sarcina has been described in the literature for 178 years but without consensus about these organisms role in disease. We documented a novel Sarcina bacterium while investigating a long-term epizootic of 100% lethal disease in sanctuary common chimpanzees in Sierra Leone. The new bacterium, Ca. S. troglodytae, infected 13 of 19 of cases but not controls, and the bacterium was the only infectious agent statistically associated with these cases. In some instances, Ca. S. troglodytae was present in deep tissues (e.g., brain, spleen, lung), which is indicative of severe infection. Ca. S. troglodytae has the 4-cell (tetrad) morphology characteristic of members of the Sarcina genus, but its cell size is intermediate between S. ventriculi and S. maxima. Genetically, Ca. S. troglodytae clusters with S. ventriculi and S. maxima but is sufficiently distinct to be considered a representative of a new species. The Ca. S. troglodytae genome contains a variety of genes whose products may contribute to pathogenesis in primates. Overall, these results implicate Ca. S. troglodytae as the cause of the epizootic and as a particularly virulent bacterium. The genus Sarcina appears to include a complex of species for members ranging from benign environmental bacteria to frank bacterial pathogens.