Root sepsis associated with insect-dwelling Sebaldella termitidis in a lesser dwarf lemur (Cheirogaleus medius)

Sebaldella termitidis is a rare fastidious microorganism of the Leptotrichiaceae family. A variety of closely related species are associated with severe and even life-threatening disease in humans and animals, such as Streptobacillus moniliformis, the etiological organism of rat-bite fever as well as members of Leptotrichia spp. and Sneathia sanguinegens, which have been reported from cases of septicaemia. In contrast, since its description some 50 years ago, S. ermitidis has so far never been reported as a vertebrate pathogen, nor has it been found aside from its natural termite host. A lesser dwarf lemur was presented with unilateral facial inflammation originating from rotten maxillary teeth and septic root abscess. Surgical intervention and root extraction significantly improved the clinical cause in that a pus-filled cavity underneath the right eye could be drained, sampled and flushed. Bacteria displaying substantial characteristics of S. termitidis were cultured from the sampled pus. Morphological features observed included strictly anaerobic regular Gram-negative rods. Significant shared biochemical properties included negative reactions for cytochrome oxidase, catalase, urease, nitrate reduction and indole production. Furthermore, 16S rRNA gene sequencing revealed 99.9 % sequence homology to the S. termitidis type strain NCTC 11300ᵀ, from which it, nevertheless, differed with respect to rep and rep- and RAPD-PCR profiles. An affiliation of the lemur isolate described in this study with the type strain of S. termitidis as well as a clear discrimination from other members of the Leptotrichiaceae could also be confirmed by matrix-assisted laser desorption/ionization time-of flight mass spectrometry and Fourier transform-infrared spectroscopy. This is the first evidence for clinical disease caused by S. termitidis in a vertebrate species indicating a broader host spectrum of this rarely encountered microorganism.