First case report of human infection with Mycobacterium stomatepiae

We describe the first detailed case report of human infection with Mycobacterium stomatepiae. Infection with non-tuberculous mycobacteria (NTM) related to M. stomatepiae is well described, despite the lack of previous confirmed reports of M. stomatepiae-related human disease. Localised cervical lymphadenitis is the most common NTM disease in children, with species closely related to M. stomatepiae, such as Mycobacterium triplex and Mycobacterium florentinum, having been shown to be rare causative agents.

A 19-month-old girl presented with persistent unilateral neck lumps which developed following a facial laceration. Both lumps were fluctuant with overlying erythema and no fistulae present. Incision and drainage with curettage was performed. The operative sample of purulent fluid revealed pleomorphic bacilli on Ziehl-Neelsen staining. The isolate cultured was referred for further genotypic identification via 16S rRNA gene sequencing, identifying the organism as M. stomatepiae.

We describe the first detailed case report of human infection with M. stomatepiae. This organism can now be added to the growing list of NTM that are opportunistic human pathogens, though it is likely to remain a very rare causative agent of this clinical syndrome. Early diagnosis relies on clinical suspicion by the treating doctor, flagging potential cases to the microbiology laboratory and hence allowing correct specimen set-up. Laboratory diagnosis requires incubation of cultures at lower temperatures, and definitive identification is best performed by sequencing methods, including 16S rRNA gene sequencing. The description of novel species of NTM causing human disease is likely to increase with further advancements in diagnostic methods.