A Rare Case of Mycobacterium Monacense Osteomyelitis: A Case Report

Mycobacterium monacense (M. monacense) is a yellow-pigmented, rapidly growing non-tuberculous mycobacterium (RGM). It is a rare pathogen in humans, and only a very few cases of skin and lung infection related to it have been reported. In this report, we present the case of a 70-year-old Hispanic male who was brought to the hospital with back pain for 11 months. His physical exam on admission showed point tenderness in the lumbar and thoracic spine. MRI demonstrated severe spinal stenosis, discitis, and adjacent osteomyelitis at the T11-T12 vertebral bodies. Mycobacterium culture with fluorochrome smear from thoracic spine T12 tissue revealed mycobacterium species, but not Mycobacterium tuberculosis (M. tuberculosis). The final culture report led to the identification of M. monacense, which was confirmed by DNA sequencing. This case illustrates the rare manifestations of M. monacense and highlights the use of molecular biologic techniques to reach a definitive diagnosis in suspected cases. Infections caused by M. monacense are rarely reported in humans. Even though a few cases have reported M. monacense isolated from human samples, the clinical importance of it is not fully understood. A drug susceptibility test for antibiotic therapy is essential for this patient population. The interpretation of these cultures often generates unclear results. However, the aggravation of the disease on imaging and isolation of M. monacense alone from the cultured specimens obtained suggested that this pathogen may have caused the infection presented in this case.