The researchers led by Didi Bang from the Statens Serum Institute in Copenhagen, Denmark, said their finding might help improve the diagnosis and treatment of similar infections.
The scientists noted some rare genetic diseases can make patients susceptible to infections with Mycobacterium species, the bacteria that, among other diseases, cause tuberculosis and leprosy. Those patients often suffer from recurring mycobacterial infections throughout their lives.
"We isolated an unknown species of bacteria from a 7-year-old child who has a genetic immune defect," said Bang. "The infection had caused bone lesions and this is where we found the newly described bacteria.
"Initial tests suggested we had found a Mycobacterium. By sequencing some of the bacterium's genes we showed that we had discovered an undescribed species," Bang added. "We called the bacterium Mycobacterium arosiense."
The name comes from Arosia, the Latin name of the city of Aarhus in Denmark, which is where the bacterium was found.
The research is detailed in the International Journal of Systematic and Evolutionary Microbiology.