Scientists Discover Bacteria That Can Cause Bone Infections

Scientists have discovered that a bone infection is caused by a newly
described species of bacteria that is related to the tuberculosis
pathogen. The discovery may help improve the diagnosis and treatment of
similar infections, according to an article published in the October
issue of the International Journal of Systematic and Evolutionary
Microbiology.


Some rare genetic diseases can make patients susceptible to infections
with Mycobacterium species, the bacteria that amongst other diseases,
cause tuberculosis and leprosy. These patients often suffer from
recurring mycobacterial infections throughout their whole lives. Because
of this, researchers are trying to identify unusual species that cause
disease in order to improve treatment strategies.


"We isolated an unknown species of bacteria from a 7 year old child who
has a genetic immune defect," said Dr Didi Bang from Statens Serum
Institut in Copenhagen, Denmark. "The infection had caused bone lesions
and this is where we found the newly described bacteria."


Mycobacterial infections can be very difficult to treat. The bacteria
have unique cell walls that protect them from several antibiotics. As
well as being resistant to treatment, they can also survive attack with
acids, alkalis and detergents. Most mycobacterial infections can be
treated with antibiotics such as clarithromycin and rifamycins, but some
species are becoming resistant to these antibiotics, so new drugs for
treatments must be developed.


"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," said Dr Bang. "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 first
found. We showed the position of the new bacterium on the Mycobacterium
family tree by sequencing genes and comparing them to related bacteria."



The new pathogen is closely related to Mycobacterium intracellulare and
Mycobacterium avium, which cause a lung disease similar to tuberculosis
in people, especially those with weak immune systems such as HIV
patients that are immunologically suppressed. It is rod-shaped and grows
slowly.


"Mycobacterium arosiense can be killed by several antibiotics in the
lab, including clarithromycin and rifamycins. However, resistance to
fluoroquinolones and isoniazid was observed," said Dr Bang. "Little
knowledge is available on performing resistance tests on mycobacteria
other than tuberculosis."


"We hope that this discovery will help doctors to diagnose similar
diseases in the future and that further investigation may improve the
treatment of people with similar infections."


Society for General Microbiology

socgenmicrobiol.uk



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