TB Related Bacteria Found to Cause Bone Infections

by VR Sreeraman on Oct 19 2008 10:06 AM

A newly described species of bacteria related to the tuberculosis pathogen has been found to cause bone infections, a discovery that may pave the way for better diagnosis and treatment of similar infections, says a new study.

Patients having some rare genetic diseases are prone to infections with Mycobacterium species, the bacteria behind tuberculosis and leprosy. The patients often suffer from recurring mycobacterial infections throughout their whole lives.

Thus, 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. The infection had caused bone lesions and this is where we found the newly described bacteria," said Dr Didi Bang from Statens Serum Institut in Copenhagen, Denmark.

Owing to their antibiotic resistant cell walls and immunity towards treatment, bacteria can survive attack with acids, alkalis and detergents.

While the majority of mycobacterial infections can be treated with antibiotics such as clarithromycin and rifamycins, 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 Bang.

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

Closely related to Mycobacterium intracellulare and Mycobacterium avium, the new pathogen leads to 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.

Bang said: "Mycobacterium arosiense can be killed by several antibiotics in the lab, including clarithromycin and rifamycins. However, resistance to fluoroquinolones and isoniazid was observed. 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."

The study is published in the latest issue of the International Journal of Systematic and Evolutionary Microbiology.