Jan 24, 2013 10:14 PM IST | Source: PTI

Tall, thin women at greater risk of lung infection: Study

Tall and thin women face a greater risk of lung infection with nontuberculous mycobacteria (NTM), cousin of the bacteria that causes tuberculosis, according to a new US study.

Tall and thin women face a greater risk of lung infection with nontuberculous  mycobacteria (NTM), cousin of the bacteria that causes tuberculosis, according to a new US study.

"Nontuberculous mycobacteria are widespread in the  environment, yet only some people develop infections," said  Edward Chan, senior author and professor of medicine at  National Jewish Health in US. "These findings help us identify who is at greater risk  for the disease, and may point to more effective therapies  down the road," Chan said.

Although the organisms can infect skin and other body  parts, they most commonly infect the lungs. Lung infections  are very difficult to treat, often requiring surgery and years  of therapy with powerful intravenous antibiotics.  NTM species are widespread in water and soil, yet only  about five to six people per 100,000 develop NTM infections  each year; the incidence is higher in individuals older than  50 in the US .

An estimated 30,000 to 120,000 people in the US currently  have NTM infections.  Researchers at National Jewish Health, which sees more NTM  infections than any other medical center in the world, tried  to figure out why only some exposed patients develop these  difficult infections.

Elderly women represent the vast majority of NTM patients, accounting for 85 percent of the patients seen at National  Jewish Health during the study, and averaging about 64 years  of age.  Researchers compared the NTM patients with control  subjects at an osteoporosis clinic because these individuals  were similar age, race, and gender as the NTM patients.

When compared to the women visiting the osteoporosis  clinic, the NTM patients were on average almost two inches  taller, had body mass indices almost two points lower and 5.7  pounds less fat on their bodies.

The NTM patients also more frequently had concave chests,  a condition known as pectus excavatum, and scoliosis, or  curvature of the spine.  "Tall, thin women definitely appear to be more susceptible  to NTM infections," said Chan.

"They share some characteristics of people with Marfan Syndrome. Since the syndrome is caused by a mutation in the  fibrillin-1 gene, we plan to look at that gene as a potential  source of NTM susceptibility," Chan said in a statement.

The Marfan syndrome is a disorder of connective tissue, the  tissue that strengthens the body's structures. People with  Marfan tend to be unusually tall, with long limbs and long,  thin fingers.  Women with NTM infections also showed a weakened immune  response associated with their fat cells.

The study was published in The American Journal of  Respiratory and Critical Care.

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