In a recent review published in the International Journal of Mycobacteriology, a team of researchers examined the factors that might contribute to the predisposition of women to developing Nontuberculous mycobacterial infections.
Nontuberculous mycobacteria (NTM) are environmental microbes that cause a variety of diseases, including chronic lung infections. NTM are normal inhabitants of soil and drinking water and hence are typically acquired from these sources. Similar to Tuberculosis, NTM can infect any organ system. However, pulmonary infections, lymphadenitis and skin and soft tissue infections are the most common. The condition is increasing in prevalence with recent epidemiological studies showing that it affects 15.5 cases per 100,000 in persons over 50 years of age in the United States.
This increase in the prevalence of the condition can be attributed to the increased number of studies examining the16S rNA gene sequencing to detect the presence of mycobacteria and awareness of the importance of NTM species as human pathogens.
Risk factors for the condition include chronic obstructive pulmonary disease (COPD), cystic fibrosis, silicosis, and alpha-1 antitrypsin deficiency. Recent studies have also found an association between non-CF bronchiectasis and non-tuberculous mycobacterial infections, with results showing that this association is seen more often in post-menopausal women. Although the association between non-CF bronchiectasis and NTM has been document, it remains unknown its sequential causality.
In order to determine the mechanisms that contribute to the predisposition of women to developing mycobacterial infections, in their review titled “Gender susceptibility to mycobacterial infections in patients with non-CF bronchiectasis,” Mirsaeidi Mehdia from the Division of Pulmonary and Critical Care Medicine, University of Illinois at Chicago and Ruxana T. Sadikotb from the Division of Pulmonary and Critical Care Medicine Emory University in Atlanta, determined that current evidence shows that the presence of the Mycobacterium avium complex (MAC) is often the cause of NTM. This may be the result of improved diagnostics and increased recognition of the importance of NTM as a causality of lung disease.
The authors determined that the diseases that mostly contribute to the NTM are cystic fibrosis, COPD, and alpha-1 antitrypsin deficiency, however it is necessary to continue to do research regarding its association with bronchiectasis.
Results from epidemiological studies indicate that NTM has a predilection to affect thin, elderly (post-menopausal) women without underlying lung disease for unclear reasons. The evidence that the review authors explored revealed that women are more prone to NTM than mean due to different sex hormones and mediators, such as leptin and adiponectin, which modulate key cytokines such as TGF-β. According to the authors, other mediators such as fibrillins and matrix metalloproteinases might contribute to the pathogenesis of dual disease with NTM and bronchiectasis.
As the authors concluded is necessary to carry out more researchers regarding the contribution of hormones, mediators and nutritional status in the immuno-pathogenesis of NTM infections.