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HONOLULU -- Whether patients with nontuberculous mycobacterial (NTM) lung disease respond to antibiotic treatment seemed to be related to their microbiome profile, a small study found.

Out of 14 patients who were on antibiotic treatment during some point from 2020 to 2022, seven were refractory to over 12 months of antibiotic treatment, and seven achieved microbiological cure, reported Noeul Kang, MD, PhD, of Samsung Medical Center in Seoul, South Korea, during the CHEST annual meeting hosted by the American College of Chest Physicians.

Sputum samples before and after antibiotics, with 6 months in between, suggested that several species were particularly abundant in those who reached microbiological cure of NTM infection:

• Streptococcus pneumoniae
• Prevotella melaninogenica
• Haemophilus parahaemolyticus

Patients who maintained long-term disease stabilization without recurrence tended to have higher microbial diversity than those not responding to treatment.

Depending on the microbiome diversity index evaluated, the baseline samples of the refractory group could be considered as having significantly lower alpha diversity, or microbial diversity within a sample, than the microbiological cure group at baseline.

Beta diversity, the measure of the similarity or dissimilarity between samples, also showed species-level differences between the two study groups.

"Based on our findings, the sputum microbiome diversity during treatment for NTM-PD [pulmonary disease] could serve as a biomarker for assessing the efficacy of the treatment and that a specific microbiome environment contributes to the stabilization and cure of NTM-PD," Kang said in a press release.

Also known as atypical mycobacteria, NTM are mycobacteria excluding tuberculosis-causing M. tuberculosis and leprosy-causing M. leprae.

Kang cited data showing that NTM lung disease is a growing healthcare burden and has been trending upward in prevalence in the U.S. These pathogens can have an incubation period of months, or even years, and infections are not limited to the lungs. Recently, it was found that vanadium and other trace metals in drinking water may promote NTM disease.

NTM are environmental organisms that can be found in soil, dust, and water, including natural water sources and municipal water sources, . Additionally, NTM have been found in medical devices such as heater-cooler units used in open heart surgery.

The majority of NTM lung disease in the U.S. is caused by (51%). M. abscessus and M. kansasii also infect lungs to a lesser degree.

Kang noted that treatment outcomes differ according to the etiologic organism.

There is a 60% rate of treatment success for M. avium complex. Treatment success for M. abscessus ranges from 30% to 70%, depending on the subspecies.

In Kang's report, eight out of the 14 patients tested positive for M. abscessus, which was more likely to be found in the microbiological cure group than the refractory group (71.4% vs 42.9%).

The 14 study participants had a median age of 61 years. Women and never-smokers each made up 86% of the cohort. Additionally, 29% had a past history of pulmonary tuberculosis, and 21% had chronic aspergillosis.

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