Studies Evaluate Nontuberculous Mycobacterial Lung Disease

The incidence of nontuberculous mycobacterial (NTM) lung disease is increasing and current treatment options rely on long-term antibiotic regimens that have limited efficacy and are difficult to tolerate. Video-assisted thoracoscopic surgery (VATS) may be a potential treatment for certain NTM patients, according to research.

A study¹ presented at the American Thoracic Society 2018 International Conference aimed to address the areas that are poorly penetrated by antibiotics and may have a higher risk of disease recurrence through surgical resection.

“To date, adjuvant video-assisted thoracoscopic surgery (VATS) is not yet a standard care option for individuals with NTM lung disease and more outcome data about the use of this procedure in the NTM patient population is needed,” the study authors wrote.

The researchers conducted a review of patients at 2 NTM institutions—Oregon Health & Science University (OHSU) and University of Texas Health Science Center at Tyler—who underwent pulmonary resection for NTM between January 2009 and August 2017.

Of the 71 patients who were identified, the median time from the last positive culture prior to surgery was 17 months and 35 patients at OHSU received perioperative amikacin for a median duration of 1 month. Also, of the patients who completed therapy, the median duration of NTM multidrug therapy postsurgery was 12 months. Although all patients continued on the same presurgical multidrug regimen, 96% of patients—excluding patients with a pneumonectomy—underwent VATS for their resection.

According to the results, VATS exhibited a low morbidity and mortality rates and therefore requires future research as a potential treatment for NTM patients.

Another study² at the meeting evaluated drug resistance (DR) mutations in order to better understand DR genotypes and their relationships to antimicrobial susceptibility test (AST) results.

The study used the NTM Genomic Database at National Jewish Health to assess the DR mutations in the 16S ribosomal RNA (rRNA) and 23S rRNA genes corresponding to amikacin and macrolide resistance.

The results showed that DR mutations in the 16S rRNA at position 1408, corresponding to amikacin resistance, were found in 4.9% of isolates and 4 of 6 NTM species. Additionally, DR mutations in the 23S rRNA at positions 2058 and/or 2059, which correspond with macrolide resistance, were observed in 5.4% of isolates and 5 of 6 species.

“DR mutations in the 16S and 23S rRNAs are present in low frequencies (~5%) in clinical NTM populations, but are not found in environmental isolates, suggesting that DR genotypes may be selected for in patients exposed to antibiotic treatment,” concluded the authors.

References

1. Siegel S, Watson J, Philley J, et al. Video-assisted thoracoscopic surgery (VATS) for nontuberculous mycobacterial lung disease in the setting of structured lung disease. Presented at the American Thoracic Society 2018 International Conference. May 20, 2018; San Diego, California. Abstract A2612/824.

2. Davidson R, Kammlade S, Nick SE, et al. Prevalence of drug resistance mutations in clinical and environmental nontuberculous mycobacteria isolates in the US. Presented at the American Thoracic Society 2018 International Conference. May 20, 2018; San Diego, California. Abstract A7705/825.