Epidemiology, Outcomes and Tolerability of Protracted Treatment of Nontuberculous Mycobacterial Infections at a Community Teaching Hospital in the Southeastern United States

Abstract

Nontuberculous mycobacterial (NTM) infections present a treatment challenge for clinicians and patients. There are limited data about current susceptibility patterns and treatment outcomes in U.S. adults. This was a 10-year, single-center, retrospective, observational cohort study of adults with a positive NTM culture and clinical suspicion of infection between 1 January 2010 and 30 June 2020. The primary objective was to identify predictors for favorable treatment outcomes. Key secondary objectives were characterization of NTM epidemiology, susceptibility profiles, and safety and tolerability of treatment, including the proportion of subjects with an antimicrobial change and the reasons for the change. Of 250 subjects diagnosed with NTM infection, the most prevalent NTM isolates were Mycobacterium avium intracellulare complex (66.8%) followed by Mycobacterium abscessus (17.6%). Antimicrobial susceptibility data were available for 52.4% of the cohort (45.8% slow growers; 54.2% rapid growers). Only 88 (35%) subjects received treatment with evaluable clinical outcomes. The proportion of subjects with a favorable outcome was 61.4%. More subjects in the unfavorable outcome group experienced a change in antimicrobial therapy (73.5% vs. 51.9%, p = 0.043). The most common reason for antimicrobial change was adverse drug events (n = 36, 67.9%). In the regression model, private insurance was associated with a favorable outcome, whereas having multiple antimicrobial changes was associated with an unfavorable outcome. The complexity of NTM treatment and high incidence of medication-related issues suggest the necessity of interdisciplinary collaboration to improve overall treatment outcomes in NTM infections.

Keywords: Mycobacterium abscessus; Mycobacterium avium complex; nontuberculous mycobacteria; susceptibility.

Figure 1

Study Cohort. ^a Other reasons for not treating included the following: lost to follow-up (n = 10), source controlled (n = 5), patient refused treatment (n = 5), hospice/palliative care (n = 2), risks outweigh benefits per clinicians’ recommendation (n = 2), pregnancy (n = 1), and unclear/undetermined (n = 10).

Figure 2

Distribution of NTM Isolates. Other Rapid Growers included: M. chelonae (n = 5), Other Rapid Growers included: M. chelonae (n = 5), M. fortuitum (n = 16), M. mucogenicum (n = 3), M. brisbanense (n = 1), M. goodii (n = 2), M. smegmatis (n = 1), and M. immunogenum (n = 1). Other Slow Growers included: M. kansasii (n = 2), M. marinum (n = 2), M. neoarum (n = 1), M. haemophilum (n = 2), M. simiae/interjectum (n = 1), M. lentiflavum (n = 1), and M. asiaticum (n = 1).