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Nontuberculous mycobacteria (NTM) are environmental organisms that can cause opportunistic pulmonary disease with species diversity showing significant regional variation. In the United States, Hawai’i shows the highest rate of NTM pulmonary disease. The need for improved understanding of NTM reservoirs led us to identify NTM from patient respiratory specimens and compare NTM diversity between outdoor and indoor locations in Hawai’i. A total of 545 water biofilm samples were collected from 357 unique locations across Kaua’i (n = 51), O’ahu (n = 202), Maui (n = 159), and Hawai’i Island (n = 133) and divided into outdoor (n = 179) or indoor (n = 366) categories. rpoB sequence analysis was used to determine NTM species and predictive modeling applied to develop NTM risk maps based on geographic characteristics between environments. M. chimaera was frequently identified from respiratory and environmental samples followed by M. chelonae and M. abscessus; yet significantly less NTM were consistently recovered from outdoor compared to indoor biofilms, as exemplified by showerhead biofilm samples. While the frequency of M. chimaera recovery was comparable between outdoor and indoor showerhead biofilms, phylogenetic analyses demonstrate similar rpoB gene sequences between all showerhead and respiratory M. chimaera isolates, supporting outdoor and indoor environmentsmore »as possible sources for pulmonary M. chimaera infections.« less

ABSTRACT Environmental nontuberculous mycobacteria (NTM), with the potential to cause opportunistic lung infections, can reside in soil. This might be particularly relevant in Hawai’i, a geographic hot spot for NTM infections and whose soil composition differs from many other areas of the world. Soil components are likely to contribute to NTM prevalence in certain niches as food sources or attachment scaffolds, but the particular types of soils, clays, and minerals that impact NTM growth are not well-defined. Hawai’i soil and chemically weathered rock (saprolite) samples were examined to characterize the microbiome and quantify 11 mineralogical features as well as soil pH. Machine learning methods were applied to identify important soil features influencing the presence of NTM. Next, these features were directly tested in vitro by incubating synthetic clays and minerals in the presence of Mycobacteroides abscessus and Mycobacterium chimaera isolates recovered from the Hawai'i environment, and changes in bacterial growth were determined. Of the components examined, synthetic gibbsite, a mineral form of aluminum hydroxide, inhibited the growth of both M. abscessus and M. chimaera , while other minerals tested showed differential effects on each species. For example, M. abscessus (but not M. chimaera ) growth was significantly higher in themore »presence of hematite, an iron oxide mineral. In contrast, M. chimaera (but not M. abscessus ) counts were significantly reduced in the presence of birnessite, a manganese-containing mineral. These studies shed new light on the mineralogic features that promote or inhibit the presence of Hawai’i NTM in Hawai’i soil. IMPORTANCE Globally and in the United States, the prevalence of NTM pulmonary disease—a potentially life-threatening but underdiagnosed chronic illness—is prominently rising. While NTM are ubiquitous in the environment, including in soil, the specific soil components that promote or inhibit NTM growth have not been elucidated. We hypothesized that NTM culture-positive soil contains minerals that promote NTM growth in vitro . Because Hawai’i is a hot spot for NTM and a unique geographic archipelago, we examined the composition of Hawai’i soil and identified individual clay, iron, and manganese minerals associated with NTM. Next, individual components were evaluated for their ability to directly modulate NTM growth in culture. In general, gibbsite and some manganese oxides were shown to decrease NTM, whereas iron-containing minerals were associated with higher NTM counts. These data provide new information to guide future analyses of soil-associated factors impacting persistence of these soil bacteria.« less