Abstract

Non-tuberculous mycobacteria (NTM) cause opportunistic lung disease though environmental exposure pathways. Among the United States, Hawaii has a significantly higher infection rate. Preliminary studies have shown certain environmental factors, such as phosphorus and other select soil geochemical characteristics, to be statistically significant to NTM occurrence. However, a model to predict NTM occurrence based on soil geochemistry had yet to be attempted. A selection of 40 NTM positive and 40 NTM negative soils from Oahu were selected for a geochemical analysis to search for possible correlations to mineralogy and elemental abundances that may promote, or inhibit, NTM growth in the environment. Oahu results were compared with soil chemistry from the Kilauea and Kohala areas of Hawaii Island. Parameters included mineralogy, total organic carbon (TOC), pH, major elements, and trace elements. Statistical analyses performed include: student's t-test, multidimensional hypothesis tests, principal components analysis (PCA), and multidimensional statistical analysis. The data for Oahu showed NTM presence correlated with 1:1 clays and NTM absence correlated with goethite, 2:1 clays, Nb, Ce, La, Ba, and Rb. Kohala soil data showed NTM presence correlated with Al2O3, Ce, Sc, and Sm and NTM absence correlated with rainfall, Cr, Pb, and S. Kilauea data showed NTM presence correlated with TOC, pH, P, mafic silicate minerals, and Pb and NTM absence correlated with transition metals and oxides such as TiO2, Zr, and Nb. The results of the multidimensional statistical analysis were used to build a predictive model of NTM occurrence. The best model for Oahu had an accuracy of 65.9%, while Kohala had an accuracy of 71.7% and Kilauea 79.9%. A selection of five Hawaiian rock samples consisting of basalt, volcanic glass, and saprolite were used to culture clinically significant M. abscessus and visualize the effect mineralogy has on NTM growth. NTM cells were found on all mineral surfaces. However, volcanic glass was shown to visibly increase NTM growth and survival. As time passes, the ability to predict soil features that enhance NTM predictability decreases from 79.9% in modern Kilauea soils, to 71.7% in 0.17 Ma Kohala soils, to 65.9% in ~2 Ma Oahu soils. With age, it appears that distinct properties that enhance NTM survival are either erased or weathered to a more uniform state. Nonetheless, the NTM risk remains high in Hawaii due to environmental factors.

Degree

MS

College and Department

Physical and Mathematical Sciences; Geological Sciences

Rights

https://lib.byu.edu/about/copyright/

Date Submitted

2023-06-06

Document Type

Thesis

Handle

http://hdl.lib.byu.edu/1877/etd12794

Keywords

Mycobacteria, soil chemistry, geochemistry, NTM, multivariate statistics

Language

english

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