Isolation of diverse nontuberculous mycobacteria from Hawai’i feral pigs and identification of Mycobacterium abscessus subsp. bolletii

Abstract Background Nontuberculous mycobacteria (NTM) are environmentally acquired opportunistic pathogens that can cause recalcitrant pulmonary disease, particularly in susceptible individuals. Hawai’i has a high incidence of NTM infections, meriting a better understanding of the potential zoonotic and environmental reservoirs of NTM. Mycobacterium porcinum is a frequently identified NTM species from the Hawai’i environment, and based on its previous association with pigs, we hypothesized feral pigs may serve as animal reservoirs for pathogenic NTM in Hawai’i. Our goals were to determine the NTM species diversity among Hawai’i feral pigs and compare survival of pig-derived isolates in cell culture models of human and porcine macrophages. Methods A matched set of nasal and fecal samples from 50 deceased feral pigs and 50 soil samples were microbiologically cultured and NTM were initially identified using partial rpoB gene sequencing. In vitro assays revealed differential control of pig-derived NTM by human and pig macrophages and varied immunological responses to infection. Whole genome sequencing (WGS) and comparative phylogenomics were used to discriminate a single Mycobacterium abscessus isolate derived from a single pig fecal sample. Results While possible environmental contaminants, 15 diverse NTM species were recovered from Hawai’i feral pigs, including pathogenic slow- and rapid-growing mycobacteria, but not M. porcinum. WGS comparisons revealed novel discovery of M. abscessus subsp. bolletii from a single pig. Conclusion This study suggests that feral pigs in Hawai’i harbor pathogenic and clinically relevant NTM species and may contribute to the prevalence of NTM in Hawai’i.