Mycobacteria
Mycobacterium is a genus of bacteria with more than 190 recognized species. This rod-shaped bacteria can cause severe disease in animals and humans – including tuberculosis (M. tuberculosis complex) and leprosy (M. leprae). Many Mycobacterium species reside in diverse environments, existing as environmental opportunistic pathogens.
Core genome phylogenetic trees of Mycobacterium abscessus subspecies, showing case identities, cystic fibrosis (CF) status, and sequence types
Nontuberculous Mycobacteria
Nontuberculous mycobacteria (NTM) are members of the Mycobacterium genus that do not cause tuberculosis or leprosy. Unlike TB, NTM infections usually arise from environmental sources rather than person-to-person transmission, highlighting the role of environmental reservoirs in disease risk. Most NTMs do not cause illness, but immunocompromised individuals, particularly those with underlying lung conditions, are at increased risk. The most common human infections are caused by M. avium complex, which are often resistant to standard antibiotics, making treatment challenging.
The Guthrie Lab investigates NTM diversity and transmission, including a recent global genomic characterization of M. avium hominissuis, which uncovered three novel lineages, and studies linking environmental reservoirs to human infections. Additionally, a genomic analysis from our lab, published in The Journal of Infectious Diseases, indicates that Mycobacterium abscessus infections are unlikely to result from health care–associated person-to-person transmission and may instead originate from a common environmental source. Together, this work helps fill gaps in understanding disease variability, prevalence, and the complex interplay between humans, pathogens, and the environment.
Tuberculosis
Tuberculosis (TB) is a disease that primarily affects the lungs and is often associated with severe symptoms. Latent TB is the existence of a TB infection with no symptoms due to inactive bacteria. Latent TB can progress into TB disease – an active condition that is contagious and threatens the health of the individual and community. From sanatoriums to the BCG vaccine and streptomycin, we have made many advancements in the treatments available over the last 100 years. Currently, there are standardized treatments for both active and inactive TB that are antimicrobial susceptible.
Despite the advancements that have been made, TB is still a worldwide public health concern. The emergence of drug-resistant TB has created difficulties for healthcare professionals when treating these strains. TB is more prevalent in low- and middle-income countries and in communities where there is a high poverty index. TB has a more considerable impact on marginalized groups due to social determinants impacting their health outcomes. Many healthcare systems are inadequately equipped to deal with outbreaks due to societal and economic conditions. Drug-resistant TB and the prevalence of TB in areas with people living in poverty demonstrate the health threats imposed by infectious diseases and the impacts on the healthcare system.
Pediatric TB patients in British Columbia (2005-2014). (A) Summary of acquisition and travel history; (B) stratification of birthplace and source of transmission. (Figure 2. Guthrie et al. 2018)