Methodological and Clinical Aspects of the Molecular Epidemiology of Mycobacterium tuberculosis and Other Mycobacteria

Abstract

SUMMARYMolecular typing has revolutionized epidemiological studies of infectious diseases, including those of a mycobacterial etiology. With the advent of fingerprinting techniques, many traditional concepts regarding transmission, infectivity, or pathogenicity of mycobacterial bacilli have been revisited, and their conventional interpretations have been challenged. Since the mid-1990s, when the first typing methods were introduced, a plethora of other modalities have been proposed. So-called molecular epidemiology has become an essential subdiscipline of modern mycobacteriology. It serves as a resource for understanding the key issues in the epidemiology of tuberculosis and other mycobacterial diseases. Among these issues are disclosing sources of infection, quantifying recent transmission, identifying transmission links, discerning reinfection from relapse, tracking the geographic distribution and clonal expansion of specific strains, and exploring the genetic mechanisms underlying specific phenotypic traits, including virulence, organ tropism, transmissibility, or drug resistance. Since genotyping continues to unravel the biology of mycobacteria, it offers enormous promise in the fight against and prevention of the diseases caused by these pathogens. In this review, molecular typing methods forMycobacterium tuberculosisand nontuberculous mycobacteria elaborated over the last 2 decades are summarized. The relevance of these methods to the epidemiological investigation, diagnosis, evolution, and control of mycobacterial diseases is discussed.

Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for Combined Species Identification and Drug Sensitivity Testing in Mycobacteria

“…Whereas M. tuberculosis is an obligate pathogen, nontuberculous mycobacteria (NTM) are environmental organisms which occasionally act as opportunistic pathogens, leading to a wide array of clinical syndromes (3). The number of reported cases of NTM infections has risen dramatically in the past decade, which has been linked to increasing numbers of immunocompromised patients, the implementation of advanced diagnostic tools, and increased awareness of the role of NTM in diseases (4,5). However, while only 29 of the Ͼ160 recognized NTM species are associated with human disease, others (such as M. gordonae) are frequent contaminants from sample collection or processing (4).…”

Education and training in microbial forensics

“…Molecular epidemiology focuses on the contribution of potential genetic, identified at the molecular level, and environmental risk factors to the etiology, distribution, and prevention of disease within families and across populations (Riley, 2004;Eybpoosh et al, 2017;Jagielski et al, 2016) [(3) also see the Genomics section below]. The field provides a good example where application of newer technologies may help overcome many of the same problems encountered with traditional epidemiology with respect to study design and interpretation (4).…”

Human zoonotic tuberculosis and livestock exposure in low‐ and middle‐income countries: A systematic review identifying challenges in laboratory diagnosis

“…Over the last two decades, zoonotic tuberculosis (zTB) has received increasing recognition as a growing public health threat, especially in low‐ and middle‐countries (LMICs) where the incidence of zTB is largely unknown. The Mycobacterium tuberculosis complex species that cause zTB include M. bovis (cattle), M. caprae (sheep and goats), M. microti (rodents), M. mungi (banded mongooses), M. orygis (members of the Bovidae family) and M. pinnipedii (seals and sea lions) (Jagielski et al, ). M. bovis is primarily transmitted to humans by cattle through the consumption of cattle products, such as unpasteurized milk and raw meat products contaminated with M. bovis lesions, and aerogenously (Center for Food Security & Public Health [CSFPH], ).…”