Related Experiment Video
Updated: May 5, 2026

Intradermal Inoculation of Mycobacterium avium in the Mouse Ear
Published on: July 3, 2025
Association between polyclonal and mixed mycobacterial Mycobacterium avium complex infection and environmental
Kohei Fujita1, Yutaka Ito, Toyohiro Hirai
11 Department of Respiratory Medicine.
Rationale:
Polyclonal and mixed mycobacterial Mycobacterium avium complex (MAC) infection is observed in pulmonary MAC disease. Human living environments contain multiple species or genotypes of nontuberculous mycobacterial strains and are considered sources of infection.
Objectives:
To investigate the association of environmental exposure with polyclonal and mixed mycobacterial infection in pulmonary MAC disease after adjustments for potential confounding diseases and conditions and radiographic findings.
Methods:
We collected two separate sputum samples from 102 patients and single sputum samples from 18 patients in whom the second MAC strain was not isolated in our prospective cohort of pulmonary MAC disease. MAC isolates from sputum samples and patients' residential soils were used for variable number of tandem repeats (VNTR) analyses. Polyclonal and mixed mycobacterial MAC infections were defined as having different VNTR genotypes and other mycobacterial species, respectively. Monoclonal MAC infection was defined as all isolates showing a single VNTR genotype. Associations of the type of infection with clinical and radiographic findings and environmental exposure were measured.
Measurements And Main Results:
Polyclonal and mixed mycobacterial MAC and monoclonal infections were observed in 42 and 78 patients, respectively. By stepwise regression analysis, patients with polyclonal and mixed mycobacterial MAC infections were associated with history of asthma (odds ratio [OR], 11.56; 95% confidence interval [CI], 1.41-255.77; P = 0.021), high soil exposure (≥2 h/wk; OR, 4.31; 95% CI, 1.72-11.45; P < 0.01), shower use in a bathroom (OR, 4.57; 95% CI, 1.28-23.23; P = 0.018), and swimming in a pool (OR, 9.69; 95% CI, 1.21-206.92; P < 0.01).
Conclusions:
Environmental exposure was associated with polyclonal and mixed mycobacterial MAC infection in pulmonary MAC disease.
More Related Videos
08:34Identification of Virulence Markers of Mycobacterium abscessus for Intracellular Replication in Phagocytes
Published on: September 27, 2018
06:57Author Spotlight: Adjuvant Activity of Mycobacterium paratuberculosis in Enhancing the Immunogenicity of Autoantigens During Experimental Autoimmune Encephalomyelitis
Published on: May 12, 2023
Related Concept Videos
Pulmonary Tuberculosis III
The first classification is based on the development of the disease, and it includes the following categories:
Atypical Pneumonia
Pulmonary Tuberculosis I
Causative Organism
The primary infectious agent causing tuberculosis is Mycobacterium tuberculosis, a slow-growing, acid-fast, aerobic rod that exhibits sensitivity to heat and ultraviolet light. Instances of Mycobacterium bovis and Mycobacterium avium contributing to the development of TB infection are rare.
Mode of...
Pulmonary Tuberculosis II
Here is a detailed explanation of its pathophysiology:
Transmission: The process begins when a person inhales droplet nuclei containing M. tuberculosis. These are typically released into the air when an individual with pulmonary or...
Pulmonary Tuberculosis IV
Several diagnostic approaches are used to detect TB. The conventional method is the Tuberculin Skin Test (TST), also known as the Mantoux test. However, this method has...