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Polyclonal Mycobacterium avium complex infections in patients with nodular bronchiectasis
R J Wallace1, Y Zhang, B A Brown
1Departments of Microbiology and Pathology, and Center for Pulmonary Infectious Disease Control, University of Texas Health Center, Tyler, Texas, USA.
American Journal of Respiratory and Critical Care Medicine
|October 14, 1998
Summary
Patients with nodular bronchiectasis often have multiple Mycobacterium avium complex (MAC) infections, unlike those with cavitary lung disease who typically have a single MAC strain. Genetic analysis revealed significant genotypic diversity in bronchiectasis patients.
Area of Science:
- Medical Microbiology
- Pulmonology
- Infectious Diseases
Background:
- Mycobacterium avium complex (MAC) is a significant pathogen in chronic lung diseases.
- Understanding MAC heterogeneity in different lung disease presentations is crucial for effective treatment.
Purpose of the Study:
- To investigate the genetic diversity of MAC isolates in patients with chronic lung disease.
- To differentiate MAC infection patterns between nodular bronchiectasis and upper lobe cavitary disease.
Main Methods:
- Utilized genetic identification methods, including pulsed field gel electrophoresis (PFGE), to analyze MAC isolates.
- Collected multiple cultures per patient from distinct clinical groups.
- Employed seroagglutination for isolate characterization.
Main Results:
- Nodular bronchiectasis patients (n=17) exhibited high MAC genotypic diversity (mean 2.9 genotypes/patient), with 88% having ≥2 genotypes.
- Cavitary disease patients (n=9) showed limited MAC diversity (mean 1.2 genotypes/patient), with only 11% having ≥2 genotypes.
- Mycobacterium intracellulare was common; many isolates were rough or seroagglutination-nontypable. Related genotypes with shared PFGE bands were observed within patients.
Conclusions:
- Nodular bronchiectasis is associated with multiple and/or repeated MAC infections.
- Upper lobe cavitary disease is typically linked to a single MAC strain infection.
- MAC genotypic heterogeneity differs significantly between these chronic lung disease phenotypes.