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Comparison of Mycobacterium avium complex (MAC) strains from pigs and humans in Sweden by random amplified
P Ramasoota1, N Chansiripornchai, G Källenius
1Department of Veterinary Microbiology, Section of Bacteriology, Swedish University of Agricultural Sciences, Box 7036, S-750 07, Uppsala, Sweden.
Abstract:
Infections with atypical mycobacteria belonging to the Mycobacterium avium/intracellulare complex (MAC) can cause infection in both animals and humans. Using a standardized reagents commercial kit for random amplified polymorphic DNA (RAPD) analysis, 49 MAC strains isolated from 32 slaughter pigs and 17 humans in Sweden were identified and sorted out, yielding 6 RAPD types. By combining the results of RAPD primers 4 and 5 and the primer IS1245A, we found that pigs and humans may be infected with the same types of MAC strains, since 14 strains from humans and 8 strains from pigs were essentially identical and together, comprised RAPD type 2, the largest group of strains (44.8% of strains). With respect to grouping of strains, serotype and RAPD type were uncorrelated, except for serotype 20 and RAPD type 6. Using standardized beads, RAPD analysis is a reproducible technique for typing MAC strains, as the indistinguishable banding patterns obtained with repeated analyses of two isolates from each strain in this study demonstrate. However, primer selection and DNA purity were crucial for differentiating closely related strains.
Insights
This study reveals that the same Mycobacterium avium/intracellulare complex (MAC) strains infect both pigs and humans. Random amplified polymorphic DNA (RAPD) typing confirmed shared MAC strains between animal and human populations.
Area of Science:
- Veterinary Microbiology
- Human Infectious Diseases
- Molecular Epidemiology
Background:
- Mycobacterium avium/intracellulare complex (MAC) infections pose a One Health challenge, affecting both livestock and humans.
- Accurate strain differentiation is crucial for understanding transmission dynamics and implementing control strategies.
Purpose of the Study:
- To investigate the genetic relatedness of MAC strains isolated from pigs and humans in Sweden.
- To evaluate the utility of Random Amplified Polymorphic DNA (RAPD) analysis for MAC strain typing.
Main Methods:
- Analysis of 49 MAC strains (32 from pigs, 17 from humans) using a commercial RAPD kit.
- Employing specific RAPD primers (4, 5, and IS1245A) for strain differentiation.
- Assessing reproducibility of RAPD typing using standardized beads and repeated analyses.
Main Results:
- Six distinct RAPD types were identified among the MAC strains.
- A significant overlap was observed, with 22 strains (14 human, 8 pig) belonging to RAPD type 2, indicating shared strains.
- Serotype and RAPD type were generally uncorrelated, with an exception for serotype 20 and RAPD type 6.
Conclusions:
- Random Amplified Polymorphic DNA (RAPD) analysis, when optimized with appropriate primers and DNA purity, is a reproducible method for typing MAC strains.
- The findings suggest potential zoonotic transmission or a common environmental source for MAC infections in pigs and humans.
- Further research into primer selection and DNA quality is essential for robust strain differentiation.