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High resolution genotyping of clinical Aspergillus flavus isolates from India using microsatellites
Shivaprakash M Rudramurthy1, Hanneke A de Valk, Arunaloke Chakrabarti
1Mycology Division, Department of Medical Microbiology, Post Graduate Institute of Medical Education and Research, Chandigarh, India.
Background:
Worldwide, Aspergillus flavus is the second leading cause of allergic, invasive and colonizing fungal diseases in humans. However, it is the most common species causing fungal rhinosinusitis and eye infections in tropical countries. Despite the growing challenges due to A. flavus, the molecular epidemiology of this fungus has not been well studied. We evaluated the use of microsatellites for high resolution genotyping of A. flavus from India and a possible connection between clinical presentation and genotype of the involved isolate.
Methodology/Principal Findings:
A panel of nine microsatellite markers were selected from the genome of A. flavus NRRL 3357. These markers were used to type 162 clinical isolates of A. flavus. All nine markers proved to be polymorphic displaying up to 33 alleles per marker. Thirteen isolates proved to be a mixture of different genotypes. Among the 149 pure isolates, 124 different genotypes could be recognized. The discriminatory power (D) for the individual markers ranged from 0.657 to 0.954. The D value of the panel of nine markers combined was 0.997. The multiplex multicolor approach was instrumental in rapid typing of a large number of isolates. There was no correlation between genotype and the clinical presentation of the infection.
Conclusions/Significance:
There is a large genotypic diversity in clinical A. flavus isolates from India. The presence of more than one genotype in clinical samples illustrates the possibility that persons may be colonized by multiple genotypes and that any isolate from a clinical specimen is not necessarily the one actually causing infection. Microsatellites are excellent typing targets for discriminating between A. flavus isolates from various origins.
Insights
Molecular epidemiology of Aspergillus flavus in India reveals significant genotypic diversity using microsatellite markers. This study highlights the potential for multiple genotypes in infections, impacting disease understanding.
Area of Science:
- Mycology
- Molecular Epidemiology
- Infectious Diseases
Background:
- Aspergillus flavus is a significant human pathogen globally, causing allergic, invasive, and colonizing diseases.
- It is particularly prevalent in tropical regions for fungal rhinosinusitis and eye infections.
- Limited molecular epidemiological data exists for A. flavus, hindering effective disease management.
Purpose of the Study:
- To investigate the molecular epidemiology of Aspergillus flavus in India using high-resolution genotyping.
- To assess the correlation between A. flavus genotypes and clinical presentations of infections.
- To evaluate the utility of microsatellite markers for discriminating A. flavus isolates.
Main Methods:
- Selection of nine polymorphic microsatellite markers from the A. flavus genome.
- Typing of 162 clinical A. flavus isolates using these markers.
- Analysis of genotypic diversity and discriminatory power of the markers.
Main Results:
- High genotypic diversity was observed among clinical A. flavus isolates from India, with 124 distinct genotypes identified from 149 pure isolates.
- A combined discriminatory power of 0.997 was achieved using the panel of nine microsatellite markers.
- No significant correlation was found between the genotype of the A. flavus isolate and the clinical presentation of the infection.
Conclusions:
- Clinical isolates of A. flavus from India exhibit substantial genotypic diversity.
- The presence of multiple genotypes in clinical samples suggests possible co-colonization and that not all isolates may be causative agents.
- Microsatellite markers are highly effective for discriminating A. flavus isolates, aiding in molecular epidemiology studies.
