Molecular typing of aspergilli: Recent developments and outcomes

Area of Science:

• Medical Mycology
• Molecular Epidemiology
• Infectious Diseases

Background:

• Aspergillus species are significant causes of opportunistic infections.
• Epidemiological studies are crucial for understanding the transmission and sources of Aspergillus-related diseases.
• Accurate strain typing is essential for clinical and public health investigations.

Purpose of the Study:

• To review and highlight the utility of DNA-based typing techniques for Aspergillus species.
• To discuss the implications of typing results for understanding invasive aspergillosis (IA) and fungal pathogenicity.
• To explore the population genetics and evolutionary history of key Aspergillus species, particularly Aspergillus fumigatus.

Main Methods:

• Review of epidemiological studies utilizing various DNA-based typing methods.
• Analysis of typing results from clinical and environmental Aspergillus isolates.
• Examination of genetic data to infer population structure and evolutionary processes in Aspergillus.

Main Results:

• DNA-based methods like RFLP and multilocus sequence typing are effective for Aspergillus strain differentiation.
• Most invasive aspergillosis patients are infected by a single Aspergillus strain.
• No genetic distinction exists between clinical and environmental Aspergillus fumigatus, indicating environmental strains are potential pathogens.
• Typing identified new pathogenic species (e.g., A. lentulus) and revealed two distinct genetic groups within A. fumigatus.
• Aspergillus fumigatus exhibits characteristics of a cosmopolitan fungus with evidence of recombination, likely due to sexual reproduction.

Conclusions:

• Strain typing is indispensable for tracking infection sources and understanding Aspergillus epidemiology.
• Environmental Aspergillus strains pose a significant risk for invasive infections.
• Aspergillus fumigatus has a complex population structure, suggesting a history of recombination and sexual reproduction, contributing to its global distribution.