Cryptococcus neoformans: size range of infectious particles from aerosolized soil

Area of Science:

• Mycology
• Infectious Diseases
• Environmental Microbiology

Background:

• Cryptococcosis is primarily a chronic central nervous system disease.
• The lungs are considered the main entry point for Cryptococcus neoformans.
• Evidence for airborne Cryptococcus neoformans particles reaching alveoli is limited.

Purpose of the Study:

• To determine if viable airborne Cryptococcus neoformans particles are small enough for deep lung deposition.
• To investigate the size distribution of airborne Cryptococcus neoformans over time.

Main Methods:

• Inoculation of Cryptococcus neoformans strains into sterile soil.
• Aerosolization of soil using a Waring blender in a sealed chamber.
• Collection and analysis of airborne particles using an Anderson air sampler.

Main Results:

• 15% of viable airborne organisms were 0.65 to 2 microns in diameter.
• Particle size decreased, and the number of 0.65 to 2 micron cells increased with incubation time.
• Viable Cryptococcus neoformans cells capable of deep lung deposition were identified in soil aerosols.

Conclusions:

• Viable Cryptococcus neoformans cells can exist in sizes (0.65-2 microns) capable of reaching the alveoli.
• Environmental conditions can influence the size of airborne Cryptococcus neoformans.
• These findings support the hypothesis of deep lung deposition as an entry route for cryptococcosis.