Control of Fungi

Principles and Practice of Controlling Fungal Growth

Control by Management of Environmental and Biological Factors

  • Physical and Environmental Control: Fungi can be managed through temperature control and atmospheric conditions.

    • Controlled Atmosphere Storage: Utilizes cool temperatures and elevated CO₂ levels for storage and shipment of produce.

  • Sanitation and Quarantine:

    • Prevent spread through cleanliness and controlled environments.
    • Effective strategies for avoiding diseases.

  • Crop Management Techniques:

    • Crop Rotation: Traditional method for controlling various plant diseases.
    • Meteorological Forecasting: Use of weather forecasts in disease management.
Biological and Integrated Control
  • Biological Control: Involves the management of pests through natural organisms rather than chemicals.
Chemical Control of Fungi
  • Principal Cellular Targets of Antifungal Agents:
    1. Cell Membrane: Targeting ergosterol unique to fungi.
    2. Microtubules and Microfilaments: Disrupted by antibiotics like griseofulvin.
    3. Mitochondrial Respiration: Affected by specific plant fungicides.
    4. Cell Wall Components: Especially β1-3 glucans targeted by echinocandins.
    5. General Metabolism: Various fungicides affect metabolic pathways.
Types of Fungicides
  • Classification by Functionality:
    • Inorganic Fungicides: Sulphur, copper, and mercury-based. Limited due to solubility issues but effective for surface infections like powdery mildew.
    • Organic Contact (Protectant) Fungicides: Protect plant surfaces and control existing infections; e.g., dithiocarbamates.
    • Systemic Fungicides:
    • Absorbed and distributed internally to protect new growth.
    • Early examples include benzimidazole compounds like thiabendazole and benomyl.
Control of Fungal Infections in Humans
  • Challenges: Infections in immunocompromised individuals are particularly difficult to manage.
  • Griseofulvin: Naturally occurring antibiotic used for dermatophyte infections but requires prolonged treatment due to fungistatic properties.
Key Antifungal Antibiotics
  • Examples:
    • Griseofulvin:
    • Produced by: Penicillium griseofulvum
    • Action: Targets fungal tubulins
    • Polyene Macrolides:
    • Derived from Streptomyces spp.
    • Examples include amphotericin B and nystatin.
    • Azole Drugs: Ergosterol biosynthesis inhibitors, effective against systemic mycoses (e.g., fluconazole, ketoconazole).
New Developments in Antifungal Therapy
  • 5-Flucytosine (5-FC): Initially an antitumor agent, now also effective against Candida and Cryptococcus when combined with amphotericin B.
  • Echinocandins:
    • Inhibit β1-3 glucan synthesis, recent developments include caspofungin, micafungin, and anidulafungin.
Future Directions in Fungal Infection Control
  • Need for New Antifungal Drugs: Slow pace of development heightens the risk of resistance emergence.
  • Vaccine Development: Ongoing research focused on vaccines against endemic pathogenic fungi like Coccidioides immitis and Paracoccidioides brasiliensis.
References
  • Key Texts: Fungal Biology by J.W. Deacon 4th Edition, Introduction to Mycology - C.J. Alexopoulos
  • Various online drug databases and resources to access specific medication information and latest research.