' and Fungal Infections

Eukaryotic Cells

Overview

• Eukaryotic cells include:
  • Fungi
  • Algae
  • Protozoa
  • Helminths
  • Viruses (not classified as eukaryotic but discussed in context)

Fungi of Medical Importance

Candida albicans

Characteristics

• Opportunistic fungal infection.
• Commonly causes:
  • Oral Candidiasis (Oral Thrush): Characterized by aphthous ulcers with tenderness.
  • Vaginal Candidiasis: Symptoms include cheesy/curd-like vaginal discharge, severe pruritus, and scaly erythematous vulva with maculopapular lesions, particularly in the vulva and inguinal regions.
  • Systemic Infections: Can lead to endocarditis, particularly in drug users who share needles.

Predisposing Factors

• Immunocompromised patients (e.g., those in a coma, HIV-positive).
• Prolonged steroid use (common in organ transplant patients).
• Diabetes Mellitus: Symptoms include polyuria, polydipsia, and polyphagia.
• Malnutrition.
• Prolonged antibiotic use.
• Elevated pH (alkaline conditions).
• Menopause.
• Frequent use of panty liners.
• Pregnancy (oral antifungal drugs are contraindicated; vaginal suppositories are preferred).

Laboratory Tests for Candida albicans

• KOH Smear: Helps visualize fungal elements.
• Gram Staining: To identify fungal characteristics.
• Culture: Cultured on Sabouraud’s Agar for identification.

Mode of Transmission (MOT) for Candida albicans

• Coitus.
• Changes in pH.
• Needle-sharing.
• Trauma.

Treatment

• Fluconazole (Diflucan): 150 mg, single dose once a week for 4 weeks.

Other Opportunistic Fungal Infections

Aspergillus fumigatus

Disease

• Allergic Bronchopulmonary Aspergillosis: Results in a chronic, hard, non-productive cough.
• Lung Cavitary Aspergilloma: Appears as a “fungus ball” on chest X-ray.

Morphological Characteristics

• Mold with septate (segmented) hyphae branching at a 45-degree angle (V-shaped).

MOT

• Aerosol transmission.

Treatment

• Nystatin (Mycostat): Oral drops.
• Fluconazole, Clotrimazole, Ketoconazole: Other antifungal treatments.

Cryptococcus neoformans

Lab Test

• Negative Staining with India Ink: Helps identify encapsulated yeasts.

Disease

• Cryptococcal Meningitis.

Affected Individuals

• Common in immunocompromised patients (HIV, coma).

MOT

• Contact with pigeon or bird droppings.

Treatment

• Amphotericin-B, Fluconazole.

Mucor and Rhizopus

Disease

• Mucormycosis.

Affected Individuals

• Ketoacidotic diabetic patients, leukemic patients.

Treatment

• Treatment with azoles.

Pneumocystis carinii

Classification Change

• Previously classified as protozoa, now considered fungi.

Disease

• Diffuse Interstitial Pneumonia.

Affected Individuals

• Immunocompromised, particularly HIV-positive patients.

MOT

• Inhalation of aerosols.

Lab Test

• Silver Staining from lung biopsy or lavage.

Treatment

• Co-trimoxazole, Dapsone, Pentamidine.

Morphological Characteristics

• Spores.

Systemic Mycoses

Histoplasmosis

High-Risk Factors

• Exposure to bird or bat droppings.

Blastomycosis

Geographic Distribution

• Found in North America (Ohio, Mississippi river valleys, Great Lakes) and also in Canada, Africa, and India.

Infection Method

• Breathing in air containing spores.

High-Risk Groups

• Immunocompromised individuals, organ transplant recipients, those with chronic illnesses.

Sporotrichosis

Geographic Distribution

• Occurs worldwide, particularly in the United States, South Africa, Mexico, and South America.

Disease Characteristics

• Caused by the dimorphic fungus Sporothrix schenckii.
• Symptoms include subcutaneous nodules that may ulcerate and discharge pus.
  • Lymphocutaneous lesions commonly occur on hands, arms, neck, and feet due to traumatic implantation from rose thorns.

Cutaneous Mycoses

General Characteristics

• MOT: Prolonged skin-to-skin contact.

Fungal Diseases

Dermatophytes

• Genera include Microsporum, Tricophyton, and Epidermophyton.

Fungi Associated with Specific Conditions

• Malasezzia furfur: Causes Tinea versicolor.
• Cladosporium werneckii: Causes Tinea nigra, located on the palm and sole.