Fungal pathology

Fungal pathology

1. Dermatophytes

   • group of keratinophilic fungi seen as the cause of disease in skin, hair and nails
   • 3 general types
     • trichopyton
     • microsporum
     • epidermophyton
   • originate in:
     • soil = geophilic
     • animals = zoophilic
     • confined to humans = anthropophilic

2. Tina pedis

   • uni- or bilateral
   • itching, flaking, fissuring of skin
   • interdigital: tower skin wet and macerated
   • plantar: soles of feet dry and scaly
   • hyperhidrosis, secondary infection, may increase severity
   • may spread to infect toenails
   • typical cause = Trichophyton rubrum

3. Tina unguium (onychomycosis)

   • thickening, discolouring, dystrophy
   • 4 main types
     • lateral/distal subungual
     • superficially white (usually immunocompromised)
     • proximal
     • total nail dystrophy
   • typical causes = Trichophyton rubrum and T. interdigitale

4. Tina cruris

   • more prevalent in men
   • itching, scaling, erythematous, plaques w/ distant edges
   • satellite lesions sometimes present
   • may extend to buttocks, back and lower abdomen
   • typical cause = T. rubrum

5. Tina capitis

   • range from slight inflammation, scaly patches to sever inflammation
   • Kerion celsi
     • boggy, inflamed lesions
     • usually from zoophilic dermatophytes
   • Favus
     • presence of cup-shaped crusts or scutula
   • hair invasion
     • endothrix = spores in the hair shaft (leads to black dots)
     • favic = hyphae only in the hair shaft
     • extothrix = spores outside the hair shaft

6. Tinea corporis

   • circular, single or multiple erythematous plaques
   • may extend e.g scalp to groin
   • invasion of follicle
     • "Majoccis's follicle"
   • typical cause = wide range of dermatophytes; anthropophilic or zoophilic

7. CANDIDA

   • large genus of yeast
   • colonises the mucosal surfaces and GI tract in healthy people
   • causes superficial mucosal ideas (oral and vaginal) "thrush"
   • cause of systemic disease once in circulatory system, can infect almost any organ
     • candida sp. can infect almost any organ in the body
     • defined by site of infection
     • usually acquired from colonised skin or mucosal sites or from GI tract
     • usually seen in compromised host
     • candida albicans is the most common
   • caused by a range of Candida species
     • Candida albicans
     • Candida parapsilosis
     • Candida glabiata
     • Candida kruse
   • Superficial candida infection of oral mucosa
     • acute pseudo-membranous --> low CD4 count, younger patients with asthma
     • chronic atrophic --> older patients, erythema
     • angular cheilitis
     • chronic hypoplastic --> oral leukoplakia, lesions may undergo malignant transformation
   • Epidemiology of oral candidosis
     • HIV/AIDS --> sometimes even with anti-retroviral therapy; T-cell immunity important to prevent mucosal candidosis
     • Antibiotic use --> suppresss normal bacterial flora, less competition for yeasts
     • Head and neck cancer --> radiotherapy and chemotherapy affect immune responses and salivary secretions
     • General debilitation in hospital patients --> increases colonisation and risk of oral disease

8. Candida vulvovaginitis

   • affects 70-80% of all women during child bearing years
   • parities, burning sensation, possibility of discharge
   • inflammation of vaginal epithelium, may extend to labia majora
   • often more florid infections during pregnancy
   • approx 10% of women get recurrent infections

9. Candida oesophagitis

   • mainly in HIV
   • in 10-20% of patients who have oropharyngeal disease
   • painful/difficult to eat/swallow
   • diagnosed by endoscopy and biopsy

10. Candida endocarditis

    • rare consequence of candidaemia
    • IV drug abusers, valve surgery
    • vegetations on heart valves
    • fever, weight loss, fatigue, heart murmur
    • difficult to treat w/o valve replacement

11. Renal candidosis

    • candida from blood lodges in the kidney during filtration
    • immunocompromised, premature neonates
    • fever, abdominal pain, oliguria, anuria

12. Urinary tract candida infection

    • ascending from genital tract, infection/colonisation or from catheterisation
    • more common in:
      • women
      • damaged/abnormal urinary tracts
      • diabetics
    • hard to manage as few anti-fungals are secreted in urine

13. Candida peritonitis

    • complication of peritoneal dialysis
    • perforation of bowel during surgery
    • fever, abode pain, nausea, vomiting
    • treatment = source control/drainage, antifungals

14. Hepatosplenic candidosis

    • disseminated form of candidosis
    • leukaemia, other herpetological malignancies
    • candidaemia during period of neutopenia
    • during neutrophil recovery, yeasts lodge in the liver and spleen
    • access formation, fever, liver function disturbance
    • anti-fungal therapy may be ineffective as dead fungus continue to trigger inappropriate inflammatory response

15. Candidaemia

    • candida in the blood
    • appropriate responses:
      • remove lines where possible
      • start anti-fungal therapy
      • check heart and eyes

16. ASPERGILLUS

    • genus of moulds- filamentous fungi
    • airborne spores
    • exposure is universal by inhalation
    • airway may be colonised by aspergillus s.p
    • examples of important species:
      • A. niger
      • A. flavus
      • A. terreus
      • A. fumigatus
    • Aspergillosis
      • reaction to inhaling aspergillus
      • space occupying/non-invasive in the lung cavity = aspergilloma (fungal ball)
      • allergic reaction - asthma, CF
      • chronic infection - chronic lung infection --> chronic pulmonary aspergillosis
      • invasive infection - immunocompromised (leukaemia) --> invasive pulmonary aspergillosis
      • Allergic forms of aspergillosis:
        • 1) Asthma
          • severe asthma w/ fungal sensitisation
          • wheezing, breathlessness
          • IgE reaction to fungi
          • responds to anti-fungal therapy and steroids
        • 2) CF
          • allergic broncho-pulmonary aspergillosis
          • wheezing, breathlessness, loss of lung function, bronchiectasis
          • airway inflammation
          • IgE and IgG reaction
          • responds to anti-fungal therapy and steroids
    • Aspergilloma
      • patients with cavities from previous TB, sarcoid, surgery
      • form solid balls of fungus
      • often indolent, may break up

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