L30. Fungal infections: susceptible in AIDS Flashcards
What are the two classifications of Fungi, appearance and reproduction and give eg of the most common ones
- Yeast
- Round/oval single cell organism.
- Reproduce by budding
eg. Candida albicans, Cryptococcus neoformans
- Moulds
- Tubular hyphae,
- Reproduce by generating spores extending from tubular hyphae.
eg. Dermatophyes,
Aspergillus sp.
What are the potential differentials for slowly developing headache, fever and impaired thinking in AIDS
- Brain parenchyma abscess due to
eg. Toxoplasma Gondii:
- from cat faeces
- Reactivation of chronic infection
eg. bacteria
- Meningitis due to
eg. Cryptococcus neoformans
- usually held off by immune system
eg. virus, bacteria
3.Encephalitis: diffuse infection of brain parenchyma (viruses)
Order the aids diagnoses in relation to declining CD4 count (most to least)
Tb, causes of headache, candidiasis, CMV disease`
- TB, Herpes zoster, oral candidiasis
- Pneumocystis pneumonia, oesophageal candidiasis
3.Toxoplasma brain abscesses
Cryptococcal meningitis, Kaposi’s sarcoma
4.CMV disease,
MAIC disease
Where does Candida albicans commensal, how can it cause disease and what types of disease
- Lives on mucosal surface of mouth, gut and vagina. Not blood.
- Disease/ overgrowth due to
- antibiotics: (loss of competition)
- Immune suppression (loss of host defences)
- hormonal effects (cycle),
- Foreign bodies eg. catheter - Disease:
- Oral/vaginal thrush - generally palate
- Cutaneous or nail candidiasis
- Urinary catheter related bladder infection
- Rare systemic infection if long time central IV line
How is Candida albicans diagnosed and treated
Swabs taken.
Grown on blood agar, seen as black yeasts with pseudohyphae on gram stain.
Treated with topical cream/pessary or sometimes oral if its nail.
- Nystatin suspension
- Amphotericin B pastilles
- Azole pessary/cream
Where does Cryptococcus neoformans come from, how can it cause disease and what types of disease
Associated with pigeon faeces (other types with eucalyptus bark
Diseases (only in severe immunodeficiency - neutropenia
- Pulmonary infection
- Spreads via blood to CSF to cause Meningitis : slow deterioration in mental state with headache and fever.
How is Cryptococcus neoformans diagnosed and treated
Lumbar puncture of CSF:
- 10-100 WBC, lymphocytes low neutrophils.
- Raised protein, low glucose
Culture:
- Encapsulated yeasts seen w India ink stain
- Brown colonies on bird seed agar
- ELIZA cryptococcal antigen positive in CSF and serum
Treatment : 6 wks therapy
- IV amphotericin B
- IV or oral fluconazole
What diseases does dermatophytes cause, how is it transmitted and how does it present
Diseases
1. Tinea/ringworm of capitis (dandruff/loss of hair) , corporis, cruris, pedis, nails
- Scaly skin/red
Have human or animal hosts but are never invasive
- Pityriasis versicolor : hyper-pigmented macules on trunk
- Seborrheic dermatitis: greasy facial rash forehead, /dandruff
What is the diagnosis and treatment for dermatophytes disease
Microscopy and culture from skin flakes to diagnose
Treatment
- Topical azole for skin
eg. Ketaconazole, miconazole - Oral agent for nails: terbinafine or itraconazole for 3-4 months- no guarantee of getting rid of
Where does Aspergillus fumigatus come from, what diseases does it cause and how,
What treatment
- come from rotting vegetation
2a) Rare cause of severe disease in neutropenic patients
or
b) allergic bronchopulmonary aspergillosis due to persistent colonisation of the lung due to excess fluid
- -> cavitating pneumonia, trigger asthma.
Treatment:
- Voriconazole starting with IV-> Oral
- Amphotericin B IV for weeks
- Surgery
Describe the mechanism of function of amphotericin B and Azole - eg. ketaconazole, fluconazole
and the SE
Amphotericin binds to ergosterol only found in fungi cell wall to disrupt it.
SE: infusion related anaphylactic reaction , nephrotoxicity with K+ loss
Azoles inhibit the synthesis of ergosterol
SE: relatively non-toxic
