Fungi by the Tristram scheme

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Fungi by the Tristram scheme
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Opportunistic Fungal Infections (M8.1)with minor
updates sorry!

• In the past, all fungi were categorised as
  pathogens or saprophytes those days are gone
  forever.
• Hyaline hyphomycetes
• Aspergillus, Scedosporium, Fusarium, others.
• Zygomycetes
• Mucor, Rhizopus, Rhizomucor, others.

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Common factors (M8.2)

• Common in environment.
• Abundant conidia / release, and therefore
  frequent airborne contaminants.
• Grow rapidly.
• Initial entry is usually pulmonary (for systemic
  disease).
• Interpretation of culture can be a problem
• Contaminant, coloniser, infection?

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Hyaline hyphomycetes (M8.3)

• Colourless septate hyphae and pigmented conidia
  (if thallus is pigmented)
• Important genera
• Aspergillus (green to black)
• Scedosporium (Pseudallescheria)
• also rans
• Fusarium (pinkish)
• Paecilomyces (pinkish)
• Penicillium (green to brown)

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Penicillium spp. (M8.4)

• Nearly always a contaminant
• Important to recognise
• Has NO vesicle.

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Aspergillosis (M8.5)

• 600 species, 20 in humans, 4 common
• A. fumigatus, flavus, niger, terreus
• Identification
• Macroscopic morphology (pigmentation)
• Microscopy
• Head coverage
• Length of conidiophore
• Uniseriate or biseriate

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Aspergillosis (M8.6)

• Clinical manifestations
• Contaminant
• Superficial
• Otomycosis and keratitis
• Respiratory
• Colonising, allergic, aspergilloma, acute
  invasive.
• Disseminated
• Immunosuppressed, nosocomial

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Laboratory diagnosis (M8.7)

• Direct microscopy
• Helpful in establishing veracity of isolate.
• Septate, dich branching hyphae (non spec)
• Culture
• Non fastidious, but cyclohexamide S
• Problems with dissemination
• Non culture
• Antibody, antigen, metabolites, PCR

Invasive aspergillosis has a crude mortality rate
of 95, due to nature of patient AND to problems
in rapid diagnosis.
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Impact of Early Diagnosis (M8.7a)(from Perfect
ASA 2004)

• Aspergillus pneumonia
• 10 d mortality 9/22 (41)
• gt10d mortality 9/10 (90)t
• Systematic CT scan (2d) 20 mortality
• on indication CT scan (7d) 58 mortality?
• t von Eiff et al, Resp. 1995
• ? Caillot et al, J. Clin. Oncol. 1997

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037
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Zygomycetes (M8.8)

• Mucor, Rhizopus, Rhizomucor
• Sexual stage has zygospores, but the asexual
  stage is typical with BROAD non septate hyphae
  and sporangia

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Zygomycosis (8.9)

• Also called Mucormycosis
• Acquired by inhalation, affects neutropenics,
  diabetics, malignancy
• Can disseminate to any organ.
• VASCULAR INVASION and infarction.
• Rhinocerebral mucormycosis
• A special case, uncontrolled diabetes

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582
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580
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Case Study

• Liang et al JCM 2006, 44,3.
• 50 year old diabetic.
• R eye pain and proptosis
• Debridement and amp B.

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Agar flotation method

• A method apparently useful in making some of
  the weakly sporulating Zygomycetes produce
  spores.
• Also use 1 water agar (D. Ellis)
• Probably amounts to fungal abuse

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Zygomycosis (8.10)

• Laboratory diagnosis
• Urgency
• Direct microscopy typical
• Culture
• Can be negative after maceration.
• Very rapid growth.

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585
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Case Study

• Salinas et al, Lab Medicine, 2004, 335
• 24 year old male, motorcycle accident
• Facial laceration, facial and neck fractures,
  bleeding from nares, SAH and SDH.
• Day 4 wound culture grew E. coli and .

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• Within 5 days colony filled plate.
• No fruiting bodies.
• Fontana-masson stain on Bx
• (?dermatiaceous sic)

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• Day 9 necrosis on neck 72 hrs debride x 3.
• 1 water agar induction of sporulation.

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• Apophysomyces elegans
• 15 body debridement topical/oral Amp B

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Scedosporium spp.

• S. apiospermum (Pseudallescheria boydii)
• S. prolificans
• Both common causes of mycetoma worldwide
• Increasing incidence, esp in Aus of pulmonary and
  disseminated disease.
• Colonising airways - CF patients, lung Tx
• Dissemination in neutropenics

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Treatment of Scedosporium infections

• Very very difficult.
• Both species are resistant to most commonly used
  antifungal drugs.
• Successful therapy often involves experimental
  combinations of drugs.

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530
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Case study

• Kowacs et al J Clin Path 2004, 57.
• 32 year old male, post near drowning in pig
  sewerage reservoir.
• 15 days post, fever, headache.
• CT scan abscesses or granuloma.
• CTX, MTZ, fluconazole and discharged.

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• 2 weeks later, returned CSF 1300 / mm3
• Mannitol, dexa, vanc, rif, ctx, carbamazepine.
• 2 days later, siezures, CSF 3000 / mm3
• Neg microbiology but suspect Scedosporium
• Add amphotericin B and itraconazole.
• Worsened clinically
• Neg Cryptococcus, amoebae, bacteria
• Finally grew Scedosporium apiospermum
• Dexa, clonaz, phenytoin, cefipime, vanv, MTZ,
  fluc, amp B, intra-thecal miconazole.
• Died 3 days later (3 months post pres)

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Nosocomial fungal infections (M8.11)

• Increasing, and at a disproportionate rate to
  other nosocomial infections.
• Risk factors
• Immunosuppression
• profound and prolonged neutropenia following
  chemotherapy
• post transplant (bone marrow, heart are high)
• Increased access via catheters and other.

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Nosocomial fungal pathogens (M8.12)

• Candida albicans
• 7th most common nosocomial pathogen!
• Fungaemia and dissemination
• Other yeasts
• Candida spp, and non Candida
• Aspergillus spp.
• Other emerging pathogens.

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Nosocomial fungal infections (M8.13)

• Epidemiology
• Endogenous vs Exogenous
• Hepa filters, no plants
• Body surveillance for Candida albicans
• Outbreaks
• Airborne (construction)
• Cross infection minor issue
• Contamination - TPN

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Nosocomial Fungal Infections (M8.14)

• Very high mortality
• 30 of deaths following prolonged neutropenia are
  diagnosed with fungal infection post mortem.
• 2x mortality if nosocomial fungal
• 50 crude mortality for Candidaemia.
• Poor diagnostic tools
• Relatively poor drugs (getting better)
• Non routine sens testing
• Contribution of host factors.

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Fungi and air quality (M8.15)

• sick building syndrome
• Respiratory problems, sneezing, congestion,
  cough, eyes burning, SOB
• CNS problems, headaches
• Proliferation of moulds (moisture) and dispersal
  of conidia.
• Water bed!, pot plants, windows in cold climates,
  air conditioning systems.

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Mycology Review

• Fungal structure
• Yeasts vs moulds vs dimorphism
• Birds and the bees
• Superficial mycoses
• Cutaneous mycoses
• Subcutaneous mycoses
• Endemic systemic dimorphic mycoses
• Pathogenic yeasts
• Hyalohyphomycetes
• Zygomycetes