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MycologyLec,7

Opportunistic mycosis Dr.Huda Ibrahim

Oppurtunistic mycosis

Ordinary fungi causing extraordinary disease Infections due to fungi of low virulence in patients who are immunologically compromised

Opportunistic fungi

1. Saprophytic - from the environment e.g.,Cryptococcus sp. , Aspergillus, Zycomycetes.2. Endogenous – a commensal organism e.g., Candida sp. Include many species from: A (Aspergillus)To Z (Zygomyces)

Predisposing Factors: Providing a Route/ Source

Antibiotics Burns and other skin problems Catheter- related problems Devices (prosthetic) Effects on mucosal integrity Fungus isolated previously

Inducing Immunosuppression

AIDS Bone marrow/ organ transplantation Cancer: Leukemia, lymphoma etc Drugs: Cytotoxic drugs,steroids etc Endocrine related: Diabetes Failure of organs: multi-organ

Candida albicans and other Candida species

Harmless inhabitants of the skin and mucous membranes of all humans Normal immune system keeps candida on body surfaces


THE MOST IMPORTANT RISK FACTORS
1. Neutropenia(less than 100 N/L) 2. Diabetes mellitus 3. AIDS 5. Myeloperoxidase defects 6. Broad-spectrum antibiotics

THE MOST IMPORTANT RISK FACTORS

7. Indwelling catethers 8. Major surgery 9. Organ transplantation 10. Neonates 11. Severity of any illness 12. Intravenous drug addicts

INVASIVE CANDIDIASIS

If phagocytic system is compromised, infection spreads to many organs and causes focal infection in these organs (kidney ,eye ,heart , liver , meninges) mortality of candidemia is 30-40% Prophylactic antifungal drugs during cytotoxic course of therapy

DIAGNOSIS OF INVASIVE CANDIDIASIS

Gram stain and isolation from blood, CSF , urine ,sputum or peritoneal fluid Serology PCR (promising) isolation and/or pathology positive of organ involved

EPIDEMIOLOGY

Although candidiasis is endogenous in most cases, cross infections are described, especially in intensive care unit patients. Account for 80% of nosocomial fungal infections Account for 30% of deaths from nosocomial infections

* Cryptococcosis and Cryptococcus neoformans

Cryptococcus neoformans causes cryptococcosis. A widespread encapsulated yeast that inhabits soil around pigeon roosts Common infection of AIDS, cancer or diabetes patients Infection of lungs leads to cough, fever, and lung nodules Dissemination to meninges and brain can cause severe neurological disturbance and death.

Diagnosis

Microscopic India Ink for capsule stain (50-80% + CSF) Gram Silver stain Culture Bird seed agar Routine blood culture Serology

* Aspergillosis: Diseases of the Genus Aspergillus

Very common airborne soil fungus600 species, 8 involved in human disease; A. fumigatus most commonlySerious opportunistic threat to AIDS, leukemia, and transplant patientsInfection usually occurs in lungs – spores germinate in lungs and form fungal balls; can colonize sinuses, ear canals, eyelids, and conjunctivaInvasive aspergillosis can produce necrotic pneumonia, and infection of brain, heart, and other organs.Amphotericin B and nystatin

* Zygomycosis

Zygomycota are extremely abundant saprophytic fungi found in soil, water, organic debris, and food. Genera most often involved are Rhizopus, Absidia, and Mucor. Usually harmless air contaminants invade the membranes of the nose, eyes, heart, and brain of people (Rhinocerebral mucormycosis) with diabetes and malnutrition, with severe consequences. main host defense is phagocytosis

Diagnosis is made by direct smear and by isolation of molds from respiratory secretions or biopsy specimens. Treatment: Control Diabetes ,surgery & amphotericin B Prognosis: very poor

Diagnosis of opportunistic infections requires a high index of suspicion

Atypical signs or symptom...M.furfurUnusual organ affinity…liver candidiasisOutside the endemic areaUnusual Histopathology…necrosisEtiologic agent may be a “saprophyte”Serological response may be suppressed

IMPROVING TREATMENT

New Drugs…EchinocandinNew therapeutic regimenAggressive therapy…prophylacticConjunctive therapy..ImmunotherapyIL, IFN,CSF

“Only the prepared mind can help the impaired host”Libero Ajello, Chief Mycology Division, CDC 1972


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