Clinically Important Fungi Flashcards
Culture Medium For Fungi
Sabouraud dextrose agar (slightly acidic, has some antibactrial agents)
Stains used for fungi
Gram stain (positive), Periodic Acid Schiff and India Ink
Primary Pathogens Def
Organisms that cause disease in immunocompetent and immunosuppressed individuals. Eg cryptococcus
Opportunistic Pathogens
Organisms that cause disease in immunocompromised individuals eg Candida
Why most fungi don’t effect immunocompetent individuals
High innate immunity (barriers eg skin and white blood cells eg neutrophils) and presence in normal flora
Types of fungal pathogenicity
Infection (invasion with immune response), hypersensitivity (allergy response, asthma) and toxins
Types of Infection
Superficial (skin, hair and nails eg dermatophytes, thrush), Subcutaneous (deep skin tissue, muscles. Eg Sporotrichoses) and Systemic (lungs spreading to rest of body eg cryptococcus)
What does a severe superficial infection indicate
Problems with immune system
3 dermatophytes genra
Trichophyton (tinea pedis), Epidermophyton (tinea ungiuim (nail) and skin foldings) and microsporum (tinea capitis)
How to handle fungi sample under microscope
Treat with KOH to remove keratinised cells (human cells). Allows clearer viewing
Sporothrix Schenkii Outline
Subcutaneous infection from thorns and soil. Initial ulcer may result in granuloma. May develop local osteoarticular or disseminated infection
Conidia Outline
Subcutaneous Infection. May result in pulmoanry disease
4 systemic fungal infections
candida (immunocompromised), Cryptococcus (immunocompromised, HIV positive), histoplasma capsulatum and aspergillus
Candida Albican Outline
Pseudo yeast (identified by psuedo hyphae under microscope (failure in bussing)). Opportunistic pathogen (part of normal mouth and intestine flora). Can be cultured on candida chrome agar
Mucosal Candida Infection Symptoms
erythema, plaque like swllings, found in warm moist swelling (skin foldings) and itchy, red malcar rash
Candida Risk Factor
Antibiotic, pregnancy, steroids and immunosupresssion
Mucosal Candida Treatment
Topical antifungal: clotrimazole and oral: fluconazole
Invasive Candida Infection Outline
Immunocompromised host. Common source of BSI in hospitals
Invasive Candida Risk Factors
Antibiotic/steroid therapy, immunosupressed (HIV, chemo), transplant, post-operative, IV catheters, diabetes mellulitis and burns
Invasive Candida Symptoms
Fever, no response to broad spectrum antibiotics, multi-site colonisation. Microscopy: budding conidia, purple gram stain and pseudo hyphae. Sabouraud dextrose and chromogenic agar
Cryptococcal Infection
Suspect based on patient history and co-morbidities. Antigen detection in blood/CSF. White creamy colonies on sabouraud dextrose
