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25 Cards in this Set
- Front
- Back
What are the different types of INFECTIONS that FUNGI may cause?
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1) SUPERFICIAL
2) CUTANEOUS 3) SUBCUTANEOUS INFECTIONS |
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1) SUPERFICIAL MYCOSES?
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- these are infections limited to the outermost layer of skin and hair
- they do not elicit a host cellular response because they grow on tissues that are not living - TINEA NIGRA and TINEA VERSICOLOR are infections of keratinized layer of skin - WHITE and BLACK piedra are infections of the hair |
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2) CUTANEOUS MYCOSES?
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- these infections are deeper in the epidermis, but also infect the hair and nails
- they're called "ringworm" or tinea - these are keratinophilic and have keratinases that allow them to use keratin as a substrate for growth |
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3) SUBCUTANEOUS MYCOSES?
What is it and what are 2 examples of it? |
- this involves the dermis, and subcutaneous tissues
- infections occur at sites of trauma where the organism has implanted into the tissue 1) LYMPHOCUTANEOUS SPOROTRICHOSIS: is a chronic infection characterized by nodular and ulcerative lesions that develop along the lymphatic glands that drain the primary site of innoculation 2) CHROMOBLASTOMYCOSIS: is the development of warty nodules that appear at sites of implantation of fungal elements - bacterial infections mimic fungal infections, and it is important to establish the cause as bacterial or fungal for treatment |
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What is the CLINICAL SIGNIFICANCE of FUNGAL INFECTIONS?
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1) superficial mycoses are significant as cosmetic problem
2) TINEA CAPITUS is a problem in the pediatric population... boys > girls 3) subcutaneous infections are rare in teh US and highly developed countries |
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What are the PROPERTIES/ CHARACTERISTICS OF PATHOGENS in each types of infection?
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*
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1) SUPERFICIAL MYCOSES?
What are 2 examples that cause disease and where are these organisms acquired from? |
*MALASSEZIA FURFUR is lipophilic and grows around sweat glands
*TINEA NIGRA is caused by melatonin- producing dimorphic fungi: CLADOSPORIUM WERNECKII - these organisms are acquired from the soil, animals, or other people via direct contact |
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2) CUTANEOUS MYCOSES?
What causes these infections? What are the 3 generas? |
*CUTANEOUS infections are caused by DERMATOPHYTES.
* there are 3 generas: 1) MICROSPORUM 2) TRICHOPHYTON 3) EPIDERMOPHYTON - these are geophilic, zoophilic, and anthrophilic depending if they are associated with soil, animals, or humans |
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3) SUBCUTANEOUS MYCOESES?
What organisms cause this? |
* these infections are caused by a heterogenous group of organisms
1) SPOROTHRIX SHENKII: sporotrichosis - - causes chromoblastomycosis |
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How do you diagnose these infections?
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diagnosis depends on observing fungal elements in clinical specimens
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What's ENDO/ECTOTHRIX?
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ENDOTHRIX: refers to fungal elements inside the hair shaft
ECTOTHRIS: refers to infection AROUND the hair shaft |
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How do you treat such infections?
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1) Topical/ oral administration of various antifungal drugs
2) AZOLES are useful for dermatophyts with griseofulvin 3) surgical intervention may be required for some |
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What are the 3 main groups of fungal diseases?
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1) MUCOUSAL AND CUTANEOUS CANDIDA INFECTIONS
2) PRIMARY INFECTIONS 3) SECONDARY/ OPPORTUNISTIC INFECTIONS |
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I. MUCOUSAL AND CUTANEOUS INFECTIONS
* CANDIDA ALBICANS * |
*
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A. FREQUENCY AND IMPORTANCE (CLINICAL SIGNIFICANCE) OF C. ALBICANS?
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- this is the MOST IMPORTANT fungal pathogen of man in terms of frequency, number of types of disease, and severity
- frequent cause of DIAPER RASH and THRUSH in infants - frequent cause of severe infections in IMMUNOSUPPRESSED individuals (ex. vaginitis) |
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B. ECOLOGY
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- ENDOGENOUS
- it is a COMMON INHABITANT OF MUCOUS MEMBRANES AND GUT and IS NOT found free-living in nature - it is usually found in host without disease |
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C. CHARACTERISTICS
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- gram +ve, UNLIKE MOST FUNGI
- grows predominantly in budding yeast form on usual laboratory culture media, and forms creamy, white yeast colonies on most media - forms vegetative hyphae beneath the agar surface on rich media at neutral pH - also forms pseudohyphae that are an intermediate growth form yeast, pseudohyphal and hyphal growth forms are seen in infections - hyphae and pseudohyphae predominate in tissue invasion |
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D. INFECTIONS/ PATHOGENESIS (SPECTRUM OF DISEASES)
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- it may invade the upper cell layers of stratified squamous epithelium, causing pathology
- this epithelium lines the oral cavity, tongue, and esophagus and vagina - pathology is mild in immunocompromised hosts and increases in severity with the extent of IS impairment - INFLAMMATION of the mucousa affects 40% of the people infected with this 1) THRUSH: white patches on the mucousa 2) ERYTHEMATOUS CANDIDIASIS: mild, reddening of the mucousa 3) ANGULAR CHEILITIS: invasion of the epithelium at the corners of the mouth |
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E. IMMUNITY
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- the EPIDERMIS and EPITHELIAL lining mucousal surfaces are the primary host defense
- secretions such as HISTATIN in the saliva and DEFENSINS in the epithelium are active against C. ALBICANS - use DTH to determine that the host has a normal cell mediated IR- - lack of DTH response show a weakened cell mediated immunity |
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F. VIRULENCE FACTORS
Which forms of fungi are more adherent and invasive? What is expressed on only hyphae and not yeast? What is the cross-linking enzyme? **What are the specific virulence factors? |
- Hyphal and pseudophyphal forms are more adherent and invasive than other forms of yeast.
- Hyphal Wall Protein I (HWP1) is abundantly expressed on true hyphae and not on yeast- - and they mimic epithelial cell wall proteins that are substrates for an enzyme that forms protein cross-links and allows C. ALBICANS to cross- link other mucousal surfaces. - This enzyme is EPITHELIAL TRANSGLUTAMINASE which functions to create primary host defense barrier by cross- linking epithelial proteins through their glutamines and lysines - The specific virulence factors are: 1) ADHESINS: which permit attachment to mucousal epithelial cels 2) HYDROLYTIC ENZYMES: like proteinases and phosphatases and other enzymes that degrade host proteins |
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G. EPIDEMIOLOGY AND DIAGNOSIS
Where does the fungi come from? How is it spread? |
- The source is usually one's own organism, but organisms can be transmitted orally and sexually.
- Person to person spread occurs in hospitals where outbreaks may occur. - You detect fungal infections by KOH mount or gram stain |
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H. MULTIPLE RISK FACTORS
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There are multiple risk factors that predispose one to candidiasis. Including:
1) Factors that alter the oral mucousal environment. ex) oral epithelial dysplasia 2) Factors that alter the immune status of the host: - age - radiation/ chemotherapy - HIV infection - endocrine abnormalities - hypo/ hyperthyroidism - diabetes etc.. 3) Association with increased rates of vaginal colonization and disease - high estrogen content - high glycogen level and enhanced avidity of vaginal epithelium - ab usage etc.. *Lactobacilli levels are reduced during candidiasis |
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I. LAB EVALUATIONS
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germ- tube formation
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J. PREVENTION/ TREATMENT
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AZOLES FOR MUCOUSAL INFECTIONS!
- these inhibit enzymes involved in ergosterol synthesis - resistance has resulted in low administration of drug |
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K. OTHER PATHOGENIC CANDIDA FUNGI
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*
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