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25 Cards in this Set

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What are the different types of INFECTIONS that FUNGI may cause?
1) SUPERFICIAL
2) CUTANEOUS
3) SUBCUTANEOUS INFECTIONS
1) SUPERFICIAL MYCOSES?
- 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
2) CUTANEOUS MYCOSES?
- 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
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
What is the CLINICAL SIGNIFICANCE of FUNGAL INFECTIONS?
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
What are the PROPERTIES/ CHARACTERISTICS OF PATHOGENS in each types of infection?
*
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
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
3) SUBCUTANEOUS MYCOESES?

What organisms cause this?
* these infections are caused by a heterogenous group of organisms

1) SPOROTHRIX SHENKII: sporotrichosis - - causes chromoblastomycosis
How do you diagnose these infections?
diagnosis depends on observing fungal elements in clinical specimens
What's ENDO/ECTOTHRIX?
ENDOTHRIX: refers to fungal elements inside the hair shaft

ECTOTHRIS: refers to infection AROUND the hair shaft
How do you treat such infections?
1) Topical/ oral administration of various antifungal drugs

2) AZOLES are useful for dermatophyts with griseofulvin

3) surgical intervention may be required for some
What are the 3 main groups of fungal diseases?
1) MUCOUSAL AND CUTANEOUS CANDIDA INFECTIONS
2) PRIMARY INFECTIONS
3) SECONDARY/ OPPORTUNISTIC INFECTIONS
I. MUCOUSAL AND CUTANEOUS INFECTIONS

* CANDIDA ALBICANS *
*
A. FREQUENCY AND IMPORTANCE (CLINICAL SIGNIFICANCE) OF C. ALBICANS?
- 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)
B. ECOLOGY
- 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
C. CHARACTERISTICS
- 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
D. INFECTIONS/ PATHOGENESIS (SPECTRUM OF DISEASES)
- 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
E. IMMUNITY
- 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
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
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
H. MULTIPLE RISK FACTORS
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
I. LAB EVALUATIONS
germ- tube formation
J. PREVENTION/ TREATMENT
AZOLES FOR MUCOUSAL INFECTIONS!
- these inhibit enzymes involved in ergosterol synthesis
- resistance has resulted in low administration of drug
K. OTHER PATHOGENIC CANDIDA FUNGI
*