Final Exam: Micro: Fungi That Infect Hair, Nails, And Subcutaneous Tissue

Front 1

What are the different types of INFECTIONS that FUNGI may cause?

Back 1

1) SUPERFICIAL
2) CUTANEOUS
3) SUBCUTANEOUS INFECTIONS

Front 2

1) SUPERFICIAL MYCOSES?

Back 2

- 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

Front 3

2) CUTANEOUS MYCOSES?

Back 3

- 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

Front 4

3) SUBCUTANEOUS MYCOSES?

What is it and what are 2 examples of it?

Back 4

- 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

Front 5

What is the CLINICAL SIGNIFICANCE of FUNGAL INFECTIONS?

Back 5

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

Front 6

What are the PROPERTIES/ CHARACTERISTICS OF PATHOGENS in each types of infection?

Back 6

*

Front 7

1) SUPERFICIAL MYCOSES?

What are 2 examples that cause disease and where are these organisms acquired from?

Back 7

*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

Front 8

2) CUTANEOUS MYCOSES?

What causes these infections?

What are the 3 generas?

Back 8

*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

Front 9

3) SUBCUTANEOUS MYCOESES?

What organisms cause this?

Back 9

* these infections are caused by a heterogenous group of organisms

1) SPOROTHRIX SHENKII: sporotrichosis - - causes chromoblastomycosis

Front 10

How do you diagnose these infections?

Back 10

diagnosis depends on observing fungal elements in clinical specimens

Front 11

What's ENDO/ECTOTHRIX?

Back 11

ENDOTHRIX: refers to fungal elements inside the hair shaft

ECTOTHRIS: refers to infection AROUND the hair shaft

Front 12

How do you treat such infections?

Back 12

1) Topical/ oral administration of various antifungal drugs

2) AZOLES are useful for dermatophyts with griseofulvin

3) surgical intervention may be required for some

Front 13

What are the 3 main groups of fungal diseases?

Back 13

1) MUCOUSAL AND CUTANEOUS CANDIDA INFECTIONS
2) PRIMARY INFECTIONS
3) SECONDARY/ OPPORTUNISTIC INFECTIONS

Front 14

I. MUCOUSAL AND CUTANEOUS INFECTIONS

* CANDIDA ALBICANS *

Back 14

*

Front 15

A. FREQUENCY AND IMPORTANCE (CLINICAL SIGNIFICANCE) OF C. ALBICANS?

Back 15

- 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)

Front 16

B. ECOLOGY

Back 16

- 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

Front 17

C. CHARACTERISTICS

Back 17

- 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

Front 18

D. INFECTIONS/ PATHOGENESIS (SPECTRUM OF DISEASES)

Back 18

- 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

Front 19

E. IMMUNITY

Back 19

- 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

Front 20

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?

Back 20

- 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

Front 21

G. EPIDEMIOLOGY AND DIAGNOSIS

Where does the fungi come from?

How is it spread?

Back 21

- 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

Front 22

H. MULTIPLE RISK FACTORS

Back 22

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

Front 23

I. LAB EVALUATIONS

Back 23

germ- tube formation

Front 24

J. PREVENTION/ TREATMENT

Back 24

AZOLES FOR MUCOUSAL INFECTIONS!
- these inhibit enzymes involved in ergosterol synthesis
- resistance has resulted in low administration of drug

Front 25

K. OTHER PATHOGENIC CANDIDA FUNGI

Back 25

*