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104 Cards in this Set

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why dont superficial mycoses not elicit a host cellular response
they grow in tissues that are not living
cutaneous mycoses infect deeper in the epidermis and hair and nails what do they have that allows for growth
keratinases that allow them to use keratin as a substance for growth
tinea nigra and tinea versicolor are infections of what layer of skin
the keratinized layer of skin
clinical manifestations of cutaneous mycoses
"ring worm" or tinea
a chronic infection characterized by nodular and ulcerative lesions athat develop along the lymphatic glands that drain the primary site of inoculation
lymphocutaneous sporotrichosis

a subcutaneous infection caused by sporothrix shenkii
development of warty nodules that appear at sites of implantation of fungal elements
chromoblastomycosis

a subcutaneous infection caused by dematiaceous fungi (fungi with brown to black melanin)
lipophilic and grows in sweat glands
Malassezia furfur
(
tinea nigra is caued by melanin-producing dimorphic fungus called
cladosporium (exophiala) werneckii

this is a superficial infection
malassezia furfur and cladosporium wernickii are acquired from
soil, animals, or other people by direct contact

they are superficial pathogens.
cutaneous infections are caused by what kind of fungi
dermatophytes
three genera of dermatophytes
microsporum
trichophyton
epidermophyton
three classifications of dermatophytes
geophilic (from soil)
zoophilic (animals)
antrophilic (humans)
causes sporotichosis and is found in decaying vegetation
is dimorphic
grows as budding yeast at 37' and hypahae at 24'
sporothrix shenkii
causes chromoblastomycosis
dematiaceous fungi (fungi with brown and black melanin)
diagnosis of superficial and cutanteous myscoses depends on
observing fungal elements in clinical specimans and NAOH mount
endothrix
refers to fungal elements inside hair shaft
ectothrix
refers to infection around the hair shaft
this group of drugs is helpful for treatment of dermatophytes along with griseofulvin
azoles
what might be required for subcutantous fungal infetions
surgical interventsion
the most important fungal pathogen of man in terms of frequency, the number of types of diseases, and severity
C. albicans
frequent cause of diaper rash and viginitis
C. albicans
fungi imperfecti (deurteromycetes means
sexual forms are unknown

e.g C. albicans (although they mate via cell fusion)
common inhabitant of mucous membranes and digestive tract of humans - not found to be free living
c. albicans
stains for C. albicans
gram stain - unlike most fungi
C. Albi grows in what form
budding yeast of culture - forms creamy white east colonies
C. albicans forms what beneath agar surface on rich media at neutral pH
c. albicans
vegetative hyphae
C. albi - form aerial hyphae?
no
chlamydospores forms what forms at the ends of hyphae under nutrient limiting conditions in what fungi
c. albicans
what kind of form of C. albicans is predominate in tissue invasion
hyphae and pseudohyphae
what kind of epithelium does c. albicans invade
stratified squamous lines oral cavity, tongue, esophagus, and vagina
oropharyngeal candidiases is inflammation of
mucosa or mucositis -
affects 40% of pts receiving chemotherapy. often causes pain.
thrush =
acute pseudomembranous candidiases

white patches on mucosa
erythematous candidiases
mild, reddening of mucosa
flattening of tongue papilli happens in what kind of infection
c. albicans

central papilary atrophy of dorsal tongue
invasion of epithelium at corners of mouth where upper and lower lips meet - caused by C. albicans
angular cheilitis
what is the primary defense against C. albicans
epidermis and epithelial lining of mucosal surfaces
secretions in saliva that work against c. albicans
histatin in saliva and definsins in epithelium
intradermal injection with C. albicans and a positive DTH would indicate
host has normal cell mediated immune response because c. albicans is part of the normal flora - lack of DTH and you know you are dealing with a compromised pt
Ab against C. albicans
present but not associated with protection
abundantly expressed on true hyphae an not yeast which mimics mammalian epithelial cell proteins and allows C. albicans to become crosslinked to mucosal surfaces w/ host enzyme
Hyphal Wall Protein (Hwp1
cross linking enzyme that links host and C. albicans
transglutaminase
permits attachement of C. albicans to mucosal epithelial cells and to host proteins such as fibronectin
adhesions from laarge agglutinin like sequences gene family (ALS)
secreted aspartyl proteinases (SAPs)
hydrolytic enzymes, along with phosphatases allow c. albicans to degrade host proteins
important mechanism of azole drug resistance
efflux pumps
the source of c. albicans is usually
from the host themselves (although can be spred orally and sexually)
laboratory evaluation and identification of C. albicns
(2 - presumptive vs. definitive)
presumptive: germbe tube formation in serum w/in 1-2 hours
Definitive: fermenatation and assimilation of carbohydrate and other compounds

note: variable germ tubes can help distinguish isolates
azoles work how
inhibit enzymes involved in erogosterol synthesis.
why not use azoles prophylactically
drug resistance
used for severe candida infections - binds ergosterol
Amphotericin B - cidal!
two common resistance mechanisms for anti-fungals
mutation of target enzyme and increased expression of efflux pump
found in pts with HIV - differing in repetitive DNA from C.albicans
C. dubliniensis

forms germ tubes but less frequently than C. albicans
two organisms that account for approxiamately 70-80% of yeast isolated from patiets with invasive candidiases
C. glabrata and C. albicans

Glabrata has recently become important because its increase incidence - less suseptible to azoles and Amphotericin B
recently has become important because of its increasing incidence worlwide and intrinsically less suscepttible to azoles and Amphotericin B then C. albicans
C. glabrata
how do macrophages contribute to the response by host to a primary fungal infection
macrophages become activated and "wall off" fungi

can be latent for years with no symptoms - then reactivated when host is immunosuppressed
histoplasma capsulatum displays what kind of typical fungal growth
dimorphic, growing in hyphal form in enviroment and yeast form in infected tissue
mycelial
hyphal
hyphal characteristics of histoplasma capsulatum
septate branching hyphae that bear spores called microconidia. macroconidia are called tuberculate
tuberculate
macroconidia of histoplasma have a characteristic morphology and are called
yeast form of histoplasma capsulatum yeast form is found w/in what kind of cell
macrophages (some in epithelial cells)
an inportant attribute for virulence for H. capsulatum
can grow in macrophages - surviving phagocytic vacuole

migrates to mediastinal lymph node, spleen, liver
once histoplasma capsulatum has replicated w/in marocphages - it gets transfered via migration to
to lymph nodes, sleen, liver
yeast prliferate for 9-15days
onset of host cell-mediated immunity
(sometimes found in epithelial cells)
mostly intracellular infection unless there is an overwhelming histoplasmosis
acute versus chronic pulmonary histoplasmosis would be seen in what individuals
acute in immunocompetent

chronic in immunosuppressed
chronic pulmonary histoplasmosis is often mistaken for
TB -
native habitat and mode of transmission for histo. capsulatum
soil is habitat and transmission is not person to person
a positive histoplasm skin test indicates
exposure to organisma and not necessarily active infection
for disseminated histoplasmosis what test will always be positive
Wright stain of peripheral blood showing intracellular yeasts w/in macorphages - organism can also be isolated from blood cultures
for chronic pulmonary histoplasmosis, what may aid in diagnosis
chest X-ray, CF test, sputum cultures, and possibly wright test of sputum
histoplasma uses wright stain
common infection fo dogs, mainly sporadic infections in immunocompetant (primary pathogen) many cases in immunocompromised
Blastomycosis (bastomyces dermatitidis
Blastomyces dermatitidis - hyphal growth?
hyphal growth with aerial spores
growth of b. dermatitidis in culture
cultures appear cottony - at 37' - grow as yeast with single buds having characterisitic broad base
smooth or rough colonies (b. dermatitidis)
smooth
pathogenesis of B. dermatitidis
1. B dermatitidis dwells as saprophyte - human inhales spore from soil
2. acute primary pulmonary infection may be asymptomatic
3. may resolve or progress i lungs or other organs (trophism for skin and bones)
B. dermatitidis is tropic for what organs
skin and bone
Bad1
(Blastomyces adhesin 1)
surface protein on B. dermatidtidis required for virulence by promoting the uptake by macrophages
Bad1 has homology to invasin genes of gram negative bacteria and promotoes uptake by
gram negative

macrophages
pathogenesis of histoplasma capsulatum
inhaled spores (microconidia)
reach small bronchioles or alveoli
germinat 2-3 days
yeasts proliferate w/in macro
macropha migrate to lymph nodes, sleen, liver
yeast prliferate for 9-15days
onset of host cell-mediated immunity
(sometimes found in epithelial cells)
mostly intracellular infection unless there is an overwhelming histoplasmosis
acute pulmonary histoplasmosis and disseminated histoplasmosis caused by histoplasma capsulatum would be seen in what individuals
acute seen in immunocompetant and chronic in immunocompromised
chronic pulmonary histoplasmosis is often mistaken for
TB -
native habitat and mode of transmission for histo. capsulatum
soil is habitat and transmission is not person to person
a positive histoplasm skin test indicates
exposure to organisma and not necessarily active infection
for disseminated histoplasmosis what test will always be positive
Wright stain of peripheral blood showing intracellular yeasts w/in macorphages - organism can also be isolated from blood cultures
for chronic pulmonary histoplasmosis, what may aid in diagnosis
chest X-ray, CF test, sputum cultures, and possibly wright test of sputum
common infection fo dogs in endemic zones and canine infection are often sever or lethal
Blastomycosis (bastomyces dermatitidis
structure of b. dermatitidis
dimorphic
filamentous haypa forms w/ associated aerial spres
growth of b. dermatitidis
enviroment (and culture): hyphi w/ aerial spores
37 degrees: yeast - single buds, broad base
smooth or rough colonies (b. dermatitidis)
smooth
pathogenesis of B. dermatitidis
1. B dermatitidis dwells as saprophyte - human inhales spore from soil
2. acute primary pulmonary infection may be asymptomatic
3. may resolve or progress i lungs or other organs (trophism for skin and bone)
B. dermatitidis is tropic for what organs
skin and bone
Bad1
surface protein on B. dermatidtidis required for virulence and promotes the uptake of fungi by macrophages
Bad1 has homology to invasin genes gram Gram what bacteria
and promotoes uptake by
gram negative

macrophages
B dermatidis is antigenically cross reactive with
H. capsulatum
B. dermitidis grows exclusively in what form in host

may be detected w/
yeast

KOH mounts or fungal stains in infected area
immunodiffusion test for detection of what is used for detecting B. dermatitidus
immunodiffusion test for patient antibodies to "A" antigen produced fro cultures filtrates of B. dermatidis
40% of infected individuals have symptoms consistant w/ lower respiratory infection and/or systemic illness w/ cough, sputum production, chest pain, malaise, fever, chills, night seats, anorexia, weakness, arthralgia
Coccidioides immitis
how long does the disease caused by coccidioides immitis last
2-6 days
valley fever caused by
coccidioides immitis
a small number of cases progress to a chronic pulmonary form characterized by cavity formation
barrel-shaped arthroconidia which are easily fragmented and highly infectious
Coccidioides immitis
spherules are form in host, rupture leads to large numbers of endospores in tissue which develop into spherules
Coccidiodides immitis
how does one become infected with coccidioides immitis
inhaled
initial response to coccidioides immitis consists of what cells
macrophages and neutrophils

but fungi are resistant to killing by neutrophils
symtoms are more common in dark skin men
coccidioides immitis
wagon whell appearance of yeasts found in tissues
paracocidioides brasilliensis
yeast has single bud coming off yeast w/ broad base
blastomyces dermatitidis
Wright stain helps with the diagnosis of
Histoplasmosis