Exam 2: 15-16 Flashcards
DIMORPHISM
Between Yeast and Mold which is found in the heat and which is found in the cold?
Purpose is to help escape phagocytosis
YEAST = HEAT
MOLD = COLD
Dimorphism
During what phase would you find the hyphae in soil and decaying vegetation, making spores
25 C
SAPROBIC Phase
During what phase would you find yeast adapted to grow in 37 C, reproduce asexually in mucosa and escape host immunity
More rapid than hyphae and less immunogenic
PARASITIC Phase
Spores are easily phagocytosed
- Macrophages/Neutrophils recognize these spoers –> phagosome
- NADPH oxidase and iNOS activation releases what to prevent DNA replication/expression and inactivate enzymes ?
NADPH Oxidase and iNOS activation release ROS and RNS
What does the phagosome do to the pH to be fuse with the lysosome and digest microbes using acid hydrolases
LOWERS pH by pumping H+
Yeasts are resistant to phagocytosis
What do yeasts do to allow them to be resistant from phagocytosis?
Shed immunodominant antigen from the cell surface and modify the cell wall components to block phagocytosis
WI-1 is shed permitting blastomyces escape from phagocytosis
CD4+ T Cells Release ____ – recruit other cells
CD8+ T Cells Release ____ – kill pathogens and infected host
CD4+ T Cells Release CYTOKINES
CD8+ T Cells Release CYTOXINS
Which T cell respnose involves macrophage function, pro-inflammatory
Th1
Which T cell response recruits and activates neutrophils
Th17
Which T cell responses are MOST effective for fungal response?
Th1 and Th17
Which T cell response would allow fingus to evade immunity?
Th2 cells promote B cell, mast cell and eosinophil activation – allergy and anti inflammatory which sustains viability of the fungus
this saprobe is small in size and easily aerosolized so when inhaled it can access the lower respiratory tract
ARTHOCONIDIA
these have a protein covering allowing it to be antiphagocytic, therefore if taken up the conidia are not digested
HYDROPHOBINS
this coats spherule and modulates for Th2 response
SOWgp (SOW glycoprtein)
– favors fungal persistence
HISTOPLASMA CAPSULATUM
inhaled conidia spores transform into yeast –> alveolar macrophages (ingestion by phagocytes)
* pH of phagolysosome INC preventing what??
preventing the activation of acid hydrolases and interefering with antigen processing
Histoplasma Capsulatum
Alpha (1,3) glucan in the cell walls allow for what?
Allows for replication in phagolysosome and phagocyte lysis
Cryptococcus Neoformans
Encapsulated Yeast protects the fungus from phagocytosis how?
Negative charge of capsule repells immune cells
Blocks NO access to the fungus
Interferes with antigen processing
Cryptococcus Neoformans
What in the cell wall contributes to the NEG charge in the cell wall/capsule and contributes to protection form phagocytosis, NO, temp. extremes, and iron loss
MELANIN
Urease catalyzes hydrolysis of urea to yield ammonia therefore doing what to pH
Saprobe urease release – alkaline soil for optimal growth
INC pH – INC ALKALINITY
Both saprobe and parasitic forms produce proteinases during cell growth, which are responsible for the breakdown and degradation of?
breakdown of ECM proteins and degrade hemoglobin and IgA and IgG
allows fungus to breach respiratory mucosal barrier/ enter blood stream
this type of fungi produces the disease by going on/in host
Ex: Athletes Foot
MYCOSES
exposure to toxins/metabolites of toxin produces the disease
Mycotoxicoses
= toxigenic fungi
- dont produce significant amount during disease
- synthesis requires a temp lower than body temp
MYCOTOXINS
this toxin is found in PEANUTS, MAIZE and CORN
made when aspergillus replicates, invades crops in tropical areas
AFLATOXINS
mechanism of toxin
this toxin metabolizes in the liver to an EPOXIDE whivh interfers with DNA replication and cell division
AFLATOXIN
mycotoxins
seen on moldy corn
inhibits ceramide generation, INC TNF-alpha production and induces cell apoptosis
FUMONISMS
mycotoxin
dark in grain kernels that can be milled into flour
Can cause VASOSPASMS – constriction (lack of O2 can cause gangrene)
ERGOT
Microscopic Exam
specimen can be immediately stained with reagents
Add Stain: KOH, lactophenol cotton blue, india ink
WET MOUNT
Lactophenol Cotton Blue has three components:
Phenol – kills fungi
Lactic Acid – preserves
Cotton Blue stains the ___ in the cell wall
stains the chitin in the cell wall
Microscopic Exam
This stain stains the polysaccharide in fungal walls to stain bright red
Periodic Acid Schiff (PAS) Stain
Microscopic Exam
This stain causes fungi to turn black with a green background
Used for Pneumocystis Jirovecii using bronchoalveolar lavage
Grocott Gomoris Methenamine Silver GMS Stain
Microscopic Exam
used for detection of fungal spores and hyphae
Calcofluor White binds to CHITIN in cell wall – fluoresces in UV
Wood Lamp detects dermatophytes
Immunofluorescence
Culture of Fungi
This has DEXTROSE which promotes fungal growth (pH 5-6)
Inhibits growth of bacteria (Antibiotics – chloramphenicol)
Incubate between 25-37 C
Sabouraud Dextrose Agar SDA
This test is used for specific antibodies, to screen for disease, establish specifi diganoses and montior disease
Performed with puriofied or recombinant Ags to detect disease-specific anitbodies
Postive indirect test for Antibodies and Antigens
AGGLUTINATION
Aggulination Method
Ags attached to a carrier (RBC or beads) –> add sample –> if Ig is present in the sample what will happen?
Ag-coated RBC or beads will clump
Fungal Pathogen
Characterstics of this fungi:
Yeast Cells bud with a unique”lip” – colarette
Liphophilic fungi – growth stimulated by oil
Malassezia Furfur
transmission of this fungi
is through direct/indirect transfer of keratinous material from person-to-person
Prevalence in the tropics
Malassezia Furfur
PITYRIASIS
this fungi presents as small, hypopigmented/hyperpigmented spots on chest, back, arms, shoulders
Malassezia Furfur
Microscopy
spaghetti and meatball appearance = mix of hyphae and yeast
Malassezia Furfur
Characterstics
Dematiaceous = soil fungi dark in color due to melanin expression
branched septate hyphae
Melanin = antiphagocytic virulence factor
Hortaea Weneckii
Presentation – Tinea Nigra
solitary, irregular pigmented macules on palms and soles
Biopsy to r/o melanoma
Hortaea Weneckii
Trichophyton, Epidermophyton and Microsporum are reffered as?
Produce keratinases to utilize keratin as a nutrient
Dermatophytes
Presentation – RINGWORM – Tineas
classic pattern = ring of inflammatory scaling with diminution of inflammation toward center of lesion
if nails are infected they will thicken, discolor, raise and be deformed
Jock Itch – groin, feet – athletes foot
Trichophyton, Epidermophyton and Microsporum
Characterstics – dimorphic fungi
Mold = daisy petal conidia in soil
Yeast = cigar shaped blastoconidia in humans
outbreaks from gardencing – rose growers disease
Sporothrix Schenckii
Presentation – sporothrichosis
painless nodular lesions (cellulitis) along lymphatics draining from inoculation site
May ulcerate with pus formation
Entry = spores introduced into skin but damage (thorn)
Sporothrix Schenckii
Virulence Factor – Sporothrix Schenckii
blocks the action of ROS to evade phagosome-mediated damage in phagocytes
Ergosterol Peroxide
Characterstics
Gray to wooly colony growth on SDA cycloheximide
Mucorales
Presentation – zygromucosis – rhinocerebral
meningitis also involving facial structures, nasal sinuses and orbits
necrotic eschars on nasal cavity, hard palate, or face
Mucorales
Presentation – zygromucosis – pulmonary
focal pulmonary lesions with necrosis – fungus ball
fever, labored breathing, cough
Mucorales
Presentation – zygromucosis – cutaneous
cellulitis that progresses to dermal necrosis and black eschar formation
associated with IV drug use
Mucorales
Virulence Factor – Mucorales
proliferate in the walls of blood vessels and cause tissue infarcation
Invasive Hyphae
Characterstics
Dematiaceous
Muriform Bodies founds in animals and humans = brown septated cells with vertical/horizontal lines in same planes
Chromoblastomycosis
Presentation – fonsecaea pedrosoi
Chronic, pruritic, progressive warty papules
Develop - cauliflower like lesions clustering in the same region
Chromoblastomycosis
