17-20 Flashcards
Characterstics
Dimorphic Fungi
Septate hyphae produce conidia upon inhalation
Forms a BROAD BASED BUD
Orginate in Mississippi River Valley
Blastomyces Dermatitidis
Presentation: Blastomycosis
Pulmonary – flu like illness/lobar infiltrates
Cutaneous – painless raised warty lesions (face, upper limbs/neck)
Blastomyces Dermatitidis
Virulence Factor
blocks phagocytosis and promotes Th2 differentation to aid in colonization and replication
W1
of Blastomyces Dermatitidis
Characterstics
Dimorphic
“The Great Imitator”
septate hyphae produce arthocondidia resistant to phagocytosis
transmation through inhalation of arthocondidia from soil containing bat/rodent droppings
Coccidioides immitis and C posadasii
Virulence factor:
glycoprotein coating that serves as major antigen for T cell responses; promotes Th2 response
SOWgp – sherule outer wall glycoprotein
Coccidioides immitis and C posadasii
Virulence Factor
degrade ECM and Ig to permit colonization of spores/endospores and spherule formation in tissues
ECM and Ig proteinases
Coccidioides immitis and C posadasii
Virulence Factor
protein coating to block phagocytosis of the spores
Hydrophobins
Coccidioides immitis and C posadasii
Presentation – coccidioidomycosis
Flu Like illness can resolve (primary)
Pulmonary granulomas become more extensive and necrotic (cavitation) – secondary
Coccidioides immitis and C posadasii
Characterstics
dimorphic
yeast resides in phagolysosome by INC pH
transmission through inhalation of microcondidia from soil with chicken/bat.starling droppings
Mississippi-Ohio River Valleys
Histoplasma Capsulatum
Presentation – histoplasmosis
Acute – flu like illness/granulomas can form
Progressive – persistence leads to destruction/fibrosis of lungs
Disseminated – oropharyangeal ulcers
Histoplasma Capsulatum
production of bicarbonate and ammonia by the fungi raises phagosome pH and inactivates degradative enzymes of the phagolysosome
ALKALINE SUBSTANCE Production
Virulence Factor – histoplasma capsulatum
Presentation
Yeast has a thick cell wall with multiple buds
found in areas of Mexico
Pneumonia and granulomatous lung infection
“ship captain’s wheel”
Paracoccidioides brasiliensis
Presentation
Mold makes a rose colored pigment, yeast are oval/elongated with central septum
TB like disease in patients with AIDS
Penicillium marneffei
Virulence Factor –
allows for resistance to high concentrations of antimicrobials
Yeast – inital attadhment
Hyphae = invasion of tissues – puncture phagocyte allowing fungal escape
Biofilms
candida albicans
Presentation – vulvovaginitis
vaginal itching and discharge – overgrowth due to increased pH, diabetes, antibiotic use
Candida Albicans
Presentation – chronic disease (chronic mucocutaneous candidiasis)
due to prolonged infections of the skin, oral, genital mucosa and nails that occurs in individuals deficent in T cell immunity
patients with mutations in the genes encoding IL-17 and the IL-17R receptor are predisposed to CMC
Canidia Albicans
Characterstics
produces carotenoid pigment on SDA generating pink to red colonies on SDA
Transmission from enviroment or endogenous
Rhodotorula spp.
Presentation – rhodotorulosis
Meningitis – AIDS = single largest risk factor
Fungemia – flu like illness – sepsis
Peritoneal Dialysis – cloudy dialysis fluid
Rhodotorula spp.
Virulence Factor –
narrow based budding yeast surrounded by polysaccharide capsule which suppresses T cell function
prevents ROS and RNS access to fungus
Capsule
crytococcus neoformans/C. Gattii
Virulence Factor –
lysis of host cell membranes to penetrate tissues and lysis of phagosome (enzyme)
Phospholipase
C. Neoformans
Characterstics
acute branching, septate hyphae
Highly invasive hyphae – can penetrate alveolar epithelia into bloodstream and then into other tissues
Aspergiullus spp.
Virulenece Factor –
supresses macrophage and neutrophil functions induce apoptosis
Gliotoxin
aspergillus
Virulenece Factor –
Bloacks action of ROS
Catalase SOD
aspergillus
Presentation – aspergillosis
Allergic – immune response to spore inhalation
Pulmonary– wheezing, SOB, elevated serum IgE, eosinophills
Sinsues – nasal congestion, runny nose
Aspergillus spp.
Presentation – aspergilloma
Fungus Ball
forms in paranasal sinsuses or preformed cavities secondary to old tuberculosis
asymptomatic unless pulm. hemorrhage
cough, hemoptysis, shortness of breath
Invasive – occurs in neutropenic and immunodeficent patients
Aspergillus
Characterstics
Transient flora in up to 20% of adults at any time
Diseease the result of immunosuppression
Life cycle includes both sexual/asexual components
Pneumocystis jirovecii
Presentation – PCP
upon entry an inflammatory exudate (cytokines) of mostly plasma cells occurs, oxygen exchange is reduced and difficulty breathing develops
Pneumocystis jiroveci
Polyenes include what two two drugs
Amphotericin B (AmpB)
and Nystatin
Mechanism of Action
Binds to ergosterol –> Forms pores/channels –> causes electrolyte leakage
Amphotericin B – Polyene
Nystatin
Adverse Effects
lipid formulations (costly) bind to mammalian membranes less readily therefore they reduce drug induce renal impairment (dec toxicity)
Amphotericin B (AmpB)
Mechanism of Action
flucytosine gets deaminated to 5-fluorouracil (5-FU) – inhibits thymidylate synthase enzyme (inhibits DNA/RNA biosynthesis)
HUMANS DONT HAVE CYTOSINE DEAMINASE – cant covert flucytosine to 5-FU
Flucytosine
Adverse Effects
reversible bone marrow suppression, GI effects
Flucytosine
Mechanism of Action
inhibits ergosterol biosynthesis by inhibiting sterol 14-alpha demethylase enzyme – no phospholipid packing
Imidazoles and Triazoles
Imidazoles/Triazoles
Sporanox, oral and parenteral for deep mycoses
Suppressive therapy for hisoplasmosis in HIV seropositive patients
Itraconazole
Imidazole/Triazole
Diflucan, oral, parenteral
Suppressive therapy and primary treatment of cryptococcal meningitis in AIDS patients
Fluconazole
Imidazole/Triazole
routinely used systemically
deep systemi mycoses, candidiasis in AIDS
DONT GIVE TO PREGNANT/NURSING MOTHERS
Ketoconazole
Oral systemic antifungals for mucocutaneous infections
this is fungistatic, insoluble in water
MOA: inhibits mitosis during metaphase by disrupting spindle formation
binds avidly with new synsthesized keratin
Griseofulvin
Terbinafine = oral systemic antifungal for mucocutaneous infection
Echinocandins
Dervived from aspergillus
MOA:** inhibits glucan synthase **which helps to make B-glucan = a component of cell wall
Anidulafungin
Echinocandins
Used to treat candida infection, aspergillosis, and Pneumocystis carinii
Caspofungin
these are organisms that live in or on a host organism and feed at the expense of their host
Often oppotunisitic infections
PARASITES
Amoebae, flagellates, apicomplexa, and ciliophora are classified as?
Protozoans
Nematodes, Cestodes and Trematodes are classified as
Helminths
Mites, Lice and Ticks are classified as?
Arthopods
Morphology of what group?
single celled eukaryotes
free living/parasitic in nature
cell membrane; ectoplasm/endoplasm, single/double or multiple nucleus, multiply in humans
Morphology of Protozoa
active feeding and growing stage of protozoa =
resting/resistant stage of protozoa =
Trophozoites
Cysts
Amoeba Protozoa
cysts ingested from contaminated food/water –> becomes trophozites in intestines
Cyst Walls = highly resistant to gastric juices
Pathogenesis –> amoebic dysentery (blood), submucosal ulcers, liver abscess
Entamoeba histolytica
Flagellated Protozoa
ingestion of cysts –> trophozites in small intestines –> both are excreted in stool
Pathogenesis = trophozoties adgere to intestinal mucosa –> inflammatory damage to villi; results in fat malabsorption/diarrhea = steatorrhea
Giardia Lamblia
Apicomplexa Protozoan
Cysts ingested from undercooked meat, contaminated water/food, cat litter
Cysts –> bradyzoites/tachyzoites in small intestines –>brain, liver via blood / vertical transmission (blood transfusion)
Pathogenesis: inflammatory reaction to tissue cysts –> chorioretinitis, intracerebral calcifications
Toxoplasma Gondii
Ciliated Protozoan
cysts –> trophozoites
Pathogenesis: trophozoites –> large intestines –> inflammatory reaction –> mucosal ulcers/submucosal abscesses
Common in immunocompromised patients
Balantidium Coli
Multicellular Worms
Covered with cuticle
requiers intermediate host
Helminths
Round worms are called
Nematodes
Tape worms are called
Cestodes
Flukes are called
Trematodes
Characterstics of a group of worms
Elongated, cylindrical, unsegmented
Pseudocele = tough cuticle + body cavity
Diecious = sexes are seperate
can reside in GI tract, blood, lymphatics/subcutaneous tissues
NEMATODES
Nematode
“Pin Worm”
embryonated eggs ingested from contaminated perianal area or hands –> enter intestine form larve + adult worms in large intestines
Pathogeneis = sticky eggs deposited in perianal region –> inflammation/pruritis
* Children – autoinoculation – itch – scratch – oral
* may migrate into vagina/cervix
Enterobius vermicularis
Nematode
“Whip Worm”
embryonated cysts (contaminated food/water) –> hatch into larve in intestines –> adult worm
Pathogenesis – larve causes diarrhea
Adult worm causes appendticitis/rectal prolapse
Trichuris trichura
Nematode
Infection from bite of black fly – larva enters wound –> subcutaneous tissue –> painless skin nodules
Mirofilariae produced/released in blood –> eyes
Pathogenesis – allergic rxn to adult worms/microfilariae –> dermatitis, chorioretinitis (RIVER BLINDNESS)
Onchocerca volvulus
Nematode
bite of Culex mosquito – transmits larvae into blood/lmyph
Pathogenesis – inflammatory rxn in lymphatics –> lymphangitis, lymphadenopathy, lymphedema
Blockage = ELEPHANTITIS
Wuchereria bancrofti
Characteristics of a group of helminths
phylum Phatyhelminths
ribbon like
adult worm = 3 parts – head = SCOLEX, neck/trunk = STROBILA, most have 4 suckers, some have hooks
Embyro inside eggs = oncospheres – 3 pairs of hooks
common in GI tract
Cestodes = tapeworms
Cestode
“Hydatid Cyst”
acquired by ingestion of embryonated eggs from contaminated food
Eggs from oncospheres –> penetrade intestinal wall –> tissues –> liver, lungers/heart/spleen –> tissue CYST
Echinococcus granulosus
pathogenesis of cestode
hydatid cyst –> obstruction/mass efect in tissue (R liver = most common)
Hypersensitivity to cyst fluid –> anaphalyxis
Echinoccus granulosus
Cestode
“pork tapeworm”
ingestion of raw pork –> cysticerci penetrates intestinal wall –> muacle
Stool: eggs/proglottids
taenia solium
taenia saginate = beef tapeworm (cattle)
Characterstics of a group of helminths
unsegmented, flattened
have prominent suckers
two muscular cup shaped suckers
No body Cavity
hermaphrodites
Trematodes = flukes
trematode
“Chinese Liver Fluke”
ingestion of infected freshwater fish –> larva reside in duodenum –> adult forms in bile ducts
Snail = intermediate host – eggs = cercariae –> metacercaria into fish
Pathogenesis = larvae in bile duct – inflammatory rxn. –> cirrhosis of liver, cholecystocarcinoma
Clonorchis sinensis
Trematode
“Blood Fluke”
skin penetrated by freshwater cercaria – enters blood via portal circulation to liver –> bladder via venus plexus
Pathogenesis – cercarial dermtitus, katayama fever
Schistosoma haematobium
