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Micro--Exam 1
viruses, parasites, fungi
63
Medical
Graduate
09/19/2014

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Term
Toxin effect for C. Diphtheria
Definition
A/B toxin inhibits protein synthesis (alpha subunit inhibits EF2 needed for transcription)
Term
Toxin effect for Pseudomonas aeruginosa
Definition
inhibits protein synthesis (affects EF transcription factor)
Term
toxin effect for C. Botulinum
Definition
protease cleaves SNARE proteins at the neuromuscular junction so there is no neurotransmitter release and resulting paralysis
Term
toxin effect for Clostridium Tetani
Definition
Blocks the inhibition of GABA neurotransmitter; there is no "off switch" at the NMJ which results in repetitive stimuli (tetanus--muscle spasms)
Term
Toxin effect for Vibrio cholera
Definition
increases cAMP cascade which bind epithelial G protein cascade causing excretion of ions (diarrhea)
Term
toxin effect for Bordatella pertussis
Definition
increases cAMP messengers increasing insulin release leading to hypoglycemia
Term
toxin effect for Shigella dysenteria
Definition
inhibits protein synthesis by cleaving and deactivating RNA
Term
toxin effect for E. Coli
Definition
inhibits protein synthesis by deactivating ribosomes
Term
Microsporum, Trichophyton, Epidermophyton
Definition
Cutaneous--Microsporum, Trichophyton, Epidermophyton (jock itch, athlete’s foot)
ringworm infection; colonizing keratinized epithelium
remove keratin with KOH; wood’s lamp
tx: topical antifungal
Term
Sporothrix schenckii
Definition
Subcutaneous--Sporothrix schenckii (Rose Gardener’s Disease)
from hyphae to yeast
on soil/plants introduced via trauma forming local nodules (can spread to lymph)
Tx: oral potassium iodide
Term
C. immitis
Definition
C. immitis (Valley Fever→ SW US)
hyphae→ spheres containing endospores
spores in soil are inhaled (infection in lung)
immunocompromised can cause pneumonia and spread via blood forming granulomas
Term
H. capsulatum
Definition
H. capsulatum (Histoplasmosis→ Mississippi/SE US)
hyphae→ yeast (in macrophages)
spores from bird droppings inhaled→ macrophage phagocytose and the spores can spread (look like calcium deposits on Xray)
Tx: amphotericin B
Term
A. fumigatus
Definition
A. fumigatus (aspergillosis)
mold grows on vegetation and are inhaled
allergy reaction (↑ IgE)
deposit in lung cavity as a ball
invade lung tissue and blood→ pulmonary infarction
Tx: surgery, corticosteroids, antifungal (amphotericin B)
Term
C. neoformans
Definition
C. neoformans (cryptococcosis→ most common fungal meningitis)
INDIA INK prep (stains polysaccharide capsule) show budding yeast
found in pigeon droppings and is inhaled
local lung infection or spread via blood to CNS (↑ CSF pressure)
Tx: amphotericin B
Term
C. albicans
Definition
C. albicans (candidiasis→ vaginitis, esophagitis)
normal flora for GI, respiratory, vagina
mouth (oral thrush), vaginal (vaginitis), cutaneous (under breasts)
Tx: mouth (fluconazole, nystatin mouthwash), vagina (fluconazole), systemic (amphotericin B)
Term
C. parvum
Definition
C. parvum (cryptosporidiosis)
WATERY DIARRHEA
fecal-oral transmission: ingested oocysts into small intestines
Tx: supportive
Term
G. lamblia
Definition
G. lamblia (giardiasis: mustachioed trophozoite!)
OILY DIARRHEA--trichrome smear
fecal-oral: trophozoite attaches to duodenal wall→ malabsorption
Tx: metronidazole
Term
E. histolytica
Definition
E. histolytica (amebiasis)
BLOODY DIARRHEA
fecal-oral of cysts: transforms to trophozoite in ileum and invade colon (necrosis) or enter portal circulation to form abcesses
Tx: metronidazole, drain hepatic abcesses
Term
T. vaginalis
Definition
T. vaginalis (trichomoniasis): 5 flagella/1 nucleus tear drop shape
sexual transmission: females have green discharge; males asymptomatic (or w/ urethritis)
Tx: metronidazole
Term
P. falciparum
Definition
P. falciparum (all RBCs), vivax, ovale, malariae (old RBCs) (Malaria)--GIEMSA STAIN
mosquito bite releases sporozoite into blood carried to liver, liver cells burst and invasion of RBCs (hemolysis→ anemia); RBC rigidity→ splenomegaly
Tx: chloroquine, mefloquine, primaquine (liver infection)
Term
T. brucei
Definition
T. brucei (sleeping sickness)
tsetse fly bite releases protozoan into blood→ enlarged lymph nodes and fever; infection of CNS (meningitis, encephalitis, somnolence)
Tx: suramin; eflornithine/melarsoprol (if CNS infection)
Term
T. gondii
Definition
T. gondii (toxoplasmosis)
ingested from undercooked meat or CAT FECES penetrates intestines and is spread after invasion of macrophages
can cross the placenta
Tx: sulfonamide and pyrimethamine
Term
Enterobius vermicularis
Definition
Enterobius vermicularis (pinworm)
fecal-oral: egg ingested hatch in duodenum and mate in colon leave to perianal skin to lay eggs (ITCHY butt)
SCOTCH TAPE TEST
Term
A. lumbricoides
Definition
A. lumbricoides (ascariasis) → most common helminth infection
eggs ingested in contaminated soil, enter blood to the lungs→ inflammation and maybe pneumonia (larvae can go to intestines and cause malnutrition)
eosinophilia
Tx: pyrantel pamoate, mebendazole
Term
T. saginata
Definition
T. saginata (beef tapeworm)
ingested in poorly cooked beef
stool: progottids, eggs
Tx: niclosamide, cathartic
Term
T. Solium
Definition
T. Solium (pork tapeworm)
ingested in poorly cooked pork (larvae go to intestines)
or eggs ingested from feces and these hatch and travel to other tissues (brain, eye, muscles) → eosinophilia
Tx: niclosamide and cathartic (intestines); praziquantel/steroids (to reduce inflammation of dying cysts)
Term
Schistosoma spp.
Definition
Schistosoma spp.
larvae from snails into fresh water penetrate human skin and enter blood to the portal circulation or bladder
hematuria, eosinophilia
adult form coats itself with host antigen (can survive long time)
Tx: praziquantel
Term
W. bancrofti
Definition
W. bancrofti (elephantiasis)
mosquito transmission enters blood carried to lymph nodes of genitals and lower extremities
obstruction of lymph drainage→ edema in legs/scrotum
Microfiliariae are most common at night
Tx: diethylcarbamazine (only work on the microfilariae)
Term
HIV (HIV1 is global; HIV2 is Africa)
Definition
genome and life cycle
enveloped, ssRNA
ssRNA uses reverse transcriptase to make dsDNA then uses host machinery (for transcription/translation) making protein
Life cycle
viral gp120 binds CD4 cell surface (CXCR4 or CCR5 receptors on T cell)
can bind CCR5 for macrophages
gp41 mediates viral-cell fusion
viral genome uncoating→ ssRNA uses reverse transcriptase to make dsDNA, integrase inserts copies randomly into the host (remains latent)
activation--provirus genes expressed
gag: encodes polyprotein virion core
pol: encodes protein for reverse transcriptase, integrase, and protease
env: encodes envelope proteins
viral protease cleaves polyproteins
disease caused
acute viremia: vigorous host immune response (like mono)
latent stage: virus replication (lymph area), immune response, mutations in virus
↑ viral load, ↓ CD4
AIDS: CD4 count less than 200/uL (immunocompromised)
Tx: nucleoside reverse transcriptase inhibitors (AZT); protease inhibitors (indinavir, nelfinavir)
Term
rhinoviruses
Definition
genome: ssRNA
life cycle: contact/aerosol transmission binds epithelial cells in resp. tract causing inflammation
exudate may block passageways
acquired IgA immunity to a serotype afterwards
disease caused: common cold
Tx: supportive care (no vaccine→ too many serotypes)
Term
Adenovirus
Definition
genome: nonenveloped, dsDNA
life cycle:
aerosal, fecal-oral→ enters and lyses mucosal cells
disease caused: resp. infection, conjunctivitis, gastroenteritis
Tx: vaccine (live virus)
Term
Herpes simplex virus 2
Definition
genome:
enveloped, dsDNA linear
life cycle: transmission by sexual contact, infection of mucous membranes can cause lesions in genital area
virus enters nerves
can cross placenta
disease caused: genital herpes, neonatal herpes
Tx: Acyclovir
Lytic/Latent infection
latent: enters the nerves of lumbosacral ganglia
lytic: stress (menstruation, fever, sunlight) reactivates and virus is transported to nerve endings
Term
Varicella zoster virus
Definition
genome
enveloped, dsDNA linear
life cycle: inhalation → flu symptoms leading to rash
disease caused: chickenpox or shingles
Tx: supportive, acyclovir (if severe), anti-VZV immunoglobin (if immunocompromised)
Lytic/Latent infection
latent: virus enters the sensory dorsal root ganglion and when reactivated is transported to nerve endings causing painful rash over sensory dermatome (SHINGLES)
Term
Human papilloma virus
Definition
genome: dsDNA, nonenveloped
life cycle: close contact transmission infects epithelial cells of epidermis or mucous membranes
disease caused
Tx: vaccine
Lytic/Latent infection
lysogenic: basal cell infection, virus transforms the basal cell→ warts
lytic: infects keratinized epithelium, DNA replication/assembly and lysing
Term
Conjugation--horizontal transfer
Definition
plasmids (transposon insertion)
Term
transformation
Definition
uptake of naked DNA from environment
Term
transduction
Definition
phages, randomly moving pieces of DNA (only if the phage is induced are the genes expressed)
Term
catalase
Definition
(pos. is staph); indicates usage of O2
Term
oxidase
Definition
(neg. is E. Coli; pos. is Pseudomonas); used in e- transport chain
Term
targets of peptidoglycan
Definition
bacitracin, fosfomycin, B-Lactams
only affect growing cells
Term
targets of Gyrase (topoisomerase)
Definition
fluoroquinolone
Term
metronidazole
Definition
blocks DNA pol
Term
Gram positive
Definition
thick peptidoglycan, 1 membrane, Teichoic Acid & LTA, M proteins (bind Factor H to look like self)
Term
Gram negative
Definition
thin peptidoglycan wall; 2 membranes (outer: LPS--lipid A, core, O antigen-->target of complement); can be killed by MAC
Term
IgM
Definition
mu cassette (first made); 10 binding sites (pentameric); high avidity low affinity; fixes complement
Term
IgG
Definition
gamma cassette (2nd in class switch); high affinity; 2 binding sites; fixes complement
Term
IgA
Definition
alpha cassette; mucus, high affinity (no fixing of complement)
Term
MHC II
Definition
docks with CD4 along with PAMPs
Term
inoculum
Definition
dosage of the virus associates with the severity
Term
intracellular infection
Definition
b cell antibodies CANT reach (can only work on cell surfaces)
Term
interferon
Definition
made by the infected cell (local infection)
alpha (autocrine): binds to self and halts host cell translation of proteins (so no viral protein production means no productive infection--this is temporal)
beta (paracrine): binds neighbor so they can't become infected
Term
live (attenuated) vaccines
Definition
replicate slowly so triggers a full immune response (B cell, T cell, antibody production)
Term
killed virus
Definition
good for immunocompromised; can't infect the cells (so no CD8 response) but can still produce an antibody and CD4 response
Term
fungi
Definition
yeast (actively dividing--warm temperatures); mold (hyphae--ambient temp)
Term
dimorphic fungi
Definition
can assume both mold and yeast forms (temperature dependent)
Term
fungi cell wall component
Definition
ergosterol (azoles and amphotercerin B target this); chitin
Term
response of immune from a fungal infection
Definition
innate immunity, non-specific inflammatory neutrophil response; t cells (granulomatous and macrophages)
Term
high eosinophilia
Definition
corresponds with protozoa or helminth infection
Term
hemolysins
Definition
strep O makes pores in cell membranes
Term
superantigens (hormone analogs)
Definition
binds MHC receptor between APC and T cell (super stimulation of T cell so high cytokine production) leads to SHOCK [staph]
Term
Gram negative evasion techniques
Definition
pilli or fimbriae
long O antigen keeps the MAC away
special outer membrane proteins block opsonization
sialic acid in O antigen (look like host)
capsule binds Factor H
Term
Type III secretion
Definition
Gram neg:
1. used to inject effector proteins to avoid phagocytosing
2. Salmonella uses to induce uptake then switches to a different Type 3 to get phagocytosed into a macrophage
Term
gram positive evasion techniques
Definition
pilli
strep M proteins (prevent complement fixation and bind factor H)
bind fibronectin
Hyaluronic Acid capsule
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