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35 Cards in this Set
- Front
- Back
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gram positive bacteria |
thick peptidoglycan layer that takes up stain cocci- staph, strept, enterococcus rods- bacillus, clostridium, corynebacterium |
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gram negative bacteria |
thin peptidoglycan layer, has an outer membrane lipopolysaccharide on the outer membrane most are rods; only gram neg cocci are in human ds E.coli, salmonella, capylobacter (enterics!- cytochrome oxidase negative, facultative anaerobes) |
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endotoxins |
LPS- gram negative only! 3 parts lipid A- causes enodtoxic shock cores- short chain LPS 0 side chain- long chain LPS (length and variability can determine virulence)
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exotoxins |
proteins- both gram negative and gram positive have specific and targeted actions- make them good candidates for vaccines toxoid- inactivated exotoxin used in some vaccines antitoxin- premade antibody to exotoxin that can be used in treatment
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capsule |
polysccharide or polypeptide surrounding a bacterial cell on gram positive or gram negative bacteria virulence factor! it inhibits phagocytosis- easy for the capsule to slip away from the macrophages |
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spores |
very resistant dormant bacterial state; withstands high temp, drying, chemicals, pressure has a peptidoglycan and cysteine rich protein layer; makes its strong, but will not take up stain! almost all are gram positive- bacillus, clostridium |
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acquisition of virulence factors |
random mutations conjugation- transfer of DNA via sexual pili transformation- bacteria pick up naked DNA from the environment transduction- DNA from virus |
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biofilms |
multi-layered bacterial community embedded in a polysaccharide matrix ability to adhere to surfaces such as catheters, implants, bone, foreign body they aren't very resistant but they are hard to treat- when abx on, they die but they can grow again when abx stops
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3 consequences of the innate immune activation |
1. pathogens can be engulfed and killed by tissue macrophages 2. tissue macrophages can make cytokines and chemokines to signal neutrophils, monocytes, lymphocytes 3. DCs leave the tissue and go to LN for t and b cell activation |
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types of dendritic cells |
conventional- engulf organism, process it and activate T cells. CCR7 chemokine directs it to the LN. have MHC II and B7 expressed on the surface to activate T cells plasmacytoid- cell population not very good at phagocytosis. produce type 1 interferon |
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t cell activation |
1. TCR on t cell binds to MHC complex on DC 2. CD28 on t cell binds to B7 on DC 3. third step not necessary- cytokines allow differentitation |
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b cell activation |
1. Binds native antigen 2. CD40L / CD40 on t helper cells |
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how do pathogen specific T and B cells find each other |
B and t cells express chemokines and receptors T cells express CCR7- localizes it to the T cell zone B cells have simlar cytokine that allow it to localize to B cell follicle T cells then upregulate chemokine rec that directs it to the B cell zone (b cells do the same thing when activated) they line up on the edge of the b cell follicle and deliver signals to each other |
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smallest and largest viruses |
smallest- DNA circovirus (18nm) biggest- small pox (300nm) |
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RNA viruses |
All are single stranded except for reovirus, BIRNA |
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DNA viruses |
All are double stranded except for circovirus, parvovirus |
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morphology- naked virus |
Genome in the middle- DNA or RNA Surrounded by capsid (hexagon) protects the genome Proteins on the outside- receptor binding proteins- allows the virus to bind to the host and determines host specificity |
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virus symmetry |
icosehedral- cubic symmetry 20 faces, 12 points- most stable helical- built like a helix rabies, membrane on the outside complex symmetry- poxviruses |
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components of fungi cells |
cell wall- very different from bacterial cell walls; contains chitin, beta glucan- target of antifungal drugs like glucan synthase inhibitor cell membrane- contains ergosterol |
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mechanisms of antifungals |
glucan synthase inhibibtor- targets cell wall amphotercin B- binds to ergosterol in the membrane and makes cations leak, killing the cell azole drugs- targets the synthesis of ergosterole, doesn't kill as rapidly |
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mold vs. yeast |
mold- filamentous fungus that forms hyphae, which can branch yeast- single cell fungus that reproduces by budding |
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fungal terminology |
mycelium- a mat of hyphae conidia- reproductive unit, spores fruiting structure- repro strucutre generally only seen in culture, it makes the conidia arthroconidia- condidia that form as the result of fragmentation of hyphae dermatophyte- causes ringworm anamorph- asexual repro stage telomorph- sexual repro stage |
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habitat for fungus |
survive on dead or decaying material usually don't need a host to propagate themselves exceptions- dermatophytes need to be on host to propogate itself candida albicans- usually only found on mucus membranes in animals |
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fungal morphology |
hyphal- septate vs. nonseptate septate- have dividers between the cells, non-septate are one long cell with many nuclei |
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aspergillus |
segmented, branhcing gram stain positive can cause respiratory problems in birds |
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cryptococcus |
is a yeast (much larger than bactertia)- colonies can look like bacteria, first do a gram stain! nasal or systemic disease in dogs, cats, huiman infection from the environment, produces abundant capsule which can be observed with india ink stain (looks like a blue haze)
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examples of dimorphic fungi |
coccidioides immitis/posadasii valley fever- causes systemic disease
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factors predisposing to fungal infection |
immuno-compromise- diabetes mellitus, hyperadrenocorticism break in host's defenses- break in skin, URI prolonged abx use- disrupts normal bacterial flora, may influence innate immunity |
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Pulsed field gel electrophoresis |
tells us if two samples have the same DNA, used in forensics, determining outbreaks such as e.coli in food |
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real time PCR |
has a higher sensitivity |
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conventional PCR |
j |
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sequence analysis |
j |
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MALDI-TOF |
j |
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morphology- enveloped virus |
h |
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replication of viruses |
er |
