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99 Cards in this Set
- Front
- Back
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What is a plasmid?
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small circular piece of DNA in bacteria
often carrying genes for antibiotic resistance or toxin production, etc. |
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what actually causes the immune response to gram-negative bacteria?
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Lipid A on the outer cell wall of the bacteria leads to response
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what 2 species are spores found in?
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Bacillus and Clostridium
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Pseudomonas, E. coli, Haemophilus, Bacteroides, etc
are what? |
rod gram negative bacteria
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Neisseria is what?
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cocci gram negative bacteria
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Corynebacteria and Listeria are what
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rod gram + bacteria
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Staphylococcus and Streptococcus are what
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Gram positive cocci
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bacteria that require a very enriched medium to grow are termed
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fastidious (Neisseria, Haemophilus)
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please describe bacteria that are Strict aerobes
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(eg. Neisseria or Pseudomonas)
• Respiration by electron transport chain → terminal electron acceptor is O2 • Cytochrome oxidase enzyme |
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2 Example of strict aerobes?
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Neisseria or Pseudomonas
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Example of a Obligate anaerobe?
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Clostridium
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Describe Facultative anaerobes
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grow aerobically in presence of oxygen and anaerobically in absence of oxygen (eg. E. coli)
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What is an example of an aerotolerant organism
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most Streptococcus
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What are b-lactams?
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• Penicillins
• Cephalosporins • Carbepenems note: Transpeptidase (TP) enzymes reform the peptide cross links for the cell wall |
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What is Vancomycin
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bind to peptides of ppg monomers and block transglycosidase
• Disrupts cell wall Transglycosidase (TG) enzyme insert and link monomers into the new ppg, so you are disrupting this activity |
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what is Bacitracin
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blocks dephosphoralization of bactoprenol phosphate
• Disrupts cell wall Bactoprenol phosphate is responsible for the transport ppg monomers across cell membrane, thus bacitracin disrupts formation of cell wall |
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what is Cycloserine
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an anologue of D-ala, blocks addition of dipeptide to UDP-NAM
• Disrupts cell wall |
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what is fosfomycin?
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inhibits phosphoenopyruvate transferase and prevents formations of NAM
• Disrupts cell wall |
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What blocks the initiaiting complex of the ribosome cycle?
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Linezolid
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30S inhibitors?
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Tetracycline
• Aminoglycosides |
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50S inhibitors
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Macrolides
• Chloramphenicol |
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What do Fluoroquinolones do?
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inhibits DNA gyrase or topoisomerase
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Metronidazole does what
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Disrupts DNA helical structure under anaerobic conditions
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Rifampin does what
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Binds to RNA polymerase
antibiotic |
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• Sulfonamides do what?
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• Blocks synthesis of dihydropteroic acid
• Folate antagonists |
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Trimethoprim does what
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Blocks synthesis of tetrahydofolate
• Folate antagonists |
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Polymyxins do what
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Interact with phopholipids
• Disrupt cytoplasm membrane |
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disinfect vs. decontaminate
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• Define disinfect
• to sanitize -reduce the number of pathogens to a safe level • Define decontaminate • to render a microbe laden surface safe to handle |
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varicella-zoster virus evades the immune system how?
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Block MHC I, II presentation of viral antigens
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Ebola virus, hepatitis C virus evade the immune system via what mechanism?
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Prevent proliferation of activated T-cells; stimulate production of null cells
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herpes simplex virus, West Nile virus evade the immune system how?
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Block production or activation of complement, cytokines, interferon
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See Negri bodies what are you thinking?
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RABIES
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What are the 3 virus structures?
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Icosahedral
Helical Complex |
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there are 5 steps to virus replication, please give them in order
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1. attachment
2. penetration/uncoating 3.biosynthesis 4.maturation 5.release |
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do sexual or asexual spores lead to infection?
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asexual
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do yeast release spores?
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no they bud!
spores can reproduce as yeast cells though |
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What are the 3 major fungal genera
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Trichophyton
Microsporum, Epidermophyton. |
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comparing bacteria vs. fungi
Cell type (prokaryotic, eukaryotic) |
Bacteria: Prokaryotic
Fungi: Eukaryotic (has nucleus, chromosomes) |
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what species are best at adhering?
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Candida:
that adhere best to epithelial cells are most often isolated from infections |
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comparing bacteria vs. fungi
cell wall |
Bacteria: peptidoglycan
Fungi: peptidomannan, glucan, chitin, cellulose, chitosan |
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comparing bacteria vs. fungi
cell membrane importance of this? |
Bacteria: no sterols
Fungi: no cholesterol (ergosterol) different enough from cholesterol that our treatments target ergosterol and look to inhibit its synthesis |
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if you have a clinical fungus that is cutaneous, what is it doing?
what causes the response? |
eat both live and dead keratin, don't respond immunologically, respond to metabolic products
living tissue is not invaded; organisms colonize the keratinized stratum corneum because of their keratinolytic ability. Disease is as a result of the reaction of the host to the percutaneous absorption of the metabolic products of the fungus (inflammation, DTH reactions). Commonly called tineas or ringworm. |
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Candins, pradimicins, nikkomycins target what to fight fungal infections?
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the cell wall of the fungi (peptidomannan, glucan, chitin, cellulose, chitosan)
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What is a resistance (R) plasmid?
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Conjugative plasmid
Replication and transfer genes *****Multiple resistance genes against antibiotics Resistant genes are often parts of transposons* |
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What is horizontal gene transfer?
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Genetic Recombination in Bacteria
Part of chromosome is transferred from a donor to recipient cell Must recombine as a double crossover to be passed on to progeny |
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what is bacterial transformation
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Donor cell releases free DNA by lysis
DNA attaches to a recipient cell where it is cut into small pieces and reduced to a single strand Genes on the single strand recombine with the recipient’s chromosome |
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if a bacteria does NOT have a capsule, is it virulent?
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noooo
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what is bacterial conjugation?
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Certain plasmids (F) can transfer themselves
Occasionally the plasmid integrates itself into the chromosome (Hfr) When the plasmid is transferred to another cell it drags along the chromosome with it Integration occurs via a double crossover |
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the efflux pump on a bacteria will prevent the activity of what antiboitic?
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Tetracycline
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Staphylococcus aureus is resistant to what (that we used to use to treat it)
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Methicillin
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Enterococcus is resistant to what?
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vancomycin
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Streptococcus pneumoniae is resistant to what?
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Penicillin
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what is Generalized transduction
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transfers any bacteria gene
Transfer of genes from one bacteria cell to another by means of a phage basically: get replication |
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what are B-lactamase and Aminoglycoside examples of
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mechanisms by which the bacteria can degrade or alter the antiboitic
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what is Specialized transduction
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transfers only genes adjacent to site of integration
Transfer of genes from one bacteria cell to another by means of a phage |
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what is transduction?
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Transfer of genes from one bacteria cell to another by means of a phage
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What is a tranposon?
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jumping gene
Carry both insertion sequences plus other genes Often confer a selective advantage like antibiotic resistance |
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What are the key factors that would lead you to suspect that a parasite (rather than a virus or bacterium) was responsible for some gastrointestinal illness? 4 things
*objective |
1) potential for exposure (travel history)
2) identification of parasite, larval forms, eggs, cysts 3)Lab tests (EIA, immunofluorescence, PCR, etc) 4)Eosinophilla |
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intermediate host
*objective |
host in which asexual reproduction or larval development occurs
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how do you determine btw virus and bacterial gastroenteritis?
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if you can identify when the ingestion took place
if the clinical signs are within a few hours: toxin produced by bacteria if the clinical signs occurs within a day or so: virus (or growing bacteria) if it takes a week or 10 days: parasite |
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what is the number one cause of gastroenteritis?
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bacteria or virus
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see someone out camping in the woods or hiking in the mountains, what does that guy have? *** likely on test
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giardia
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What is the difference between a trophozoite and a cyst?
*objective |
A trophozoite is the metabolically active and motile stage of many protozoan parasites.
The cyst form is generally smaller, and has an outer protective layer to enhance survival in the environment |
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amoeba, sporozoa, flagellates, ciliates are all examples of?
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protozoa
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definitive host
*objective |
host in which the parasite reaches sexual maturity
sexual replication takes place here |
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which is more geared for survival between trophozoite and a cyst?
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cyst
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Describe the probable roles of IgE antibody and eosinophils in combating parasitic infections
*objective |
eosinophils have FC receptors for IgE
the IgE acts as a bridge for the eosinophil this is the mechanism that works against the WORM infection |
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what is the number one cause of parasitic gastroenteritis?
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giardia
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Your patient is a 5-year-old female accompanied by her mother. The chief complaint is nausea, vomiting, and foul-smelling diarrhea for several days. The mother states that the watery stool looks greasy. The child has had little appetite.
The patient attends a pre-school this year, and had been in day care since she was 2-years-old. Physical exam reveals moderate epigastric tenderness. The child is slightly below normal weight what is this due to? |
giardia
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Cite 2 examples where insect vectors transmit parasitic organisms to humans.
*objective |
mosquito (for malaria and elephantitus)
tic (transmits blood parasite |
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in addition to direct mechanisms, how can the immune system indirectly remove a parasitic worm in the GI tract?
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increase non-specific inflammatory processes (TNF, IL-1) leading to increased mucous secretion that can coat the parasite and help get it out
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Reservoir
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species where the parasite can survive and proliferate but not necessarily
cause disease |
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what is the number one cause of gastroenteritis?
what is the number one cause of parasitic gastroenteritis? |
generally bacteria or viruses cause gastroenteritis, but for parasitic it is almost always giardia
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TH2 releases what leading to?
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IL4,5 for mast cell, eosinophils and IgE production
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What cell types mediate antibody-dependent cellular cytotoxicity (ADCC)?
**objective |
Specific antibodies are formed (with the help of T cells) to the microbial invader. The microbe is targeted for destruction by these antibodies.
2) Killer cells that have receptors for the Fc portion of the antibody (i.e. Fc receptors) destroy the target cells. 3) The antibody (usually IgG isotype) basically acts as a bridge to connect the killer cell and the target cell. 4) ADCC killer cells include: NK cells and macrophages |
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CRP
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C reactive protein
acute phase protein made during inflammatory rxn, measurable for systemic inflammation |
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what mechanism is best at fighting extracellular bacteria
objective |
Antibody and complement
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a patient presents to your office with recurrent bacterial infections, you ask yourself in general, what immune response is likely missing from this person
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Antibody and complement
these respond best to bacteria |
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What are perforin and Nitric oxide? What are their roles in host defenses?
**objective |
Nitric oxide is a gas produced in phagocytic cells and is toxic to many organisms
perforin when released can polymerize and cause transmembrane pores to form. Perforin is structurally similar to the C9 component of complement. CTL granules also contain proteolytic enzymes and TNF-α, all of which can damage target cells. |
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if you have problems with phagocytosis what are you most likely to get as far as infections go?
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fungal
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a patient presents to your office with recurrent fungal infections, you ask yourself in general, what immune response is likely missing from this person
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problem with phagocytosis
because fungi are weak, and should just be gobbled up |
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What intracellular killing mechanisms are present within activated macrophages?
**objective |
produce oxygen free radicals for intracellular killing
remember NADPH oxidase |
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TH1 leads to what?
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INF gamma to macrophage activation
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What is a granuloma? What is the potential significance of granuloma formation?
**objective |
cannot kill the cell after it is phagocytized due to lack of reactive O2 species in macrophage
a granuloma is the walled off problem that is not killed this is seen in chronic granulatomous disease |
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what mechanism is best at fighting fungi
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phagocytosis (neutraphils and macrophages)
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what does TGF B do? 2
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turns off T cells
isotype switch to IgA*** |
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IL 10 does what?
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turns off TH1
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What is the primary role of Natural Killer Cells (NK cells) in the immune response?
**objective |
NK cells are "large granular lymphocytes" with no discernible antigen receptor. However, antibody can provide the specificity and activate NK cells via ADCC. NK Cells major role may be to destroy infected cells
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what 2 components of the immune system are important for fighting early viral infection
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type I interferons (think mucous)
and NK cells |
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CTLA-4
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T-cell inhibitor
prevents co-stimulatory signals (stops CD28 to B7 binding) |
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intracellular viral infections what is most important?
objective |
t cell
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you have this patient. he is super annoying. keeps coming in getting viral infections. finally you are like geeze, either this guy is just continually rolling around garbage or he has a deficiency in his....
(part of the immune system) |
T cell
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Describe the role(s) of T-helper cells and cytotoxic T-cells in a virus infection.
**objective |
Cytotoxic T-cells (CTL), which are usually CD8+, are known to kill virus-infected cells and tumor cells. This killing is 1) antigen specific 2) MHC Class I restricted, i.e. target cell must have MHC class I with antigenic peptide in the binding groove; and may cause cell lysis by 3) inducing "programmed cell death" (apoptosis), or 4) release of pore-forming proteins like perforin.
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What is the immunologic advantage of using an oral or nasal influenza vaccine in place of or in addition to the traditional parenteral vaccine?
**objective |
advantage of oral:
absorbed in intestines, returned to heart via thoracic duct, then pumps all over your body |
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What types of infections would you expect to see in a person with a total deficiency in antibody production?
**objective |
extracellular bacterial infections are most common
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T cell vs. NK
mediate ADCC |
NK
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3 most important antiviral immune cells
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type 1 interferons, NK, cytotoxic T cells
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What is the basic difference between TH1 and TH2 type T-lymphocytes?
**objective |
TH1 cells release IL-2 and IFN-gamma (enhance cell-mediated responses; some IgG)
TH2 cells release IL-4, IL-5, IL- 6, and IL-10 (enhance humoral responses; IgE) |
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CXCR4
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chemokine receptor
important for getting cells to where they are needed |
