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116 Cards in this Set
- Front
- Back
__________ is an invasion of the body by a microbe (ie: bacterium, virus, fungus, or parasite) that causes damage either directly or indirectly.
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INFECTION
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What are the 6 steps in the infectious diseases process?
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1. Encounter
2. Entry 3. Spread 4. Multiplication 5. Damage 6. Outcome |
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T/F Some infections are considered endogenously acquired?
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True
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What does it mean to acquire an endogenous infection?
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endogenous infections are caused by agents on or in the body (many oral infections are considered endogenous)
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Where do the bacteria enter?
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Most tissues are normally thought of as inside the body are topologically connected with the outside
(we are a hollow tube with hollow cavities) So the "external surfaces of the body" include: Nose, Mouth, respiratory tract, anus, alimentary canal, female genital tract, urinary tract |
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What are the two ways that the term "ENTRY" can be used?
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1. Ingress of microorganisms into the body cavities that are connected to the external environment.
(ex: inhalation or ingestion) 2. Penetration of microorganisms into deeper tissues after crossing an epithelial barrier. (ex. insect bites, cuts and wounds, organ transplants and blood transfusions) |
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T/F Many pathogens MUST penetrate tissues in order to cause disease.
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true
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Penetration of a bacteria into epithelial cells usually involves what two steps?
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1. Attachment to specific cell surface receptors
2. Internalization - Host-mediated internalization - Pathogen - mediated internalization - Invasion |
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T/F The nose, mouth, respiratory tract, alimentary canal, anus, female genital tract and urinary tract are all in direct contact with the exterior and are therefore generally not considered inside the body.
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true
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T/F The ability of microbes to invade the host can be dependent up on the inoculum SIZE.
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True - example in class was of hot tub - bacteria harmless until in large quantities
(but remember that it varies with different organisms) |
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Spread of the microbes is important for disease progression. Spread can occur primarily through 2 different mechanisms - which are?
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1. Lateral propagation(or mvt) to contiguous tissues
2. Dissemination to distant sites (microbes must overcome host defenses in order to spread and/or multiply) |
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T/F Microbes MUST overcome host defenses in order to multiply and spread.
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True
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There are 4 possible outcomes of a host-parasite interaction: which are?
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1. the host wins out and clears the infection
2. the parasite overcomes the host. 3. the host and parasite adapt to each other 4. neither host or parasite win. This chronic infection can continue indefinitely. |
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Damage to the host can be caused by?
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1. Infectious Organism
- lytic viral infections - toxin producing microbes 2. Host Response (immune system) - phagocytes - cytotoxic T cell activity 3. BOTH |
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The body contains approx. ______ as many microbes as host cells.
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10x
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T/F all surfaces contain a normal microbial flora (or microbiota) and have many beneficial effects on the host.
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true
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Is it true that the normal microbiota can coexist with the host without causing harm?
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true
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T/F NO microorganism is intrinsically benign or pathogenic.
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TRUE, even the most domesticated microorganism can cause trouble if given the opportunity (in class he gave the example of a Hummer crashing into a car and a man standing on the Hummer - it can go either way)
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The great majority of microorganisms are commensal. what does that mean?
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They coexist without causing harm. It can be difficult to identify a bacterium as a commensal.
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T/F Commensal bacteria can form a protective barrier over epithelial surfaces.
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true
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Many commensal bacteria produces subastance that ________ (activate/inhibit) colonization by potential pathogens?
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INHIBIT
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Many places on the body can safely harbor bacteria - give an example.
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1. GI tracts
- 10^12 bacteria per gram 2. MOUTH - estimated 500 different species |
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What is more simple? A bacterial cell or fungal (eukaryotic) cell?
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Bacterial cell
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What is an example of normal microbiota?
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Skin: staph, enteric bacillia
Oropharynx: strep, Corynebacterium, Haemophilius, spirochetes, neisseria Large intestine Vagina - the main point: there are many |
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What stains pink and what stains purple when comparing gram + and gram - cells?
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gram + purple
gram - pink |
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Gram positive bacteria have a ________ cell wall made up of _______ (peptidoglycan).
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THICK cell wall - made of MUREIN
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Murein is made up of long chanse of ____- and ______ linked together by short polypeptides.
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NAM (N-aceytlmuramic acid)
NAG (N-aceytlglucosamine) |
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Gram negative bacteria have a __ (thick/thing) layer of murein between _____ (1/2/3) membranes (lipid bilayers).
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THIN layer of murein
2 lipid bilayers |
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What membrane bound acids are found in gram positive bacteria?
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TEICHOIC ACID
LipoTEICHOIC ACID |
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From external to internal name the structures in both gram + and gram -
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gram +
- Teichoic acid - Cell wall (murein) - Cell membrane (lipid bilayer) gram - - membrane proteins - outer mem. - cell wall (lipoproteins and murein) - periplasm - inner mem. |
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Why does gram - bacteria have 2 lipid bilayers?
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needs more structure for help
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T/F murein is a peptidoglycan
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TRUE
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What is the favorite target of many antibiotics in association with murein?
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antibiotics attack the short peptide bonds that link the NAM/NAG chains together
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T/F Murein is unique to bacteria
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true
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What is the sequence/order for the NAM and NAG in murein?
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NAM and NAG alternate - in normal cell must bind together in cytoplasm
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What is the outside of the outer mem. of gram gen. bacteria made up of? Does it differ btwn diff. bacteria?
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LPS - lipopolysacchardes - that is different for different bacteria.
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Is LPS an endotoxin?
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yes, even in its purified form (which means it is TOXIC)
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What is LPS made up of?
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LIPID A: a lipid region (fatty acids attached to a phophorlyated disaccharide) that faces into the mem. and a CORE POLYSACCHARIDE polysaccharide region facing out. REPEATING O-ANTIGEN SUBUNITS - The outer (O-antigen) region is highly variable and antigenic.
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Is the O-antigen associated with LPS static or variable?
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HIGHLY variable and antigenic
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Explain the regions of biosynthesis of murein and the antibiotic action.
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antibiotics can act in many places to disrupt a bacterium - formation of murein is one of it's areas of action:
1. can act within cytoplasm where formation of murein is occuring 2. can act within periplasm where NAG/NAM chains are being brought together 3. Can act in periplasm to disrupt formed murein |
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What are the 3 methods of transport across the bacterial cell membrane that are facilitated by permeases?
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1. Carrier-mediated diffusion (facilitated)
2. Phosphorylation-linked transport (group translocation) 3. Active transport (energy dependent) |
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Bactericidal agents _____- bacteria while bacteriostatic agents ____________ ______.
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bactericidal: KILLS
bacteriostatic: INHIBIT GROWTH |
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Are Penicillins and other beta-lactams (antibiotics) tat affect the cell wall bacteriocidal or static?
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BACTERICIDAL - KILLS
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_________- often work by targeting bacterial ribosomes to disrupt the bacterium.
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Antibiotics
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T/F PART of the incubation period during infection is related to the growth curve of the microbe
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TRUE - only PART of it!
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What does the bacterial growth curve look like and include?
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Lag (slowly increasing slope)
Exponential (high slope) STATIONARY - Total count (static peak) - Viable count (decreasing slope) |
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How long does it take for DNA to replicate in bacteria?
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40 min.
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Why does bacterial DNA divide so quickly?
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multiple replication forks
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What is the difference between replication of DNA in slowly and rapidly dividing E. coli?
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(see figure in slides)
- Slow - growing have less replication forks ex: from 1 -> 2 -Fast growing have MANY replication forks ex: from 1 -> 4 |
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Do bacteria need many nutrients to grow?
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No, bacteria can grow with very few nutrients - see table in slide for growth medium - glucose minimal medium table 3.4
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What are the 3 bacterial responses to oxygen?
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1. Strict aerobes: MUST have oxygen to grow (use O in electron transport)
2. Obligate anaerobes - cannot tolerate oxygen 3. Facultative anaerobes - can grow with or without oxygen (most medically important bacteria). |
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What allows antibiotics to specifically target prokaryotes vs. eukaryotes.
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Prokaryotic ribosomes are sufficiently different from eukary ribosomes to allow specific targeting of antibiotics.
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How many subunits are there to bacterial ribosomes? What are they?
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2, 30S and 50S
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What is the 30S subunit primarily responsible for?
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translation of mRNA
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What is the 50S subunit responsible for?
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joining AA together and moving the complex along the mRNA molecule
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Can antibiotics target the 30S or 50S?
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BOTH, various antibiotics interrupt in diff. stages of the cycle.
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What acid is impt. in the production of various AA?
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Folic Acid - PAB (P-aminobenzoic acid) reacts with precursors to form folic acid.
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What type of inhibition is used and by what to stop Folic acid production and thus stop the bacteria from producing proteins?
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COMPETITIVE Inhibition - Sulfonamides and tripmethoprim inhibit folic acid metabolism
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What antibiotics inhibit protein synthesis?
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Aminoglycosides (streptomycin, kanamycin etc.) tetracyclines and erythromycin inhibit protein synthesis.
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What antibiotic inhibits DNA synthesis?
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Metronidazole
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What antibiotics inhibit murein synthesis?
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B-lactams:
penicillin and cephalosporins |
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SIDE EFFECTS OF ANTIBIOTICS:
- what is the therapeutic index? |
the ratio between the effective and the toxic dose.
Topical application are less likely to produce side effects. |
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Because of the selective pressure exerted by antibiotics, bacteria have become resistant within ____ human generation. This is because of antibiotic _______.
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ONE human generation
ANTIBIOTIC RESISTANCE |
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What are the 3 steps in the action of antibiotics? Where does the resistance to these drugs occur?
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1. Drug penetratres the envelope
2. Transport into the cell 3. Drug binds to target - resistance to drugs occurs at each of these steps. |
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What are the mechanism of drug resistance?
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Synthesis of enzymes that inactivate the drug
Prevention of access to the target site - Inhibiting uptake - Increasing secretion of the drub Modification of the target site |
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Why would increasing the secretion of the drug help in drug resistance by the bacteria?
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it help pump it out of the cell
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Drug resistant genes are often found on _______- that can be transferred readily from one bacteria to another.
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plasmids
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An example given in class of drug resistance was to penicillins and cephalosporins (murein synthesis inhibitors) - how does it work?
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the Beta-lactamases are produced by the bacteria to inactivate the drug - they clip the structure in specific places to inactivate it.
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T/F antibody resistance has predated antibodies
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true, natural phenomenon
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What is the Progression of drug resistance in bacteria?
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1. Chromosome associated resistance
2. Plasmid mediated resistance 3. Rapid spread of resistance - (prob in clinic) |
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What is a strategy to combat bacterial infections expressing antibody resistance?
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Multiple Drug therapy
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What are the 3 effects of multiple drug therapy?
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Synergism: 2 drugs in combination work better than either work alone
Antagonism: undesirable effect that may lead to treatment failure Indifference - each drug acts independently of the other (no additional gain) |
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Below are several drawbacks of _________ antibiotic therapy.
failure to "cover" the pathogen The synergistic toxicity of multiple drugs Possible antagonism between drugs Increased likelihood of superinfection by resistant bacteria |
"shotgun" antibiotic therapy
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Below are found all the indication for ____________ therapy,
Prevent the emergence of resistant organisms Treatment of severe infections caused by organisms that are potentially drug resistant An initial empiric therapy to "cover" multiple potential pathogens to treat usually fatal infections. |
Combined therapy indicated
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What type of parasites can only gow inside host cells.
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Obligate INTRAcellular parasites.
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Teichoic acids are ONLY found on what type of bacteria?
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GRAM POSITIVE!
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LPS are found on what type of bacteria?
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GRAM NEGATIVE
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What exactly are teichoic acids? What is a LIPOteichoic acid?
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*repeated sugars bound to murein (bind to peptide crosslinks btwn NAM - covalent bond)
Lipoteichoic acids: go ALL the way down to the lipids and bind there. |
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What is a LPS and where are they found?
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Lipopolysaccharide - gram neg. bacteria.
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What is the LIPID A portion of a LPS?
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fatty acids attached to a phosphorylated dissaccharide
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What is the O-antigen of the LPS?
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highly variable repeating sugar subunits
THE O ANTIGEN IS THE MAIN REASON FOR THE DIFF. ANTIGENIC SPECIFICITIES AMONG GRAM-NEG BACTERIA. |
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T/F does a gram neg bacteria differ at the lipid A site?
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a little bit
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T/F O-sugars are what stimulate the immune response.
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true
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T/F
LIPOPOLYSACCHARIDES = LPS, AND ENDOTOXIN? |
True
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What are LPS and teichoic acid so impt?
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They are considered pathogen associated molecular patterns (PAMPs)
Cells of the immune system can recognize PAMPs using pattern recognition receptors (PRRs) |
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Toll-like receptor 4 recognizes ____
Toll-like receptor 2 recognizes _____ Toll-like receptor 2 and 6 together recognize ______ ______ |
4 - LPS
2 - Peptidoglycan (murein) 2 & 6 - teichoic acids |
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Capsules, Pili (fimbriae), and flagella are also __________ structures of the bacterium.
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extracellular
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Pili (or fimbriae) are specialized structures on the surface of bacteria that are involve in ?
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adhesion to cells or other surfaces
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Sex pili are specialized pili that link a donor cell to a recipient cell during?
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transfer of DNA
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Flagella are surface structure used for ______. Which way do they rotate to move? Tumble?
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Locomotion; they cause mvt. when they rotate COUNTERclockwise and tumbling when they rotate CLOCKwise
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_______-- mvt is used by bacteria for chemotaxis: the movement toward substance that attract and away from substances that repel.
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flagellar
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What are adhesins associated with and how are they used?
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found on the tip of fimbriae - specialized proteins that are more specifically developed for adherence
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Mvt. caused by flagella can be random or directed - when it is directed it is known as?
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chemotaxis
- bacteria with flagella are referred to as motile |
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can chemotaxis can be directed toward something good or away from something bad?
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yes
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There is also a CAPSULE - which is made of ?
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glycocalyx
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why would capsules be beneficial to pathogens?
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protection for invasion
recognition, covering surfaces structures, hiding LPS or teichoic acid |
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Can the immune system ever recognize a bacterium that has a capsule?
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Yes -
toll-like receptors 5 can recognize flagella sometimes the capsular polysaccharide can be recognized |
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What does the capsule do?
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helps with recognition and prevention against immune system
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What happens when the immune system recognizes a microbe?
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phagocytoses the microbe and prodcues cell (NK, PMN leukocyte, Monocyte, T lymphocyte) and also produces chemical mediators
also, sends signal to rest of body that there is an infection |
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Bacteria are often classified via their surface antigens (referred to as serotype). WHat does O H and K refer to?
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O: refers to LPS (gram neg. bact)
H: flagella K: capsule |
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Pattern recognition receptors recognize pathogen associated molecular patterns or
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PRRs -> PAMPs
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In order to survive as an infectious agent, bacteria must:
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1. avoid being washed away
2. find a nutritionally compatible niche 3. survive host defenses 4. transfer to a new host |
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Damage to a host as a result of infection can be cause by many things - name them.
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cell death, pharmacological alterations of metabolism, mechanical causes, host responses, and bacterial toxins.
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Many structures on the microbial surface consists of repeated molecules -- referred to as
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Pathogen associated molecular patterns
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Mucosal surfaces are the primary portal of entry for infectious microbes.
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true
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mucosal surfaces have many defenses including:
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microbiota, mucous, movt. of fluids, and antimicrobial peptides.
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Antimicrobial peptides are ________-and are thus attracted to _______ surfaces. Many structures on microbes are __.
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cationic, anionic
many structures on microbes are ANIONIC |
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Lysozyme targets?
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murein
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Defensins create?
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pores in microbes
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Lacteferrin binds up?
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iron
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THe natural microbiota creat a barrier to pathogens? true or false?
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true
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Normal physiological properties influence microbial pop. and pathogen level on mucosal surface, such as
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acid, motility, mucous, and oxygen levels.
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Tight junct. btwn. mucosal epithelial cells prevent ________ from entering the body by passing in btwn. epithelial cells.
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microbes
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An over-reactive TNF-alpha response will disrupt ____ _______
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tight junctions
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There are huge number of innate and adaptive immune cells within __________ ____-----
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mucosal tissues
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Mucosal tissues are found in close proximity to a dense network of ?
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lymph nodes
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