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69 Cards in this Set
- Front
- Back
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What is the distinguishing step of the gram stain? (that distinguishes gram + and gram -)
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Ethanol (decolorizing agent)
This destains Gram NEG only, due to only a single layer of peptidoglycan. |
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Acid fast stain (AFB – Acid Fast Bacteria) is used primarily to identify what species of bacteria?
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Mycobacterium sp
These bacteria stain pink due to their unique high content of mycolic acid. |
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The negative stain is a differential stain used to _
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detect the presence of capsules. this is aka the capsule stain.
It uses a special type of medium while culturing, which is made from skim milk |
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_ dye is used to stain endospores
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malachite green
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_ is a classis organism that causes hemolysis
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Streptococcus Pyrogenes
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Phase contrast in light microscopes allows light to _, this makes the organism more _
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refract differently though cell components which vary in density, this makes the organism more refractile.
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Differential interference contrast (DIC) yields _
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a 3D image
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You can create a 3D image by optically sectioning the specimen using _, and then recombining the image via computer software
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confocal laser scanning
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What are the Five categories for the diagnosis of infectious diseases
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Smears and Stains
Cultures Serologic testing Skin testing (hypersensitivity) Tissue biopsy (fungal/parasite studies) |
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4 steps of gram stain?
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1. Crystal violet – primary stain
Stains all cells purple 2. Gram’s iodine – mordant Fixes crystal violet into the cell wall 3. 95% ethanol – decolorizer Destains gram-negative bacteria only (due to only a single layer of peptidoglycan) Dehydrates and locks in the crystal violet with gram-positive bacteria 4. Safranin – counterstain Stains gram-negative bacteria pink/red Gram-positive bacteria remain purple |
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General purpose culture media is designed to _. What is an example of a general purpose agar?
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grow most microorganisms
blood agar medium |
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PEA agar is a _ culture media. What is it used for?
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selective.
It inhibits the growth of gram negative microorganisms, used to grow gram + ONLY |
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Simmons Citrate Agar is a _ agar. What is it used for?
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differential agar
a differential agar distinguishes microorganisms having a defined metabolic activity over others that lack it. In this case, citrate is a carbon source only certain microorganisms can use ( an example would be salmonella typherium) |
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Mannitol Salt Agar is a _ media, and is used for what?
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selective and differential media,
In this case, 7.5% salt inhibits all but staphylococci, and the mannitol gets fermented specifically by staph aureus. Staph aureus will turn the agar from red to yellow |
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To determine if a specific organism is staphylococcus aureus, what is the best agar to use?
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Mannitol Salt Agar
It is a selective/differential agar, staph aureus will ferment the mannitol turning the agar yellow |
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PEA agar supports what type of bacteria
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Gram-positive
CNA is another version of PEA that is used to provide rapid growth of gram + |
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Mannitol Salt Agar contains _% salt, and is selective for _,
This is what type of agar? |
7.5
staphylococcus aureus (agar will turn yellow) Both differential and selective |
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Clostridium sp is often differentiated using what type of medium?
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Egg yolk
Clostridium has lecithinase activity, which degrade phospholipids in the medium into insoluble diglycerides, turning the agar opaque |
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Mac Agar is selective for _bacteria
Contains _ |
Gram-negative
bile salts which inhibit Gram-positive bacteria Gram-negative bacteria which ferment lactose (E. coli) changes the neutral red indicator in the medium to dark pink/red causing those colonies of bacteria to appear red to dark-pink (differential for lactose fermenters!!) |
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Regarding the Mac Agar...Gram-negative bacteria which _ changes the neutral red indicator in the medium to dark pink/red causing those colonies of bacteria to appear red to dark-pink
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ferment lactose (E. coli)
(differential for lactose fermenters!!) |
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Salmonella and Shigella are grown best on _ agar, due to its high concentration of _
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hektoen enteric., bile salts
High concentration of bile salts inhibit gram-pos and some gram-neg except Shigella and Salmonella. |
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Hektoen Enteric Agar, in addition to bile salts, contains _ and _. What is the purpose of these?
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lactose and thiosulfate
thiosulfate which Salmonella reduces to hydrogen sulfide (black precipitate) lactose distinguises fermenters from nonfermenters |
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On a xylose lysine desoxycholate agar, _ distinguishes Salmonella from Shigella
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H2S Production
Salmonella produces H2S |
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BG Agar is selective for _
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Bordetella pertussis (whooping cough)
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Lowenstein-Jensen agar is used for the isolation of _
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mycobacterium sp
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MES agar contains _, which does what? What is this agar used to isolate?
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(aka Ureaplasma agar) Contains horse serum, which supplies cholesterol needed for stabilizing Ureaplasma Urealyticum, which lacks a cell wall. This colony has a FRIED EGG MORPHOLOGY
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To distinguish between a staphylococcus and a streptococcus, what biochemical test is done?
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Catalase!
- Bubbly appearance is Pos. Staph - POSITIVE, Strep - NEG |
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You're trying to figure out what a particular organism is. It has tested positive for the catalase test, Now what test do you perform?
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Coagulase Test
Pos Catalase means it's a staphylococcus, Coagulase tests to see if its staph aureus. It will bind fibrinogen and initiate clotting in the test tube. |
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To test for Neisseria, you want to perform the _ test
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oxidase.
This detects the activity of the cytochrome oxidase enzyme, if present, it will form indophenol, a purple end product |
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A positive indole test means it is positive for what bacteria?
This Detects activity of the _ enzyme on _, if pos it will be red. |
E Coli
This Detects activity of the tryptophanase enzyme on tryptophan, if pos it will be red. |
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Group D streptococci, now called enterococcus will be positive in what test
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bile esculin.
These bacteria can hydrolyze esculin |
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The _ test is the Presumptive test for Streptococcus pneumoniae
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Optochin test or P disc,
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What test can you perform to distinguish between S pyrogenes and S agalactiae?
S. pyrogenes will be _ for this test, while S agalactiae will be _ |
A disc is Used to differentiate group A streptococci.
+ - |
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Majority of fungal studies is done through _
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microscopy
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Periodic acid-Schiff stain is specific for _
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fungi!
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Grocott-Gomori methenamine-silver nitrate stain stains _ black
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fungal elements
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Taq polymerase is associated with what molecular diagnostic?
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PCR
polymerase chain reaction |
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IgE antibody predominately mediates what type of hypersensitivity?
What cells are responsible for the mechanism? |
Immediate hypersensitivity, Type I
Mast cells and their mediators |
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Antibody mediated Type II hypersensitivity is predominately mediated by what antibodies?
What is the mechanism? |
IgG and IgM
Opsonization and phagocytosis of cells, complement system |
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Give an overview of Type I, immediate hypersensitivity
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Activation of Th2 cells by antigen
Induced B cell class switching to IgE Production of IgE and binding of secreted IgE to Mast cell FceR Activation, degranulation, and tissue damage by Mast cells upon secondary exposure to antigen |
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Th2 differentiation depends on the presence of _
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IL4
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Mast cells are produced in the _ and are released as immature cells, they mature in _
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bone marrow
tissues |
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- FceRI has a very high affinity for _
Crosslinking of this receptor and its ligand leads to the release of _ |
IgE
granules |
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The Immediate response is aka _. This response is due to _ release that leads to _
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wheal and flare
histamine vasodilation and vascular leakage |
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_ is initially released from vesicles, is toxic to parasites, increases vascular permeability and causes smooth muscle contraction
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histamine
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_ is synthesized after initial activation and vesicle release. It promotes inflammation, stimulates cytokine production, and activates endothelium
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TNF alpha
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_ stimulates and amplifies Th2 cell response
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IL4
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_ promotes eosinophil production and activation
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IL3, IL5, GM-CSF
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_ cause smooth muscle contraction, increase vascular permeability, causes mucus secretion
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Leukotrienes C4, D4, and E
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Late phase synthesized agents (e.g. _) tend to have (larger/smaller/same) effect but (larger/smaller/same) magnitude than immediate released agents (e.g. _).
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leukotrienes,
the same larger histamine |
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Late phase occurs _ hours later, and involves synthesized secretion of _, _, and _
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leukotrienes, chemokines, and cytokines
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Immediate phase, aka _, involes _ degranulation, and _ release
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wheal and flare
mast cell histamine |
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_ are Functionally similar to mast cells, though related developmentally with eosinophils, they are recruited to
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basophils
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During the immediate response, Th2 cells release IL10,IL4, and IL5. IL10 is responsible for _, IL4 is responsible for _, and IL5 plays a role in _
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IL10 suppresses macrophage activation, IL5 causes eosinophil activation, and IL4 allows for production of IgG, IGE (and as a result, mast cell degranulation). It also plays a role in macrophage suppression
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Histamines role is to contract all smooth muscle - T/F
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False. It contracts most smooth muscle EXCEPT blood vessel smooth muscle
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In systemic anaphylaxis, what happens after the allergen is introduced into the blood stream?
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Mast cells THROUGHTOUT the body respond with degranulatiion.
Smooth muscle contraction occurs in GI and Resp, causing cramps, vomiting, difficulty breathing. Increased capillary permeability in vascular system causes low blood pressure, swelling, reduced o2 to tissues, loss of consciousness |
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Give an overview of type I hypersensitivity
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Activation of Th2 cells by antigen
Induced B cell class switching to IgE Production of IgE and binding of secreted IgE to Mast cell FcR Activation, degranulation, and tissue damage by Mast cells upon secondary exposure to antigen |
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You can treat/prevent type I hypersensitivity at any part in the process...give a few examples
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1. Avoidance (don't allow the Th2 cells to be activated by not having the antigen present)
2. Modify the response (with antihistamines, anti IgE) 3. Change the IgE to IgG by desensitization...exposing the pt to the allergen inducing the change 4. Vaccine - also induces tolerance |
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With regards to Type I hypersensitivity....
It is an _ response to antigen _ is bound to mast cells causing the release of _. Last phase type I involves a _ response, and it's primary mediators are _ |
ACUTE
IGE HISTAMINE larger (more diffuse), LEUKOTRIENES |
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Type II hypersensitivity is when _ is generated against a self antigen that is _
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IgM or IgG
fixed (cell surface) |
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Classic symptoms of class II hypersensitivity include _ or _. What is the most common cause?
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drug induced anemia or thrombocytopenia.
Most common - penicillin (note that penicillin allergies can cause type I, II or III reaction) |
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Grave's disease and myasthenia gravis are examples of _ reactions
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type II reactions
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Type III hypersensitivity is _ mediated. _ is present but it is generated against a _ antigen.
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immune complex
IgG (just like in II) but it is against a soluble antigen (not cell fixed like type II) Pts with type III hypersensitivity have a wide variety of symptoms |
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Common systems with type III hypersensitivity include _, _ and _.
Classic reactions include _ and _ |
vessels, kidneys, and joints!
arthus reaction and serum sickness |
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Arthus reaction is similar to type _ hypersensitivity (but is actually _). One of the differences is that arthus reaction occurs _ after injection of the antigen
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I
III 1-2 hours (as opposed to immediate) *This commonly occurs during desensitization injections to treat type I hypersensitivity |
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With Serum Sickness (which is a type _ reaction)....the onset of symptoms occur when?
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III, 7-10 days after exposure
This happens when there is IV injection of high doses of a drug |
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Type IV hypersensitivity is _ mediated, predominately _ cells
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T cell, TH1 cells (although can include Th2 or CTL)
*Response requires 100-1000 times more antigen than those required to elicit antibody-mediated hypersensitivity. T cells get activated by antigen presenting cells and produce cytokines, resulting in inflammation |
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What is the classic example of type IV hypersensitivity?
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Delayed skin inflammation, such as poison ivy, poison oak
Symptoms arise 24-72 hours after exposure |
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Examples of autoimmune T cell responses include...
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type I diabetes, rheumatoid arthritis, Multiple sclerosis, inflammatory bowel disease, guillain barre syndrome
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