Micro Test 1 Test Questions – Flashcards
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| MacConkey Agar |
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| Selective for Gram Negative Differential for Lactose fermenting bacteria (Red) |
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| Mueller-Hinton Agar |
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| Medium for susceptibility testing of bacteria |
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| Thioblycolate broth |
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| Supplementation with Vitamin K and Hemin Differentiate between Strict Aerobe, Facilitative Anaerobe, Aeroltolerant anaerobe, strict anaerobe |
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| Ziehl Neelson |
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| Acid-Fast stain: requires HEATING and after Basic fuchsin is added so stain penetrates into the bacteria |
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| Kinyoun stain |
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| COLD acid-fast stain. Heating is not need bc the concentration of the basic fuchsin is increased as well as the phenol concentration |
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| Modified Kinyoun |
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| COLD acid fast stain. Differs by using a WEAK acid solution in alcohol. |
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| Fluorochrom stain |
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| replaces basic fuchsin with 2 fluorescent dyes: AURAMINE and RHODAMINE more sensitive than kinyoun stain |
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| Acridine orange stain |
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| a type of fluorochrome stain. At an acidic pH, Bacteria= orange WBC=Green *cannot differentiate between G- and G+ |
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| Trichrome stain |
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| a type of fluorochrome stain Good for Intestinal Protozoa |
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| Mannitol Salt Agar |
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| Selective for Staph (HIGH SALT) Differential for S. Aureus |
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| LJ Medium (Lowenstein Jenson) |
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| Isolation of MYCOBACTERIA Malachite Green inhibits G+ |
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| Middlebrook Agar |
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| Isolation of MYCOBACTERIA Malachite Green inhibits G+ **In contrast to LJ, it is solidified by AGAR |
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| PEA agar (phenylethyl alcohol) |
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| Selective for STAPH and STREP inhibits most G- |
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| Thayer Martin Agar |
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| Selective for Pathogenic Neisseria (Vancomycin, colistin, nystatin, trimethoprim lactate) |
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| Hektoen Enteric Agar |
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| Differentiation of Lactose and Sucrose Fermenters (yellow) and non fermenters AND H2S producers (black)/non producers *inhibits G+ |
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| Polyclonal Antibodies |
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| Heterogeneous antibody preps that can recognize many epitopes on a single antigen |
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| Monoclonal Antibody |
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| recognize individual epitopes on an antigen Advantages: very specific, can prep as industrial sized Disadvantages: too specific |
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| Flow Cytometry |
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| used to analyze the immunofluorescence of cells in suspension and is especially useful for identiying and quatifying lymphocytes |
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| FACS (fluorescence-activated cell sorter) |
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| a type of flow cytometer. can also isolate specific subpopulaiton of cells for tissue culture growth on the basis of size and immunofluorescence |
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| Rapid EIA |
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| Lateral flow self contained EIA Cartrides. Can detect antigen or antibody in 20 minutes |
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| Pathogenicity Islands |
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| large chromosonal regions containing sets of genes encoding virulence factors |
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| Adhesion by E coli |
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| produces a fimbrial adhesin termed "P fimbriae" the P blood group antigen stucture on human erythrocytes and uroepithelial cells *can cause pyelonephritis |
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| Strep pyogenes: binding |
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| uses lipoteichoic acid and F proteins to bind to epithelial cells |
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| Neisseria gonorrhoeae: binding |
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| pili to bind to oligosaccharide receptors on epithelial cells |
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| Biofilm |
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| *made by Pseudomonas aeruginosa biogilms are bound within a sticky web of polysaccharides that holds them together to the surface *protects bacteria from host deferense and antibiotics *Dental Plaque is an example of biofilm |
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| Binding of Enteric Bacteria |
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| * eX: Shigella, salmonella, and Yersinia use fimbriae to bind to M (microfold) cells of the colon. Inject proteins into the M cells that stimulate the cell membrane to surround and take in bacteria |
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| Toxin definition |
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| Bacteria products that directly harm tissue or trigger destructive biological activities cause lysis of cells or specific receptor-binding proteins that initiate toxic reactions in a specific tissue |
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| Preformed toxin |
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| from bacteria that cause food poisoning ex: Staph aureus, Bacillus cereus, Clostridium botulinum |
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| Exotoxins |
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| cytolytic enzymes receptor-binding proteins that alter a function or kill the cell Toxin genes encoded on plasmids, toxin genes as bacteriophages |
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| A-B Toxins |
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| Dimeric proteins: B portion binds to a specific cell surface receptor A subunit transferred to the interior of the cell, where cell injury is induced *Diptheria, Cholera, Tetanus |
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| Superantigens |
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| (group of toxins) TSS caused by S aureus and Steph enterotoxins Action: activates T cells by binding simultaneously to T cell receptor and a MHC II on an APC without requiring antigen |
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| Cytokine Storm |
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| related to superantigens activates lots of T cells to release IL (IL1, IL2, TNF), can also lead to death of T cells |
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| LPS (lipopolysaccharide) |
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| produces by only G - bacteria powerful activator of acute-phase and inflammatory reactions =ENDOTOXIN |
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| Endotoxin action |
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| Lipid A portion of LPS only by G- acts on PMN, Macrophages, platelets, IgE, cotting... results: low iron, fever, acute phase proteins, hypoglycemia, DIC thrombosis, shock, hypotension, increased vascular permeability |
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| S. pyrogenes Defense |
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| forms a CAPSULE mimics human connective tissue (hyaluronic acid) |
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| Strep pneumoniae defense |
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| antiphagocytic capsule |
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| Francisells tularensis defense |
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| intracellular growth |
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| Strep pyogenes defense |
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| degrades C5a limits the chemotaxis of leukocytes to the site of the infection |
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| Neisseria gonorrhea defense |
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| anti-immunoglobulin proteases |
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| Steph Protein A |
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| IgG binding protein |
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| Legionella and Mycobacterium tuberculosis defense |
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| inhibition of phagolysosome fusion |
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| Listeria, Francisells, Rickettsia defense |
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| adaptation to cytoplasm replication |
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| M tuberculosis defense |
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| produces GRANULOMAS |
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| How are positive cultures detected in blood samples? |
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| Microbes will metabolize nutrient and release CO2 in medium, automated detection is integrated in the bottom of bottle, fluorescence of the vial sensor, then Gram stained |
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| CSF analysis |
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| specimen is centrifuges, cultured, Gram stained |
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| bacteria (2) that commonly cause Bacterial meningitis? |
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| Neisseria meningitides, Strep pneumonia |
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| Expectorated Sputum analysis from Lower respiratory tract |
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| Specimen quality assessed by GRAM STAIN prior to acceptance of culture for further analysis *If containing many squamous epithelial cells and no neutrophils should not be preossed--- it will be REJECTED |
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| Syphilis diagnosis |
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| Treponema pallidum is a non cultivatable organism best diagnosed by BLOOD SEROLOGY |
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| 4 Most common pathogenic organisms |
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| S. aureus, E coli, Pseudomonas aeruginosa, Klebsiella pneumonia |
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| 2 most common causes of Meningitis |
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| Neisseria meningitis and Strep pneumoniae |
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| purpose of ASTs |
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| To predict clinical response to an antibiotic |
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| AST- Broth Dilution Method |
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| 18-24 hr culture colonies definition: serial dilutions of an antibiotic in nutrient broth incubation with a standardized inoculum of the organism to be tested |
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| MIC |
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| Minimum Inhibitory Concentration *determined and reported as Susceptible, Intermediate or Resistant based on standards determined by the CLSI (clinical laboratory standards institute) |
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| Dilution AST Methods |
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| to determine MIC *ug/mL of an antimicrobial agent required to inhibit or kill a microorganism |
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| Agar Diffusion testing: AST |
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| standardized inoculum of bacteria spread over the agar and disks with antibiotics are placed on the agar *zone of inhibition used to determine MIC |
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| "Kirby Bauer or KB" |
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| AKA Disk Diffusion Testing (AST) Drug diffuses in agar and zone of inhibition is created and concentration can be figured out |
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| disadvantages for KB testing (Kirby Bauer) |
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| *Inadequate for detection of vancomycin intermediate S. aureus *Does not detect daptomycin resistance in staphylococci or enterococci or colistin resistance in GNR *only qualitative |
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| Gradient Diffusion Method (E test)-AST |
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| *Quantitative AST that incorporates a preformed antimicrobial gradient applied to one side of a plastic strip to provide drug diffusion into an agar medium *similar to a disk diffusion test *strips are placed on agar *After incubation, the MIC is read directly from a scale on the E test Strip at the point where the ellipse of organism growth inhibition intersects the strip *determine MIC |
