Lecture 321. What are the typical sources of specimensa. Specimens are taken close to infection sites using aseptic methods 2. Be able to state the medical terms for bacteria in the blood and urinea. Blood- Look for bacteremia and viremiai. Can also test blood for the presence of antibodies to a pathogenb. Urine- bacteriurua- presence of bacteria in urine; most often detected using urine-analysis dip stick or growth dependent methods 3. Know the Biosafety levels for laboratories working with pathogens a. BSL-1- few safety controls; open lab bench; non-pathogenic organisms; limited accessb. BSL-2- can have open bench, but gloves, lab coat, eye protection required; used for moderate pathogensc. BSL-3-designed for pathogens; organisms manipulated in biological safetycabinets; room under slight negative pressure; extensive filtration of aird. BSL-4- used for life-threatening pathogens that can be transmitted by aerosols; pressurized suits for workers; ebola, Marburg viruses4. Know the difference between differential and selective media a. Differential- Included compounds that allows visualization of certain biochemical pathways and products b. Selective- Contains substances that inhibit growth of certain types of bacteria5. Be able to describe the three common methods used to test sensitivity of a pathogen to an antibiotic a. Minimum inhibitory concentration (MIC)- using tube dilution assayb. Disk diffusion assay- Pure culture is spread on plate; then disks containingdifferent antibiotics are placed on plate. Also called a Kirby-Bauer testc. E test- MIC is read form the edge of the clear zone using the scale on the strips6. Define an antibody titer and how it changes during the course of an infectious disease a. Antibody titer- antibody concentrationb. Antibodies will rise after initial infection then the titer will go down.c. Starts to decrease at about 3 week the exponentially declines 7. How is a Mantoux skin test performed and how is it interpreted a. Detected by inflammatory response to injection of a purified antigen under the skin.b. Look at test results and if positive you do another response8. Define serologya. The use of antigen-antibody reactions to detect9. Describe what an epitope isa. Reaction of specific because antibodies recognize and bind to small epitopes on proteins, glycoproteins and other biomoleculesi. Positive and negative controls must be preformed 10. Understand how agglutination assays are used to detect antibodies or antigens from a patient a. Soluble a ntibodies cause clumping of antigens that are on the surface of a synthetic particle or celli. Examplesii. Agglutination of blood cells in blood typing- hemagglutinationiii. Agglutination of bacterial cells- serotyping11. Understand direct and indirect EIA a. EIA- Enzyme Immunosorbent Assays- Uses enzymes that are chemically attached to purified antibodies b. Direct immunoassays- Use immobilized antibody to test for an antigen from the patientc. Indirect immunoassays use immobilized antigen to detect antibodies from a patient 12. Know how can PCR be used to identify pathogen DNA in a patient a. Provides diagnostic primers into a PCR reaction that will give a specific PCR double stranded DNA product only if there is pathogen DNA (template DNA) in the patient samplei. PCR product is only made if the primers exactly base-pair with pathogen NDA 1. PCR primer sequences exactly base pair with pathogen DNA- PCR product made2. PCR primer sequences do not base pair with pathogen DNA- No PCR product 13. Briefly describe what qPCR is and how it works a. Quantitative real-time PCRb. Requiresi. A PCR thermocycler that includes fluorescence measurement capabilities of each individual reactionii. A fluorescent probe that is included in the reaction1. Fluorescence increases as double-stranded DNA product is madeiii. RNA from pathogens can be detected by first performing a reverse-transcriptase reaction to convert RNA to
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