MMG301 1st Edition Lecture 38Outline of Last Lecture I. Cancelled – fire alarm went ofOutline of Current Lecture II. Growth methodsIII. Bio safety levelIV. Sources for specimensV. Testing methodsCurrent Lecture-Growth-dependent methods: isolate microbe from patient and obtain as pure culture-Growth-independent methods: detect pathogen directly using molecular methods-BSL: biosafety level; 4 classifications based on levels of risk and containment-BSL-1 – few safety controls; open lab bench; non-pathogenic organisms; limited access-BSL-2 – can have open bench, but gloves, lab coat, eye protection required; used for moderate pathogens-BSL-3 – designed for pathogens; organisms manipulated in biological safety cabinets; room under slight negative pressure; extensive filtration of air-BSL-4 – used for life-threatening pathogens that can be transmitted by aerosols; pressurized suits for workers; Ebola, Marburg viruses-Samples may be taken using swab, aspirate with syringe/needle, sputum sample-Common sources for specimens include:-Blood – look for bacteremia (bacteria in the blood); or test for the presence of antibodies to a pathogen-Severe bacteremia can lead to a medical condition septecemia These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.-Urine – bacteriuria – presence of abnormal pathogens in urine; most often detected using urinanalysis dip stick-Feces – pathogens can deteriorate rapidly, so diagnostic tests must be done soon after collection-Abscesses and wounds – swab or needle aspiration of purulent (contains pus) discharge-Throat/nasal swabs – soft cotton swabs to collect bacterial samples-Genital samples – narrow swabs-testing methods1. Minimum inhibitory concentration (MIC): lowest concentration of antibiotic that inhibits growth; using tube dilution assay2. Disk difusion assay – pure culture is spread on plate; then disks containing diferent antibiotics are placed on plate; disk dried antibiotic3. “Etest” – MIC is read from the edge of the clear zone using the scale on the strips; large zone of inhibition means that bacteria is more sensitive to that
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