Microbiology Csmls Exam Prep Exam Questions With Correct Verified Answers | 100% Pass (A+ Certified)

If there is no zone of inhibition, what do you record? Answer 6mm because that accounts for the disc What causes sharp irregular zones around the sensitivity discs? Answer beta-lactam antibiotics - indicates that beta-lactamase production by the bacteria and should be interpreted as resistant Susceptible vs intermediate vs resistant Answer - susceptible = susceptible to action of the antimicrobials and is stopped or killed by it - intermediate = used for certain drug combinations that are difficult to test or produce results of certainty - resistant = resistant to the action of antimicrobial and keeps growing in its presence Qc for susceptibility tests Answer - each time new discs or panels are received - each time tests are performed (once a week) - organisms are staph aureus, , pseudo, enterococcus How should antimicrobial discs be stored? Answer - long term = frozen at -20c - working supply in 4c Mrsa conditions Answer - addition of nacl - 30-35c (lower temp is better) - displays trailing on disc diffusion methods - healthcare workers are screened for it - use oxacillin screen test Haemophilus test medium (htm) is supplemented with Answer - bovine hematin - yeast extract - nad - thymidine phosphorylase E-test is beneficial for using it on Answer - anaerobes - fastidious bacteria E-test results interpretation: low mic and high mic Answer low mic - sensitive High mic - resistant Staphylococcus aureus characteristics Answer - double zone of beta hemolysis - creamy yellow color from lipochrome @48h - ferments mannitol (yellow) - catalase positive - nitrate positive - slide or tube coagulase positive Msa media (mannitol salt agar) Answer - 7.5% nacl - differential = mannitol and phenol red - if it ferments mannitol it will be yellow, if it does not then it will be red - staph aureus ferments (yellow) Mrsa oxacillin screen test Answer - 6ug oxacillin - 4% nacl - any growth on plate = resistant Slide coagulase vs tube coagulase Answer - slide = bound coagulase - tube = free coagulase False negative coagulase tests are commonly from Answer weak bacterial suspensions Gold standard of staph aureus is Answer positive tube coagulase What is found on the cell wall of s. Aureus but not other staph species? Answer protein a and clumping factor = used in latex reagent methods Thermostable nuclease test is used for Answer id of staph aureus - food microbiology investigations of food poisoning Staphylococcus saprophyticus id Answer - bright white opaque colonies - catalase positive - nitrate positive - novobiocin resistant - common uti What virulence factors does staphylococcus aureus have? Answer - leucocidin - hyaluronidase - staphylokinase (clots) - hemolysins _______ is the most common cause of skin, soft tissue and