Environmental effects on microbial growth lab report

Wymeshia Robinson SCORE Antimicrobial Sensitivity Testing: KirbyBauer 92% Prelab Briefing 100% List the general steps of the KirbyBauer method for determining antimicrobial drug 100% effectiveness Place the steps of the KirbyBauer method of antibiotic susceptibility testing in the order in which they are performed. Did you know the answer: You said 'Unsure'. You answered correctly: • Using a cottontipped swab, inoculate a plate of MuellerHinton agar with the bacteria to be tested, covering all surfaces of the plate in order to develop a lawn of growth. • Place antibiotic disks onto the surface of the inoculated plate, and tap slightly so that they will adhere to the surface. • Incubate the inverted plate at 37 degrees C overnight. • Observe plate and measure diameters of the zones of inhibition. • Compare diameters to chart of interpretive criteria. Define the zone of inhibition and how it is measured 100% Which of the following correctly describes measurement of the zone of inhibition: Did you know the answer: You said 'Unsure'. You answered correctly: Measure the complete diameter of the zone, from the edge of the zone on one side of the disk, across the disk to the edge of the zone on the other side, in mm. Explain how to evaluate the measured results of a KirbyBauer test 100% What factors influence the size of the zone of inhibition for an antibiotic? Did you know the answer: You said 'Unsure'. You answered correctly: • The growth rate or inhibition of growth of the bacteria in the presence of the antibiotic • The rate of diffusion of the antibiotic through the Mueller Hinton agar. Experimental Learning Objectives 89% Label plates 100% Labeling sterile agar plates before inoculating with an organism is an important step for ensuring correct data collection after incubation. Inoculate one sample onto each plate 100% You correctly inoculated two plates, one with each of the two different species of bacteria. This allows you to compare the effects of antimicrobial drugs on the two different species. Use aseptic techniques 100% By using all of the correct steps of aseptic technique, you avoided errors that could arise from contamination. Allow the plates to dry 100% This keeps the disks from slipping across the surface of the plate. Place 6 disks on both plates with dispenser 100% The dispenser perfectly places the different antimicrobial disks on the surface of the plate so that the zones of inhibtion can easily be measured. Incubate for 16-18 hours at 37 degrees 100% Incubation promotes optimal growth of bacteria, and it is best to take measurements at standard times for determining susceptibility of the bacteria to the antimicrobial drugs. Measure the inhibitions zones for each disk on both plates 57% You did not not correctly measure the diameter of all the clear zones surrounding each antimicrobial disk. Remember to measure by placing the ruler across the center of the disc millimiters. Determine the susceptiblity of each organism to the antimicrobial drugs 57% You did not correctly use the zone measurements and the standard chart to determine the susceptibility for all of the antimicrobial drugs. Using the chart, you should look up the zone measurement and see if that measurement indicates sensitive, intermediate or resistant for that species to that drug. Post-Lab Questions 100% Correctly analyze the results of a KirbyBauer test 100% The zone of inhibition is ________. Did you know the answer: You said 'Unsure'. You answered correctly: 21 mm On a plate inoculated with Staphylococcus aureus and incubated for 16 hours, you measure the diameter of the zone of inhibition around the penicillin disk. It measures 25 mm. This means that S. aureus is _________ to penicillin. Did you know the answer: You said 'Unsure'. You answered correctly: