The goal of Disc diffusion test is Select one: to determine the suitable concentration of an antibiotic To identify the type of the bacteria all choices are correct to choose a suitable antibiotic
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The goal of Disc diffusion test is
to determine the suitable concentration of an antibiotic
To identify the type of the bacteria
all choices are correct
to choose a suitable antibiotic
Step by step
Solved in 3 steps
- In a plate count, 1 mL of culture is spread on a plate and incubated for 24 hours. 250 colonies are counted. Answer the question below. there were _____cells in the 1 mL of culture that was spread on the plate. If the culture was diluted 1:100 prior to plating, how many cells were there per mL in the original culture? _________You are given a bacterial culture which has a concentration of approximately 5.0 x 10^8 cells/mL. List a series of dilutions and platings that you could carry out in order to determine the exact concentration of the culture. Note that you must plate four plates from a minimum of two dilution tubes. The volumes plated should be in the range of 0.1 mL – 1.0 mL. Duplicate volumes may not be plated from any one dilution tube. Each plating should aim for a count between 30 and 300 CFUs. You can select any value from 30-300 for CFU and any volume from 0.1-1.0 to find out dilution schemeA sample of well water is tested for its bacterial content in a plate count assay. A one-milliliter sample of the water is diluted in a 1:10 dilution series. One milliliter of the fourth dilution tube is plated in a pour plate. After incubation, the plate has 83 colonies. How many bacteria did the original sample contain?
- You decide to sample the bacteria growing on several items in a laboratory space. You follow aseptic techniques and use applicator swabs dipped in a sterible broth solution to sample from the floor, the sink, and your shoe. You spread each sample on separate labeled agar plates for incubation. a. You want to be sure that the sterile solution you used for sampling was not contaminated. How would you set up a negative control to test this? b. What result for your negative control would indicate that something is contaminated?A patient sample will be analyzed. You are responsible to quantify the bacteria number. The dilution series shown in the Figure ( Dilution.jpg) is prepared and 1 ml from each tube is plated. Plates were grown 24 hours resulting in colonies in each plate. Which plate you will use to quantify the bacteria in the patient sample? Why did you pick that plate? What is the dilution factor used in this series? Calculate the number of bacteria in the original patient sample. What would you do and why, if there were too many colonies to count on each plate?For a laboratory exercise of antibiotic susceptibility test in a disk-diffusion method. What are the concentrations of antibiotic applied in the test?
- You are testing ground beef to determine how many bacteria are present per gram of meat. You place 1 gram of meat in sterile water, mix vigorously, and then do serial dilutions as shown below. You inoculate a plate with 0.1 ml of the sample from the last tube. The next day you count 122 colonies. How many bacteria/ml were in the undiluted sample?A bacterial culture has a concentration of 3.2 x 108 cells /mL. You dilute this culture as follows: 1/50, then 10-3 and finally 1/20. If you then plate 0.2 mL of the final dilution, how many CFU would you expect following incubation?A lab technician is working with a bacterium in pure culture (in 5 ml of liquid media in a test tube). The bacterium is a mesophile that can infect humans. Which of the following is NOT true (with regards to temperature conditions for this bacterial culture)? Lowering the temperature to -10 deg C for at least an hour will likely kill all the bacteria. Placing the tube at 37 deg C will likely facilitate rapid growth of the bacteria. Raising the temperature to 90 deg C for at least an hour will likely kill all the bacteria. Placing the tube at 4 deg C will likely slow or halt growth of the bacteria.
- You were asked to prepare a dilution series of a bacterial culture where only 3 tubes will be used (all with 5 mL total solution). Draw a schematic diagram to make tube 1 have a 10-2 dilution, tube 2 have 10-3 dilution, and tube 3 to have 10-5 dilution You were instructed to dilute an antibiotic solution 1/10, redilute 1/25, and again 1/50, then you need to make 100mL of each dilution. How would you go about preparing this dilution series? (Present your answer in a schematic diagram)As part of an experiment where absorbance values are measured using a spectrophotometer, you are taking readings of your sample every 20 minutes. The non-motile microbe you're testing has a generation time of roughly 20 minutes at an incubation temperature right around room temperature. Things start out fine, with the expected results — as time goes by at the correct incubation temperature, absorbance starts to rise as the medium starts to become more cloudy with growing microorganisms. But roughly 2 hours into the process, you notice that the absorbance levels flatten out, and then start to decrease unexpectedly. What is most likely taking place in your experiment?A microbiology student was given a mixed culture of two different gram positive bacteria species to grow into a culture medium using correct aseptic techniques. After two days,one gram positive bacterial species grew on the media and the growth appeared red on the surface of the medium. Tthe second gram positive bacterial species grew and the growth appeared yellow on the surface of the medium. What is the possible explanation for the differences in the color of the bacterial growth? A. the culture was contaminated B. the microbiologist put too much inoculum on the culture medium C. the medium was a selective medium D. the medium was differential