Lab 7 Secondary Assays for Bacterial Characterization (1)

For laboratory exercise of Antibiotic susceptibility test in disk-diffusion method. What does an ‘I’ result mean in disk diffusion susceptibility test?

for E-coli- Describe results for Gram reaction, cell shape and arrangement (look up information) What color changes were observed for each test? Any zones of inhibition (for antibiotics only)?

a.Describe what makes thioglycollate medium suitable for culturing anaerobes. What would the growth patterns of Clostridium sporogenes and Micrococcus luteus be in this medium?  b. In the Kligler test, why do we inoculate the surface of the agar slope and then stab into the butt of the slope? What does a pink coloured colony indicate when using MAC (MacConkey Agar)?

For a laboratory exercise of antibiotic susceptibility test in a disk-diffusion method. With reference to the table below, determine the antibiotic susceptibilities of different antibiotics against E.coli and S.aureus.

Answer the problem.

Antibiotic sensitivity testing: The Kirby-Bauer. 1) What do the following terms mean? a. PPNG b. MRSA 2) How does the MIC test differ from the Kirby-Bauer test? 3) Were all of the conditions of a standardized Kirby-Bauer test met as you performed this assay? If not, which were not? 4) What is the significance of colonies that develop within otherwise clear zones of inhibition? If the laboratory report for one of your patients indicated colonies within the zone, what concerns would you have for your patient?

For a laboratory exercise of antibiotic susceptibility test in a disk-diffusion method. What are the concentrations of antibiotic applied in the test?

Please answer fast Dilution Problem. A culture of Staphylococcus is diluted as follows: (1) 20mL are added to 80mL of water. (2) 10uL from (1) are then added to 9.99mL of water. (3) A 10-2 dilution is made from tube # (2). (4) 100uL from (3) are plated for a pour plate and incubated.   Growth Problem.A culture with approximately 2x103 cells/mL were incubated. After 3 hours, the number of cells had increased to 3x105. a) How long was the generation time in minutes?b) How many generations have occurred

Solution!

Ex. 17: Chemotherapeutic Agents Using the Antimicrobial Susceptibility Table on pg 62 in the lab manual, determine whether not the bacteria plated in this Kirby-Bauer test are resistant (R), intermediate (I), or susceptible (S). The bacterial species tested was Escherichia coli (Gram negative). Ciprofloxacin Diameter = 20 Streptomycin Diameter 30 Carbenicillin Diameter 17 + Erythromycin Diameter = 23 Novobiocin Diameter = 0 bacterial growth = disk with antibiotic (see labels) = no growth

in lab: . cath sample + antibiotic susceptible A. baumanii  _occurrence of conjugation and colonies seen ( WHITE)   question:   Why was there growth in sample (a) listed above?

A culture of Staphylococcus of unknown density is diluted as follows (letters represent each step): • 60 mL of a bacterial culture is diluted by adding 440 mL of water • 1000 microliters from (A) is added to 9 mL of water • Dilution (B) is used to prepare a 103 dilution in water • 100 ul from dilution (C) is plated to nutrient agar and incubated at 37°C Following incubation, colonies are uniformly distributed on the agar, and 102 colonies are counted on one half of the plate. 1. Express the total CFU/mL of the original culture in scientific notation. 2. If 10 ul is plated from dilution (C), how many colonies should grow on the plate? Edit View Insert Format Tools Table

Which biochemical test is this? Name the organism that will test positive for this. Was this an important test for gram negative bacteria? Which tube is positive and negative?

What is the principle of freezing of cell lines and primary cells.Describe the general protocol for freezing cultured cells.In detail.

Please discuss how the Methyl Red-Vogues Proskauer test helps distinguish microbes from each other.

covert the procedure to passive voice and past tense

a. Explain whether or not any of the methods in fi gure 2.9 could beused to determine the total number of cells present in a patient’s specimen.b. After performing the streak plate method on a bacterial specimen, theculture was incubated for 48 hours at 37°C. Upon viewing the plate, therewas heavy growth (with no isolated colonies) in the fi rst quadrant, but nogrowth was apparent in the remaining quadrants. Please discuss errors in the procedure that could have produced this result.

Question:- How to perform a bactericidal test bactericidal test of Dental Pulp Stem Cell (DPSC)?

Discuss about the reagents used for agarose gel electrophoresis (not Polyacrylamide gel electrophoresis)

Topic: Isolation of Crude Ovalbumin from Egg White by Ammonium Sulfate Precipitation(Salting Out) The computed amount of powdered ammonium sulfate was added to the egg white sample portion byportion with constant stirring while submerged in an ice bath. The solution is expected to become moreturbid, and a white precipitate is expected to form.   Explain the purpose of using powdered ammonium sulfate in the isolation of ovalbumin from egg whites.

WIDAL TEST Principle: The test depends on the ability of antibody in the patient’s serum to agglutinate the stained bacterial antigens. When this occurs, the aggregates become clearly visible to the naked eye. Task: Illustrate(draw) how the antigens aggregate in the Widal Test

explain how the following genotypic andphenotypic methods of microbe identification is done. Use diagrams or schematic representations to explain yourwork.  1.Gram Staining2.Biochemical Reactions: Multiple Tube Fermentation Technique3.(Biochemical Reactions: IMViC Test

present briefly the principle of size exclusion chromatography.  give a brief description of the use of protein assays.

What is meant by the word sterile? Why is aseptic techniquenecessary for successful maintenance of pure cultures in thelaboratory?

You have retrieved your MHA (Mueller-Hinton agar) plate, your materials, and your E. coli culture.  What is the first step to prepare your Kirby-Bauer test?

A researcher is planning to plant antibiotic-resistant Escherichia coli pure bacteria sample in antibiotic (ampicillin) solid media in his experiment. Describe each of the sterilization methods that this researcher should use while preparing this solid medium with antibiotics and in cultivation of the bacteria on the solid medium, indicating the stages at which it should be used and giving the mechanism of action.

If both plates were accidently incubated at 37°C, how might interpretation of the results change? Explain.

Show steps pls

Make the Dichotomous key for M. luteus, Bacillus subtilis, bacillus, Megaterium, Bacillus cereus, E.coli, S. Marcescens, and Enterobacter aerogenes based on catalase test, (lactose, sucrose and glucose fermentation tests) and other biochemical test for accurate identification and colony morphology.

Which bacterial culture (Lb. plantarum, P. acidilactici, or P. pentosaceus) was most effective against monocytogenes and Salmonella? Explain why. What are the limitations of using an agar disk diffusion assay to assess the effectiveness of an antiseptic, disinfectant, or, in this case, a biological control agent on the growth of bacteria of interest?

Activity 2. Media Used in Isolating Coliforms You are a group of microbiologists tasked to test the presence of coliforms in the newly built water station. You are asked to isolate E. coli, Salmonella, and Shigella. Enumerate the media used for each step of isolating these bacteria. Include pictures and references. Bacteria Enrichment (Broth/Agar) Presumptive test (Broth/Agar) Isolation Media (Broth/Agar) E. coli Salmonella Shigella 1. How can you confirm that E. coli, Salmonella, and Shigella are present in the newly built water station? Explain. 2. What is the difference between nutrient broth and nutrient agar? 3. What is the importance of these steps (Enrichment, Isolation, and presumptive test) in isolating bacteria? Conclusion about the process of isolating bacteria

Think about minimal inhibitory concentration (MIC) assays.  A set of tubes, all containing the same amount of bacterial cells, have decreasing amount of antibiotic X added to them.  Tube 1 had 0mg/ml, Tube 2 has 100mg/ml, tube 3 has 50mg/ml, 4=25, 5=12.5, 6=6.25, and tube 7 has 3.125.  If bacteria grew in tubes 1, 4, 5, 6, 7, what is the MIC of this antibiotic for this bacteria? Select one: a.None of the Above b.3.125 mg/ml c.25 mg/ml d.0 mg/ml e.50 mg/ml

Briefly compare the following test systems, Micro-tox, ATP-Tox, and Daphnia magna IQ test . Explain how each assay works (the principle), not the test procedure.