A serial dilution was performed for a viable count of bacteria. The original bacterial cuture contained 100.000 celts el Three diution tubes each containing 9.0 ml of nutrient broth were used.1 miof cells was transferred between tubes 1 mi from the third tube was plated on an gar plate The number of colonies expected on the plate is Oa 1000 Ob. 10 Oc 10.000 Od 100

A serial dilution was performed for a viable count of bacteria. The original bacterial cuture contained 100.000 celts el Three diution tubes each containing 9.0 ml of nutrient broth were used.1 miof cells was transferred between tubes 1 mi from the third tube was plated on an gar plate The number of colonies expected on the plate is Oa 1000 Ob. 10 Oc 10.000 Od 100

Basic Clinical Laboratory Techniques 6E

6th Edition

ISBN:9781133893943

Author:ESTRIDGE

Publisher:ESTRIDGE

Chapter7: Basic Clinical Microbiology

Section7.4: The Gram Stain

Problem 5RQ

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Five mL of bacterial culture is added to 45 mL of sterile diluent. From this suspension, the following serial dilutions were made, two 1:100 and one 1:10 dilutions, and 0.1 mL is plated onto Plate Count Agar from the last dilution. After incubation, 186 colonies were counted on the plate
Five ml of bacterial culture is added to 45 ml of sterile diluent. From this suspension, the following serial dilutions were made, two 1:100 and one 1:10 dilutions, and 0.1 ml is plated onto Plate Count Agar from the last dilution. After incubation, 186 colonies were counted on the plate. 1. What is the dilution factor, or how much of the original sample was diluted?
Ten grams of hamburger were added to 90 mL of sterile buffer. This was mixed well in a blender. One-tenth of amL of this slurry was added to 9.9 mL of sterile buffer. After thorough mixing, this suspension was further dilutedby successive 1/100 and 1/10 dilutions. One-tenth of a mL of this final solution was plated onto Plate Count agar.After incubation 145 colonies were present. How many colony-forming units were present in the total 10 gramsample of hamburger?
A sample of water was enumerated using a counting chamber (haemocytometer) and 220 bacterial cells were counted in 25 small squares (each of volume 2.5 x 10-7 cm3). Viable counts were carried out on the same culture using both the pour plate method (incorporating 1 mL samples of a range of dilutions into plate count agar plates) and the Miles & Misra spread plate method, where 0.02 mL samples were spread on sectors of a plate count agar plate. For the pour plate count the average of triplicate samples was 178 colonies per plate of the 10-4dilution. For the Miles and Misra count the average of triplicate samples was 21.3 colonies per sector of the 10-4 dilution. Calculate the total count and the viable pour plate and spread plate counts and suggest possible reasons for the difference between the three different counts.
A laboratory technician performed a series of 10 fold serial dilutions shown below. he plated 0.1 mL from each dilution tube onto NA and got the follow numbers per plate dilution 1:10 1:10 1:100 1:1000 1:10000 1:100000 colony count >1000 >1000 808 303 38 3 calculate the concentration of bacteria in the undiluted stock (in CFU/mL)
What was the concentration of bacteria (CFU/mL) in the original suspensions used for dilutions and plating below: Dilution Amount plated # of colonies counted 10-4 1.0 mL 271 10-5 0.1 mL 36 10-6 1.0 mL 9
Answer each of the questions below using the plate images provided. Nutrient Agar 1 EMB Blood Agar 1. How many colonies are on NA plate 3?. 2. How many bacteria were transferred to NA plate 3?. 3. How many colonies are on NA plate 2? 4. How many bacteria were transferred to NA plate 2?. 5. How would you describe the growth on NA plate 1?. 6. How many colonies grew together on NA plate 1? 7. How many bacteria were transferred to NA plate 1? Nutrient Agar 2 8. How many bacteria collected from the source? (Hint: What fraction of tube 1 was spread on NA plate 1?) 9. Were any of the bacteria from the source Gram-negative? How can you tell?. 10. Could any of the bacteria from the source ferment lactose? How can you tell? Nutrient Agar 3 11. Were any of the bacteria from the source hemolytic? How can you tell?. 00
You are given a 1 gram soil sample of unknown bacterial load. After doing 10-fold serial dilutions of the soil in sterile water, 100 uL volumes are taken from each dilution for preparation of pour plates. Following incubation, each half of the 10-8 plate has 46 colonies.a) What was the dilution factor?b) How many bacteria were present in the soil?2. Staphylococcus aureus divides every 20 minutes. A culture begins with 10 bacterial cells.a) After 5 hours, how many generations have occurredb) After 5 hours, how many bacteria are present?3. How many milliliters would you need to prepare a 10-2 dilution from a 10ml starting culture?
This agar plate was obtained by spreading 0.1 ml of a 1:1,000 dilution of a bacterial sample taken from cole slaw, and then incubating at 37oC for 24h. This plate indicates that: a. there are 42 bacteria/ml on the cole slaw b. there are at least 4 different types of bacteria in the cole slaw c. there are approximately 42,000 bacteria/ml in the cole slaw sample d. there are approximately 420,000 bacteria/ml in the cole slaw e. these bacteria cannot cause illness because they came from the person’s skin who made the cole slaw
A 1.5-year-old child developed vomiting, diarrhea, and fever. Stool sample were inoculated into the Endo media. After 18 hours on the surface of the medium grew medium-sized, round, slightly convex red colonies with a metallic luster. The doctor suspected Escherichia coli. 1. Name the composition of the Endo agar media. 2. Describe the properties of bacterial colonies on the Endo media. 3. What purpose differential diagnostic Endo media used for?
Determine what percentage of the culture was living (viable) and what percentage was dead (mortality). Plates Plate Dilution Volume plated No.of colonies Avg No Concentration of diluted sample Cd(cells/mL) Concentration of original sample Cu(cells/mL) 1 10^-3 10ul R1=130,R2= 110,R3=210 150 150mL 1.50*10^6 Volume of cells(mL) Volume of diluent(mL) Total dilution(D) Hemocytometer count Avg cells in 1 mm^2 area Concentration of diluted sample Cd(cells/mL) Concentration of original sample Cu(cells/mL) 4.3 0.5 0.1 grid 1= 171 , grid2 = 185 178 1.78*10^5 1.78*10^6
1 ml of a patient sample was added to 999 ml of media. From this 0.1 ml was transferred to the plate. After 24 hours there were 60 colonies on the plate. What is the dilution factor here. What's the number of bacteria per ml of the original patient sample. a. The dilution factor is 1000. The patient sample contains 600 cells/ml b. The dilution factor is 1000. The patient sample contains 600,000 cells/ml c. The dilution factor is 100. The patient sample contains 600,000 cells/ml d. The dilution factor is 10. The patient sample contains 6000 cells/ml e. It cant be determined its too many cells