Concept explainers
In the use-dilution test, a chemical is evaluated by its ability to kill
To write:
The consideration of the use-dilation test as a stringent test.
Introduction:
Chemicals do not readily penetrate bacterial endospores, and the number of endospores used is higher than expected in a normal use of a disinfectant. When gram positive bacteria are in endospore state, they are resistant to disinfection and there is a limited number of agents that can destroy endospores and not the medical devices.
Explanation of Solution
In the use-dilution test, a chemical is evaluated by its ability to kill 106to 108 dried Clostridium sporogenes or Bacillus subtilis endospores. Bacterial endospores are highly resistant to hostile physical and chemical conditions. Only a few genera like Bacillus subtilis or Clostridium sporogenes are capable of forming endospores. These are the dormant forms of bacteria that allow it to survive the sub-optimal environmental conditions.
The spores are highly resistant to heat, radiation, disinfection and dessication. They are difficult to eliminate from the medical pharmaceutical materials and frequent cause of contamination as well. These different and difficult conditions along with the highly active chemicals to use for killing them and cause damage to the instrument makes it get considered as a stringent test. Chemicals do not readily penetrate bacterial endospores and the number of endospores used is higher than would be expected in the normal use of a disinfectant.
Thus, the conditions with the highly active chemicals to use for killing them and cause damage to the instrument makes it get considered as a stringent test.
Want to see more full solutions like this?
Chapter 24 Solutions
Laboratory Experiments in Microbiology (11th Edition)
- This is a Microbiology question about blood culture analyzers such as the BactecWhat is the process a technician takes if the analyzer alarms for a positive bottle?What action(s) are taken if there are no organisms seen in the Gram Stain made from that bottle?arrow_forwardColony formation can be observed in liquid media. a) Trueb) Falsearrow_forwardCITRATE TESTThis test determines the ability of bacteria to use citrate as source of carbon andinorganic ammonium salt as a source of nitrogen. The following are the stepwise procedurein conducting citrate test:1. Infuse the Simmons citrate agar on the slant by touching the tip of sterilized needleto a colony.2. Incubate at 37 degree Celsius for 24 to 48 hours.A positive result is indicated by the pH indicator, bromothymol blue which turns the growthgreen to blue. Task: In a tabulated form, determine if Salmonella typhi the are positive or negative withcitrate test. Interpret your answer and include the reaction of organism on this test.arrow_forward
- CITRATE TESTThis test determines the ability of bacteria to use citrate as source of carbon andinorganic ammonium salt as a source of nitrogen. The following are the stepwise procedurein conducting citrate test:1. Infuse the Simmons citrate agar on the slant by touching the tip of sterilized needleto a colony.2. Incubate at 37 degree Celsius for 24 to 48 hours.A positive result is indicated by the pH indicator, bromothymol blue which turns the growthgreen to blue. Task: In a tabulated form, determine if the Pseudomonas aeruginosa, are positive or negative withcitrate test. Interpret your answer and include the reaction of organism on this test.arrow_forwardCITRATE TESTThis test determines the ability of bacteria to use citrate as source of carbon andinorganic ammonium salt as a source of nitrogen. The following are the stepwise procedurein conducting citrate test:1. Infuse the Simmons citrate agar on the slant by touching the tip of sterilized needleto a colony.2. Incubate at 37 degree Celsius for 24 to 48 hours.A positive result is indicated by the pH indicator, bromothymol blue which turns the growthgreen to blue. Task: Answer the following In a tabulated form, determine if the Salmonella typhi, are positive or negative withcitrate test. Interpret your answer and Include the reaction of organism on this test.arrow_forwardwhich of these tests (i.e gram stain, acid fast stain, endospore, oxidation to fermentation, catalase test, oxidase test, PCR test, urea hydrolysis test, aglutination test, northern and southern test.) can be used on the disease causing organism below that can help draw a flow chart or ditochomy key? And will the test results in positive or negative to these disease. Folliculitis Schistosomiasis Gas gangrene Infectious mononucleosis Primary Amebic Meningeocephalopathy Traveler's Diarrhea Blastomycosis Hensen's Disease Bacteria Vaginosis Mumpsarrow_forward
- 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. There were 34 colonies counted on one quarter of the plate following incubation. a) What was the overall dilution?b) How many cfu/mL were present in the original culture?arrow_forwardYou have been asked to determine the bacterial count in a sample of water. The number of CFU from 1 ml of a 10-6dilution was 43 and 49 on duplicate agar plates. What is the total number of microorganisms per ml of the original sample of water?arrow_forwardIn the image attached is a unknown bacteria lab. The gram stain result and growth result is already given to us and is shown. What other tests (1-2 examples) could we use to follow up this test. Explain why we should use those tests with justification.arrow_forward
- An otic product was subjected to AET and tested with the challenge microorganisms. An initial concentration of 2 x 10^5 cfu/mL of Escherichia coli was computed. Compute for the log reduction from the initial calculated count if the cfu/mL obtained is 1.2 x 10^4 at 7 days.arrow_forwardA 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?arrow_forwardKligler’s iron agar and SIM are multiple test media.. Both media are stabbed but for different reasons. Explain.arrow_forward
- Comprehensive Medical Assisting: Administrative a...NursingISBN:9781305964792Author:Wilburta Q. Lindh, Carol D. Tamparo, Barbara M. Dahl, Julie Morris, Cindy CorreaPublisher:Cengage Learning