Antibiotics Flashcards
What is the purpose of the D-Test (Double Disk Diffusion Test)?
- Used to detect inducible clindamycin resistance among strains of S. aureus.
When is the D-Test typically performed?
- Done when the initial result shows discrepancy, with Clindamycin being susceptible and Erythromycin being resistant.
What are the specifications for the antibiotic disks used in the D-Test?
- Employs 15 ug Erythromycin and 2 ug Clindamycin disks, positioned 15 mm apart on the agar plate.
What is the characteristic result of a positive D-Test when performing the Double Disk Diffusion Test for antibiotic susceptibility?
- Characterized by the blunting or flattening of the Clindamycin zone.
How does a negative D-Test result differ from a positive D-Test result in the Double Disk Diffusion Test?
- There is no flattening or blunting of the Clindamycin zone; only erythromycin is resistant in this case.
What does a positive D-test result for clindamycin indicate?
- Indicates that the bacteria is resistant to clindamycin.
What does a negative D-test result for clindamycin suggest?
- Suggests that the bacteria is sensitive to clindamycin.
What is the purpose of the D-TEST (Double Disk Diffusion Test) in relation to the ERM gene?
- Assesses the activation of resistance to clindamycin
What is the Epsilometer “E” Test used for?
- Used for determining the minimum inhibitory concentration (MIC) of a single antibiotic against a specific organism.
How does the Epsilometer “E” Test work?
- It uses a strip with decreasing concentrations of a single antibiotic
- Which is placed on the inoculated culture medium. The antibiotic diffuses into the agar
Why is the Epsilometer “E” Test not routinely used in clinical settings?
- It is not routinely used due to its cost, making it more suitable for research purposes.
What types of organisms is the Epsilometer “E” Test well-suited for?
- The test is well-suited for fastidious organisms and anaerobes.
What advantage does the Epsilometer “E” Test offer in terms of antibiotics?
- By offering a strip with a range of antibiotics at different concentrations, allowing for comprehensive testing.
What is the meaning of the (+) result in the Epsilometer “E” Test (MIC ON A STICK)?
- The (+) result indicates the presence of an ellipse of growth inhibition in the test.
What is the main purpose of the Serum Bactericidal Test (SCHLICTER TEST)?
- To determine if the patient is receiving effective treatment for infection.
What is the test medium used in the SCHLICTER TEST?
- Is the patient’s serum containing the therapeutic antimicrobial agents the patient has been receiving.
Why is using the patient’s serum important in this test?
- Using the patient’s serum in the test allows the detection of bacteriostatic and bactericidal activity
- Which helps observe the antibacterial effect of factors other than antibiotics, such as antibodies and complement.
When is the trough specimen collected in the Serum Bactericidal Test (SCHLICTER TEST)?
- Is collected just before (within 30 minutes) the patient is to receive the next antimicrobial dose.
When is the peak specimen collected in the Serum Bactericidal Test (SCHLICTER TEST)?
- The peak specimen is collected after the antimicrobial agent(s)
- Is given when the serum antimicrobial concentration is at its highest.
Why does the appropriate time to collect the peak specimen vary in the SCHLICTER TEST?
- It depends on the pharmacokinetic properties of the antimicrobial agents and their route of administration
- Which can affect when their concentration peaks in the bloodstream.
What is the purpose of the Serum Bactericidal Test (SCHLICTER TEST)?
- To predict the clinical efficacy of antimicrobial therapy, specifically for staphylococcal endocarditis.
What is the recommended time frame for conducting the SBT when administered intravenously?
- The Serum Bactericidal Test (SBT) should be conducted within 30-60 minutes.
How long does it typically take to perform the SBT when administered intramuscularly?
- The Serum Bactericidal Test (SBT) is typically performed within 60 minutes.
What is the time frame for conducting the SBT when administered orally?
- The Serum Bactericidal Test (SBT) should be conducted within 90 minutes.
What is the principle behind the Modified Hodge Test for detecting carbapenemase production?
- By observing the growth of a carbapenem-susceptible organism toward a carbapenem disk
- Resulting in a cloverleaf-like indention pattern.
What is the purpose of the Modified Hodge Test?
- Used to detect the ability of Enterobacteriaceae organisms to produce the enzyme CARBAPENEMASE
- Which can lead to resistance against Carbapenem (Beta-lactam) antibiotics.
What is the characteristic result of the Modified Hodge Test when it’s positive?
- A cloverleaf-like pattern of the zone of inhibition and indented growth of the Escherichia coli control strain toward the carbapenem disk.
How does the Modified Hodge Test result appear when it’s negative?
- There is no indentation of growth of the E. coli control strain from the zone of inhibition.
What is the quality control (QC) strain used in the Modified Hodge Test, and what is its susceptibility to carbapenem?
- The QC strain is E. coli ATCC 25922, and it is carbapenem susceptible.
