50 Questions
Which of the following is NOT a cause of antibiotic therapy failure?
Suppressed host response
What is the purpose of carrying out microbial diagnosis?
To identify the type of bacteria
How is resistance determined using disk-diffusion method?
By measuring the relative diameter of inhibition
What are clinical breakpoints used for?
To define resistance based on MIC values
Which organization sets lab standards for antibiotic resistance testing in the US?
CSLI
What is the MIC value used to define resistance in the example criteria?
More than 128
Which of the following is an example of intrinsic resistance?
Bacteria lacking a target for a specific antibiotic
What is the major mechanism of resistance for β-Lactams?
Cleavage by β-lactamases
Which of the following is an example of acquired resistance?
Bacteria acquiring a new gene for resistance
What is the role of methicillin in methicillin resistance?
Binding to alternate PBP (Mec)
Which of the following is NOT a common resistance mechanism for β-Lactams?
Reduced permeability to the drug
What is the purpose of efflux systems in bacteria?
To pump drugs out and maintain a low level of the drug
Which mechanism of resistance is associated with aminoglycosides?
Enzymatic modification
Which mechanism of resistance is associated with quinolones?
Target mutations
Which mechanism of resistance is associated with glycopeptides?
Altered cell walls peptides
Which mechanism of resistance is associated with tetracyclines?
Mainly efflux
Which mechanism of resistance is associated with rifamycins?
Altered mutated RNA polymerase
Which mechanism of resistance is associated with oxazolidinones?
Mutations in 23S rRNA genes followed by gene conversion
Which mechanism of resistance is associated with pleuromutilins?
Ribosomal proteins preventing binding to target
What is the region between MIC and MSC called?
Minimum selected concentration
What is the purpose of measuring sensitivity in antibiotic resistance testing?
To determine the concentration of antibiotics needed to inhibit bacterial growth
What is the main difference between disk-diffusion and MIC determination methods in antibiotic resistance testing?
Disk-diffusion measures the relative diameter of inhibition, while MIC determination measures the antibiotic concentration
What are clinical breakpoints used for in antibiotic resistance testing?
To determine whether a bacteria is sensitive or resistant to a specific antibiotic
Which organization sets lab standards for antibiotic resistance testing in Europe?
EUCAST
What is the major mechanism of resistance for β-Lactams?
Target site modification
What is the MIC value used to define resistance in the example criteria?
Greater than 128
What is the major difference between intrinsic and acquired resistance?
Intrinsic resistance is an innate ability while acquired resistance is obtained through exposure to drugs
What is the main mechanism of acquired resistance by mutation and modification of the target?
Mutation of target site
Which group of antibiotics inhibits cell-wall synthesis?
β-Lactams
What is the major mechanism of resistance for β-Lactams?
Cleavage by β-lactamases
Which bacteria are generally resistant to cephalosporins?
Enterococci
What is mecA in the context of methicillin resistance?
An equivalent of PBP with lower affinity for methicillin
Which of the following antibiotics inhibits the formation of the 70S ribosomal complex?
Oxazolidinones
Which resistance mechanism is associated with mutations in the 23S rRNA genes and ribosomal proteins preventing binding to the target?
Mutations in the 23S rRNA genes
Which term is used to describe strains that are resistant to up to three clinical antimicrobial categories, but still have usable options?
MDR
Which resistance mechanism is associated with altered cell wall peptides and efflux?
Altered cell wall peptides
Which factor increases the risk of selection for resistance?
Length of selected levels
Which resistance mechanism is associated with enzymatic modification, efflux, and ribosomal mutations?
Efflux
Which antibiotic inhibits transcription by targeting the RNA polymerase?
Rifamycins
Which antibiotic should be administered using the highest possible doses to achieve concentration-dependent killing?
Aminoglycosides
Which one of these is a cause of antibiotic therapy failure?
Unjustified therapy
What is the purpose of conducting culture and antibiotic sensitivity testing?
To determine the resistance profile
How is resistance determined using disk-diffusion method?
By measuring the relative diameter of inhibition
Which type of resistance occurs when a microorganism obtains the ability to resist the activity of a new drug?
Acquired resistance
Which of the following is an example of intrinsic resistance?
Poor permeability due to outer membrane
Which resistance mechanism is associated with alteration of the drug, alteration of the target site, and efflux systems?
Efflux systems
Which antibiotic inhibits cell-wall synthesis?
Glycopeptides
What is the purpose of good antibiotic stewardship?
To limit the use of antibiotics only when necessary
Which term is used to describe strains that are resistant to all antimicrobial agents listed?
PDR
What is the region between MIC and MSC called?
Minimum selected concentration
Test your knowledge on the principles of antibiotic resistance and the causes of antibiotic therapy failure. Learn about unjustified therapy, poor selection, wrong dose regimen, suppressed host response, and resistance. Discover the importance of microbial diagnosis, sensitivity measurements, recommended dose adherence, and owner compliance. Explore an example resistance profile from a diagnostics lab.
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