Antibacterials II: Antimicrobial Susceptibility Testing

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What does CFU stand for in microbiology?

Cell Forming Unit

Colony Focus Unit

Colony-Forming Unit (correct)

Concentration of Formed Units

What is the significance of Minimum Inhibitory Concentration (MIC) in antimicrobial testing?

Concentration at which resistance appears

Concentration necessary for complete eradication of bacteria

Lowest concentration inhibiting visible growth (correct)

Highest concentration that promotes visible growth

What does the term 'Minimum Bactericidal Concentration (MBC)' refer to?

Maximum concentration where bacteria survive

Concentration at which resistance becomes irrelevant

Lowest concentration causing significant bactericidal activity (correct)

Lowest concentration resulting in visible growth inhibition

What is the range for the frequency of resistant mutants among viable bacterial cells?

1 mutant per 10^4 to 10^8 viable bacterial cells Signup and view all the answers

What is the primary purpose of breakpoints in antimicrobial susceptibility testing?

To assist clinicians in selecting antibiotics Signup and view all the answers

Why is susceptibility not a guarantee of therapeutic success with antibiotics?

Factors beyond susceptibility influence therapeutic success Signup and view all the answers

What does an MIC of 2 μg/ml really signify?

It could be 1, 2, or 4 μg/ml Signup and view all the answers

What is the significance of Susceptible Dose Dependent (SDD) for certain drugs?

They require higher dosages for favorable clinical outcomes Signup and view all the answers

Which committee is responsible for determining breakpoints for antibiotics?

FDA - Food and Drug Administration Signup and view all the answers

What is the major disadvantage of Microbroth Dilution Method compared to Macrobroth Dilution Method?

It cannot measure MBC Signup and view all the answers

What is the purpose of the Inoculum Effect in relation to a MIC test?

To provide a much lower inoculum than in actual infections Signup and view all the answers

Which testing method is described as 'like taking a poll' in terms of sample size accuracy?

Microbroth dilution Signup and view all the answers

Why is it crucial to detect resistance in pathogens?

To prevent poor therapeutic outcomes Signup and view all the answers

What is a significant consequence of undetected resistance?

Spread of resistance Signup and view all the answers

Which type of infection involves "~25% of all infections in ICU"?

Hospital Acquired Pneumonia Signup and view all the answers

What percentage of hospital acquired pneumonia cases involve gram-negative bacteria?

~50% Signup and view all the answers

Why is Hospital Acquired Pneumonia (HAP) particularly challenging to diagnose?

Conventional diagnosis is slow and time-consuming Signup and view all the answers

What microbial etiology complicates the diagnosis of Hospital Acquired Pneumonia (HAP)?

Gram-positive and Gram-negative bacteria, viral, and fungal infections Signup and view all the answers

What type of testing is necessary to identify resistance mechanisms?

PCR Signup and view all the answers

What is a key feature of molecular diagnostic testing?

It plays a role in identifying resistance mechanisms Signup and view all the answers

What are some common types of infections that may require rapid pathogen identification?

Bloodstream infections Signup and view all the answers

What is a potential consequence of inadequate therapy for S.pneumoniae infections?

Increased mortality rates Signup and view all the answers

What is a disadvantage of the agar dilution method mentioned in the text?

MICs are lower than macrobroth Signup and view all the answers

Which method involves applying a plastic strip coated with an antibiotic gradient?

E-test Signup and view all the answers

What is a common drawback of qualitative disk diffusion assays?

Cannot determine how sensitive a bacteria is Signup and view all the answers

What is the aim of automated susceptibility tests mentioned in the text?

To detect important isolates and trends within bacterial populations Signup and view all the answers

What can be a limitation of molecular detection of resistance genes according to the text?

Negative result always implies bacterial susceptibility Signup and view all the answers

In the context provided, what can rapid susceptibility methods help determine for serious infections?

The point at which the chosen treatment will have minimal impact Signup and view all the answers

What was a significant finding in the Doern study comparing different antibacterial testing methods?

'Procedures' used were fewer in the rapid group Signup and view all the answers

What societal impact did rapid susceptibility methods have as mentioned in the text?

$2.4 million saved over one year in overall therapy costs Signup and view all the answers

In the context provided, what is a concern associated with the routine use of molecular detection of resistance genes in hospitals?

Overcalling resistance by detecting non-resistant genes Signup and view all the answers

What is highlighted as a significant advantage of rapid susceptibility methods based on environmental impact?

Correlation between drug use and reduced resistance rates Signup and view all the answers