24 Questions
What is the mechanism of action of attachment antagonists?
Blocking viral attachment or receptor proteins
Why can physicians safely use antimicrobial drugs despite their potential danger?
The benefits of the drugs outweigh the risks
What is an ideal characteristic of an antimicrobial agent?
Nontoxic and nonallergenic
What is a potential consequence of using broad-spectrum antimicrobial agents?
Killing of normal flora and reduced microbial antagonism
What is the term for the number of different pathogens a drug acts against?
Spectrum of action
Which test assesses the efficacy of antimicrobials by measuring the diameter of the zone of inhibition?
Diffusion susceptibility test
Why is it important to consider the spectrum of action of an antimicrobial agent?
To minimize the risk of superinfections
What is a key factor in the development of antimicrobial drugs?
Readily available and inexpensive
What is the primary concern when prescribing antimicrobial drugs to pregnant women?
Potential toxicity to the fetus
What is the therapeutic index of a drug?
The ratio of the effective dose to the toxic dose
What is a potential consequence of disrupting normal microbiota with antimicrobial drugs?
Overgrowth of normal flora, causing superinfections
How do bacteria acquire resistance to antimicrobial drugs?
Through both mutation of chromosomal genes and acquisition of R plasmids
What is the primary reason physicians do not always prescribe the antimicrobial with the largest zone of inhibition?
Consideration of therapeutic index and potential side effects
What is the term for the ratio of the dose of a drug that can be tolerated to the drug's effective dose?
Therapeutic index
What is a potential consequence of antimicrobial drug toxicity?
Toxicity to kidneys, liver, or nerves
Why are hospitalized patients at greater risk for secondary infections due to disruption of normal microbiota?
Because they are more likely to be exposed to antimicrobial drugs
What is the purpose of the minimum inhibitory concentration (MIC) test?
To determine the lowest concentration of an antibacterial drug that inhibits the growth of a microorganism
What is the advantage of the oral route of administration for antimicrobial drugs?
It is a self-administered route that does not require a needle
What is the difference between the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of an antibacterial drug?
The MIC is the concentration that inhibits growth, while the MBC is the concentration that kills the microorganism
What is the purpose of the Etest?
To combine the aspects of the Kirby-Bauer test and the MIC test
What is the importance of considering the route of administration when prescribing an antimicrobial drug?
It affects the distribution of the drug to the infected tissues
What is the zone of inhibition in a Kirby-Bauer test?
The area where the microorganism is completely inhibited
What is the purpose of the Kirby-Bauer test?
To determine the zone of inhibition of an antibacterial drug
What is the importance of considering the distribution of an antimicrobial drug to the infected tissues?
It affects the efficacy of the drug in treating the infection
Study Notes
Mechanisms of Antimicrobial Action
- Attachment antagonists block viral attachment or receptor proteins, a new area of antimicrobial drug development.
Clinical Considerations in Prescribing Antimicrobial Drugs
-
Ideal antimicrobial agent characteristics:
- Readily available
- Inexpensive
- Chemically stable
- Easily administered
- Nontoxic and nonallergenic
- Selectively toxic against a wide range of pathogens
-
Spectrum of action:
- Narrow-spectrum: effective against few organisms
- Broad-spectrum: effective against many organisms, but may allow for secondary or superinfections to develop by killing normal flora and reducing microbial antagonism
Effectiveness of Antimicrobial Agents
- Efficacy assessment methods:
- Diffusion susceptibility test
- Minimum inhibitory concentration (MIC) test
- Minimum bactericidal concentration (MBC) test
Routes of Administration
- Methods of administration:
- Topical application for external infections
- Oral route for self-administration
- Intramuscular administration via needle into muscle
- Intravenous administration directly to the bloodstream
- Importance of knowing how the antimicrobial agent will be distributed to infected tissues
Safety and Side Effects
- Toxicity:
- Cause of many adverse reactions is poorly understood
- Drugs may be toxic to kidneys, liver, or nerves
- Consideration needed when prescribing drugs to pregnant women
- Therapeutic index is the ratio of the dose of a drug that can be tolerated to the drug's effective dose
- Allergies:
- Allergic reactions are rare but may be life-threatening
- Anaphylactic shock
- Disruption of normal microbiota:
- May result in secondary infections
- Overgrowth of normal flora, causing superinfections
- Of greatest concern for hospitalized patients
Resistance to Antimicrobial Drugs
- Development of resistance in populations:
- Some pathogens are naturally resistant
- Bacteria acquire resistance through:
- New mutations of chromosomal genes
- Acquisition of R plasmids via transformation, transduction, and conjugation
This quiz covers the mechanisms of antimicrobial action, including prevention of virus attachment and entry, and the use of antimicrobial drugs.
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