Pharmacology Chapter 14 Flashcards

Questions and Answers

Which of the following is not a mechanism of microbial resistance?

Pump antimicrobial drug out of the cell before it can act

Slow or prevent entry of drug into the cell

Increase drug availability in the cell (correct)

Produce enzyme that destroys or deactivates drug

What does Multiple Resistance and Cross Resistance refer to?

Pathogen can acquire resistance to more than one drug

The smallest amount of the drug that will inhibit growth and reproduction of the pathogen is known as the ______.

Minimum Inhibitory Concentration (MIC)

The Kirby-Bauer test determines the bactericidal activity of antimicrobial drugs.

False Signup and view all the answers

What is the purpose of Retarding Resistance?

Maintain high concentration of drug in patient for sufficient time Signup and view all the answers

What characteristic distinguishes Bacteriostatic drugs from Bactericidal drugs?

Bacteriostatic drugs keep bacteria from replicating Signup and view all the answers

What tests are used to assess the efficacy of antimicrobials?

Diffusion susceptibility test, Minimum inhibitory concentration test, Minimum bactericidal concentration test Signup and view all the answers

What does the Minimum Bactericidal Concentration (MBC) Test involve?

Transferring samples from clear MIC tubes to drug-free growth medium and monitoring for bacterial replication. Signup and view all the answers

The Etest combines the principles of the _ and the _ tests.

Kirby-Bauer, MIC Signup and view all the answers

Cross resistance may develop to similar drugs.

True Signup and view all the answers

What is selective toxicity?

Selective toxicity refers to the ability of a drug to target sites that are relatively specific to the microorganism responsible for infection. Signup and view all the answers

How do some antiviral drugs interfere with metabolism?

Some antiviral drugs, like sulfa drugs, inhibit metabolic pathways used for the biosynthesis of DNA and RNA nucleotides. Signup and view all the answers

What are considerations for routes of drug administration?

Considerations include physician medication order, patient's current status, the purpose of the drug, the necessity for immediate action, onset, peak, duration, and ensuring therapeutic range. Signup and view all the answers

What are three side effects of antimicrobial therapy?

<ol> <li>Toxicity to organs, 2. Allergic response, 3. Disruption of normal flora.</li> </ol> Signup and view all the answers

What is the therapeutic index?

The therapeutic index is a comparison of the amount of a therapeutic agent that causes the therapeutic effect to the amount that causes toxicity. Signup and view all the answers

How can microbial resistance be prevented?

Preventing microbial resistance includes not using antibiotics for viral infections, using antibiotics only as prescribed, and completing the full prescription. Signup and view all the answers

Who were key influencers in the history of antimicrobial agents?

Key influencers include Paul Ehrlich, Alexander Fleming, Gerhard Domagk, and Selman Waksman. Signup and view all the answers

What is meant by the 'spectrum of action' of a drug?

The 'spectrum of action' refers to the number of different pathogens a drug acts against. Signup and view all the answers

What is beta-lactamase?

Beta-lactamase is an enzyme produced by some bacteria that attacks the beta-lactam ring, rendering beta-lactam antibiotics ineffective. Signup and view all the answers

What are some mechanisms of antimicrobial action?

Mechanisms include inhibition of cell wall synthesis, inhibition of protein synthesis, disruption of cytoplasmic membrane, and inhibition of nucleic acid synthesis. Signup and view all the answers

Cephalosporins and _____ are types of cell wall inhibitors.

penicillins Signup and view all the answers

Eukaryotic ribosomes are 70S.

False Signup and view all the answers

What do antifungal drugs target?

Antifungal drugs primarily target the fungal cell membranes and cell wall synthesis. Signup and view all the answers

What do inhibitors of ATP synthase do?

Inhibitors of ATP synthase, like bedaquiline, interfere with the function of ATP synthases. Signup and view all the answers

What is the role of inhibitors of metabolic pathways?

Inhibitors of metabolic pathways can act as competitive inhibitors for bacterial metabolic enzymes, impeding essential processes. Signup and view all the answers

How do attachment antagonists function?

Attachment antagonists block viral attachment or receptor proteins. Signup and view all the answers

What are the two ways bacteria acquire resistance?

Bacteria acquire resistance through new mutations of chromosomal genes and acquisition of R plasmids. Signup and view all the answers

Study Notes

Selective Toxicity

Selective toxicity allows drugs to target microorganism-specific sites, minimizing harm to the host.
Antibacterial compounds utilize structural differences between prokaryotic and eukaryotic cells for effective targeting.

Interference with Metabolism by Antiviral Drugs

Sulfa drugs inhibit pathways vital for DNA and RNA nucleotide biosynthesis.
Key examples include sulfanilamide and trimethoprim, which inactivate enzymes required for nucleotide production.

Considerations for Routes of Drug Administration

Consider the physician's order, patient's status, and the purpose of the medication.
Immediate drug action and the onset, peak, and duration of the drug's effect are critical for efficacy.
Therapeutic ranges must be monitored, including peak and trough levels, to ensure effectiveness without toxicity.

Side Effects of Antimicrobial Therapy

Potential side effects include organ toxicity, allergic reactions, and disruption of normal flora.
Developing targeted antimicrobial treatments for fungi, protozoans, and viruses is challenging due to their similarity to human cells.

Therapeutic Index

The therapeutic index compares the dose of a drug that produces therapeutic effects to the dose that causes toxicity, guiding safe use.

Preventing Microbial Resistance

Avoid using antibiotics for viral infections and always complete prescribed courses.
Combination therapy is essential for HIV to counteract mutation and resistance.
Resistance arises from overuse, misuse, and poor patient adherence to treatments.

History of Antimicrobial Agents

Antimicrobial agents have historical roots in traditional medicine, with notable contributors such as Paul Ehrlich (magic bullet theory), Alexander Fleming (penicillin), and Gerhard Domagk (sulfanilamide).
Distinctions include semisynthetics (modified antibiotics) and synthetics (lab-created antimicrobials).

Spectrum of Action

Narrow-spectrum drugs act against specific organisms, reducing the risk of superinfections and resistance.
Broad-spectrum drugs can target multiple pathogens but may lead to secondary infections and harm to normal flora.

Beta Lactamase

Some bacteria produce beta-lactamase, an enzyme that deactivates beta-lactam antibiotics, contributing to drug resistance.

Mechanisms of Antimicrobial Action

Mechanisms include cell wall synthesis inhibition, protein synthesis inhibition, and disruption of membrane integrity.
Inhibition of metabolic pathways and nucleic acid synthesis also play essential roles in antimicrobial action.

Dosage and Route of Administration

Administration routes vary: topical, oral, intramuscular, and intravenous, affecting drug distribution and efficacy.
Patient characteristics, including age and organ function, influence drug selection and dosing.

Cell Wall Inhibitors

Beta-lactams are the most common cell wall inhibitors, effective against growing bacterial cells.
They disrupt peptidoglycan synthesis, leading to bacterial lysis.

Protein Synthesis Inhibition

Targeted broad-spectrum inhibitors affect prokaryotic ribosomes (70S) but may also harm human mitochondria.

Disruption of Cytoplasmic Membranes

Polymyxins target gram-negative bacteria, damaging membrane integrity, while some antifungals disrupt fungal cell membranes through various mechanisms.

Inhibition of Nucleic Acid Synthesis

Targeting bacterial transcription and replication, inhibitors can affect both prokaryotic and eukaryotic cellular processes.

Inhibition of Metabolic Pathways

Antiviral agents and antibacterials can disrupt unique metabolic functions, inhibiting growth and replication.

Inhibitor of ATP Synthase

Bedaquiline specifically inhibits ATP synthases in mycobacteria, revealing a targeted mode of action against tuberculosis.

Antifungal Drugs

Antifungals primarily exploit differences in sterol synthesis and cell wall composition for selective toxicity against fungal cells.

Prevention of Virus Attachment and Entry

Attachment antagonists represent a novel approach in antimicrobial drug development, targeting viral entry mechanisms.

Development of Resistance in Populations

Resistance can be innate or acquired through mutations or horizontal gene transfer, with mechanisms that include drug inactivation and altered drug targets.

Multiple Resistance and Cross Resistance

Multi-drug-resistant pathogens result from R plasmid exchange, prevalent in healthcare settings due to continual drug use.

Retarding Resistance

Maintaining high drug concentrations can inhibit pathogens long enough for the immune system to clear infections.

Efficacy of Antimicrobials

Efficacy is evaluated through various testing methods like diffusion susceptibility, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC).

Zones of Inhibition (Kirby-Bauer Test)

The Kirby-Bauer test assesses antibiotic efficacy by measuring zones of inhibition, indicating how well an antimicrobial can suppress bacterial growth.

Minimum Inhibitory Concentration (MIC) Test

MIC quantifies the smallest concentration needed to inhibit pathogen growth, vital for tailoring drug therapies.

Etest

The Etest combines diffusion and MIC testing, using a gradient strip for precise antimicrobial susceptibility assessment.

Minimum Bactericidal Concentration (MBC) Test

MBC assesses the lowest concentration required to kill the bacteria after MIC testing, providing insights into treatment effectiveness.

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Explore the concept of selective toxicity through flashcards designed for Pharmacology Chapter 14. This quiz focuses on the mechanisms by which drugs selectively target microorganisms while minimizing harm to the host. Test your understanding of key terms and definitions vital for mastering pharmacological principles.