bios242 unit 4 antimicrobials (2/4)

Comprehensive practice flashcards covering antimicrobial terminology, classifications, susceptibility testing, mechanisms of action, specific drug examples, and resistance.

Who is credited with the discovery of the first antibiotic, penicillin?

Alexander Fleming

What is the definition of chemotherapeutic drugs?

Chemicals used in the treatment, relief, or prophylaxis of a disease.

What is the purpose of prophylactic drugs?

They are used to prevent imminent infection of a person at risk.

Define antimicrobial chemotherapy.

The use of drugs to control infection.

What term describes chemically altered, naturally occurring agents that are more effective or easier to administer?

Semisynthetic drugs

What are synthetic drugs?

Antimicrobials that are completely synthesized in a lab.

How are antibiotics defined in the context of microbial metabolism?

Antimicrobial agents created by the natural metabolic processes of some microorganisms or by scientists that can inhibit or destroy microorganisms.

What is a broad-spectrum antimicrobial?

An antimicrobial effective against a wide variety of microbes, such as Gram-positive and Gram-negative bacteria.

Which drug is used as an example of a broad-spectrum antibiotic effective against Gram-positive, Gram-negative, chlamydias, and rickettsias?

Tetracycline

What is a narrow-spectrum antimicrobial?

An antimicrobial effective against a limited array of microbial types.

Which two drugs are cited as narrow-spectrum examples effective against mycobacteria?

Isoniazid and polymyxin

What is the purpose of the Kirby-Bauer disc diffusion procedure?

To determine the most effective antibiotic to treat a bacterial infection.

How long are Kirby-Bauer plates typically incubated?

$$24\,\text{hours}$$

What indicates that an antibiotic is effective against bacteria in a disc diffusion test?

A clear region or zone of inhibition appears on the medium.

Define Minimum Inhibitory Concentration (MIC).

The lowest concentration of a drug capable of inhibiting microbial growth.

Which test is used to determine the MIC of a drug?

A tube dilution test

What is selective toxicity?

The characteristic of being toxic to the microbe but not toxic to the host.

Should an ideal antimicrobial drug be microbicidal or microbiostatic?

Microbicidal

What are the five major categories of antimicrobial drug action on bacterial cells?

Cell wall inhibitors, cytoplasmic membrane targets, nucleic acid disruptors, folic acid synthesis inhibitors, and protein synthesis inhibitors.

Which subunit of the ribosome do Azithromycin and Synercid target?

The $50S$ subunit

Which drugs target the $30S$ subunit of the ribosome?

Aminoglycosides, Streptomycin, Tetracyclines, and Glycylcyclines

What is the mode of action for Sulfonamides (sulfa drugs) and Trimethoprim?

They block pathways and inhibit metabolism by inhibiting folic acid synthesis.

Which two major classes of drugs act as cell wall inhibitors?

Penicillins and Cephalosporins

What chemical structure is shared by penicillin and its relatives?

The beta-lactam ring

How do Quinolones disrupt nucleic acid function?

They block DNA gyrase.

How does Rifampin inhibit bacterial transcription?

It binds more readily to RNA polymerase in prokaryotes than eukaryotes.

How do Tetracyclines inhibit protein synthesis?

They block the docking side of the transfer RNA (tRNA), preventing amino acids from being added to the polypeptide chain.

What is the mechanism of action for Chloramphenicol?

It prevents the formation of peptide bonds between amino acids.

How do Macrolides like erythromycin affect the ribosome?

They block the movement of mRNA through the ribosome.

What happens to the $30S$ ribosomal subunit when Aminoglycosides like streptomycin bind to it?

It changes shape, causing misreading of mRNA and insertion of incorrect amino acids.

Why is Polymyxin primarily used topically?

It interferes with human cell membranes and is toxic to the kidneys.

What is Isoniazid specifically used to treat?

Mycobacterium tuberculosis

Under what conditions is Vancomycin typically used?

Staphylococcal infections involving penicillin-resistance, methicillin-resistance, or penicillin allergy.

Which drug is used to treat skin infections caused by streptococci and staphylococci?

Bacitracin

What infections can be treated using Aminoglycosides like Streptomycin?

Bubonic plague, tularemia, and tuberculosis.

Which drugs are used to treat acute urinary tract infections and Pneumocystis jiroveci in AIDS patients?

Sulfonamides or Sulfa drugs (Sulfisoxazole, Trimethoprim).

What are the two most commonly used antifungal agents mentioned?

Polyenes (e.g., amphotericin B) and Azoles (e.g., ketoconazole).

How do Polyenes such as amphotericin B affect fungi?

They disrupt the fungal membrane, leading to the loss of selective permeability.

Which protozoan disease is sensitive to quinine, chloroquine, and artemisinin?

Malaria

How does Albendazole treat helminth infections?

It inhibits microtubule function and prevents glucose metabolism.

What are the three modes of action for antiviral agents?

Blocking penetration, inhibiting nucleic acid synthesis, and preventing assembly/release.

What is the mechanism of action for the antiviral drug Remdesivir?

Inhibiting nucleic acid synthesis (specifically terminating RNA replication in SARS-CoV-2).

What side effect does tetracycline have on a fetus?

It is a teratogen that crosses the placenta and accumulates in fetal bones and teeth.

Define a superinfection.

A condition where beneficial resident species are destroyed by antimicrobials and opportunistic pathogens grow in larger numbers.

How can bacteria acquire antimicrobial resistance?

Through mutations in bacterial chromosomes or by horizontal gene transfer.

What is the function of the enzyme beta-lactamase?

It destroys the beta-lactam ring, inactivating penicillins.

What are persister cells?

Bacteria that slow their metabolic rates and move into dormancy to survive antimicrobial exposure.

Name one human factor that contributes to the escalation of antimicrobial resistance (AMR).

Overuse and misuse of antibiotics in healthcare and agriculture.

What is one strategy to mitigate Antimicrobial Resistance (AMR)?

The use of probiotics and prebiotics to improve intestinal biota.

Which drug is used specifically for drug-resistant Pseudomonas aeruginosa?

Polymyxin