Antibiotics and antibiotic resistance

Question 1

What is an antibiotic?

Answer 1

A drug that selectively targets bacteria by inhibiting essential processes such as protein synthesis, enzyme activity, or DNA replication.

Question 2

What is an antimicrobial?

Answer 2

A substance that kills or inhibits microorganisms including bacteria, viruses, fungi, and parasites.

Question 3

Are antibiotics antimicrobials?

Answer 3

Yes, all antibiotics are antimicrobials, but not all antimicrobials are antibiotics.

Question 4

What is antimicrobial resistance (AMR)?

Answer 4

The ability of microorganisms to resist treatment with drugs that were once effective.

Question 5

What is antibiotic resistance?

Answer 5

A specific form of AMR where bacteria evolve to resist the effects of antibiotics.

Question 6

What is empirical diagnosis?

Answer 6

Treatment based on clinical judgment and likely pathogens before lab results are available.

Question 7

Where do most antibiotics come from?

Answer 7

They are derived from microorganisms, especially bacteria and fungi.

Question 8

What are key bacterial structures targeted by antibiotics?

Answer 8

Cell wall, plasma membrane, ribosomes, DNA, and metabolic enzymes.

Question 9

What ribosome subunits do bacterial cells have? What about human cells?

Answer 9

70S ribosomes made up of 30S and 50S subunits. Human, eukaryotic cells have 80s ribosomes

Question 10

How do beta-lactams work?

Answer 10

They inhibit cell wall synthesis by binding to penicillin-binding proteins (PBPs) and inhibiting them.

Question 11

How do tetracyclines work?

Answer 11

They bind to the 30S subunit of bacterial ribosomes and inhibit protein synthesis.

Question 12

How do macrolides work?

Answer 12

They bind to the 50S subunit and inhibit bacterial protein synthesis.

Question 13

How do aminoglycosides work?

Answer 13

They bind the 30S subunit and cause misreading of mRNA, leading to faulty proteins.

Question 14

How do fluoroquinolones work?

Answer 14

They inhibit DNA gyrase and topoisomerase IV, preventing DNA replication.

Question 15

How does metronidazole work?

Answer 15

It causes DNA strand breaks in anaerobic bacteria.

Question 16

What is a broad-spectrum antibiotic?

Answer 16

An antibiotic acts against Gram-positive and Gram-negative bacteria

wide range of bacteria.

Question 17

What is a narrow-spectrum antibiotic?

Answer 17

An antibiotic that targets specific types or groups of bacteria.

Question 18

Do antibiotics affect every bacterium?

Answer 18

No, bacteria can be naturally resistant to specific antibiotics.

Question 19

What are Gram-positive bacteria?

Answer 19

Bacteria with thick peptidoglycan walls that stain purple and lack an outer membrane.

Question 20

What are Gram-negative bacteria?

Answer 20

Bacteria with thin peptidoglycan walls, an outer LPS membrane, and that stain pink.

Question 21

What are atypical bacteria?

Answer 21

Bacteria that do not stain with Gram stain due to lacking a typical cell wall or having a unique lifecycle.

Question 22

What are the four main mechanisms of antibiotic resistance?

Answer 22

Efflux pumps, enzyme degradation (e.g., beta-lactamase), reduced permeability, target modification.

Question 23

What is horizontal gene transfer?

Answer 23

Transfer of genetic material between bacteria via plasmids, transposons, or bacteriophages.

Question 24

What is vertical transmission of resistance?

Answer 24

Passing resistance traits from parent to offspring during cell division.

Question 25

What does selection pressure mean in antibiotics?

Answer 25

The survival of resistant bacteria when susceptible ones are killed by antibiotic use.

Question 26

When are bactericidal antibiotics preferred?

Answer 26

In immunocompromised patients or when rapid bacterial killing is essential (e.g., sepsis).

Question 27

What is sepsis?

Answer 27

A life-threatening organ dysfunction caused by a dysregulated host response to infection.

Question 28

What is an endotoxin?

Answer 28

A component of Gram-negative bacteria's outer membrane (LPS) that can cause systemic inflammation.

Question 29

What is pharmacokinetics (PK)?

Answer 29

The study of how the body absorbs, distributes, metabolizes, and excretes a drug.

Question 30

What is pharmacodynamics (PD)?

Answer 30

The study of how a drug affects the body, including its mechanism of action and dose-response.

Question 31

Which antibiotic class is preferred for anaerobic infections in the colon?

Answer 31

Metronidazole or beta-lactam/beta-lactamase inhibitor combinations.

Question 32

What antibiotic would you choose for community-acquired pneumonia caused by atypicals?

Answer 32

Macrolides (e.g., azithromycin) or tetracyclines (e.g., doxycycline).

Question 33

Which antibiotic should be avoided in patients with a penicillin allergy?

Answer 33

Beta-lactams like penicillin and cephalosporins, unless the allergy is minor.

Question 34

Which drug is used to treat MRSA infections?

Answer 34

Vancomycin (for IV use) or linezolid (oral option).

Question 35

Why is vancomycin ineffective against Gram-negative bacteria?

Answer 35

It cannot penetrate the outer membrane of Gram-negative bacteria.

Question 36

How do beta-lactams and glycopeptides differ in MOA?

Answer 36

Both target cell walls, but glycopeptides (e.g., vancomycin) bind directly to D-Ala-D-Ala, while beta-lactams inhibit PBPs.

Question 37

Why are aminoglycosides ineffective in anaerobic environments?

Answer 37

They require oxygen-dependent transport into bacterial cells.

Question 38

Why are bactericidal drugs used in meningitis?

Answer 38

They kill bacteria quickly to reduce inflammation and prevent complications.

Question 39

What makes atypical bacteria resistant to beta-lactams?

Answer 39

They lack a typical peptidoglycan cell wall, the target of beta-lactams.

Question 40

Why might in vitro antibiotic susceptibility differ from in vivo efficacy?

Answer 40

Due to pharmacokinetics, tissue penetration, and immune system factors.

Question 41

How does drug half-life affect dosing frequency?

Answer 41

Longer half-life allows for less frequent dosing; shorter half-life requires more frequent administration.

Question 42

What is the significance of minimum inhibitory concentration (MIC)?

Answer 42

It's the lowest concentration of an antibiotic that inhibits visible growth of a microorganism.

Question 43

How do plasmids contribute to resistance?

Answer 43

They carry resistance genes and can be shared between bacteria via horizontal gene transfer.

Question 44

Why does overuse of disinfectants also drive resistance?

Answer 44

It can create selection pressure similar to antibiotics, encouraging survival of resistant strains.

Question 45

What is the role of beta-lactamase inhibitors?

Answer 45

They block beta-lactamase enzymes and protect beta-lactam antibiotics from degradation.

Question 46

What is the mechanism of carbapenem resistance in bacteria?

Answer 46

Production of carbapenemase enzymes, efflux pumps, and altered porin channels.