antibiotic_microbial background and resistance

Question 1

What are antimicrobials used for?

Answer 1

To treat infectious diseases by killing or suppressing microorganisms (bacteria, viruses, fungi).

Question 2

What is an antibiotic?

Answer 2

A chemical produced by one microbe that can harm other microbes.

Question 3

What is selective toxicity?

Answer 3

The ability of a drug to target and kill bacterial cells without harming human cells.

Question 4

What are three ways antimicrobials achieve selective toxicity?

Answer 4

1. Disrupt bacterial cell wall 2. Inhibit bacterial enzymes 3. Disrupt bacterial protein synthesis

Question 5

What is the difference between bactericidal and bacteriostatic drugs?

Answer 5

Bactericidal kills bacteria, while bacteriostatic inhibits growth so the immune system can eliminate the infection.

Question 6

What is a narrow-spectrum antibiotic?

Answer 6

An antibiotic that targets specific bacteria, reducing the impact on beneficial bacteria.

Question 7

What is a broad-spectrum antibiotic?

Answer 7

An antibiotic that targets a wide range of bacteria, which increases the risk of secondary infections.

Question 8

What are the mechanisms of action for antimicrobials?

Answer 8

1. Inhibit cell wall synthesis 2. Disrupt cell membrane 3. Inhibit protein synthesis 4. Interfere with DNA/RNA synthesis 5. Act as antimetabolites 6. Inhibit viral enzymes

Question 9

How are bacteria classified by staining?

Answer 9

• Gram-positive: Thick cell wall that retains violet stain (e.g., Staphylococcus, Streptococcus) - Gram-negative: Does not retain violet stain (e.g., Escherichia, Klebsiella, Pseudomonas)

Question 10

What are the three shapes of bacteria?

Answer 10

1. Bacilli - Rod-shaped 2. Cocci - Spherical 3. Spirilla - Spiral-shaped

Question 11

What is the difference between aerobic and anaerobic bacteria?

Answer 11

• Aerobic: Require oxygen for growth - Anaerobic: Do not require oxygen for growth

Question 12

What are the four basic mechanisms of acquired resistance?

Answer 12

1. Decrease drug concentration at site of action (limit uptake or pump drug out) 2. Inactivate the drug (e.g., penicillinase) 3. Alter drug target molecules 4. Produce a drug antagonist

Question 13

What is the difference between single-drug resistance and multi-drug resistance?

Answer 13

• Single-drug resistance: Caused by mutations - Multi-drug resistance: Caused by conjugation (DNA transfer between bacteria)

Question 14

What are key strategies to prevent antimicrobial resistance?

Answer 14

1. Vaccinations 2. Hand hygiene 3. Prevent infections when possible 4. Diagnose and treat infections properly 5. Use antimicrobials appropriately 6. Promote responsible prescribing 7. Reduce unnecessary antibiotic demand 8. Ensure adherence to prescribed regimens 9. Prevent transmission

Question 15

What are nosocomial infections (HAIs)?

Answer 15

Infections acquired in healthcare settings, including UTIs, surgical site infections, pneumonia, and bloodstream infections.

Question 16

What are common sources of HAIs?

Answer 16

1. Patient flora 2. Invasive devices (e.g., catheters, central lines) 3. Medical personnel 4. Contaminated medical environments

Question 17

What are examples of drug-resistant healthcare-associated infections?

Answer 17

• CAUTI (Catheter-Associated UTI) - VAP (Ventilator-Associated Pneumonia) - CLABSI (Central Line-Associated Bloodstream Infection) - SSI (Surgical Site Infection) - C. difficile (CDIFF) (Clostridioides difficile infection)

Question 18

What is the role of normal host flora?

Answer 18

1. Produce natural antibacterial substances 2. Break down toxic agents

Question 19

What happens when antibiotics kill normal flora?

Answer 19

Pathogens have room to grow, leading to superinfections.

Question 20

What is a superinfection?

Answer 20

A new infection that appears during treatment for a primary infection.

Question 21

What are common signs and symptoms of a superinfection?

Answer 21

Diarrhea, bladder pain, dysuria, vaginal discharge.

Question 22

Give two examples of organisms that cause superinfections.

Answer 22

Clostridium difficile, Candida albicans.

Question 23

What is empiric therapy?

Answer 23

Treatment based on the most likely pathogen before culture results are available.

Question 24

Why is it important to culture before starting antibiotic treatment?

Answer 24

To identify the organism and determine its drug sensitivity.

Question 25

What are the steps in a Culture & Sensitivity (C&S) test?

Answer 25

1. Obtain a specimen 2. Isolate and identify the pathogen in the lab 3. Expose the pathogen to different antibiotics

Question 26

What host factors influence antibiotic selection?

Answer 26

1. Host defenses – Strength of immune system 2. Infection site – Ability to reach site (e.g., cross blood-brain barrier) 3. Allergies 4. Blood flow to the area

Question 27

When are prophylactic antimicrobials used?

Answer 27

To prevent infection rather than treat an existing one.

Question 28

What surgeries require prophylactic antibiotics?

Answer 28

Cardiovascular, peripheral vascular, orthopedic, GI tract, hysterectomy, emergency C-sections.

Question 29

Why do patients with prosthetic heart valves need antibiotics before medical or dental procedures?

Answer 29

To prevent bacterial endocarditis.

Question 30

Who might receive antibiotics for immune suppression?

Answer 30

Patients with severe neutropenia, HIV/AIDS, chemotherapy recipients.

Question 31

What are other indications for prophylactic antibiotics?

Answer 31

1. Deep puncture wounds (e.g., dog bites, stepping on nails) 2. Preventing maternal-to-newborn transmission of infections 3. Healthcare workers after needlestick injuries 4. STI exposure 5. Recurrent UTIs

Question 32

What are common misuses of antimicrobials?

Answer 32

1. Treating viral infections 2. Treating fever of unknown origin (unless immunocompromised) 3. Incorrect dosage 4. Treating without bacteriologic information 5. Omitting surgical drainage when needed

Question 33

Why shouldn’t antibiotics be used for viral upper respiratory infections?

Answer 33

Only 1 in 4000 people benefit, but many experience side effects like diarrhea, rash, or severe allergic reactions.

Question 34

When is it acceptable to use antibiotics for a fever of unknown origin?

Answer 34

Only if the patient is severely immunocompromised.

Question 35

Why might an infection require drainage instead of antibiotics?

Answer 35

If there’s an abscess (pus), draining it is often more effective than antibiotics alone.

Question 36

What is the main function of bacterial cell walls?

Answer 36

To protect bacterial cells from the environment.

Question 37

What is the primary material in bacterial cell walls?

Answer 37

Peptidoglycan.

Question 38

What are penicillin-binding proteins (PBPs)?

Answer 38

Enzymes that help build bacterial cell walls.

Question 39

How do penicillins (PCNs) and related antibiotics work?

Answer 39

They bind to PBPs and disrupt cell wall synthesis.

Question 40

Why are penicillins more effective against gram-positive bacteria?

Answer 40

Gram-positive bacteria have a thicker peptidoglycan layer, making them more susceptible to cell wall-targeting antibiotics.