Antimicrobial Agents

Question 1

Define antimicrobials

Answer 1

Drugs with activity against microorganisms including antibacterial, antivirals, antifungals and antiparasitic agents

Question 2

Define antibiotic

Answer 2

Chemical compound made by a microorganism that inhibits or kills other microorganisms at low concentrations. Does not include synthetic agents.

Question 3

What do bactericidal agent do?

Answer 3

Bactericidal agents kill bacteria

Question 4

What do bacteriostatic agent do?

Answer 4

Bacteriostatic agents inhibit growth of bacteria

Question 5

What is the bacteria that penicillin is derived from?

Answer 5

Penicillium notatum

Question 6

What are the conditions for the ideal antimicrobial agent? (8)

Answer 6

• Selective toxicity against microbial target
• Minimal toxicity to the host
• Cidal activity (kill micro-organisms)
• Long plasma half-life
• Good tissue distribution
• Low binding to plasma proteins
• Oral and parental preparations
• No adverse interactions with other drugs

Question 7

What are some mechanisms of action for antimicrobials? (5)

Answer 7

• Inhibition of cell wall synthesis
• Inhibition of protein synthesis
• Inhibition of nucleic acid synthesis
• Inhibition of folate synthesis
• Disruption of the cytoplasmic membrane

Question 8

What are some mechanisms of resistance for antimicrobials? (5)

Answer 8

• Production of enzymes
• Alteration in the outer- membrane permeability
• Alteration of target sites
• Efflux pumps
• Alteration of metabolic pathways

Question 9

What problems arise from human use of antibacterials? (5)

Answer 9

• Adverse effects
• Drugs interactions
• Few organisms become virtually untreatable
• Rising rates of resistance
• Superinfection

Question 10

What is antimicrobial stewardship? (4)

Answer 10

A coordinated program that aims to:

1. Promotes the appropriate use of antimicrobials
2. Improves patient outcomes
3. Reduces microbial resistance
4. Decreases the spread of infections caused by multidrug-resistant organisms.

Question 11

What is the mode of action for drugs in the penicillin family?

Answer 11

Inhibit cell wall synthesis by binding to penicillin binding proteins and inhibiting transpeptidation of peptidoglycan

Question 12

What is the mode of resistance for drugs in the penicillin family? (3)

Answer 12

• Resistance by Β-lactamases
• Efflux
• Low affinity binding of antibacterial to target penicillin binding proteins

Question 13

Name some potential side effects of drugs from the penicillin family (6)

Answer 13

• Allergic reaction (anaphylactic reaction)
• Delayed hypersensitivity
• GI complications (diarrhoea)
• Renal complications
• CNS complications (seizure)
• Haemolytic anaemia

Question 14

What can be given alongside penicillin to ensure effectiveness?

Answer 14

Beta- Lactamase inhibitors

Question 15

Give some examples of macrolides (3)

Answer 15

• Erythromycin
• Clarithromycin
• Azithromycin

Question 16

What is the mode of action for macrolides?

Answer 16

Inhibit RNA-dependant protein synthesis

Question 17

What is the mode of resistance for macrolides?

Answer 17

• Decreased outer membrane permeability
• Efflux
• Alteration in rRNA
• Enzymatic inactivation by phosphotransferases

Question 18

Are drugs from the penicillin family bacteriostatic or bactericidal?

Answer 18

Bactericidal

Question 19

Are macrolides bacteriostatic or bactericidal?

Answer 19

Bacteriostatic

Question 20

What are some side effects of macrolides? (6)

Answer 20

• GIT symptoms
• Skin rash
• Fever
• Eosinophilia
• Jaundice
• Transient hearing loss

Question 21

What interactions do macrolides have with warfarin?

Answer 21

Potential for increase effect of warfarin because macrolides inhibit metabolism and clearance

Question 22

What is the mode of action for Clindamycin?

Answer 22

Inhibit RNA-dependant protein synthesis

Question 23

What is the mode of resistance for Clindamycin? (a lincosamide) (4)

Answer 23

• Resistance by decrease outer membrane permeability
• Alteration in rRNA
• Alteration in 50S ribosomal proteins of the receptor sites
• Enzymatic inactivation by transferase

Question 24

What are some side effects of Clindamycin? (5)

Answer 24

• C. difficile colitis
• Allergic reaction
• Transient hepatitis
• Neutopenia
• Thrombocytopenia

Question 25

What is the mode of action for Tetracyclines?

Answer 25

Inhibit bacterial protein synthesis (30S)

Question 26

Are Tetracyclines bacteriostatic or bactericidal?

Answer 26

Bacteriostatic

Question 27

What is the mode of resistance for Tetracyclines? (3)

Answer 27

- Resistance by efflux - Ribosomal protection protein - Enzymatic inactivation

Question 28

What are some side effects of Tetracyclines? (6)

Answer 28

- GIT symptoms - Photosensitivity - Pigmentation - Deposition in growing bone and teeth - Superinfection - Allergy

Question 29

Name 2 examples of polyenes

Answer 29

- Amphotericin (IV) | - Nystatin (PO)

Question 30

What is the mode of action for Nitroimidazoles?

Answer 30

Interact with nucleic acids and proteins causing breakage, destabilization and cell death

Question 31

What is the mode of action for Nitroimidazoles?

Answer 31

Interacts with ergosterol and forms a transmembrane ion channel in the fungal membrane which increases membrane permeability causing leakage of cell contents and cell death

Question 32

What are some side effects of Polyenes? (6)

Answer 32

- Anaphylaxis - Nephrotoxicity - GIT upset, - Muscle and joint pain - Anaemia - Cardiovascular toxicity

Question 33

What is the mode of action for Azoles?

Answer 33

Inhibit the synthesis of ergosterol

Question 34

What are the 2 subtypes of Azoles?

Answer 34

- Imidazoles | - Tiazoles

Question 35

Miconazole is an example of?

Answer 35

Imidazoles

Question 36

Fluconazole is an example of?

Answer 36

Tiazoles

Question 37

How do antivirals work? (5)

Answer 37

1. Attachment 2. Viral entry 3. Viral uncoating 4. Nucleic acid synthesis 5. Assemble and release of viral particle