anti-microbial drugs

Question 1

How do beta lactase work?

Answer 1

Bactericidal - binds to penicillin-binding protein on bacteria, inhibiting the transpeptidation enzyme (responsible for linking the peptidoglycan chains to form rigid cell walls), disrupting the bacterial cell wall structure

Question 2

Penicilin types

Answer 2

• Penicillin V
• Flucloxacillin (beta-lactamase resistant)
• Amoxicillin (broad-spectrum)

Question 3

penicillin clinical applications

Answer 3

• Bacterial meningitis
• Bone and joint infections
• Skin and soft tissue infections
• Otitis media
• Pneumonia
• UTIs, STIs

Question 4

cephalosporin types

Answer 4

• Cefalexin
• Ceftriaxone
• Cefuroxime
• Cefotaxime

Question 5

cephalosporin clinical applications

Answer 5

• Septicaemia
• Pneumonia
• Meningitis
• Biliary tract infections
• UTIs (especially in pregnancy or in patients unresponsive to other drugs)
• Sinusitis

Question 6

tetracycline moa

Answer 6

Bacteriostatic - following uptake into susceptible organisms by active transport, tetracyclines
act by inhibiting protein synthesis. They bind to bacterial ribosomes, preventing binding of tRNA to it, thus preventing the initiation of protein synthesis

Question 7

name 2 oral tetracyclines

Answer 7

• Doxycycline

- Tetracycline

Question 8

tetracycline

Answer 8

• Respiratory tract infections (particularly atypical organisms)
• Acne
• Chlamydia
• Lyme disease

Question 9

macrolide moa

Answer 9

Bactericidal/bacteriostatic - inhibit bacterial protein synthesis by an effect on ribosomal translocation

Question 10

3 macrolides

Answer 10

• Clarithromycin
• Erythromycin
• Azithromycin

Question 11

macrolide clinical applications

Answer 11

• Bacterial meningitis
• Bone and joint infections
• Skin and soft tissue infections
• Otitis media
• Pneumonia + atypical respiratory organisms
• UTIs, STIs

Question 12

nitrofurans moa and example

Answer 12

Works by being reduced to multiple reactive intermediates by nitrofuran reductase inside the bacterial cell, these intermediates then attack ribosomal and DNA proteins within the bacteria,
as well as inhibit the citric acid cycle

Main example is nitrofurantoin - up to 50% of dose is excreted via urine so acts well on bladder, so a first-line agent for UTIs

Question 13

Quinolones moa

Answer 13

Inhibit topoisomerase II (a bacterial DNA gyrase), the enzyme that produces a negative supercoil in DNA and thus permits transcription or replication

Question 14

2 quinolones

Answer 14

• Ciprofloxacin

- Levofloxacin

Question 15

quinolone clinical applications

Answer 15

• Good cover of gram -ve organisms, as well as atypicals and +ve
• Complicated UTIs
• Pseudomonas aeruginosa cover
• Gonorrhoea

Question 16

quinolone side effects

Answer 16

• Tendinitis +/- rupture
• Aortic dissection
• CNS effects (inc. Convulsions)

Question 17

trimethoprim moa and uses

Answer 17

Bacteriostatic/bactericidal - inhibits dihydrofolate reductase (necessary for biosynthesis of bacterial nucleic acids and proteins); stronger affinity for bacterial over human dihydrofolate reductase

Used for UTIs, be careful when prescribing to reproductive age females

Question 18

What is metronidazole used for?

Answer 18

Anti-protozoal but good against anaerobic bacteria as well

Has disulfiram, so patients must avoid alcohol when on it

Question 19

Aciclovir moa

Answer 19

Predominantly activated in infected cells, as the viral enzyme thymidine kinase is more effective at phosphorylating it, thus activating it; the fully phosphorylated form then inhibits viral DNA polymerase

Question 20

Aciclovir uses

Answer 20

Used for herpes simplex infection (genital herpes, encephalitis) and varicella zoster (chicken pox, shingles)