Micro + abx

Question 1

What colour do gram +ve bacteria stain?

Answer 1

Purple

Question 2

What colour do gram -ve bacteria stain?

Answer 2

Pink

Question 3

Give some examples of gram -ve bacteria

Answer 3

• E.coli
• Salmonella
• Shigella
• Pseudomonas

Remember as commonly associated with the gut

Question 4

Which gram +ve cocci form clusters?

Answer 4

Staphylococcus

Question 5

Which gram +ve cocci form chains?

Answer 5

Streptococcus

Question 6

What are the 3 mechanisms of antibiotic action?

Answer 6

1) Inhibit cell wall synthesis
2) Inhibit protein synthesis
3) Inhibit nucleic acid synthesis

Question 7

Which abx classes inhibit cell wall synthesis?

Answer 7

• Beta lactams
• Glycopeptides

Question 8

What are beta lactam abx?

Answer 8

• Penicillins
• Cephalosporins
• Carbapenems

Question 9

Which abx classes inhibit protein synthesis?

Answer 9

• Macrolides
• Tetracyclines
• Aminoglycosides

Question 10

Which abx classes inhibit nucleic acid synthesis?

Answer 10

• Quinolones
• Sulfonamides

Question 11

Give examples of penicillins

Answer 11

• Amoxicillin
• Pen V
• Flucloxacillin
• Co-amoxiclav contains clavulanic acid/amoxicillin

Question 12

Give examples of cephalosporins

Answer 12

• Cephalexin
• Ceftriaxone
• Cefuroxime

Question 13

Give examples of carbapenems

Answer 13

• Meropenem

Question 14

Give examples of glycopeptides

Answer 14

• Vancomycin
• Teicoplanin
• Telavancin

Question 15

Give examples of macrolides

Answer 15

• Azithromycin
• Clarithromycin
• Erythromycin

Question 16

Give examples of tetracyclines

Answer 16

• Doxycycline
• Lymecycline

Question 17

Give examples of aminoglycosides

Answer 17

• Gentamicin
• Neomycin
• Streptomycin

Question 18

Give examples of quinolones

Answer 18

• Ciprofloxacin
• Levofloxacine

Question 19

Give examples of sulfonamides

Answer 19

• Sulfasalazine

Question 20

What do bactericidal vs bacteriostatic abx do? When are they useful?

Answer 20

Bactericidal:
- Kill the bacteria
- Generally by inhibiting cell wall synthesis
- Useful for difficult to treat infections or those that need quick eradication e.g. meningitis

Bacteriostatic:
- Prevent bacteria multiplying
- Inhibit protein synthesis/DNA replication
- Useful for reducing toxin production e.g. in severe cellulitis/nec. fasciitis, toxic shock syndrome

Question 21

What is pharmacokinetics?

Answer 21

The movement of a drug from its administration site to the place of its pharmacologic activity and then its elimination from the body

Question 22

Which abx can cause C. Diff?

Answer 22

• Cephalosporins
• Carbapenems
• Co-amoxiclav
• Ciprofloxacin
• Clindamycin

Question 23

What are important resistant gram positive bacteria? What are they resistant to?

Answer 23

1. MRSA
   - Methicillin resistant Staph aureus
   - Resistant to all beta lactic abx as well as methicillin (?fluclox)
2. VRE
   - Vancomycin-resistant enterococci
   - Resistant to vancomycin
   - Promoted by cephalosporin use

Question 24

What are important resistant gram negative bacteria? What are they sensitive to?

Answer 24

1. ESBL
   - Extended spectrum beta lactamase
   - Sensitive to beta-lactamase inhibitors -> clavulanate added to amoxicillin = co-amoxiclav, tazobactam added to pipericillin = tazocin
2. CRE
   - Carbapenem resistant enterobacteriaceae
   - Tx options are very few and very toxic

Question 25

What stepwise approach for remembering what abx cover which bacteria?

Answer 25

1. Amoxicillin - covers strep, listeria, enterococci
2. Switch to co-amox - covers staph, haemophilus, E.coli
3. Switch to tazocin - covers pseudomonas
4. Switch to meopenem - covers ESBLs
5. Add vancomycin/teicoplanin - covers MRSA
6. Add Clarithromycin/doxycycline - covers atypical bacteria

Each consecutive step covers the bacteria in the previous