Microbiology- Antibiotic Therapy

Question 1

Selective toxicity

Answer 1

Minimal toxicity to host ie closely targets bacteria

Question 2

Bactericidial

Answer 2

kills bacteria

Question 3

Bacteriostatic

Answer 3

inhibits bacterial growth

Question 4

Ideal antibiotic

Answer 4

selective toxicity
cidal
long half life
good tissue distribution
lack of side effects
oral and parenteral preparation

Question 5

Pros of penicillins

Answer 5

• Safe
• flexible molecule
  narrow to broad spectrum
• excreted rapidly by kidneys
• safe in pregnancy

Question 6

Cons of penicillins

Answer 6

• Patients can be hypersensitive
• rapid excretion means frequent dosing
• resistance

Question 7

Common cell wall antimicrobials

Answer 7

Penicillins, cephalosporins, glycopeptid3s

Question 8

Target of beta lactams

Answer 8

Penecillin Binding Proteins

Question 9

Penicillin active against Gm +ve organisms

Answer 9

Flucloxacillin (IV, oral)

Question 10

Penicillin active against Gm +ve and -ve organisms

Answer 10

Amoxicillin and co-amoxiclav (both IV, oral)

Question 11

Penicillin active against Gm -ve organisms

Answer 11

Temocillin (IV only)

Question 12

Three principle compounds of penicillin

Answer 12

Benzylpenicillin, phenoxymethyl penicillin, benzathine penicillin

Question 13

Co-amoxiclav

Answer 13

Beta lactam and beta lactamase inhibitor

Question 14

Flucloxacillin spectrum

Answer 14

Very narrow spectrum antibiotic

Staphylococci and streptococci only

Question 15

Which type of organisms is temocillin active against?

Answer 15

Extended spectrum β-lactamases producing organisms

Question 16

What is Temocillin resistant to?

Answer 16

B lactamase resistant

Question 17

How do cephalosporins work?

Answer 17

they inhibit cell wall synthesis and are bactericidal

Question 18

Why are cephalosporins avoided in hospitals?

Answer 18

they have a broad spectrum and kill off normal gut flora, allowing for C. Diff overgrowth. this can lead to gastroenteritis

Question 19

Examples of Glycopeptides

Answer 19

Vancomycin, Teicoplanin

Question 20

Which type of bacteria do glycopeptides target?

Answer 20

ones with a gram positive cell wall

Question 21

How do antibiotics inhibit protein synthesis?

Answer 21

they attach to bacterial ribosomes (different from mammalian ribosomes)

Question 22

The only antibiotic which is bactericidal and targets protein synthesis

Answer 22

Aminoglycosides eg gentamicin- irreversibly binds to 30s ribosomes irreversible

Question 23

4 antibiotics to avoid, due to increased risk of C. Diff

Answer 23

Cephalosporins
Co-amoxiclav
Ciprofloxacin
Clindamycin

Question 24

Examples of bacteriostatic antibiotics

Answer 24

Tetracyclines

Macrolides (eg erythromycin, clarythromycin)

Question 25

How are macrocodes excreted?

Answer 25

via the liver, biliary tract and into the gut

Question 26

Which antibiotics affect nucleic acids?

Answer 26

Metronidazole Trimethoprim Fluoquinolones

Question 27

What organisms is metronidazole active against?

Answer 27

Anaerobes (and protozoa)

Question 28

Which antibiotic is commonly given for acute UTIs?

Answer 28

Trimethoprim