Antibiotics

Question 1

what are the 5 main classes of antibiotic

Answer 1

Cell wall synthesis inhibitors
Protein Synthesis Inhibitors
DNA synthesis inhibitors
RNA synthesis inhibitors
Plasma membrane agents

Question 2

Example of cell wall synthesis inhibitors

Answer 2

Beta lactams

Glycopeptides

Question 3

examples of protein synthesis inibitors

Answer 3

aminoglycosides
macrolides
tetracyclines
oxazolidinones

Question 4

examples of DNA synthesis inhibitors

Answer 4

trimethroprim
sulphonamides
quinolones
fluoroquinolones

Question 5

example of RNA synthesis inhibitors

Answer 5

rifampicin

Question 6

example of plasma membrane agents

Answer 6

daptomycin

polymycin

Question 7

which abx are beta-lactams

Answer 7

penicillins, cephalosporins, monobactams, carbapenems

Question 8

examples of some glycopeptides

Answer 8

vancomycin

teicoplanin

Question 9

examples of an aminoglycoside, and some of their side effects

Answer 9

gentamycin

nephrotoxic and ototoxic

Question 10

examples of some macrolides

Answer 10

erythromycin
clarithromycin
clindamycin

Question 11

which bacteria are penicillins active against

Answer 11

broad spectrum
gram +ve infections = streptococcus, staphylococcus
gram -ve infections = H. influenzae, E.coli
H. pylori

Question 12

why isn’t amoxicillin used in staph aureus infections

Answer 12

Staph aureus secretes beta-lactamase - destroys beta lactam ring

Question 13

which penicillin is only active against gram +ve infections

Answer 13

flucloxacillin

Question 14

what combination antibiotic can treat infections with beta-lactamase secreting organisms

Answer 14

amoxicillin + clavalunic acid = co-amoxiclav

can now target staph aureus, gram-ve anaerobes

Question 15

what is amoxicillin typically used to treat

Answer 15

gram +/-ve pneumonia (strep pneum/h. influenzae)
UTI - E. coli
HAP, inta-abdominal sepsis

Question 16

what is the main alternative to amoxicillin in allergic patients?

Answer 16

Clarithromycin

Question 17

if a patient is allergic to amoxicillin, which other drugs are they allergic too?

Answer 17

Cephalosporins (cefradine, cefuroxime, Cefotaxime)

monobactams, carbapanems (meropenem)

Question 18

indications of Cephradine?

Answer 18

2nd/3rd line treatment of urinary/respiratory tract infections
IV reserved for severe/complicated infections
Abx resistant organisms

Question 19

what effect do most abx have on warfarin

Answer 19

abx kill gut flora, which synthesis vitamin K

warfarin effect increased

Question 20

what class of drug is trimethroprim, and how does it work

Answer 20

antifolate Abx

bacteriostatic as slows folate synthesis

Question 21

which bacteria is trimethroprim effective against

Answer 21

gram +ve and -ve

particularly E.coli

Question 22

important contraindications of trimethoprim and nitrofurantoin

Answer 22

pregnancy - both will cause fetal abnormalities

Question 23

what effect does trimethoprim have on potassium

Answer 23

increases is

caution with potassium raising drugs - e.g. aldosterone antagonists, ACEi, AT blockers

Question 24

how does nitrofurantoin work?

Answer 24

metabolised by bacterial cells

active metabolite damages bacterial DNA and causes cell death

Question 25

which organisms is nitrofurantoin active against

Answer 25

gram -ves - E.coli Gram +ves - staph saprophyticus, enterococcus common UTI

Question 26

mechanism of action of tetracyclines and aminoglycosides

Answer 26

inhibits bacterial protein synthesis | binds to 30S unit of ribosome

Question 27

indications of doxycycline

Answer 27

acne vulgaris | Lower respiratory tract infections - infective exacerbation of COPD, pneumonia

Question 28

contraindications of tetracyclines

Answer 28

bind to teeth and bones during fetal development don't prescribe in pregnancy, or children under 12 avoid in renal impairment

Question 29

mechanism of action of macrolides

Answer 29

inhibit protein synthesis | bind to 50S sub-unit, block translocations

Question 30

which bacteria is gentamicin active against

Answer 30

gram -ve aerobes = E.coli, ESBL, pseudomonas | Gram +ve = MRSA, MSSA

Question 31

indications for gentamicin

Answer 31

pyelonephritis, complicated UTI biliary/intr-abdominal sepsis endocarditis

Question 32

what makes the side effects of gentamicin more likely

Answer 32

``` Ototoxic = loop diuretics, vancomycin Nephrotoxic = ciclosporin, cephalosporin, vancomycin ```

Question 33

which infections are macrolides used for?

Answer 33

Gram +ve: staph aureus, streptococcus | Gram -ve: atypical pneumonias

Question 34

side effects of erythromycin

Answer 34

``` N+V, abdo pain thrombophlebitis if given IV Cholestatic jaundice Prolong QT interval - arrhythmias ototoxic at high doses ```

Question 35

effects of macrolides on the CyP450 system

Answer 35

inhibitory, increase plasma concentrations of other drugs

Question 36

which other drugs prolong the QT interval

Answer 36

ciprofloxacin amiodarone antipsychotics SSRIs

Question 37

class and mechanism of action of ciprofloxacin

Answer 37

Quinolone | inhibits DNA synthesis

Question 38

Indications for ciprofloxacin

Answer 38

Gram -ves: | H. influenzae, E.coli, atypical pneumonias

Question 39

how does metronidazole work and what is it used against?

Answer 39

DNA destroyer | only affective against anaerobic bacteria and protozoa

Question 40

indications for metronidazole

Answer 40

anaerobic infection abx associated c.diff (gram +ve anaerobe) dental abscess aspiration pneumonia surgical/gynae infections by anaerobes from the colon

Question 41

what is important to remember about metronidazole

Answer 41

patient cannot drink alcohol! | otherwise, flushing, headache, nausea, vomiting

Question 42

mechanism of action of glycopeptides

Answer 42

inhibits bacterial cell wall synthesis in gram +ve aerobes/anaerobes inactive against gram -ves

Question 43

indication for vancomycin

Answer 43

endocarditis, MRSA, C.diff (second line)

Question 44

side effects of vancomycin

Answer 44

if infused rapidly - can cause erythema, hypotension, bronchospasm IV can cause nephron/ototoxicity

Question 45

what type of cell are gram +ves | name some examples

Answer 45

cocci | enterococcus, staph aureus, MRSA, streptococcus

Question 46

what type of cell are gram -ves | name some examples

Answer 46

rods (bacilli) | Neisseria meningitides, H.influenzae, E.coli, EBSL, psuedomonas

Question 47

are anaerobes and atypical pneumonias gram +ve or -ve

Answer 47

Gram -ve | apart from C. diff

Question 48

What are the cephalosporin generations and what are the differences between them

Answer 48

each new generation has greater gram-ve activity, although less gram +ve action 1st generation = Cefradine 2nd generation = Cefuroxime 3rd generation = cefotaxime

Question 49

common side effect to be aware of when using cephalosporins

Answer 49

abx associated colitis

Question 50

what is flucloxacillin used for?

Answer 50

MSSA - methicillin sensitive staphylococcus aureus (++++) Streptococcus (+) skin infections, endocarditis

Question 51

most effective drug for treating streptococcal infection

Answer 51

benzylpenicillin