intro to antibiotics

Question 1

what is an antibiotic

Answer 1

a drug used to treat or prevent infection
caused by micro-organisms

Question 2

what is a bacteriostatic antibiotic

Answer 2

it inhibits the growth of bacteria (most common used)

Question 3

what is a bacteriocidal antibiotic

Answer 3

it kills bacteria

Question 4

what is an example of a narrow spectrum antibiotic

Answer 4

penicillin, only effects gram positive

Question 5

what is an example of a broad spectrum antibiotic

Answer 5

tetracycline effects both gram positive and negative

Question 6

what are the characteristics of an ideal antibiotic

Answer 6

cidal (kills bacteria), long half life, appropriate tissue distribution, no adverse side effects, no drug interaction, oral preparation

Question 7

how are antibiotics commonly excreted

Answer 7

in the urine of via the liver, biliary tract and into the faeces

Question 8

what are the 3 ways of administration

Answer 8

orally, intravenously, or rarely intramuscularly

Question 9

what is the possible downside of orally given antibiotics

Answer 9

much of the antibiotic is not
absorbed and is excreted unchanged in the faeces

Question 10

what are the common antibiotic targets

Answer 10

cell wall, ribosomes, metabolic pathways

Question 11

what are the commonly prescribed cell wall antibiotics

Answer 11

penicillins, cephalosporins, glycopeptides

Question 12

examples of penicillins

Answer 12

penicillin, flucloxacillin, amoxicillin

Question 13

what are beta - lactam antibiotics

Answer 13

they mimic the shape of the side chains of the cell wall, creating a gap, allowing inhibition. (penicillins are beta-lactam)

Question 14

characteristics of penicillin

Answer 14

few side effects, variety very flexible, range from narrow broad spectrum, excreted through kidneys, safe in pregnancy

Question 15

limitations of penicillin

Answer 15

patients can be hypersensitive ‘allergic’, rapid excretion via kidneys means more frequent dosing is required, long term use can build a resistance

Question 16

example of gram positive penicillin

Answer 16

flucloxacillin

Question 17

example of gram negative penicillin

Answer 17

temocillin

Question 18

examples of gram + and - penicillin

Answer 18

amoxicillin, co-amoxiclav (both IV or oral)

Question 19

3 principle compounds of penicillin

Answer 19

Benzylpenicillin (penicillin G), Phenoxymethyl penicillin (penicillin V), Benzathine penicillin

Question 20

characteristics of amoxicillin

Answer 20

well tolerated, well absorbed when given orally, low binding to plasma, good tissue distribution, beta-lactam

Question 21

what are beta-lactamases

Answer 21

enzymes that destroy beta lactam ring

Question 22

co-amoxiclav characteristics

Answer 22

combination of amoxicillin and clavulanic acid, IV and oral, beta lactam and beta lactamase inhibitor (clavulanic acid)

Question 23

characteristics of flucloxacillin

Answer 23

very narrow spectrum, IV and oral, commonly prescribed for staph and strep skin infections or infected wounds

Question 24

temocillin

Answer 24

IV, b-lactamase resistant, restricted to coliforms (salmonella, Escherichia). been reintroduced due to increasing bacterial resistance

Question 25

characteristics of cephalosporins

Answer 25

different structure to penicillin, they inhibit cell wall synthesis, bactericidal, excreted via kidneys, few side effects, reduced allergy. narrow gram - to broad

Question 26

what do cephalosporins effect

Answer 26

broad spectrum that affect normal bowel flora, which allows overgrowth of c. difficile causing gastroenteritis. most hospitals now try to avoid using these antibiotics

Question 27

how do some antibiotics inhibit protein synthesis

Answer 27

Antibiotics that inhibit protein synthesis do so by attaching to bacterial ribosomes. Usually protein synthesis can resume when the antibiotic is removed, so most of these antibiotics are bacteriostatic.

Question 28

examples of antibiotics that inhibit protein synthesis

Answer 28

macrolides, tetracyclines (bacteriostatic), aminoglycosides (bacteriacidal)

Question 29

antibiotics that affect nucleic acids

Answer 29

metronidazole (activity against anaerobes), trimethoprim (urinary tract infections)

Question 30

what to consider when choosing an antibiotic

Answer 30

what is site of infection and what could it be. should it be given orally or IV, allergies?, is it cost effective

Question 31

side effects of antibiotics

Answer 31

nausea, vomiting, diarrhoea. Broad spectrum antibiotics increase risk of c.difficile

Question 32

why are antibiotics given in combination sometimes

Answer 32

to cover broad range, to prevent resistance, or full effect needed against certain bacteria

Question 33

which antibiotics should you never combine

Answer 33

bacteriostatic and bacteriocidal

Question 34

which 4 antibiotics do we try to avoid

Answer 34

the 4 Cs. as the increase risk of c.diff - Cephalosporins – Co-amoxiclav – Ciprofloxacin – Clindamycin