Antibiotics - Pt 1

Question 1

What ae antibiotics?

Answer 1

Chemical compound made by another microorganism which inhibits or kills bacteria
Majority derived from bacterial species - steptomyces

Question 2

What is the function of bactericidal antibiotics?

Answer 2

Kill the bacteria

Question 3

What is the function of bacteriostatic antibiotics?

Answer 3

Prevent bacteria multiplying

Question 4

What are some types of bactericidal antibiotics?

Answer 4

Penicillin, gentamicin, vancomycin, ciprofloxacin and metronidazole

Question 5

What are some types of bacteriostatic antibiotics?

Answer 5

Doxycycline, clarithromycin, azithromycin and linezolid

Question 6

What are the mechanisms of action for antibiotics?

Answer 6

Inhibition of Cell wall synthesis, Protein synthesis, DNA gyrase and Folic acid metabolism

Question 7

What are some antibiotics which inhibit cell wall synthesis?

Answer 7

Penicillin, cephalosporins, carbapenems, vancomycin and aztreonam

Question 8

What are some antibiotics which inhibit protein synthesis?

Answer 8

Gentamicin, doxycycline, clarithromycin, erythromycin, clindamycin, chloramphenicol and linezolid

Question 9

What are some antibiotics which inhibit DNA synthesis?

Answer 9

Metronidazole and fluoroquinolones

Question 10

What are some antibiotics which inhibit folic acid synthesis?

Answer 10

Trimethoprim and co-trimoxazole

Question 11

What are the groups which target bacterial cell wall?

Answer 11

Beta lactams
Glycopeptides

Question 12

Describe beta-lactams

Answer 12

3 carbon and 1 nitrogen ring - beta-lactam ring
Bactericidal
Bind to penicillin binding proteins in cell wall or cytoplasm - inhibit cell wall formation
Inhibition by beta lactamases

Question 13

Describe penicillin

Answer 13

Beta-lactam
Penicillium moulds
Composition - beta lactam and thiazolidine ring, plus Acl side chain
Wide spread of activity

Question 14

What is the bacteria which benzylpenicillin and phenoxymethylpenicillin is active against?

Answer 14

Streptococcus pneumoniae - mainly
Beta-haemolytic - Streptococcus sp.
Alpha-haemolytic - Neisseria meningitis and Clostridium perfringes

Question 15

What bacteria is amoxicillin and ampicillin active against?

Answer 15

Same as benzylpenicillin
E. coli
Enterococcus faecalis
Listeria monocytogenes

Question 16

What bacteria is flucloxacillin active against?

Answer 16

Meticillin sensitive
Staph. aureus (MSSA)
Beta haemolytic - streptococcus

Question 17

What bacteria is temocillin active against?

Answer 17

No gram positive activity
Enterobacteriaceae including AmpC and ESBL producers - Burkholderia cenocepacia

Question 18

Describe the structure of cephalosporins

Answer 18

Beta-lactam ring
Dihydrothiazine ring
R1 and R2 side chains

Question 19

Describe 1st class of cephalosporins

Answer 19

Active against gram positive
Cefazolin and cefalexin

Question 20

Describe 2nd class cephalosporins

Answer 20

Enhanced gram negative activity and varying gram positive activity
Cefuroxime

Question 21

Describe 3rd class cephalosporins

Answer 21

Markedly improved gram negative activity
Variable gram positive activity
Ceftriaxone and cefotaxime

Question 22

Describe 4th class cephalosporins

Answer 22

Broad gram positive and negative activity
Cefepime

Question 23

What do cephalosporins all cover?

Answer 23

Group A, B and C streptococci
Viridians group streptococci
E. coli
Klebsiella
Proteus mirabilis

Question 24

What do cephalosporins not cover?

Answer 24

LAME
Listeria, Atypical, MRSA and Enterococcus

Question 25

Describe carbapenems

Answer 25

Broad spectrum
Imipenem, Ertapenem and Meropenem
Fused beta lactam ring to 5 membered carbon only ring - stable against beta lactamases
IV only

Question 26

When is meropenem used?

Answer 26

Active against gram positive, gram negative and pseudomonas
Severe infections - unresponsive to other antibiotic and haematology patients
Lung infections in CF patients

Question 27

What are some mild adverse reactions to beta lactams?

Answer 27

Rash and fever

Question 28

What are some severe adverse reactions to beta lactams?

Answer 28

Anaphylaxis, angioedema, facial swelling, breathing difficulties and Steven Johnstone’s reaction

Question 29

What is the interaction between carbapenems and valproate?

Answer 29

Decreased valproate levels - increased risk of seizures
Clinically significant
Avoid concurrent use

Question 30

What is the interaction between carbapenems and probenecid?

Answer 30

Increased levels of ertapenem and imipenem
Caution and rarely used

Question 31

What is the interaction between all beta lactams and typhoid vaccine?

Answer 31

Prevents multiplication and reduces immune response achieved
Clinically significant and should be stopped 3 days before until 3 days after vaccine is given

Question 32

Describe beta lactamase inhibitors

Answer 32

Restore antibacterial activity of antibiotics - amoxicillin and piperacillin
Clavulanic acid and tazobactam - potent beta lactam inhibitors

Question 33

What bacteria is co-amoxiclav and piptazobactam active against?

Answer 33

Co-amoxiclav - meticillin sensitive - staph. aureus, klebsiella spp., proteus and anaerobes
Piptazobactam - pseudomonas and same as co-amoxiclav

Question 34

Describe glycopeptides

Answer 34

Bactericidal - Vancomycin and teicoplanin
Gram positive organisms
Inhibits peptoglycans in the cell wall - weakens cell wall and leakage of intracellular components
Large molecules - poor oral absorption

Question 35

Describe vancomycin use

Answer 35

MRSA
1st line for gram + infections in individuals with penicillin allergy
Used for skin and soft tissue infections, streptococcus meningitis and infective endocarditis
Clostridium difficile - oral vancomycin

Question 36

What is a side effect of vancomycin?

Answer 36

Red man syndrome - flushing, erythema, pruritus, affecting upper body, neck and face, myalgia, dyspnoea and hypotension

Question 37

What is the management for red man syndrome?

Answer 37

Stop infusion
Administer antihistamine
Can restart at slower rate once symptoms resolve

Question 38

Describe vancomycin dose monitoring

Answer 38

Target is 10-20mg/l
If too high then stop vancomycin until trough <20mg/l then restart at increased dose intervals
If too low then reduce dose interval then dose