CPTP 3.11/3.12 Antibiotics

Question 1

Amoxicillin, ampicillin

Class + MoA
which bacteria they work against

Answer 1

Broad spectrum penicillin

MoA: beta lactam

(for all bacteria)

Question 2

Flucloxacillin, methicillin

Class + MoA
which bacteria they work against

Answer 2

Beta lactamase resistant penicillin

MoA: beta lactam

(only for Gram POSITIVE bacteria)

Question 3

Piperacillin

Class + MoA
which bacteria they work against

Answer 3

Extended spectrum penicillin

MoA: beta lactam

(most effective against pseudomonas,
effective against most Gram NEGATIVE except Klebsiella)

Question 4

Mecillinam, Temocillin

Class + MoA
which bacteria they work against

Answer 4

Reverse spectrum penicillin

MoA: beta lactam

(more for gram POSITIVE bacteria)

Question 5

Vancomycin

Class + MoA
which bacteria they work against

Answer 5

Glycopeptide

MoA: inhibits cell wall integrity by preventing transglycosylation (binds to D-ala at end of peptidoglycan chain)

(for serious Gram POSITIVE infx e.g. MRSA, C diff)

Question 6

Name the MoA of the following TB drugs:
Isoniazid
Ethambutol
Rifampin
Pyrazinamide

Answer 6

ISONIAZID
-inhibits formation of mycolic acid in mycobacteria

ETHAMBUTOL
-inhibits arabinosyl transferase (which synthesizes mycobacteria cell wall)

RIFAMPIN
-blocks initiation of transcription by interacting with beta subunit of RNA polymerase

PYRAZINAMIDE
-unknown MoA

Question 7

Carbapenems

Answer 7

Beta lactam

for all bacteria

Question 8

Aztreonam

Class + MoA +
which bacteria they work against

Answer 8

Monobactam (beta lactam)

(for gram NEGATIVE bacteria, especially Enterobacteria & Pseudomonas)

Enterobacteria incude Salmonella, E Coli, Yersinia, Klebsiella, Shigella

Question 9

Cefuroxime

Class + MoA +
which bacteria they work against

Answer 9

2nd gen cephalosporin
(beta lactam)

(broader specificity against Gram -ve e.g. Hib, Neisseria)

Can be used for all UTI

Note: Hib is resistant to amoxycillin/ampicillin

Question 10

Ceftriaxone, Cefotaxime, Ceftazidime

Class + MoA +
which bacteria they work against

Answer 10

3rd gen cephalosporin
(beta lactam)

passes through CSF so can be used to treat meningitis bacteria

Gram NEGATIVE: Neisseria, Hib, E Coli

Gram POSITIVE: Strep pneumo (most common), Listeria (if young/old/immunocompromised)

Note: in meningitis tx, for pts >55y/immunocompromised, + amoxicillin/gentamycin to cover Listeria

Question 11

Metronidazole

Class + MoA +
which bacteria they work against

Answer 11

Inhibits nucleic acid synthesis

used against C diff

Question 12

Ciprofloxacin

Class + MoA +
which bacteria they work against

Answer 12

Quinolone

Inhibits DNA gyrase (involved in removing DNA supercoiling)

Used for UTI

Question 13

Trimethoprim

MoA +
which bacteria they work against

Answer 13

Blocks dihydrofolate reductase

Used for UTI

Question 14

Sulfonamides

MoA +
which bacteria they work against

Answer 14

Blocks dihydrofolate synthase

Sulphasalazine used for ulcerative colitis as active in gut

Question 15

Polymyxins

MoA +
which bacteria they work against

Answer 15

Disrupt inner & outer membranes

Used for gram NEGATIVE bacteria

Question 16

Erythromycin, Clarithromycin, Azithromycin

Class + MoA +
which bacteria they work against

Answer 16

Macrolides

Bind reversibly to 50S subunit, blocks P site

(Work against Gram POSITIVE e.g. Strep + Gram NEGATIVE e.g. Hib, pertussis)

Question 17

Clindamycin

MoA +
which bacteria they work against

Answer 17

Bind reversibly to 50S subunit, blocks P site (similar action to macrolides)

(Work against MRSA, Staph, Strep)

Note:
Most aerobic gram negative bacteria (Pseudomonas, Legionella, Hib) are resistant

Question 18

Doxycycline

Class + MoA +
which bacteria they work against

Answer 18

Tetracyclines

Bind reversibly to 30S subunit, interferes with binding of tRNA to mRNA

(broad spectrum action, for all)

Question 19

Gentamycin

Class + MoA +
which bacteria they work against

Answer 19

Aminoglycoside

Binds IRREVERSIBLY to 30S subunit, ribosome not fitted properly, mRNA slips out

(works against gram NEGATIVE bacteria)

Question 20

If someone is allergic to penicillins, what other types of a/b should not be given to them

Answer 20

Cephalosporins

Carbapenams

(monobactams are ok. usually dont have cross reactivity with other beta lactams)