Antimicrobials

Question 1

Penicillin G & V

Answer 1

Natural penicillins (b lactam)

Notes - Target PBPs which are enzymes for cell wall synthesis which prevents NAG/NAM cross-linking peptide formation & activate autolysins. Against gram positive. Bactericidal. G inactivated by gastric acid so can’t be taken orally. V less active by not inactivated by gastric acid. SE convulsions if given IV, <0.1% anaphylaxis

Question 2

cefradine

Answer 2

1st gen cephalosporin (b lactam)

Notes - Target PBPs which are enzymes for cell wall synthesis which prevents NAG/NAM cross-linking peptide formation & activate autolysins. Bactericidal. Highly active against gram+. Cross allergy w penicillin 5% of cases

Question 3

Aztreonam

Answer 3

Monobactam (b lactam)

Notes - Bactericidal. Targets cell wall. Narrow spectrum -> Gram + bacilli, gram - aerobic, enterobacteria, pseudomonas. Used in penicillin & cephalosporin allergy.

Question 4

Cefaclor

Answer 4

2nd gen cephalosporin (b lactam)

Notes - Target PBPs which are enzymes for cell wall synthesis which prevents NAG/NAM cross-linking peptide formation & activate autolysins. Bactericidal. activity against gram -. Cross allergy w penicillin 5% of cases

Question 5

Cefotaxime

Answer 5

3rd gen cephalosporin (b lactam)

Notes - Target PBPs which are enzymes for cell wall synthesis which prevents NAG/NAM cross-linking peptide formation & activate autolysins. Bactericidal. Activity against gram+ (but less than 1st gen) & strong activity against gram- aerobes (more than 2nd gen) Cross allergy w penicillin 5% of cases

Question 6

Cefepime

Answer 6

4th gen cephalosporin (b lactam)

Notes- Target PBPs which are enzymes for cell wall synthesis which prevents NAG/NAM cross-linking peptide formation & activate autolysins. Bactericidal. Highly resistant to beta-lactamase. Cross allergy w penicillin 5% of cases

Question 7

Ceftaroline

Answer 7

5th gen cephalosporin (b lactam)

Notes - Target PBPs which are enzymes for cell wall synthesis which prevents NAG/NAM cross-linking peptide formation & activate autolysins. Bactericidal. high activity against MRSA. Cross allergy w penicillin 5% of cases

Question 8

Amoxicillin & ampicillin

Answer 8

Broad spectrum penicillins (b lactam)

Notes - Against Gram negative. Bactericidal. Target PBPs which are enzymes for cell wall synthesis which prevents NAG/NAM cross-linking peptide formation & activate autolysins. Amoxicillin oral, ampicillin lower bioavailability. SE convulsions if given IV, <0.1% anaphylaxis. Ampicillin given with sulbactam (b lactamase inhibitor)

Question 9

Cloxacillin & floxacillin

Answer 9

b lactamase resistant penicillins (b lactam)

Notes - Target PBPs which are enzymes for cell wall synthesis which prevents NAG/NAM cross-linking peptide formation & activate autolysins. Only for methicillin SENSITIVE s. aureus (not MRSA) & some coliforms. Bactericidal. SE convulsions if given IV, <0.1% anaphylaxis

Question 10

Carbenicillin & ticarcillin & ureidopenicillin

Answer 10

Extended spectrum carboxy-penicillins (b lactam)

Notes - Target PBPs which are enzymes for cell wall synthesis which prevents NAG/NAM cross-linking peptide formation & activate autolysins. beta lactamase sensitive. Bactericidal. SE convulsions if given IV, <0.1% anaphylaxis

Question 11

imipenem, meropenem, doripenem, ertapenem

Answer 11

carbapenems (b lactams)

Notes - Bactericidal. Target PBPs which are enzymes for cell wall synthesis which prevents NAG/NAM cross-linking peptide formation & activate autolysins. widest spectrum-> gram + cocci, gram - bacilli ex p. Aeruginosa. anaerobes

Question 12

Vancomycin

Answer 12

Cell wall inhibitor (glycoprotein)

Notes - Bactericidal. drug of last resort when b lactams don’t work* On reserve for MRSA esp. S.aureus & C.diff* Forms bonds with D-Alanine in PG layer preventing incorporation of NAG/NAM. SE - RED MAN SYNDROME (rate dependent infusion reaction by activating mast cells to release histamine- not mediated by IgE), OTOTOXICITY, NEPHROTOXICITY

Question 13

Teicoplanin

Answer 13

Cell wall inhibitor (glycoprotein)

Notes - Bactericidal. Longer half life (30h) than vancomycin (4-11h) & fewer S.E. Given IV or intramuscularly

Question 14

Bacitracin

Answer 14

Cell wall inhibitor

Notes - bactericidal. Inhibits regeneration of lipid carrier of PG so can’t get to cell wall

Question 15

Cycloserine

Answer 15

Cell wall inhibitor

Notes- Bactericidal. D-Alanine structural analogue so inhibits incorporation. Used for TB

Question 16

Polymyxin B

Answer 16

Cell membrane inhibitor

Notes- Bactericidal. A detergent that displaces Mg & Ca in cell membrane making it leaky. Has high affinity for phospholipids TOPICAL USE ONLY for gram - (ex pseudomonas & coliforms) bc they have LPS layer which is exposed cell membrane

Question 17

Erythromycin

Answer 17

1st gen macrolide (inhibits protein synthesis)

Notes - Bacteriostatic @ low doses, bactericidal @ high doses. Bind 50S ribosome and prevent translocation of ribosome along mRNA. SE nausea especially with this drug!!, prolonged QT interval so c/i for heart problems. CYP inhibitor.

Question 18

Clarithromycin

Answer 18

2nd gen macrolide (inhibits protein synthesis)

Notes - Bacteriostatic @ low doses, bactericidal @ high doses. Bind 50S ribosome and prevent translocation of ribosome along mRNA. SE nausea, prolonged QT interval so c/i for heart problems. CYP inhibitor.

Question 19

Azithromycin

Answer 19

3rd gen macrolide (inhibits protein synthesis)

Notes - Bacteriostatic @ low doses, bactericidal @ high doses. Bind 50S ribosome and prevent translocation of ribosome along mRNA. Strongest effect for gram negative of all generations. SE nausea, prolonged QT interval so c/i for heart problems. CYP inhibitor.

Question 20

Doxycycline, tetracycline, minocycline, demeclocycline

Answer 20

Tetracycline (inhibits protein synthesis)

Notes - Bacteriostatic. Bind 30S ribosome and prevent tRNA adding new AA to peptide chain. These are broad spectrum & low cost alternative to penicillins and macrolides! BUT they have a big problem with resistance. SE - photosensitive, teratogenic bc chelator of calcium & metals so c/i in pregnancy & nursing, teeth stains

Question 21

Gentamycin, streptomycin, amikamycin, tobramycin

Answer 21

Aminoglycosides (inhibits protein synthesis)

Notes - Bactericidal. Bind 30S ribosome and change its shape causing misreading of the mRNA. Mainly active against gram negative aerobes. NEVER first option bc of the extreme SE NEPHROTOXICITY so c/i kidney problem patients, ototoxicity, muscular blockade by displacing calcium from NMJ, blocking Nm receptors & inhibiting ACh release …so c/i myasthenia gravis

Question 22

Clindamycin

Answer 22

Lincosamide (inhibits protein synthesis)

Notes - Bacteriostatic @ low doses, bactericidal @ high doses. Binds 50S ribosome and prevents aminoacyl translocation so prevents chain elongation. SE - C diff super-infection 2-9 days after therapy starts so c/i elderly

Question 23

Chloramphenicol

Answer 23

Protein synthesis inhibitor

Notes - Bacteriostatic. Binds 50S and prevents peptide bond formation. Reserved for life-threatening infections caused by BM depression. SE - pancytopenia & GREY BABY SYNDROME

Question 24

Sulfonamides

Answer 24

PABA analogue (inhibit synthesis & reduction of folate)

Notes - Bacteriostatic. inhibit dehydropteroate synthetase

Question 24

Linezolid & Tedizolid

Answer 24

Oxazolidinones (inhibit protein synthesis) Notes - Newest target against ribosomes. Bind 50S and prevent fMET TRNA synthesis. Only for Gram +, good for MRSA & TB multi-resistance & vancomycin resistant enterococcus. SE of linezolid - serotonin syndrome, BM suppression, optic & peripheral neuropathy, lactic acidosis "Does a "zolid" job except depresses mood, BM, eyes & causes lactic acidosis"

Question 25

Trimethoprim

Answer 25

DHFR inhibitor (inhibit synthesis & reduction of folate) Notes - Bacteriostatic. For AEROBIC only

Question 26

Ciprofloxacin, Levofloxacin, Gemifloxacin

Answer 26

Broad spectrum fluoroquinolones (inhibit DNA synthesis) Notes - Bactericidal. Inhibit DNA gyrase. SE - torsade du pontes, C. Diff superinfection. cardiac arrhythmias, convulsions, hypoglycemia

Question 27

Nalidixic acid

Answer 27

Narrow spectrum fluoroquinolone - not fluorinated (inhibit DNA synthesis) Notes - Bactericidal. Inhibit DNA gyrase. SE - torsade du pontes, C. Diff superinfection. cardiac arrhythmias, convulsions, hypoglycemia

Question 28

Flagyl

Answer 28

metronidazole (inhibit DNA synthesis) Notes - Bactericidal. Goes in bacteria & bacterial ferrodoxins activate it into active metabolites - nitro radical anions that chop DNA. for ANAEROBES only. SE - metallic taste, dark urine, stomatitis & glossitis, peripheral neuropathy, teratogenic so c/i pregnancy. Alcohol causes profuse vomiting with it so it can be used as an anti-abuse drug to deter person from drinking. DDI - warfarin*

Question 29

Rifampicin

Answer 29

RNA polymerase inhibitor - 1st line TB medication Notes - Bactericidal. Binds beta subunit of bacterial DNA dependent RNA polymerase and inhibits RNA synthesis. Used for TB. SE - HEPATOTOXICITY (must stop if bilirubin increases), ORANGE TEARS/URINE/SWEAT, IMMUNE DYSFUNCTION (thrombocytopenic purpura if intermittent use). CYP inducer

Question 30

Augmentin

Answer 30

clavulanic acid + amoxicillin

Question 31

tazobactam

Answer 31

beta lactamase inhibitor - given with beta lactamase sensitive penicillins

Question 32

Puromycin

Answer 32

Premature termination of peptide chain

Question 33

TB treatment

Answer 33

Polytherapy First line: -> 2 months isoniazid + rifampicin + pyrazinamide + (IF RESISTANT) ethambutol -> Followed by isoniazid + rifampicin for 4 months Second line: -> cycloserine (cell wall inhibitor) -> streptomycin (aminoglycoside Ab) -> clarithromycin (macrolide Ab) -> capreomycin (cyclic peptide) -> ciprofloxacin (fluoroquinolone) XDR-TB - resistant to everything MDR-TB - resistant to isoniazid & rifampicin

Question 34

Isoniazid

Answer 34

1st line TB medication Notes - inhibits mycolic acid synthesis in cell wall. SE hepatitis, peripheral neuropathy, pyridoxine (Vit B6) deficit, agranulocytosis, psychosis (Rare). CYP inhibitor

Question 35

Ethambutol

Answer 35

1st line TB medication Notes - inhibits mycolic acid movement to cell wall and inhibits RNA synthesis. SE - optic neuritis (colour deteriorates first)

Question 36

Pyrazinamide

Answer 36

1st line TB medication Notes - inhibits FAS. SE - hepatitis, athralgia, hyperuricemia. c/i in GOUT

Question 37

Gram Positive AEROBES

Answer 37

Cocci - staph, strep, entero Rods - Bacillus, listeria, nocardia

Question 38

Gram Positive ANAEROBES

Answer 38

Rods - C.diff, actinomyces

Question 39

Gram Neg AEROBES

Answer 39

Cocci - Neisseria Rods - Lactose fermenters (e. coli, klebsiella), non-lactose fermenters (salmonella, shigella), pseudomonas, vibrio, Hemophilus

Question 40

Misc. bacteria

Answer 40

Chlamydia, mycoplasma, legionella, helicobacter