antibiotics

Question 0

Penicillin G

Answer 0

= narrow use penicillin/beta lactam.
Route: IV or IM (poor oral bioavailability)
Use: lactamase sensitive gram -/+ cocci
(strep. pneumo, staph, neisseria, treponema, clostridium)

Question 1

Beta Lactams (class of antibiotics)

Answer 1

Mech: irreversible inhibition of transaminase enzyme;
Structure: 2 rings, 1 = lactam
Route: oral, not topical; excreted in urine.
SE: anaphylaxis and toxicity rare, seizures @ high doses
Resistance via: penicillinase, decreased uptake

Question 2

Penicillin V

Answer 2

= narrow spectrum penicillin/beta lactam.
Route: oral * but IV/IM if serious infection!
Use: lactamase sensitive gram +/- cocci
(strep pneumo, staph, neisseria, treponema, clostridium)

Question 3

oxacillin

Answer 3

= beta-lactamase resistant penicillin.
Route: oral, but IV/IM if serious.
Use: penicillinase-producing Staphylococci, mixed staph/strep infections. *MRSA & enterococci = resistant

Question 4

ampicillin

Answer 4

= extended spectrum penicillin. 
Route: oral, not with food 
Use: non-beta lactamase gram+/- bacilli
(Staph, strep, E. coli, H influenzae, Salmonella, shigella)
SE: rash (~common)

Question 5

piperacillin

Answer 5

= extended spectrum penicillin,
(NOT penicillinase resistant, but not recognized by B-lactamase!)
Route: parenteral
Use: ONLY for serious G+/- (Enterococci; proteus, pseudomonas, enterobacter)

Question 6

Clauvulanic acid

Answer 6

= beta lactamase suicide inhibitor (NOT antibiotic alone)
Route: oral
Use: w/ amoxicillin (=> “augmentin”) for beta lactamase producers

Question 7

Cephalosporins (class of antibiotics)

Answer 7

Structure: similar to penicillins (do NOT use if penicillin anaphylaxis)
Mech: transaminase inhibitor (same as penicillin)
Route: oral/IV/IM, (not topical); Excreted w/ urine.
SE: GI, nephrotoxicity, superinfection

Question 8

1st gen. cephalosporins

Answer 8

cephalexin (oral), cefalozin (parenteral);
Mech: inhibit cell wall synthesis
For: gram + and some community-acquired gram-; surgical prophylaxis.
*Poor CNS penetration.
SE: nephrotoxicity, allergies

Question 9

2nd gen. cephalosporins

Answer 9

cefaclor/cefprozil (oral), cefoxitin (parenteral);
mech: inhibit cell wall synthesis
For: gram -, extended spectrum, & some oral & bowel anaerobes
SE: variable toxicity (heterogenous)

Question 10

3rd gen. cephalosporins

Answer 10

cefpoxadime (oral), cefotaxime (parenteral);
mech: inhibit cell wall synth.
for: extended spectrum gram - (NOT for gram +)
* Good CNS penetration –> meningitis from…
pneumococci, H. influenzae, E. coli, klebsiella, pen-resistant N. gonorrhea

Question 11

4th gen. cephaolsporins

Answer 11

cefepime (parenteral)
Mech: inhibit cell wall synth.
For: gram - and beta-lactam resistant bacteria
* good CNS penetration –> pseudomonas, enterobacteriacae

Question 12

imipenem

Answer 12

carbapenem, w/ beta-lactam ring.
Mech: inhibit transaminase –> cell wall synth.
Route: parenteral; * good CNS penetration.
* MUST give w/ renal enzyme inhibitor, or will be hydrolyzed!
Use: only for nosocomial/mixed infections (serious!)
(wide spectrum –> Gram +, -, anaerobes, ~beta lactamase resistant) but NOT MRSA/VRSA.
SE: Seizures, nephrotoxicity, GI Sx, allergy

Question 13

vancomycin

Answer 13

tricyclic glycoside
Mech: complex inhibition of cell wall synth., bactericidal
Route: IV, or oral if gut infection
Use: gram + cocci & bacilli (NOT gram -), MRSA, pen-resistant Strep. pneumo, coag - staph…
SE: ototoxicity & nephrotoxicity! (w/ high dose), flushing, etc.

Question 14

daptomycin

Answer 14

(NOT a beta-lactam)
Mech: bactericidal, pokes holes in wall –> depolarize bacteria
Route: IV; renal elimination.
Use: gram + skin/soft tissue infections
(MRSA, streptococci, enterococci; NOT VRSA)
SE: muscle pain, elevated creatinine

Question 15

Tobramycin

Answer 15

bactericidal aminoglycoside,
Mech: mis-incorporates AAs –> block bacterial protein synth.
Route: IM/slow IV, topical (burns) or oral for gut inf.;
- renal excretion;
Use: tenacious aerobic gram - (E coli, Klebsiella, Psuedomonas)
* NOT for anaerobes.
SE: Low therapeutic index! => ototoxicity, nephrotoxicity, contraindicated in pregnancy (crosses placenta).

Question 16

Doxycycline

Answer 16

bacteristatic (non-beta lactam),
Mech: blocks bacterial protein synth via ribosome
Route: parenteral, topical. Hepatic clearance (???)
Use: Rocky mtn spotted fever, mycoplasma, chlamydia
SE: pseudomembranous colitis, GI irritation, photo-sensivity, many DDIs!

Question 17

Drug-drug interactions of doxycycline:

Answer 17

1. Barbiturates, Phenyltoin: induce metabolism of doxycycline
   
   • -> lower serum [ ]
2. may decrease Oral Contraceptive efficacy
3. increase anti-coag. effect of Warfarin (!)

Question 18

Erythromycin

Answer 18

bacteriostatic macrolide
Mech: protein synth inhibition via ribosome
Route: oral or IV, ~no CNS distribution; excreted w/ bile.
Use: gram - & + aerobes; (esp. if penicillin allergy!)
- also anaerobes: Mycoplasma pneumo, Bordatella pertussis, Legionella, Corynebacter diptheriae
SE: very safe. may inhibit cytP450 –> lower warfarin, etc. tx
may antagonize other anti-microbials!

Question 19

clindamycin

Answer 19

bacteriostatic,
Mech: blocks ribosome
Route: oral, IM, IV, topical; Not to CNS; hepatic metabolism.
Use: bacteroides (intra-abdominal inf/abscess),
- serious gram+ if penicillin allergy.
SE: diarrhea/pseudomemb. colitis, rash, crosses placenta

Question 20

Linezolid

Answer 20

synthetic anti-microbial
Mech: block protein synth.
Route: oral; hepatic metabolism
Use: MRSA/MSSA, vanc-res. enterococcus, pen-res. S. pneumo
SE: diarrhea, headache, vomiting; rarely thrombocytopenia

Question 21

sulfamethoxasole

Answer 21

bacteriostatic, selectively toxic to bacteria (folate-synthesizers)
Mech: inhibit folate synth. (PABA structural analog)
Route: oral, gets to CNS; hepatic metab. & renal excretion
* must Lower dose if renal insufficiency*
Use: UTI, acute otitis media, bronchitis exacerbation
always w/ trimethoprim
SE: crystalizes if dehydrated, acute hemolytic anemia if G6P def., aplastic anemia, crosses placenta & milk…

Question 22

sulfamethoxazole drug-drug interactions

Answer 22

increases activity of:

• anti-coagulants
• anti-convulsants

Question 23

trimethoprim

Answer 23

Mech: blocks DNA synth & cell prolif. by decrease thymine (inhibits dihydrosulfate reductase)
Route: oral; hepatic metab, renal excretion.
Use: UTIs (E coli, enterobacter, etc.)
* always w/ sulfamethoxasole*
SE: skin rxn, thrombocytopenia if already folate-def., renal impairment if already renal disease

Question 24

Ciprofloxacin

Answer 24

quinolone.
Mech: inhibits bacterial gyrase & topoisomerase –> DNA damage
Route: oral, varied metabolism/clearance.
Use: UTI, (not a 1st line drug), resp. infections
SE: rare…tendon rupture, seizures if take w/ NSAIDs

Question 25

metronidazole

Answer 25

Mech: damages cell macromolecs (ie: DNA)
* prodrug selectively activated in protozoa
Route: oral; hepatic metab/clearance
Use: anaerobes, parasites
SE: dry mouth, CNS effects… do NOT take w/ EtOH!