AntibioticsSH2

Question 1

Penicillins

Answer 1

Inhibit cell wall ( wont work on mycoplasma)
Has 5 member ring

If probenecid used ( prolongs PCN serum level)

Spectrum of activity :
Strep , peptostreptococci, Treponema pallidum ( syphilis )

Use :
Pharyngitis, rheumatic fever, syphilis, dental prophylaxis / infection

Metabolized and excreted by kidney
Preg B

Question 2

Benzathine PCN ( Bicillin L-A) vs Bicillin C-R

Answer 2

Bicillin L-A is Benzathine PCN vs Bicillin C-R is Benzathine PCN plus procaine PCN

B L-A: Group 1 strep : 1.2 million units IM single dose ( last in patients system 2 to 4 weeks so thats why single dose)
Rheumatic fever:
Syphilis 2.4 million units IM single dose
-3° syphilis: IM q week x 3 doses
-not for neurosyphilis ( IV for that )

For Bicillin C-R not FDA approved for syphilis.
B C-R: scarlet fever / group A strep

Question 3

Penicillin G

Answer 3

IV formulation

NEUROSYPHILIS

Penumcoccal pneumonia, meningitis, Neurosyphilis, Anthrax

Question 4

PCN VK

Answer 4

Pen-Vee K, Veetids
Po formulation
Take on on an empty stomach ( 1 hour before or 2 hours after a meal. )

Refrigerate soln.

If PCN allergy no ampicillin, amoxicillin or PCN

Decrease dose by 1/2 if CrCl <10

Question 5

Pencillinase resistant PCNs

Answer 5

CONDM

cloxacillin- empty stomach - not available in US.
•Oxacillin - hepatoxicity : if dose > 12 g qd LFTs- IV
•Nafcillin - MSSA . Does not need to dose adjust in renal -IV ( this does not go through kidneys) ***** eliminated primarily by hepatic
•Dicloxacillin-empty stomach PO Route
Methicillin- no longer manufactured

Question 6

AminoPCNs

Answer 6

Ampicillin, amoxicillin

Amp: empty stomach
rash diarrhea

Streptococci, enterococci, Listeria
Drug of choice for enterococcus ifx. Reality is resistance.

Reduce if CrCl < 10 ml/min -dose adjust
Recall nafcillin no dose adjust in renal

Question 7

Amoxicillin

Answer 7

Strep, otitis media, dental prophylaxis

For kids 80-90 mg/kg/day ( 1st line for OM ). Use 90. This is a daily dose.
1.75 g/day once child reaches 20 kg.
3 g/day of amoxicillin in kids over 33 kg
4 g/day in kids over 44 kg for serious infections

Dental prophylaxis: 2 g ( 50mg/kg) 1 hour prior

Oral susp : 14 days room temp or refrigerator

Infant drops: amox 50 mg/ml

Question 8

Endocarditis prophylaxis for dental procedures

Answer 8

Amox 2 g for adults 30-60 mins before
Allergy
Clindamycin 600 mg or
Azithromycin 500 mg
Clarithromycin 500 mg

Prophylaxis For who?
Valve replacement, congenital heart defects
( mitral valve prolapse, regurgitation or rheumatic heart disease do not need prophylaxis abx)

Question 9

Beta lactamase inhibitors

Answer 9

Sulbactam, Clavulanate, Tazobactam
Broaden beta lactam abx

Beta-lactam combo agents
• zosyn - piperacillin /tazobactam ( IV ) stable in D5W, NS
• ampicillin /sulbactam ( Unasyn ) IV NS
• Augmentin ( amox/clav) PO refrigerate

Zosyn and timentin are anti psedomonal

Bet lactam combo spectrum: staph, enterococcus, streptococcus, B. fragilis, H influenza, M catarrhalis, Pseudomonas ( zosyn & timentin only )

Question 10

Unasyn

Augmentin

Answer 10

Ampicillin sulbactam
Best mixed in NS

Amox/clav Augmentin
Can’t double of on lower to make higher strength. Bc clavulante component.

Refrigerate susp

Augmentin XR dont use w/CrCl <30

Question 11

PCN is the only appropriate tx for syphilis during pregnancy so if pregnant and have an allergy your option is to desensitize PCN

Answer 11

T

Question 12

Answer 12

Question 13

Zosyn

Answer 13

Only IV
Great coverage ( including pseudomonas )
Covers intra abdominal ifx ( e. Coli , B fragilis )
Pelvic infections ( E. coli )
Nosocomial pneumonia : S auerus , actinobacter, H influenzae, klebsiella, and pseudomonas ( P aeruginosa should be treated in combination with an aminoglycoside )

Must dose adjust
CrCl> 40 start with 3.375 G IV q6 hr / nosocomial : 4.5 g IV q6h

If CrCl 20-40 dose adjust / if nosocomial stay or drop to 3.375
If <20 decrease dose again

Question 14

Adverse effects

Answer 14

Allergy
PCN seizure
Augmentin : major diarrhea

Question 15

Cephalosporins and PCN allergy

Answer 15

If PCN allergy, dont give cephalosporin on test question. But reality is cross reactivity is low. ( change of cross reactivity =0.1 %) on test assume severe PCN allergy where you definitely wouldn’t

Another one to avoid in pCN allergy is carbopenum

Multiple generations

Question 16

First Gen Cephalosporin

Answer 16

covers mostly gram +, PEK organism ( Proteus , E. Coli & Klebsiella )

Cephalexin ( keflex )
-pnemonia, bone ifx,
-group A strep, skin infection( on skin we have staph or strep gram (+) ) , simple UTI
-not for otitis media

Cefazolin ( Ancef ) -surgical prophylaxis DOC ( IM/ IV )
Cefadroxil ( Duricef) -

All are preg B and RENAL
Usually 1st line for surgical prophylaxis

Question 17

Second Gen Cephalexin

Answer 17

Gaining more gram ( - )
HENPEKS
H influenzae, Enterobacter aerogenes, Neisseria, Proteus mirabilis, E. coli, Klebsiella pneumonia, Strep Pneumoniae

know formulation. If pt is discharged we want them on same gen.
Cefaclor- PO ( not used much ) , Cefprozil ( Cefzil ) PO, Cefuroxime ( zinacef, ceftin ) - IM/IV/PO , Cefoxitin ( Mefoxin ) IV
Cefotetan - IM/IV

Cefoxitin & Cefotetan active against anaerobes ( b fragilis ) so can be used in intra-abdominal surgeries
2nd gen Cephs are 2nd line agent for otitis media. ( amoxicillin is 1st line)
CEFOTETAN has an NMTT ( N-methyltiotetrazole ) side chain: can increase risk of bleeding and can cause a disulfiram rxn

Question 18

Cephs that cover pseudomonas

Answer 18

Pseudomonas aeruginosa
- Ceftazidime ( 3rd Gen )
- Cefepime ( 4th Gen ) ( IV/ IM )
- Ceftolozane/ tazobactam ( Zerbaxa a combo drug ) ( 5th gen )

Question 19

Ceftriaxone ( Rocephin ) and Ceftazidime ( Fortaz ) are the two most commonly used IV preparations

Answer 19

T

Both are 3rd gen. Both hospital use. Not ORal

Question 20

3rd gen oral Cephs

Answer 20

Cefdinir ( omnicef ) - give iron / vitamins / anatacids 2 hours apart. Dont refrigerate

Cefditoren ( spectracef ) - PO w/food. No antacids . Milk protein allergy ( recall dry powder inhalations for asthma are contraindicated )

Cefixime ( suprax ) -PO
Suspension at room temp or fridge 14 days • Ceftriaxone IM shot for gonorrhea first line. Cefixime 2nd line if they dont want a shot. ( “ please try to fix my gonorrhea “ ) Triaxone to fixime

Cefpodoxime ( PO ) / watch for antacids. With food. Susp in fridge.

Ceftibutin ( Cedax ) : PO stable for 14 d in fridge

Question 21

IV / IM formualtions Ceph ( parenteral )

Answer 21

Ceftazidime ( fortaz, tazicef ) : IM /IV : covers pseudomonas

Combo: Avycaz : ceftazidime / avibactam : better coverage of resistant enterobacteriaceae, klebsiella and pseudomonas aeruginosa, but not acinetobacter
- IV over 2 H for complicated abdominal ifx, and UTI

Cefotaxime: ( Claforan ) - IM / IV

• Ceftriaxone ( rocephin )

Question 22

Answer 22

Question 23

Ceftriaxone

Answer 23

Meningitis and endocarditis

Ceftriaxone 250 mg IM + Azithromycin oral 1 gram : for gonorrhea

No renal adjustment
Dilute with 1% lidocaine for IM use/ cant be reconstituted with Ca containing products.

Question 24

4th gen Ceph

Answer 24

IV / IM only
Cefepime ( maxipime ) : broad spectrum ( gram + /– ) and ANTI -Pseudomonal
- CNS tox : usually if high risk of renal impairment

Cefiderocol ( Fetroja ) : Trojan horse.
Covers: Acinetobacter, E. Coli, klebsiella, proteus mirabillis, PSEUDOMONAS , Enterobacter cloacae complex
- Pneumonia ( HAP & VAP )
-complicated UTI, including pyelonephritis

If CrCl ≥ 120 ml/min you can increase dose

Question 25

5th Gen Ceph

Answer 25

• Ceftaroline ( Teflaro) - only Ceph that covers skin infection MRSA.
- we can use for CAP ( MSSA covered but not MRSA)

Hospital use only. 400 / 600 mg powder in vials.

Common SE: diarrhea , nausea , rash

• Zerbaxa ( combo : Ceftolozane / tazobactam ) - IV
-intra- abdominal infections when used in conjunction with metronidazole.
Dose adjust in RENAL

Question 26

Carbapenems

Answer 26

PCN allergy: for purpose of test, you assume severe life threatening so dont give Carbapenems. ( in reality cross reactivity is low)

• Imipenum / cilastin ( Primaxin ) : cilastin prevents renal metabolism. Mix in NS. IV / IM q 6 - 8 Hr.
• Meropenem ( Merrem ) : NS or D5W
• Ertapenem ( Invanz ) : the only once daily Carbapenems. Q 24 hours. Best mixed in NS
•Doribax ( doripenem) :

Covers almost everything: gram +/– , anaerobes ,
Yes pseudomonas , acinetobacter ( but not ertapenem )
but NOT MRSA for all Carbapenems

DOC for infectious pancreatitis

Vabomere: meropenem + vaborbactam

SE: super-infection ( fungal pathogens ) bc killing off everything. PCN cross reactivity low but watch for severe PCN allergy
SEIZURES ( rate of seizures is a lot more than PCN seizure. )

DDI: Carbapenems can’t reduce valproic acid. Additive reaction: increasing seizure with ganciclovir.

Question 27

Monobactam

Answer 27

Aztreonam

Covers gram ( - ) only.
Also covers pseudomonas.
Used for UTI
Moderately severe systemic infections.

Cystic fibrosis ( we worry about pseudomonas )

Who do we use this for ? Covering gram negative. Also can use it if patient can’t use aminoglycoside ( due to nephrotoxicity ) we can instead use aztreonam.

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