Antibiotics

Question 1

Beta-lactams

Answer 1

Interfere with cell wall synthesis during multiplication, causing cell wall destruction and bacterial death. Bind to cell wall of gram positive/negative.

Target peptidoglycan synthesis by inhibiting penicillin binding proteins (PBP).

Clinical efficacy: dependent on the time the concentration is above the MIC. Dosed frequently.

Question 2

Beta-lactam adverse effects

Answer 2

Very well tolerated overall.

Common: hypersensitivity (rash mostly, can be anaphylactic), GI distress (nausea, diarrhea).

Rare: C. diff, candidiasis, bone marrow suppression.

Question 3

Penicillin-based antibiotics

Answer 3

Natural penicillins
Aminopenicillins
Anti-staphylococcus penicillins
Uridopenicillins
Combination with beta-lactamase inhibitor

Question 4

Natural penicillins/Aminopenicillins

Answer 4

Natural: Penicillin VK, Penicillin G
Aminopenicillins: Ampicillin, Amoxicillin. Better absorption, dosed less frequently than natural penicillins.

Spectrum: Streptococcus, enterococcus, treponema pallidum (syphillis)

Common indications: Strep throat, otitis media, mild URI, syphilis, UTI (if sensitive, not for empiric therapy).

Question 5

Anti-staph penicillins

Answer 5

Methicillin, nafcillin, dicloxacillin

Side R chain, protects against basic beta-lactamase resistance

Spectrum: Streptococcus, enterococcus, staphylococcus (MSSA)

Common indications: Cellulitis, MSSA infections of bone, joint, blood, lungs, prosthetic devices, heart valve, etc.

Question 6

Oxacillin, nafcillin side effects

Answer 6

Elevated LFTs, allergic interstitial nephritis (elevated Scr, urinary eosinophils, fever, peripheral eosinophilia), neutropenia (dose/duration related)

Question 7

Beta-lactam & beta-lactamase inhibitor combinations

Answer 7

Amoxicillin/clavulanate, Ampicillin/sulbactam, Piperacillin/tazobactam

Spectrum:
ALL: Streptococcus, staphylococcus, enterococcus, E.coli, klebsiella, bacteroides, peptostreptococcus

Zosyn: pseudomonas, enterobacter, citrobacter, serratia
Ampicillin-sulbactam: some acinetobacter

Question 8

Amoxicillin-clavulanate

Answer 8

Chronic sinus infection, animal bites, outpatient mild pna, uncomplicated wound infections, otitis media

Question 9

Ampicillin-sulbactam

Answer 9

Uncomplicated intra-abdominal infections, serious animal bite infections, wound infections

Question 10

Zosyn

Answer 10

Drug of choice for most moderate to severe hospital-acquired infections