Chapter 7 anti-infective agents - penicillins

Question 1

Penicillin G
Procaine Pen G
Benzathine Pen G
Penicillin V

narrow spectrum, penicilllinase-sensitive

Answer 1

• b-lactams (part of penicillin drug) bind to penicillin binding proteins part of wall (cross linkage)
• inhibiting cross linking of bacterial cell wall components

spectrum
* gram positive cocci
* neisseria (gram -)
* most mouth anaerobes
not effective for gram negative aerobes or b-lactamase producing organisms
* drug of choice for nonresistance staph, strep + b. anthracis (gram +), c. perfringens (gram +), listeria (gram +), c. tentani (anaerobe), syphillis (gram neg - t. pallidum?), n. meningitidis (gram neg)

probenicid inc half life of this drug
* distributes to eyes, joints and brain if meninges inflamed

effects
* anaphylaxis or hemolysis (hypersensitivity rxn)
* neurologic toxicity - sz d/t inhibition of GABA neurotransmission (b-lactam structurally similar to GABA)
* neutropenia
* nephrotoxicity

Question 2

nafcillin
oxacillin
dicloxacillin

group II narrow spectrum, penicillinase-resistant

Answer 2

• bulky side group protects b-lactam ring from penicillinases
• hydrophobic side disrupts these drug’s ability to penetrate gram neg bacteria via hydrophylic porins (Porins allow the diffusion of fairly small hydrophilic (and occasionally hydrophobic) molecules.)

spectrum
* gram positive cocci (including b-lactamase producers)
* some some streptococci
* not effect against gram neg aerobes
* drug of choice for penicillinase-producing staphylococcus

nafcillin - IV preferred d/t absorption reasons; high concen of bile during excretion

effects
* anaphylaxis, hemolysis (hypersens) + seizures d/t inihbition of GABA (similar b-lactam structure to GABA) + neutropenia/nephrotoxicity
* nafcillin — severe thrombophebitis + liver toxicity (inc LFT)
* oxacillin + dicloxacillin —- coagulopathy (blood’s ability to coagulate (form clots) is impaired) + interstitial nephritis (a kidney disorder in which the spaces between the kidney tubules become swollen (inflamed). This can cause problems with the way your kidneys work)

Question 3

ampicillin
amoxicillin (amoxil)
amoxicillin and clavulanate (augmentin)

group III broad spectrum, aminopenicillins

Answer 3

• amino side group makes these agents hydrophilic enough to penetrate pores in gram neg organisms
• for amoxicillin and clavulanate – clavulanate inhibits penicillinases

spectrum
FOR ampicillin and amoxicillin
* some gram neg and gram positive organisms
* not effective against b-lactamase producing organisms

////
* FOR amoxicillin and clavulanate
* gram negative and gram positive + b lactamase-producing organisms

drug of choice
* ampicillin - listeria and enterococcus (gram + both)
* amoxicillin - otitis media, sinusitis (inflammation of sinus), pneumonia (+, -, myco)
* amoxicillin and clavulanate — moraxella catarrhalis (gram neg) and H influenza (gram neg)

ampicillin (IV/IM/PO)
PO for rest

effect
diarrhea

Question 4

ticarcillin
piperacillin

extended spectrum, anti-pseudomonas

Answer 4

• side chain makes it resistant to b-lactamase from gram-neg species especially pseudomonas

spectrum:
* gram negative infection (pseudomonas)
* aminopenicillin-resistant proteus infection (gram neg)
* less effective against gram + penicillinase producing organisms
* ALL FOR TICARCILLIN
* other hand, piperacillin — include first two points + gram pos w/ anaerobic organisms

drug of choice
ticarcillin — pseudomonas
piperacillin — enterobacteria (gram neg, enterobacter) and gram positive cocci

IV - ticarcillin
PO - piperacillin

effects
FOR piperacillin — diarrhea, neutropenia, hematolgic abnormalities

Question 5

piperacillin/tazobacam

extended spectrum, anti-pseudomonas penicillins

Answer 5

• extended spectrum penicillin combined with beta lactamase inhibitor
• gram negative infection (pseudomonas)
• aminopenicillin-resistant proteus infection (gram neg)
• PLUS piperacillin-resistant gram-neg
• and gram positive penicillinase producing organisms

IV