8. Penicillins

Question 1

natural Penicillins

Answer 1

Penicillin G

penicillin V (oral)
(blue)
——————————————————————————–MOA (green)
-Beta Lactam Ring interferes with transpeptidation reaction of bacterial cell wall synthesis

-pBP forms peptidoglycan cross links, penicillin’s will halt peptidoglycan synthesis in the cell walls: bactericidal

Delivery

• penicillin V is acid stable and only used in minor infections due to poor bioavailability (oral)
• administered IV (pen G)

Used to Treat

-against gram (+) organisms (Staph and Strep)

-Oral Penicillin V treats streptococcal pharyngitis
(“Red bandanna”)

• Penicillin G or V treats rheumatic fever
• Strep Viridians endocarditis

-GBS prophylaxis

• Actinomyces Israeli
• Clostridium Perfringens causing gangrene
• pastuerella pen g
• benzathine pen g treats syphilis (spirochete)
• penicillin G - treats Neisseria meningitides

Resistance

Beta Lactamases are immune to penicillin
(“Beta Trooper shooting down a ship”)

-beta lactamases expressed by plasmid genes (“Circular shape”)

Adverse Reactions

Type 1 IgE mediated hypersensitivity reaction
(“Astronaut shutting eyes w/ IgE missiles on ship”)

-drug-induced autoimmune hemolytic anemia
(+ direct coombs test) (“Exploding asteroids w/ IgG”)

-drug induced interstitial nephritis
(“Kidney shaped nebula”)

Question 2

anti staph penicillin

Answer 2

Nafcillin
Oxacillin
Dicloxacillin

• bulky R-groups prevent beta-lactamase binding
• Narrow spectrum, only activity against staphylococci
• empiric treatment for skin and soft tissue infections (folliculitis, abscesses)

Tricuspid pyramids: treatment for staph endocarditis

Fish bones: treatment for Staph osteomyelitis

Question 3

broad spectrum penicillins

+beta lactamase inhibitors

Answer 3

• *Amoxicillin**
• amoxicillin – oral bioavailability

amoxicillin and ampicillin to treat strep throat

• amoxicillin treats otitis media and sinusitis caused by strep pneumoniae, Haemophilus influenza, moraxella catarrhalis
• amoxicillin and ampicillin treat pneumonia caused by strep pneumoniae, H. influenza

H Wing ship: activity against Haemiphilus influenza

-amoxicillin is part of the triple therapy (with clarithromycin and a PPI) for helicobacter pylori infection

• amoxicillin treats Lyme Disease caused by Borrelia burgdorferi
• amoxicillin prophylaxis against encapsulated bacteria (s. pneumo, H. Flu) in asplenic patients
• Amoxicillin prophylaxis before dental procedures in patients at high risk for endocarditis

Ampicillin
–IV administration

• ampicillin treats anaerobic infections (enterococcus)
• Gram Positive enterococcus
• ampicillin resistant strains of Enterococcus due to beta-lactamase production
• ampicillin treats meningitis caused by Listeria monocytogenes
• activity against gastrointestinal and urinary tract gram (-) rods

-sensitive to beta-lactamases
(typically used with clavulanate)

Piperacillin/Ticarcillin

• Paired with beta lactamase inhibitors to prevent cleavage of beta lactamases
• piperacillin and ticarcillin treat anaerobic infections,
• active against pseudomonas

**Beta lactamase inhibitors

Sulbactam
Tazobactam
Calvulanate**