Beta Lactam Antibiotics Flashcards
Specifically, what enzyme do beta lactams block?
Block transpeptidase to prevent cell wall synthesis
3 mechanisms of bacterial resistance against beta lactam antibiotics
- Production of beta lactamases
- Alteration in structure of PBPs (like in MRSA) leading to lower binding affinity
- Alteration of outer membrane porins leading to decreased penetration
Natural Penicillins
Penicillin G
Benzathine penicillin G (IM, long acting)
Procaine penicillin G (IM)
Penicillin VK (oral)
Organisms susceptible to penicillin G or penicillin VK
Group streptococci Viridians streptococci Neisseria spp Clostridium spp Treponema pallidum
Pencillinase Resistant Penicillins
Nafcillin
Oxacillin
Methicillin
Dicloxacillin
What are penicillinase resistant penicillins used against?
MSSA
Aminopenicillins
Ampicillin (parenteral) and Amoxicillin (oral)
What are aminopenicillins developed for?
Increased activity against Gram negative aerobes
What are aminopenicillins good to use against?
Gram Negative Proteus mirabilis Some E coli Salmonella Shigella BL- H. influenzae
Gram Positive
Enterococcus spp.
Listeria monocytogenes (!!!)
Carboxypenicillins
Ticarcillin (parenteral)
What were carboxypenicillins developed for?
Further increased Gram Negative activity
What are carboxypenicillins good against?
Pseudomonas aeruginosa
Ureidopenicillins
Piperacillin (parenteral)
Ureidopenicillins developed for?
Improved Gram positive activity while maintaining the strong Gram negative activity of carboxypenicillins
Ureidopenicillins used against?
Pseudomonas aeruginosa
Enterobacter spp.
Serratia marcescens
Some Klebsiella spp.
Good activity against anaerobes