Penicillins Flashcards
Cell Wall Inhibitors I
What are the 4 types of β-lactam antibiotics?
- Penicillins
- Cephalosporins
- Monobactams
- Carbapenems
Structure of Penicillin
beta-lactam ring + thiazolidine ring
Penicillinase
A bacteria that specifically produces against penicillin’s β-lactam ring.
How do β-lactam abx kill bacteria?
- Attack on the cell wall
2. Dysregulation of autolysis
β-lactams inhibit a family of enzymes involved in final stage of cell wall synthesis called ________. These enzymes can be detected by the covalent binding of penicillin, _______ ______ _______
transpeptidation or cross linkage. Penicillin Binding Proteins (PBPs)
Penicillin Binding Proteins are on Penicillin: T/F
False! They are produced by the bacteria and contribute to resistance by alteration.
MRSA arises from PBP’s:T/F
True! Specifically PBP2A doesn’t have an affinity to Methicillin.
Autolysis normally digest _________ in a regulated manner.
Peptidoglycan
β-lactam abx lead to _______ of ______ resulting in cell wall digestion and lysis of bacterial cell.
dysregulation; autolysins
3 Major Mechanisms of β-Lactam Resistance by Bacteria
- Inactivation of abx by a bacterial enzyme called β-lactamase
- Alteration of target site (altering PBPs)
- Decreased penetration to target site (thick outer cell membrane)
Pharmacokinetics/dynamics of β-lactam abx
short half-life, excreted by kidneys, excellent tissue distribution
β-lactam abx have their rate of killing maximized at a low multiple of the MIC (time dependent killing)
β-lactam abx operate best at above or below their MIC?
Above, you accomplish effectiveness by lower, yet more frequent dosing
β-lactam allergic reactions: immediate (w/in an hour)
IgE mediated, erythema/pruritis, angioedema, urticaria/wheezing, and ANAPHYLAXIS AKA THE WORST
β-lactam allergic reactions: late (>72 hours)
More common than immediate rxn. Rash, immune mediated destruction of WBC’s, RBC’s, Platelets, and SERUM SICKNESS (fever, rash, arthritis, glomerulonephritis)
β-lactam adverse effects
Type 1 IgE mediated reactions, serum sickness (late), dermatologic, neurologic, diarrhea, hepatitis, renal, hematologic
5 Spectrum Levels of the Penicillins
- Narrow Spectrum
- Antistaphylococcal, Penicillinase-resistant, narrow spectrum
- Intermediate spectrum
- Intermediate spectrum + β-lactamase inhibitors
- Broad spectrum + β-lactamase inhibitors
1st Spectrum: Narrow Spectrum abx is?
Penicillin
1st Spectrum: Narrow Spectrum abx features
cheap, favorable therapeutic index, excellent tissue penetration.
1st Spectrum: Narrow Spectrum abx works on which kinds of bacteria? (4)
- Gram + cocci: GAS, GBS, Enterococcus
- Gram - diplococci: Neisseria meningitidis
- Spirochetes
- Oral anaerobes
1st Spectrum: Narrow Spectrum: You can treat staph aureus with penicillin? T/F
FALSE, you would NEVER because the resistance is so high in staph aureus. (also not in gonorrhea and strep pneumonia)
1st Spectrum: Narrow Spectrum: Penicillin is prescribed clinically for 3 things
- Pharyngitis (GAS)
- Syphilis
- Dental infection
2nd Spectrum: Antistaphylococcal, Penicillinase-resistant, narrow spectrum: Abx? (2)
Oxacillin (or Nafcillin)
Dicloxacillin = oral form
2nd Spectrum: Antistaphylococcal, Penicillinase-resistant, narrow spectrum: Oxacillin is mainly used against what bacteria?
Staphylococcus Aureus (that’s not MRSA). Some against streptococci
2nd Spectrum: Antistaphylococcal, Penicillinase-resistant, narrow spectrum: Oxacillin doesn’t have activity against what?
Enterococci, gram - aerobes,
