antibiotics 1 Flashcards
provides structural integrity of the cell wall
Peptidoglycan (PG) layer
found in the periplasmic space function to crosslink the peptidoglycan chains
Transpeptidase Enzymes
what are the 4 bacterial targets
cell membrane
cell wall
NA synthesis
protein synthesis
4 abx that affect beta lactams
- penicillins
- cephalosporins
- carbapenems
- monobactams
PCN-G
natural PCN
PCN-V
natural PCN
methicillin
anti-staphylococcal PCN
dicloxacillin
anti-staphylococcal PCN
nafcillin
anti-staphylococcal PCN
oxacillin
anti-staphylococcal PCN
amoxicillin
aminopenicillin
ampicillin
aminopenicillin
piperacillin/tazobactam
Extended-spectrum (PCN’s + BLI combo)
amoxicillin/clavulanate
Extended-spectrum (PCN’s + BLI combo)
ampicillin/sulbactam
Extended-spectrum (PCN’s + BLI combo)
aztreonam
monobactam
imipenem
carbapenems
meropenem
carbapenems
ertapenem
carbapenems
doripenem
carbapenems
MOA of beta-lactam Abx
Inhibit Bacterial Cell Wall Synthesis
1. Drug binds to transpeptidase (aka Penicillin-Binding Proteins [PBP’s])
2. This inhibits bacterial peptidoglycan synthesis preventing bacterial replication (Bacteriostatic)
3. Binding to PBP activates bacterial autolytic enzymes that cause cell wall lysis (Bactericidal)
5 methods of resistance for beta-lactams
- Beta-Lactamase inactivates drug
- β-Lactamases are a large family of hydrolases that catalyze the hydrolysis of the amide bond in the β-lactam ring of penicillins and cephalosporins. - Increased number of beta-lactamases
- Decreased PBP binding affinity for drug - PCP mutation (“MRSA”)
- Diminished cell wall permeability with a loss of porins - (Gram -)
- Development of efflux pump
what must we do about abx resistances
- We MUST be careful in antibiotic selection and use
- We MUST educate patients on completion of antibiotic
spectrum of natural PCN
- g+
- Streptococcus pneumoniae
- some staphylococcus
- bacillus anthracis
- anaerobes (Clostridium perfringens) - g-
- Neisseria meningitides - spirochetes (Treponema pallidum)
natural PCN is first line treatment for ?
- Strep Throat
- Group A Beta-Hemolytic Streptococcus - Syphilis
- Treponema pallidum
cellulitis, meningitis
pros and cons of natural PCN
- Cons
1. Susceptible to hydrolysis by beta lactamase
2. Resistance increasing - Pros
1. Cheap
2. Relatively safe
susceptibility/indications to use antistaphylococcal PCN
- Susceptible to B-lactamase
- Not effective against MRSA infections - Only indicated in the treatment of skin and soft tissue staphylococcal infections**
- Staph aureus and Staph epidermidis
Susceptibility/Indications for aminopenicillins
Same as natural PCN, with better g- coverage
aminoPCN first line treatment
(Amoxicillin)
1. Otitis media
- Haemophilus influenzae
- Streptococcus pneumoniae
- Moraxella catarrhalis
2. Prophylaxis for endocarditis