Beta Lactams Flashcards
What class do PCNs fall under?
Bactericidals, Cell Wall Synthesis Inhibitors, Beta Lactams
Beta Lactams inhibit what enzyme?
Transpeptidase or PCN Binding Proteint
What is the MOA of Beta Lactams, like PCNs?
Inhibits cell wall synthesis by inhibiting transpeptidase, causing lysis
Are Beta Lactams and PCNs time dependent or concentration dependent?
Time dependent -> can require frequent dosing to keep drug concentration therapeutic
What are the mechanisms of resistance to beta Lactams, like PCNs?
- Increase # of transpeptidase enzymes
- Change binding characteristics of those enzymes (ex. MRSA)
Why to PCNs have less ability to fight MRSA?
All MRSA have a methicillin resistant gene that encodes for a transpeptidase with low affinity to bind to antistaph PCNs
PCN provides good coverage for which bugs?
Gram +: strep pyogenes (GABHS), viridans strep, some S. Pneumoniae
Gram - aerobes: N.meningitis, pasteurella multocida
Anaerobes: Clostridium
SYPHILIS***
Are PCNs used for staph a?
No. Staph aureus produce penicillinases
What two drugs are combined for GBS coverage for pregnant culture+ women?
PCN and ampicillin
What are the indications for PCNs?
Erysipelas, pharyngitis (GABHS or Strep pyogenes), prevention of rheumatic HD, syphilis, chemo-diphtheria prophylaxis
Which PCN can you give IV and for what indication?
Aqueous PCN G, for neurosyphilis
Which PCN is long acting (LA) and for what indication?
Benzathine PCN G (Bicillin L-A), syphilis
Which PCN can you give orally?
PCN V Potassium, give on empty stomach
How are PCNs, and most beta Lactams, cleared?
Renally
Are beta Lactams, and PCNs, safe or unsafe for pregnancy?
Safe, catagory B
Why is probenecid added to PCNs?
Prolongs PCN serum levels
- blocks renal tubular secretion of PCN
- alternative to standard therapy for neurosyph, which requires high frequ of dosing (500mg q6h)
- SE: N/V
What are the SE of PCNs?
- Anaphylaxis (IgE, type 1)
- rash
- nausea
- seizure, usually if taking with other drugs that lower threshold
- hyperK with aqueous PCN G (caution with CKD)
- Jarisch-Herxheimer reaction (fever, muscle aches, HA, tachycardia) with 2’ syphilis and IM PCN G
Why don’t we give PCNs for Staph A?
Staph A produces penicillinase
- but we can give Penicillinase-Resistant PCNs
- (Dicloxacillin, Nafcillin, Oxacillin)
What are the indications for Penicillinase-Resistant Penicillins?
***Staph aureus, Staph epidermis
- no gram - , no MRSA/ORSA, no enterococcus
- Skin and soft tissue infections 2’ to MSSA, endocarditis 2’ MSSA
Which Penicillinase-REsistant PCN can be given orally and for what reason?
Dicloxacillin, and like the other PR PCNs, MSSA
-give on empty stomach, excreted bile, no renal dosage
What SE does Nafcillin cause?
Neutropenia and phlebitis
-excreted bile
What are the aminopenicillins and what do they cover?
Amoxicillin and ampicillin
-gram+: strep
-gr- coverage H influenza, E.coli, proteus, lis.
- PCN-resistant pneumococci
- enterococcus
-MSSA when combined with BLI like clavunalic acid and sulbactam
General uses for aminopenicillins
-otitis media, bacterial sinusitis, cystitis, salmonella (amoxicillin), shigella (ampicillin), H. pylori, endocarditis/dental prophylaxis
- GBS (PCNs and ampicillin)
- **Listeria (meningitis) -> ampicillin, for new borns and over 60y, and meningococcal meningitis
What are the side effects for ampicillin?
GI, diffuse rash if given with EBV (mono)
SE for amoxicillin?
Diffuse rash if given with EBV (mono)
Beta Lactams/Beta Lactamase Inhibitors extend coverage to which bugs?
Pseudomonas and enterobacter
TCP= Takes Care of Pseudomonas
How do Beta Lactam/Beta-Lactamase Inhibitors work?
They are added to abx to irreversibly bond to bacterial enzymes, inactive them, and allow abx to go on for the kill
What drugs are Beta-Lactam/Beta-Lactamase Inhibitors?
Avibactam
Clavulanic acid
Sulbactam
Tazobactam
Which BLI can you take orally, what does it not cover, and what are the SE?
Amoxicillin/CA, no pseudomonas, diarrhea
Which BLI is best for pseudomonas coverage?
Piperacillin/TZ
Which BLI drugs cover pseudomonas?
Ticarcillin/CA, Pip/TZ (best), Ceftazidime/AV (also ESBLs), Ceftolozane/TZ (also ESBLs)
