Cell wall Active Agents Flashcards
Are cell wall synthesis inhibitors more effective on gram positive or gram negative? are they bactericidal or static? do they penetrate BBB well? oral administration? hepatic clearance?
- Gram+
- Bactericidal
- Poor penetration
- Oral
- No, renal clearance
Is bacitracin only for topical application? why or why not?
Yes- poorly absorbed and potential for sever nephrotoxicity
What drug is rapidly bactericidal for dividing bacteria by binding D-ala-Dala terminus of pentapeptide? what is its structure? how do we administer? spectrum?
- vancomycin
- glycopeptide [teicoplanin and dalbavancin]
- IV administered, poor absorption orally but great distribution
- narrow, gram + most MRSA
What are the 2 mechanisms of vancomycin resistance?
– VRE: Enterococci vanA, vanB or vanC genes;
bacteria make different cell wall subunits with
reduced binding to vancomycin
– VRSA: S. aureus overexpress D-ala – D-ala
(normal substrate = competitor, binds up drug)
What is vancomycin synergistic with?
aminoglycosides
What are the 4 major classes of B lactam antibiotics?
penicillins
cephalosporins
carbapenems
monobactams
Are beta lactam antibiotics bactericidal? what does this mean?
Yes- must be dividing
What gives beta lactam antibiotics their pharmacological properties?
R amino groups
Beta lactams have a wide distribution except where?
CNS
Beta lactams are renal excreted and not metabolized…what are the 2 exceptions?
nafcillin and imipenem
Do beta lactams work on spirochetes-
yes…t. pallidum
Besides production of beta lactamases what are 3 other methods of resistance to beta lactam antibiotics?
- alter target PBPs
- alter outermembrane proteins
3, increase efflux pump activity (porins)
What type of allergic reaction amongst beta lactam antibiotics causes rash? is it common?
- delayed
2. 80-90% of all allergic reactions
Is pen G or PEn V acid labile? orally administered?
- Pen G
2. Pen V- absorption is 65% vs. 30 for penG
What does procaine and benzathine do to Pen G IM?
water-insoluble, slow release into bloodstream
What is steven-johnson syndrome?
Stevens-Johnson syndrome is a rare, serious disorder of your skin and mucous membranes. It’s usually a reaction to a medication or an infection. Often, Stevens-Johnson syndrome begins with flu-like symptoms, followed by a painful red or purplish rash that spreads and blisters. Then the top layer of the affected skin dies and sheds.
What 4 drugs are in the penicillinase resistant category? are they acid stable?
methicillin
oxacillin
cloxacillin
nafcillin
Yes acid stable
What penicillinase resistant antimicrobial sometimes causes interstitial nephritis? hepatitis?
methicillin
oxacillin
Can Aminopenicillins, carboxypenicillins and
ureidopenicillins be destroyed by beta lactamases? amino penicillin examples? which one is not effected by food intake?
- Yes!!!
- [ampicillin, amoxicillin]
- amoxicillin
[used for E.Coli, H.influenzae, Salmonella, Shigella]
What drug is used for prophylaxis against bacterial endocarditis?
amoxicillin
How are carboxypenicillins administered? ureidopenicillin?
parenteral for both
What are ureidopenicillins used for? often in combo with what?
- Reserved for serious systemic infections caused
by Klebsiella or Pseudomonas infections - aminoglycoside
What are the 3 beta lactamase inhibitors?
- clavulanic acid, sulbactam, tazobactam
What are the most widely used hospital prescribed antibiotics
cephalosporins
Are cephalosporins used topically
No- orally, IV or IM
How is bacterial resistance brought about with cephalosporins?
- induce Amp C (cephalosporinase)
2. Low affinity PBPs
What cephalosporin generation is Anti-pseudomonal High resistance to -lactamases; useful for treating
Enterobacter and penicillin-resistant streptococci?
4th cefepime
What cephalosporin generation is Broadest spectrum against gram+ cocci (surgical
prophylaxis); effective against gram- bacilli
1st cefazolin
What cephalosporin generation is Only group with significant activity against anaerobes?
2nd cefuroxime
What cephalosporin generation is Anti-pseudomonal and -pneumococcal; serious graminfections
such as meningitis, pneumonia, gonorrhea
– Most widely used treatment in children / infants with
moderate to severe infections
3rd Cefotaxime
Do imipenem have beta lactam ring? can they penetrate gram-? narrowest activity of all beta lactam drugs?
- Yes, and bind more efficiently.
- yes
- broadest (not for MRSA or VRE)
Do carbapenems antagonize tidal effects of pens and cephs?
yes- because they induce beta lactamases that inactivate pens and cephs
How are carbapenems administered? metabolized and inactivated? what are they administered with?
- parenteral
- Yes imipenem is renal
- cilastatin
Can monobactams penetrate BBB?
yes when inflamed
What are monbactams limited to to treat?
gram - areobes including pseudomonas.
How is daptomycin administered? eliminated?
- IV
2. Renal elimination
What does daptomycin treat that makes it awesome?
VREF and MRSA!!!
