Antimicrobials, Anticancer, Antiviral Flashcards
What are the side effects of erythromycin?
allergic cholestatic hepatitis,
thrombophlebitis,
inhibits hepatic cytochrome P-450–mediated metabolism of warfarin, phenytoin,
What are the groups of cell wall synthesis inhibitors? always bactericidal
these are the lactam antibiotics
penicillins, cephalosporins, imipenem/meropenem, aztreonam,
not a lactam:
vancomycin
What are the groups of bacterial protein synthesis inhibitors? bacteriostatic
aminoglycosides (BC-not BS)
tetracyclines, chloramphenicol, macrolides, streptogramins, linezolid, clindamycin
What are the groups that inhibit nucleic acid synthesis? BC
(flouro)quinolones, rifampin
What are the groups that inhibit folic acid synthesis? BC
sulfonamides, trimethoprim, pyrimethamine
Which cell wall synthesis inhibitor is not a lactam?
vancomycin
What is a lactam?
Square that is very unstable, makes the bonds very tense and likely to get ruptured;
the weakest bond in the structure is between the N-C , this is the site of resistance of B-lactamases produced by bacterias-cleave the ring!
What does the sulfur bond indicate in an antibiotic?
more lipid solubility and more prone to hypersensitivity reactions
How to all lactams work?
- Bind PBP (allow crosslinking of bacterial cell wall- transpeptidation)
- Inhibition of transpeptidation
- Prevent crosslinking of the bacterial cell wall
What is the primary resistance to lactams?
- Penicillinases
- Change of PBP structure (MRSA mechanism)
- Change of porins in the gram -ve bacterias (call wall made of peptidoglycan, periplasmic space which require porins to exchange foods between the outside and the inside) ex; Pseudomonas can change porin structure
What are the four groups of penicillins?
- Narrow spectrum: Penicillin G, Penicillin V (syphilis)
- Penicillinase resistant: methicillin, nafcillin, oxacillin, dicloxacillin ( only work against Staph. Aureus) –>MRSA
B lactamse sensitive, changed solubility to allow entrance to porin channels:
- Extended spectrum: amplicillin, amoxicillin ( Gram + rod and cocci; Strep, Listeria) (Gram -; E.coli, H.pylori, H,influenzae)
- Anti pseudomonal: carbenicillin, ticarcillin, piperacillin, azlocillin
What is the actual enzyme that separates Pseudomonas from others?
Oxidase +; green coloured sputum and green colour of skin in a burn patient; inhibits euk elongation factor 2 -> blocks translocation
What are the B-lactamase inhibitors?
- clavulanic acid
- sulbactam
- tazobactam
What is the trade name of amoxicillin + clavulanic acid?
Augmentin
Assuming that all antibiotics go through renal metabolism, what are the exceptions that do not?
Nafcillin and oxacillin are more lipid soluable and need lipid metabolism largely in the bile; they don’t require dosage adjustment in renally impaired
What is the side effects of penicillins?
- hypersensitivity - all types of HS
- diarrhea-the longer you take it, the more GI distress due to killing endogenous flora; ampicillin is the worst
worry about superinfection with C.diff - Jarisch-Herxheimer reaction- only see with penicillin; occurs in treatment of syphilis; if you use cell wall synthesis inhibitor and you break the structures, antigenic proteins are released into the blood- triggers immune response of fever, joint pain, swelling
I knew it ! It was syphilis!
if patient is allergic to one penicillin, avoid all penicillins and use macrolides
Penicillin cross allergenicity with other classes of cell wall inhibitors?
Patient may have a 5-10% increased chance of having an allergy to cephalosporins if they have an allergy to penicillins
What are the mechanisms of action of cephalosporins?
Identical to penicillins -3
Modes of resistance- 3
What are the first generation cephalosporins?
Anything with a “ph”
cefazolin, cefadroxil, cephalexin
What is the contrast of cephalosporins to penicillins?
- Penicillins work mainly on gram +, whereas cephalosporins work on both gram + and some gram -
- Long duration of action than penicillins
cefazolin: prophylaxis during surgery to prevent infections
What are the second generation cephalosporins?
- Better gram - coverage
- Cefuroxime can cross the BBB: meningitis
- Cefotitam
What are the third generation cephalosporns?
ceftriaxone, cefdinir, cefixime, cefotaxime, cefibuten
- empirical management of sepsis in the hospital
- empirical management of meningitis
Which bacteria do not respond to 3rd generation cephalosporins? LAME
L-Listeria (responds to penicllin, amoxicillin)
A-Atypicals (faulty cell wall and love to live intracellularily); mycoplasma and chalmydia it is better to use protein synthesis inhibitors
M-MRSA (use vancomycin)
E- enterococci (use amoxicllin or ampicillin)
What is the 4th gen cephalosporin?
B lactamase resistant
cefepime