Pharm - Inhibitors Of Cell-Wall Synthesis Flashcards
What is the weakest bond in the lactam and what is special about it?
The bond between the nitrogen and the carbonyl group, which is the working site of B-lactamases!
Which Cell-Wall synthesis inhibitor is not a lactam?
Vancomycin
All lactams have 3 mechanisms of action..
1 Bind PBPs
2 Inhibit transpeptidation
3 Inhibit crosslinking
All lactams can be disabled my 3 mechanisms of resistance..
1 Penicillinases
2 Structural change in PBPs (MRSA) - use vancomycin!
3 Change in porin structure
On what spirochete is the the narrow spectrum Penicillin G and Penicillin V effective?
Treponema pallidum which causes syphilis.
Two broadspectrum, betalactamase sensitive penicillins?
Amoxicillin and ampicillin are used against:
1 gram + cocci(not staph)
2 gram - E. coli, H. influenzae, H. pylori
3 Borrelia
Clavulanic acid, sulbactam, tazobactam are …………
Clavulanic acid, sulbactam, tazobactam are beta-lactamase inhibitors
Two penicillins that are eliminated largely in bile?
Nafcillin and oxacillin are more lipid soluble and are therefore excreted primarily in bile.
Two penicillins where you will not have to adjust the dose in people with decreased renal function?
Nafcillin and Oxacillin - excreted in bile.
What is Jarisch - Herxhermer reaction?
Treatment of syphilis with antibiotics that destroys the Treponema and releases it into the blood stream - causing systemic infection.
Cephalosporin mechanism of action?
Like penicillins
Two first generation cephalosporins? Area of use?
Cefazolin and cephalexin. Used in surgical prophylaxis because of their long half-life that can protect against entry of bacteria from skin.
Second generation cephalosporin: first cephalosporin to cross the BBB?
Cefuroxime. Used in meningitis.
Cephalosporins used in empirical management of sepsis and meningitis?
Third generation cephalosporins: esp. ceftriaxone.
Third generation cephalosporin do not work against?
LAME
Listeria, Atypicals, MRSA & Enterococci
To treat MRSA we use….
Vancomycin
Two cephalosporins that are eliminated primarily through bile?
Cefoperazone and ceftriaxone.
What to use in case of allergies to lactams?
macrolides or aztreonam(only gram neg rods - Pseudomonas)
Most potent lactams?
Imipenem and meropenem
What is the reason for the high potency of imipenem and meropenem?
Resistant to beta - lactamases.
imipenem must be coadministered with ……….
cilastatin.
What i Cilastatin?
A renal dehydropeptidase inhibitor.
Aztreonam mechanism of action?
Same as cephalosporins and penicillins.
We use aztreonam to treat against ………
gram negative rod ONLY
Drug that have no cross - allergenicity with penicillins and cephalosporins?
Aztreonam - working against gram negative rods.
Vancomyocin mechanism of action?
binding at D-ala-D-ala Muramyl pentapeptide that interferes with transpeptidatioin(elongation of peptidoglycan cell wall)
Enterococci mechanism of resistance against vancomycin?
changing the terminal D-ala with a D-lactate, thereby removing the binding-target used by vancomycin.
VRE and VRSA are?
Vancomycin Resistant Enterococcus & Vancomycin Resistant Staphylococcus Aureus.
Two drugs used against VRE and VRSA?
Linezolid and Streptogranins
Describe host determinants for choice of drug?
- history of drug reactions
- site of infection
- renal status
- hepatic status
- immune status
- pregnancy/lactation
- metabolic abnormalities
Group of bacteria that are particularly suceptible to penicillins?
gram positives
Common beta-lactamase producing organisms include..?
S. aureus, E. coli, Salmonella, Pseudomonas, N. gonnhore, Bacillus, Proteus, Bacteroides spp.
nafcillin, oxacillin and clidoxacillin primary target?
S. aureus. NOT MRSA
Name two anti-pseudomonal ab and their target organisms?
Ticarcillin/piperacillin kills pseudomonas, E. coli, Salmonella, Proteus, Enterobacter and Klebsiella.
Amoxicillin + clavulanic acid =
Augmentin
Clavulanic acid moa?
irreversible inhibitor of Beta-lactamases
Hypersensitivity reactions are seen in how many patients?
10% is the answer to this question. 10 % is also the answer to how much I want to stay in the czytelnia at the present moment.
Endocarditis prophylaxis is indicated in…….
- GI surgery
- Pulmonary surgery
- Major dental surgery
- Genitourinal surgery
What drugs are used in prophylactic treatment of endocarditis?
amoxicillin and ampicillin. IF hypersensitive to penicillins use clindamycin or azithromycin.
Describe the structure of sephalosporins
7-aminocephalosporic acid nucleus + B-lactam ring = BOOM!
Cephalosporin mechanism of action?
same as penicillins
General characteristics of 3rd and 4th generation cephalosporins?
- Parenteral administration
- B-lactamase resistant
- penetrates CNS
The newer cephalosporins are increasingly effective against what?
penicillinases/B-lactamases
Name a drug that decrease the secretion of cephalosporins
Probenecid
3rd generation cephalosporins are increasingly effective against……
gram negs mahn! I be talkin’ bout dem gram negs
Adverse effects cephalosporins?
- hypersensitivity
- disulfiram-like effects
- bleeding(vitamin K)
- nephrotoxicity
- Clostridium Difficile Colitis
Important hypersensitivity association w/ azetreonam =
no cross-reaction with penicillins and cephalosporins
3 most important carbapenems?
imirenem
meroprenem
azetreonam
Imipenem + cilastatin =
Primaxin
Cilastatin mechanism of action?
inhibitor of of renal dehydropeptidase I, which inactivates imipenem.
Carbapenem target organisms?
- penicillinase producing Staph aureus
- E .coli
- Pseudomonas
- H. influenzae
Vancomycin + aminoglycosides relationship =
- synergistic effect
- adverse effects include ototoxicity + nephrotoxicity
Vancomycin and CNS?
penetrates only during inflammation
Vancomycin and hypersensitivity?
- slow IV infusion - rapid infusion may precipitate anaphylaxis(red neck)
- no cross reaction with penicillins or cephalosporins
Bacitracin general picture?
- gram positives
- inhibit reuse and synthesis on N-AM
- Only topical administration
Cycloserine general picture?
- inhibit alanine racemase
- mycobacteria and gram negatives
Skin lesions with large number of gram positive cocci. Administer?
Nafcillin - Nafcillin is resistant to penicillinases and is effective against most S. aureus and common streptococci
