Antimicrobial MOA Flashcards
What is the MOA of Beta-Lactam antibiotics?
Inhibits cell wall synthesis
- Inhibits Transpeptidase
- Activate autolysins
Susceptibility to Beta-Lactams depends on what?
Makeup of outer membrane
Thickness of peptidoglycan
Resistance to Beta-Lactams can be achieved how?
- Production of Beta-Lactamase
- Development of Penicillin-binding proteins PBPs with decreased affinity for the drug
- Decreased permeability of cell membrane
- Active efflux pump
What is the MOA of Vancomycin?
Inhibits cell wall synthesis Inhibits Transglycosylase (also inhibits transpeptidase but inhibits transglycosylase first)
What is the MOA of Aminoglycosides?
IRREVERSIBLY binds 30S
Blocks the initiation complex
Aminoglycosides: Bactericidal or Bacteriostatic?
Concentration-dependent or Time-dependent?
Bactericidal
Concentration-dependent
What type of bacteria have natural resistance to Aminoglycosides?
Anaerobic bacteria
What is the MOA of Macrolides?
Inhibit protein synthesis
REVERSIBLE BINDING OF 50S- blocks translocation and transpeptidation
What is the MOA of Lincosamides?
Inhibit protein synthesis
REVERSIBLE BINDING OF 50S- blocks translocation and transpeptidation
Macrolides, Lincosamides: Bactericidal or Bacteriostatic?
Bacteriostatic
What is the MOA of Tetracyclines?
Inhibit protein synthesis
REVERSIBLE BINDING TO 30S- prevents access of aminoacyl-tRNA to acceptor site
What is the MOA of Glycylcyclines?
Inhibit protein synthesis
REVERSIBLE BINDING TO 30S- prevents access of aminoacyl-tRNA to acceptor site
What is the MOA of Chloramphenicol?
Inhibits protein synthesis
REVERSIBLE BINDING TO 50S- blocks transpeptidation
What is the MOA of the Quinupristin-Dalfopristin combo?
Quinupristin binds 50S- blocks translocation
Dalfopristin binds to 50S inducing conformational change that enhances binding of Quinupristin
Only one of them used= bacteriostatic
Both used in combo= bactericidal, long postantibiotic effect
What is the MOA of Linezolid?
Inhibits protein synthesis
BINDS 50S AT SPECIFIC SITE NEAR 30S- inhibits formation of initiation complex
Linezolid: Bactericidal or Bacteriostatic?
Bacteriostatic
What is the MOA of Sulfonamides?
Inhibits NA synthesis
BLOCKS DIHYDROPTEROATE SYNTHETASE
What is the main mechanism of resistance to Sulfonamides?
Increased production of PABA
Acquired resistance to Sulfonamides is now common to which organisms?
Neisseria, Strep, Staph, Shigella, E. coli
What is the MOA of Trimethoprim?
Inhibits NA synthesis
BLOCKS DIHYDROFOLATE REDUCTASE
What is the MOA of Fluoroquinolones?
Inhibits NA synthesis
BLOCKS TOPOISOMERASE II (DNA gyrase)- prevents relaxation of supercoiled DNA- prevalent mechanism in Gram(-)
BLOCKS TOPOISOMERASE IV- interferes with separation of chromosomes- prevalent mechanism in Gram(+)
Fluoroquinolones: Bactericidal or Bacteriostatic?
Concentration-dependent or Time-dependent?
Bactericidal
Concentration-dependent
+ post-antibiotic effect
What is the MOA of Metronidazole?
Prodrug that forms highly reactive nitro radical that DAMAGES DNA
Metronidazole is only effective against what two classes of organisms?
Anaerobic bacteria
Protozoa
name a broad and narrow acting penicillin
1) Penicillin G (narrow)
2) Ampicillin (broad)
Name a first, second, third, and fourth generation cephalosporin
1st) Cephalexin
2nd) cefuroxime
3rd) ceftriaxone
4th) cefepime
name one carbapenem
imipenem
name one monobactam
aztrenoam
name one beta-lactamase inhibitor
clavulanate
are beta-lactams bactericidal or bacteriostatic?
bactericidal
T or F: beta-lactams’ killing of bacteria does not increase with increasing concentrations above the MBC
(T)
beta-lactams’ = “time dependent” so killing of bacteria continues as long as serum concentrations are greater than the MBC
is it better to give a lower dose of gentamicin 3x/day or a higher dose 1x/day?
higher dose 1x/day. Aminoglycosides have better efficacy and lower toxicity when administered this way
resistance develops mainly among which 3 bacteria for fluoroquinolones?
Psuedomonas
S. Aureaus
Serratia
