Antibiotic Drug Classes Flashcards
What are the four classifications of antimicrobial drugs based on mechanism of action?
- inhibit cell wall synthesis
- inhibit protein synthesis
- inhibit folic acid biosynthetic pathway
- inhibit DNA/RNA synthesis
Narrow spectrum penicillins
Oxacillin, Nafcillin
Broad spectrum penicillins
peperacillin
B-lactams mechanism of action is on
the bacterial cell wall
Which enzyme do B lactase work to inhibit
transpeptidase
By inhibiting transpeptidase, B-lactams prevent what in the structure of the cell wall synthesis?
Cross link of peptidoglycan molecules in bacterial cell wall to give cell wall strength
Which bacteria are more sensitive to B-lactams?
gram positive bacteria
B-lactamase inhibitors are added to some B-lactams to overcome ?
resistance by B-lactamase
Clavulanic acid is added to
amoxicillin
Tazobactam is added to
piperacillin
Which penicillin has greater activity against gram negative and why?
Amino penicillin because it makes the molecule hydrophilic to cross the LPS layer easier.
Imipenem is administered with cilastatin why?
To prevent renal metabolism of imipenem by inhibit of DHP (breaks down imipenem in the kidney) by cilastatin
The structural difference between penicillin and cephalosporin is what?
Cephalosporin is a 6 membered ring instead of 5
1st generation of cephalosporins are useful to treat?
skin infections (streptococcus or staphylococcus)
Which drug is commonly used for surgical prophylaxis? (cephalosporin)
Cefazolin
Most commonly prescribed cephalosporin for outpatient use?
Cephalexin (1st gener. oral drug)
Cephalosporins are better used to treat which type of bacterial infections?
Gram-negative
Which cephalosporin is used commonly in treatment of STDs?
Ceftriaxone
Which drug is the drug of choice for treating pediatric meningitis?
Ceftriaxone (3rd gen. IV)
Drug commonly used to treat pseudomonas infections?
Cefepime (3rd gener. IV)
Inhibition of cell wall by attaching to end of peptidoglycan precursor unit (short 4/5 aa sequence called d analyl-dalanine) to lay down in matrix
vancomycin
Vancomycin MOA is
Bacteriocidal in dividing organisms, can’t make cell wall, stops peptidoglycan synthesis
Vancomycin is only effective against which type of organisms?
gram positive organisms
Fosfomycin inhibits what?
first steps in synthesis of peptidoglycan
Aminoglycoside is a
Protein synthesis inhibitor
Aminoglycosides bind where?
to the 30S ribosomal subunit to cause proteins with incorrect amino acid sequences (low concentrations)
What is the effect of the membrane for aminoglycosides?
create fissures and pores in the outer cell membrane, leakage of intracellular contents and action against protein synthesis
Aminoglycosides are
bacteriocidal
Amino glycosides are particularly effective against what bacteria
gram negative bacteria
MOA for macrolides
binds to the 23S rRNA of the 50S subunit inhibiting peptide transferase
Macrolides are
bacteriostatic
Macrolide’s are phagocytosed by
macrophages to allow WBC to travel to sites of infection where drug is needed
Erythromycin and methylated nitrogen make
azithromycin (macrolide)
Lincosamides MOA
bind to the 23S rRNA molecule of 50S RSU, inhibits peptide transferase
Lincosamides are
bacteriostatic
Example of lincosamide
Clindamycin
Tetracyclines bind to what?
reversibly to the 16S subunit of the 30S RSU and inhibit translation, inhibits tRNA interaction
Tetracyclines are
bacteriostatic
Streptogramins bind to the
50S ribosomal subunit
Which drug will bind to the same subunit as the macrolides
Quinupristin (inhibits polypeptide elongation and early termination of protein synthesis)
Dalfopristin will do what to quinupristin
It will enhance the binding of the quinupristin at the target site
Mupirocin does what?
binds and inhibits the isoleucyl transfer RNA synthetase
Mupirocin acts against what type of bacteria and how?
bactericidal against gram-positive and select gram-negative, applied topically
Mupirocin is good against what bacteria?
Streptococcus pyogenes, methicillin-resistant strains of Staph aureus
Chloramphenicol binds where
50S subunit at peptidyltransferase site and inhibits transpeptidation reaction
Chloramphenicol binds near site of
clindamycin and macrolides
Fluoroquinolones inhibit what enzyme
DNA gyrase (Topo II) gram negative and Topo IV in gram positive
What does inhibition of DNA gyros cause/
prevents reattachment of DNA once cut –> accumulation of DNA segments, bacteriocidal
inhibition of Topo IV
interferes with separation of replicated chromosomal DNA into respective daughter cells during cell division –> halts cell division
Rifamycin binds what
bacterial RNA polymerase to inhibit RNA synthesis
Rifamycin is highly
lipophilic to allow it cross lipophilic membranes
Rifamycins can act on
biofilms!
Nitroimidazole-metronidazole is a
prodrug
Methonidazole on aerobic bacteria
oxygen terminal electron acceptor –> prodrug doesn’t convert to active form
Methonidazole on anaerobic bacteria
Drug is effective because produces toxins and free radicals that damage DNA
Daptomycin acts on the
cell wall structure in gram positive bacteria
Daptomycin lipopepetides
bind to bacterial membrane to cause depolarization of membrane potential, inhibit protein, DNA, RNA synthesis –> cell death –> bactericidal against gram positive bacteria
Pulmonary surfactant will bind to which drug to inhibit its actions?
daptomycin
Treatment of pseudomembranous colitis or C. Diff associated diarrhea
Fidaxomicin
Fidaxomicin
inhibits RNA synthesis by inhibiting bacterial RNA polymerase
Cotrimoxazole trimethoprim and sulfamethoxazole act how?
inhibit the incorporation of PABA into folic acid and reduction of dihydrofolate to tetrahydrofolate
the correct ratio of sulfamethoxazole and trimethoprim
20 parts sulfamethoxazole to 1 part trimethoprim
Trimethoprim and sulfamethoxazole are good for treatment of
UTI uncomplicated, chronic bronchitis, infection by pneumocystic jiroveci
