Antibiotic Overview Flashcards
Drugs that affect cell wall synthesis (3)
vancomycin
cephalosporins
carbapeneins
What is different in the cell was of bacteria that permits targeted therapy?
Well for one they HAVE a cell wall
Also - proteoglycan composition (fungi don’t have this, neither do mycoplasma, so keep that in mind)
Drugs that affect bacterial cell membrane
Polymyxins
daptomycin
What composition of cell wall allows eukaryote vs fungi distinction?
Ergosterol is found in fungi while cholesterol is found in humans
Drugs that inhibit 50S ribosomal subunit in bacteria
Erythromycin (macrolides)
Clindamycin
Drugs that inhibit 30S ribosomal subunit
tetracycline
streptomycin
tobramycin (aminoglycoside)
amikacin
Drugs that inhibit tRNA in bacteria
mupirocin
linezolid
Drugs that inhibit DNA gyrase
quinolones
Drugs that inhibit RNA-directed RNA polymerase
rifampin
Drugs that inhibit DNA replication in bacteria
metronidazole
nitrofuratonin
Drugs that inhibit folic acid metabolism/synthesis
trimethoprim
sulfonamide
Why is folic acid inhibition drugs used in bacteria and not eukaryotes?
Bacteria MUST synthesize folate while eukaryotes like us can just obtain it through diet
What are the three modes of drug resistance?
- ) Natural (intrinsic) resistance
- ) Escape
- ) Acquired Resistance (subtypes: chromosomal resistance and plasmid mediated resistance)
Resistance via altered binding site - penicillin binding proteins
Occurs in MRSA, pneumoniae, enterococci (gram + cocci)
Resistance to beta lactam antibiotics (penicillins, cephalosporins, carbapenems)
Resistance via altered binding site - DNA gyrase
Occurs in S. aureus, Pseudomonas
Resistance to flouroquinolones
Resistance via altered binding site - peptidoglycan sidechain
Occurs in enterococci (VRC) and staph (VRSA)
Resistance to vancomycin
Resistance via enzymatic degradation - beta-lactamase
Occurs in s. auerus, p. aeruginosa, enterococci
Resistance to beta lactams (penicillins, cephalosporins, carbapenems)
Resistance via altered binding site - 50S ribosome methylation
Occurs in strep, staph and enterococci (gram + cocci)
Resistance to erythromycin, clindamycin
Resistance via enzymatic degradation - acetyl-phospho-adenylyl
Occurs in enterococci
Resistance to aminoglycosides
Resistance via enzymatic degradation - acetyltransferases
Occurs in staph, strep, neisserria
Resistance to chloromphenicol.
Resistance via bypass pathway - overproduction of PABA/thymidine nucleotides
Occurs in strep
Resistance to sulfanomides
Resistance via decreased entry
p. auruginosa - to beta lactams
pseudomonas - to flouroquinolones
e. coli + pseudomonas - to aminoglycosides
Resistance due to efflux pump
Occurs in step, staph and entero
To tetracyclines, macrolides
Occurs ALSO in pseudomonas
To flouroquinolones
What are the features of “bactericidal” drugs
Inhibit cell wall synthesis
Disrupt cell membrane fxn
Interference w/ DNA fxn or synthesis
Preferred for severe infections, quick and irreversible, compensate for pts w/ impaired host defense and required for treatment of infections located in immune sanctuaries (such as the CNS/endocarditis)
What are the features of “bacteriostatic” drugs
Inhibition of protein synthesis
Inhibition of intermediary metabolic pathways
What is the IMPORTANT exception of protein synthesis inhibition drugs that ISNT bacteriostatic?
aminoglycosides are BACTERIOCIDAL lol
What are some examples of beneficial selective distribution?
Clindamysin in bone (osteomyelitis)
Macrolides in pulm. cells (URIs->pneumonia)
Tetracyclines in gingival crevicular fluid and sebum (periodontis + acne)
Nitrofurantoin is quick urine excretion (UTIs!)
What are some examples of TOXIC selective distribution?
Aminoglycosides in inner ear and renal brush boder (ototoxicity + nephrotoxicity)
Tetracyclines bind Ca2+ in developing bone and teeth (abnormal bone growth and tooth discoloration!)
What is renal dosing
Select dose or frequency dependent of pt’s renal fxn. Monitored by serum creatinine (SCr) and estimation of creatinine clearence (CrCl)
Concentration-dependent killing
antibiotics that kill faster in doses that result in high initial Cp levels
SUCH AS! flouroquinolones, aminoglycosides!
Time dependent killing
kill best when Cp is above MIC for longer durations
SUCH AS! beta lactams, vancomycin, macrolides
Post-antibiotic effect
antibiotics that continue action ater Cp < MIC. Less frequent dosing.
SUCH AS! AGs, FQs, macrolides, beta lactrams (gram + > gram - )
