Antibacterial Micro drugs Flashcards
(50 cards)
Penicillin
Bind PCB (transpeptidases) Block Transpeptidase cross linking of peptidoglycan in cell wall Activate autolytic enzymes
Mostly for gram positives
Tox: Hypersensitvity reactions, hemolytic anemia
Resistance: penicillinase in bacteria (Beta lactamase) - cleaves beta lactam ring
Amoxicilin, ampicillin
MOA: same as penicillin; wider spectrum
penicillin sensitive. Need clavulanic acid
Use: extended spectrum penicillin: H. influenza, H. pylori, E. Coli, Listeria, Proteus, Salmonella, Shigella
Toxicity: Hypersensitivity, rash, pseudomembranous colitis
MOR: Penicillinase (B lactamase)
Dicloxacillin, nafcillin, oxacillin
(penicillinase resistant penicillins)
MOA: same as penicillin; Narrow spectrum
Pen resistant due to bulky R group
Use: S aureus except MRSA
Tox: hypersensitivity reactions, interstitial nephritis
Piperacillin, ticarcillin (antipseudomonals)
Same as penicillin, extended spectrum
Use: Pseudomonas species and gram negative rods; penicillinase sensitive; use with Beta lactamase
Tox: Hypersensitivity reactions
Beta lactamase inhibitors
Clavulanic acid, Sulbactum, Tazobactum
Cephalosporins
Beta lactam drugs that inhibit cell wall synthesis but less susceptible to penicillinases; Bactericidal
Tox: Hypersensitivity reactions, autoimmune hemolytic anemia, disulfirum like reactions, vitamin K deficiency. increase nephrotoxicity of Aminoglycosides
MOR: structural change in PBP
Organisms not covered by Cephalosporins
LAME: Listeria, Atypicals(Chlamydia, Mycoplasma), MRSA, Enterococci
Cefazolin, cephalexin
Cefoxitin, cefuroxime
Ceftriaxone, cefotaxime , ceftazadime
Cefepime
Ceftaroline
1st generation - gram positive cocci
2nd gen: gram pos and H. flu, E coli, Neisseria, Proteus, Klebsiella
3rd gen: serious gram negative infxn resistant to other Beta lactams
Cefepime - 4th gen: against Pseudomonas
Ceftaroline - 5th gen with broad gram pos and neg and MRSA coverage
Ceftriaxone
Ceftazidime
3rd gen cephalosporin for Meningitis, gonorrhea, disseminated Lyme disease
Pseudomonas - Ceftazidime
Carbepenems
Imipenem, -penem
Imipenem: Broad spectrum B lactamase resistant
Need Cilastatin (inhibit renal dehydropeptidase I) to decrease inactivation of drug in renal tubules
Meropenem: stable to DHP1 in renal tubule, low risk of seizures
Use: Gram pos cocci, gram negative rods, and anaerobes
tox: GI distress, skin rash, CNS tox (seizures) at high plasma levels
Monobactum
Aztreonam
Prevents peptidoglycan cross linking by binding PBP3. Synergistic with Aminoglycosides
Use: gram negative rods only
Nontoxic
Vancomycin
Inhibit peptidoglycan synthesis by binding D-ala D-ala part of cell wall
Use: gram positive only; MRSA, S. epidermidis, Enterococcus, Clostridium difficile (for pseuodmembranous colitis)
MOR: modify D-ala D-ala
Vancomycin toxicity
Nephrotoxicity, Ototox, Thrombophlebilit, diffuse flushing (red man syndrome
Prevent red man syndrome with antihistamines
Aminoglycosides
Gentamicin, Neomycin, Tobramycin, Streptomycin
Irreversible inhibition of initiation complex by binding 30S -> misreading of mRNA. Blocks translocation
Needs O2 for uptake; ineffective for anaerobes
Use: gram neg rods; synergistic with B lactams
MOR: acetylation, phosphorylation or adenylation of drug
Aminoglycoside toxicity
nephrotoxicity, Neuromuscular blockade, ototoxicity (esp if used with loops), teratogen
Tetracyclines (bacteriostatic)
Tetracycline, Doxycycline
Bind 30S, inhibit aminoacyl tRNA binding
CI with milk (Ca) or antacids (Ca or Mg) or Iron, divalent ions inhibit drug absorption from gut
Use: Borrelia, M. pneumonia; Since intracellular accumulation: Rickettsia and Chlamydia
Tetracycline toxicity
Discoloration of teeth and inhibit bone growth in children, photosensitivity
CI in pregnancy
MOR: efflux or decreased uptake by plasmid encoded transport pumps
Chloramphenicol
Blocks peptidyltransferase at 50S
Use: Meningitis (H. influenza, Neisseria meningitis, Strep pneumo) and Rickettsia (RMSF)
Tox: Anaplastic anemia, gray baby syndrome in premature babies
Clindamycin
Blocks peptide transfer (translocation) at 50S
Use: Bacteroides, Clostridium - Anaerobics in aspiration pneumonia, lung abscesses, and oral infections; Group A Strep
Toxicity: Pseudomembranous Colitis
hint: treat anaerobic infections above the diaphragm v. metronidazole
Linezolid
Prevent initiation complex, binds 50S
Use: Gram positives: MRSA, VRE
Toxicity: Bone marrow suppression (thrombocytopenia), peripheral neuropathy, serotonin syndrome
CI in patients taking SSRIs.
Macrolides
Azithromycin, Clarithromycin, Erythromycin
blocks 23S rRNA of 50S
Tx: Atypical pneumonia (Mycoplasma, Chlamydia, Legionella), STIs (Chlamydia), gram pos cocci, B. pertussis
Toxicity: Motility issues, Arrhythmia - prolonged QT, Cholestatic hepatitis, Rash, Eosinophilia
Increases Theophylline levels, oral anticoagulant levels
Clarithromycin and Erythromycin inhibit cyt P450
MOR: methylate 23S rRNA
Trimethoprim
Inhibits bacterial DHF reductase
Use: Combo wth Sulfonamides for UTIs, Shigella, Salmonella, PCP
Tox: Megaloblastic anemia, leukopenia, granulocytopenia. Tx with supplemental folic acid
Sulfonamides
Sulfamethoxazole, sulfadiazine
Inhibit folate synthsis. PABA antimetabolite inhibit Dihydropteroate synthase.
Close related drug: Dapsone - lepromatous leprosy - inhibits folate synthesis
Sulfonamide tx
Gram pos, negatives, Nocardia, Chlamydia. Triple Sulfa or SMX for simple UTI
Tox: Hemolysis if G6PD deficient, nephrotox (tubulointerstitial nephritis), photosensitivity, kernicterus in infants, displace drugs (warfarin) from albumin
MOR: Altered enzyme (bacterial DHP syntase), or increased PABA
