Antibiotics Flashcards
antiseptic
kills and inhibits organisms on body
disinfectant
kills and inhibits organisms on inanimate objects
sterilization
all organisms killed
common antiseptics in surgery
iodophors (betadine) - good for GPCs, GNRs, and poor fungi Chlorhexidine gluconate (Hibiclens) - good for GPCs, GNRs, and fungi
Inhibitors of cell wall synthesis
PCNs, cephalosporins, carbapenems, monobactems, vancomycin
Inhibitors of 30s ribosome and protein synthesis
tetracycline, aminoglycosides (tobramycin, gentamicin), linezolid
Inhibitors of 50s ribosome and protein synthesis
erythromycin, clindamycin, chloramphenicol, synercid
Inhibitor of DNA helicase (gyrase)
quinolones
Inhibitor of RNA polymerase
rifampin
Metronidazole (flagyl)
produces oxygen radicals that breakup DNA
Sulfonamides
PABA analogue, inhibit purine synthesis
Trimethoprim
inhibits dihydrofolate reductase, inhibits purine synthesis
Bacteriostatic antibiotics
chloramphenicol, tetracycline, clindamycin, erythromycin (all have reversible ribosomal binding), bactrim
Aminoglycosides
have irreversible binding to ribosome and are considered bactericidal
PCN resistance
plasmids for beta-lactamase
Transfer of plasmids
most common method of antibiotic resistance
MRSA
resistance caused by mutation of cell wall binding protein
VRE
resistance develops from mutation in cell wall binding protein
Gentamicin resistance
resistance due to modifying enzymes leading to decrease in active transport
Vanc level
peak 20-40 ug/mL; trough 5-10 ug/mL
Gentamicin
peak 6-10 ug/mL; trough < 1 ug/mL
Peak too high
decrease amount of each dose
Trough too high
decrease frequency of doses (increase time interval between doses)
PCN
GPCs – strep, syphilis, beta-hemolytic strep, anthrax;
GPRs – Neisseria meningitides, clostridium perfringens; not effective against Staph or Enterococcus
Oxacillin / nafcillin
anti-staph PCNs (staph only)
Ampicllin / amoxicillin
same as PCN; GPCs – strep, syphilis, beta-hemolytic strep, anthrax; GPRs – Neisseria meningitides, clostridium perfringens; also picks up Enterococci
Unasyn (ampicllin / sulbactam) and Augmentin (amoxicillin / clavulanic acid)
broad spectrum, pick up GPCs (staph and strep), GNRs, +/- anaerobic coverage, effective for enterococci;
not effective for pseudomonas, acinetobacter, or serratia
Sulbactam and clavulanic acid are beta lactamase inhibitors
Ticarcillin / piperacillin
antipseudomonal PCNs; GNRs - enterics, Pseudomonas, Acinetobacter, Serratia
side effects: inhibits platelets, high salt load
Timentin (ticarcillin / clavulanic acid) and Zosyn (piperacillin / sulbactam)
broad spectrum, pick up GPCs (staph and strep), GNRs, anaerobes, enterococci, Pseudomonas, Acinetobacter, Serratia
side effects: inhibits platelets, high salt load
First generation cephalosporins (cefazolin, cephalexin)
GPCs - staph and strep
not effective for enterococcus; does not penetrate CNS; cefazolin (ancef) has longest half-life best for ppx
side effects: can produce positive Coombs test
Second generation cephalosporins (cefoxitin, cefotetan, cefuorxime)
GPCs, GNRs, +/- anerobic coverage, Pseudomonas, Acinetobacter, Serratia; lose some staph activity; not effective for enterococcus; effective only for community acquired GNRs; cefotetan has longest half life best for ppx; side effects: prolonged PT
Third generation cephalosporins (ceftriaxone, ceftazidime, cefepime, cefotaxime)
GNRs mostly, +/- anaerobic coverage, Pseudomonas, Acinetobacter, Serratia; not effective for enterococcus
side effectis: cholestatic jaundice and sludging in gallbladder (ceftriaxone)
Monobactam (aztreonam)
GNRs; picks up Pseudomonas, Acinetobacter, Serratia
Carbapenems (meropenem / imipenem)
broad spectrum, GPCs, GNRs, anaerobes
not effective for MEPP: MRSA, Enterococcus, Proteus, Pseudomonas
cilastatin - prevents renal hydrolysis of the drug and increases half-life
side effects: seizures
Bactrim
GNRs, +/- GPCs;
not effective for enterococcus, pseudomonas, acinetobacter and serratia
side effects: teratogenic, allergic rxns, renal damage, Stevens-Johnson syndrome (erythema multiforme), hemolysis in G6PD-deficient patients
Quinolones (cipro-, levo-, trovafloxacin)
GPCs, mostly GNRs, Pseudomonas, Acinetobacter, Serratia; not effective for enterococcus; 40% of MRSA sensitive; same efficacy PO and IV
Aminoglycosides (gentamicin, tobramycin, amikacin)
GNRs, good for Pseudomonas, Acinetobacter, Serratia; not effective for anaerobes (need O2),
resistance due to modifying enzymes leading to decreased active transport,
synergistic with ampicillin for enterococcus (facilitate aminoglycoside penetration)
side effects: reversible nephrotoxicity, irreversible ototoxicity
Erythromycin (macrolides)
GPCs; best for community acquired PNA and atypical PNA
side effects: nausea (PO), cholestasis (IV)
also bind motilin receptor and is prokinetic for bowel
Vancomycin (glycopeptides)
GPCs, enterococcus, c diff (PO), MRSA
binds cell wall proteins
resistance develops from change in cell wall-binding sites
side effects: HTN, Redman syndrome (histamine release), nephrotoxicity, ototoxicity
Synercid (streptogramin, quinupristin-dalfopristin)
GPCs; includes MRSA, VRE
Linezolid (oxazolidinones)
GPCs; includes MRSA, VRE
Tetracycline
GPCs, GNRs, syphilis
side effects: tooth discoloration in children
can interfere with beta-lactams
Clindamycin
anaerobes, some GPCs, good for aspiration PNA, can be used to treat C. perfringens
side effects: pseudomembranous colitis
Metronidazole
anaerobes
side effects: disulfiram-like reaction, peripheral neuropathy
Amphotericin
binds sterols in wall and alters membrane permeability
side effects: nephrotoxic, fever, decreased potassium, hypotension, anemia
fluconazole / ketoconazole
not all candida spp. are sensitive
prolonged broad spectrum antibiotics + fever
fluconazole
possible fungal sepsis
amphotericin
Isoniazid
anti-TB; inhibits mycolic acids
side effects: hepatotoxicity, B6 deficiency
Rifampin
anti-TB; inhibits RNA polymerase
side effects: hepatotoxicity, GI symptoms, high rate of resistance
Pyrazinamide
anti-TB
side effect: hepatotoxicity
Ethambutol
anti-TB
side effect: retrobulbar neuritis
Acyclovir
antiviral; inhibits DNA polymerase, usually used for HSV infections, can be used for EBV
Ganciclovir
antiviral; used for CMV infections
side effects: decreased bone marrow, CNS toxicity
Effective for enterococcus
vanc, timentin/zosyn, ampicillin/amoxicillin, or gentamicin with ampicillin
Effective for Pseudomonas, Acinetobacter, Serratia
ticarcillin/piperacillin, timentin/zosyn, third generation cephalosporins, aminoglycosides (gentamicin and tobramycin), meorpenem/imipenem (resistance can develop in Pseudomonas), or fluoroguinolones; double cover pseudomonas
Perioperative antibiotics
used to prevent incisional wound infections; need to be given within 2 hours before incision