microbiology

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Author:
mattnjaneal
ID:
224192
Filename:
microbiology
Updated:
2013-06-17 19:21:22
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chemotherapeutic agents
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Description:
chapter 12
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  1. antibiotics
    chemical substance produced by MO's in inature to inhibit or kill other MO's (competitor)
  2. synthetic drug
    semi-synthetic; can be a modified antibiotic
  3. spectrum of activity
    what types of MO's are targeted
  4. broad spectrum
    • effective against different types of MO's
    • ex: erythromycin workds against gram + and gram -
  5. narrow spectrum
    • effective against a few pathogens
    • penicillin G - gram + infections
  6. selective toxicity
    maximum effect against the microbes and little or not toxicity (harm to the host)
  7. types of adverse effects
    • allergic reactions - rash to anaphylaxsis
    • toxic effects - can effect kidneys, liver, CNS
    • suppress our natural flora, create imbalance
  8. mechanisms of drug resistance
    • DRO's drug resistant organism
    • * plasmids - can carry antibiotic resistance genes (R factors)
    • * contributing factors:  overuse, environmental, non-compliance
  9. mechanisms of action
    • inhibit cell wall synthesis
    • disrupt nucleic acid synthesis
    • inhibit protein synthesis
    • disrupt cell membranes
    • antimetabolites
  10. inhibit cell wall synthesis
    • disrupt peptidoglycan synthesis, prevent peptide bridge formation (NAM-NAM) or assembly
    • ex: penicillin family, cephalosporins, bacitracin, vancomycin
  11. disrupt nucleic acid synthesis
    • base analog
    • block synthesis by blocking enzymes
    • ex: quinolones, base analogs
  12. inhibit protein synthesis
    • bind to ribosome to prevent translation
    • prok. ribosomes differ from euk. ribosomes
    • ex: aminoglycosides, tetracycline, chloramphenicol, macrolides, synercid, oxazolidinone
  13. disrupt cell membranes
    • by interacting with phospholipids or sterols
    • ex: polymyxin B, "azoles"
  14. antimetabolites
    • mimics growth factor
    • competitive inhibition
    • ex: sulfonamides
  15. penicillin family
    • inhibit peptidoglycan synthesis by preventing Nam-Nam crosslinking, cell wall weakens and lyses
    • action:  Beta lactam ring must be intact
    • resistance - have Beta lactamase to break ring
    • spectrum - narrow, gram +
    • a) natural penicillin - penicillin G (Alexander Fleming 1929) penicillium notatum
    • b) semisynthetic penicillin - methicillin (MRSA), amoxicillin, ampicillin
  16. cephalosporins
    • same action as penicillin family
    • natural - cephalothin
    • semisynthetic - ceflacor & cephalexin
    • spectrum - gram + (a few gram -)
  17. bacitracin
    • produced by bacillus
    • toxic to your kidneys
    • use topical only
    • ex: neosporin
    • spectrum : gram +
  18. vancomycin
    • action: disrupt peptidoglycan
    • orally: only effective for GI infections
    • IV - systemic infections
    • Resistance: VRE - enterococcus; VRSA - staph aureus
  19. aminoglycosides
    • target the 30s subunit (smaller) of the prok. ribosome
    • The ribosome can't "read" mRNA
    • ex: kanamycin, streptomycin, gentamycin, neomycin, tobramycin
    • produced by streptomyces
    • broad spectrum
    • toxicity - kidneys and auditory nerve
    • important to check peak and troughs
  20. tetracycline
    • action: block tRNA from binding to 3s, blockelongation
    • spectrum - broad, gram +/-
    • ex: tetracycline - diarrhea, sensitivity to light (sunburn), complexes with calcium and discolors teeth and weaken bones
    • ex: doxycycline and trimocycline
  21. chloramphenicol
    • action: binds 50s subunit
    • toxicity: can cause aplastic anemia and neurological damage
    • treat: typhoid fever, salmonella typhi
  22. macrolides
    • action: bind 50s
    • spectrum: gram + and some gram -
    • ex: erythromycin, clarithromycin, azithromycin
  23. synercid
    • man made
    • blocks 50s
    • disrupts cell wall synthesis
  24. oxazolidinone
    • blocks protein synthesis
    • disrupts cell wall synthesis
  25. quinolones
    • action: inhibit topoisonmerases that relieve tension on unwinding DNA
    • spectrum: broad
    • ex: ciprofloxacin
  26. sulfonamides
    • prevents folic acid synthesis, mimics PABA
    • action: broad spectrum, UTI's
    • side effects: allergic reactions, anemia, jaundice, 3rd trimester of pregnancy can cause mental retardation
    • ex: bactrum, SXT
  27. polymyxin B
    • destroys cell membrane
    • use: topical; toxic to kidneys
    • spectrum: gram -, pseudomonas
  28. azoles
    • antifungals
    • action: interfere sterol synthesis
    • ergosterol: fungus only
    • ex: ketoconazole (topical, oral), fluconazole, clotrimazole, miconazole (topical, mucous membranes)

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