micro_drugs

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soren101
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80506
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micro_drugs
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2011-05-04 16:53:50
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micro drugs
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microbiology drugs
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  1. b-lactam
    functions as competitive inhibitor of transpeptidase activity

    G+ & G-

    pen derivatives:cephalosporins, monobactams, carbapenems, and lactamase inhibitors
  2. Cephalosporins
    competitive inhibition of transpeptidase activity

    hydrolysis of B-Lac ring

    G+ & G-

    1st GEN PRIMARILY G+ COCCI

    2nd ON PRIMARILY G- RODS

    new generation drugs better against res G-

    6-RING, PEN IS 5-RING
  3. Vancomycin
    • Binds to D-ala-D-ala portion of UDP-muramylpentapeptide after transfer out of
    • cytoplasm; inhibits both transglycosylation and
    • transpeptidation

    replacement of D-ala-D-ala with D-ala-D-lac (2)
  4. Quinolone
    binds to the a-subunit of DNA gyrase causing immediate cessation of DNA synthesis (3)
  5. Macrolide/Erythromycin
    PROT SYNTH

    REVERSIBLY BINDS TO 50S ribosomal subunit, blocking peptide bond formation (3)

    G+; CHLAMYDIA, MYCOPLASM, TREPONEMA, RICKETTIA

    RESP INFECTIONS

    ex ERYTHROMYCIN, AZITHROMYCIN, CLIRITHROMYCIN

    methylation of adenine residues in 23S ribo RNA (3)
  6. Chloramphenicol
    binding to 50S subunit of 70S ribosomes

    acetylation
  7. SULFONAMIDES - Trimethoprim
    TRI - competitive inhibition of dihydrofolate reductase

    SULFA - ANALOG OF PABA - COMP INH DIHYDROPTEROIC ACID SYNTHASE

    G+ & G-

    ALSO PNEUMO JIROVECII (P. CARNII)

    TRI RESISTANCE - PLASMID production of MODIFIED dihydrofolate reductase IN G+ & G- RODS(3).

    Sulfa RESISTANCE - plasmid production of modified dihydropteroic acid synthetase.

    Enterococcus RES- ability to utilize exogenous thymine & thymidine to escape inhibition of folate pathway, confering resistance
  8. Amphotericin B
    • competitive
    • inhibition of dihydrofolate reductase
  9. Rifampicin
    PROT SYNTH

    G+; TB

    forms complexes with the b-subunit of RNA polymerase, preventing transcription (3)

    Binds to DNA-dependent RNA polymerase of bacteria preventing initiation of DNA transcription

    G+, TB

    RESISTANCE -- CHROM MUTATIONS -- SINGLE AA CHANGES IN THE b-SUBUNIT OF RNA POLYMERASE
  10. Glycopeptide antibiotics
    affect cell wall synthesis at a different site than penicillins

    INTERFERES WITH COMPLEXING OF PEPTIDOGLYCAN PRECURSOR

    G+ (MRSA)

    ex VANCOMYCIN

    • gram neg are resistant b/c impermeability of the outer
    • cell membrane to the large, hydrophobic glycopeptide molecules. Enterococcus species modify the D-ala-D-ala to either D-ala-D-lac or D-ala-D-ser.
  11. Isoniazid
    An antibiotic that resembles nicotinamide in structure and competes with it for incorporation into NAD
  12. Nalidixic acid
    DNA gyrase
  13. Fuscidic acid
    • EF-G
    • (elongation factor G)
  14. Tetracycline
    PROT SYNTH

    REVERSIBLY BINDS TO 30S ribosomal subunit

    G+ & G-

    ex DOXYCYCLINE, MINOCYCLINE

    active efflux - energy dep pump removes Ab from cell before ribosomal target can be affected. Ribosome protection & altered permeability - porin modification --> MAR system

    production of resistant dihydrofolate reductase (3)
  15. Streptomycin
    Binds 30S bacterial ribosomal subunit causing distortions in the A site

    • ultimately inhibits elongation of the growing
    • peptide chain
  16. Aminoglycosides
    PROT SYNTH -- Binds irreversibly to 30S ribosomal subunit

    AEROBIC G- RODS, TB, OR SYNERGISTIC AGAINST RES G+ (ENTEROCOCCI)

    STREPOMYCIN, GENTAMYCIN

    • intrinsic resistance - fail to actively transport aminoglycosides across the cell membrane into the
    • cytoplasm where ribosomal targets are (enterococci, anaerobes & streptococci)

    Acquired resistance - by plasmid or transposon - acetylate AA, adenylate hydroxyl groups, phosphorylate hydroxyl groups
  17. Anitibiotic
    • natural
    • inhibitory product of microorganism
  18. Sulfonamide
    • non-antibiotic,
    • antimicrobial agent
  19. Clavulanic acid
    irreversible b-lactamase inhibitor
  20. Nitrofurantoin
    UTI

    inhibtis protein synthesis at multiple levels
  21. Bacteriostatic
    inhibitory, but non-lethal effect
  22. Minimal bactericidal concentration
    killing of 99.9% of bacterial population
  23. Plasmids
    extrachromosomal genetic element
  24. Penicillin-binding proteins
    targets of b-lactam antibiotic
  25. Synergy
    effect of two drugs together better than combined separate drug effects
  26. most common mechanism of antimicrobial resistance
    production of drug-inactivating enzymes
  27. Bactericidal antibiotics owe their effectiveness to
    irreversible binding to a target enzyme or molecule
  28. Methylation of adenine residues in 23S ribosomal RNA, which results in the MLS antibiotic resistance of phenotype, is an example of which mechanism of resistance
    alteration of antibiotic target site
  29. Principal mechanism of antibacterial action of b-lactam antibiotics
    inhibition of cell wall peptidoglycan cross-linking.
  30. The structural feature shared by all b-lactam antibiotics
    four-membered b-lactam ring
  31. b-lactamase produced by gram-positive bacteria such as Staphylococcus & enterococcus is ...
    an extracellular protein
  32. Important factors in order for an antibiotic to be effective clinically (3)
    Antibiotic must have high affinity for its microbial agent

    Non-toxic to mammalian systems at concentrations similar to those required for its antimicrobial activity

    Should not induce resistance to itself during therapy and should be chemically stable
  33. Most effective means of minimizing the emergence of antibiotic resistance
    using antibiotics only when indicated
  34. Streptococcus pyogenes has remained uniquely susceptible to penicillins (2)
    Know This
  35. Antibiotic that is bacteriocidal
    Vancomycin
  36. Methicillin resistant S. aureus (MRSA) are now resistant to all clinically useful antibiotics except
    Vancomycin
  37. Resistance of Strep pneumoniae to high levels of penicillin is due to
    acquisition of b-lactamase encoding plasmids
  38. Requirement for active growth and cell division in order to function applies to antibiotics that inhibit
    cell wall synth
  39. Tests or methods you would need to determine both the MIC and the MBC of an antibiotic
    broth dilution
  40. CARBAPENEMS
    Beta-lactam like mech, but different central ring structure (carbon-sulfur switch).

    Better against bacteria with beta-lactamase

    G+ & G-

    ex IMIPENEM

    Broadest spectrum

    BAC WITH CARBAPENEMASES can destroy all current b-lac drugs
  41. MONOBACTAMS
    B-LAC - UNIQUE MONOCYCLIC STRUCTURE

    AEROBIC G- ONLY (PSEUDOMONAS, ENTEROBACTER)

    AZTREONAM ONLY
  42. POLYMYXINS
    CELL MEM SYNTH (DAPTOMYCIN DEPOLERIZE CELL MEM)

    INTERACT WITH PHOPHOLIPIDS IN G- MEMs CAUSING LEAKAGE

    G-

    USED TOPICALLY

    TOXIC TO HUMANS

    - only used systematically if infection is life threatening

    ex P. auruginosa, A. baumannii, b/c toxic to humans
  43. Daptomycin
    Lipopeptide antibiotic causing CA++ mediated depolarization of cell membrane (POLYMYXIN -- CELL SYNTH)

    G+ (MRSA, VRE)

    INJECTABLE FOR SEVERE DRUG RES G+
  44. G- are intrinsically resistant b/c of poor permeability of outer membrane to these agents. Active efflux of macrolides but no
    clindamycin. Target modification by
    methylation of 50S ribosomal subunit (ketolides are less susceptible to this)
    MACRILIDES, KETOLIDES LINCOSAMIDES, STREPTOGRAMINS

    Active efflux of macrolides but no clindamycin. Target modification by methylation of 50S ribosomal subunit (ketolides are less susceptible to this)
  45. Ketolides
    PROT SYNTH

    Like Macrolides, but better against macrolids resistant strep and staph

    G+

    FOR MACROLIDE RES STRAINS

    TELITHROMYCIN
  46. Lincosamides
    PROT SYNTH

    Like Macrolides, broader spectrum, prevent polypeptide chain elongation

    G+

    GOOD FOR ANAEROBIC G-

    ex CLINDAMYCIN
  47. Streptogramins
    PROT SYNTH

    • Given as quinupristin and dalfopristin combo (SYNERGY). Quin targets same 50S as Macrolides, but Dalfo. Targets
    • 50S at different site

    G+

    GOOD FOR VRE AND MRSA

    ex QUINUPRISTIN, DALFORPRISTIN
  48. Oxazolidinones
    PROT SYNTH

    Targets 50S ribosome, and inhibits the initiation of translation, but is not bacteriocidal.

    AEROBIC G+

    For REALLY resistant stuff like MRSA, VRSA, VISA

    ex LINEZOLID
  49. Mupricin
    PROT SYNTH

    Inhibits tRNA synthetase

    G+

    TOPICAL APPLICATION
  50. Fluoroquinolones
    DNA REPLICATION

    Inhibits DNA-gyrase or bacterial topoisomerase IV

    G+ & G-

    MOST FREQUENTLY PRESCRIBED - BROAD SPECTRUM

    ex - CIPROFLOXIN, LEVOFLOXACIN, MOXIFLOXACIN

    Alteration of the structure of the target A subunit of the DNA gyrase enzyme - Ab cannot bind to active site. Efflux pumps -- G-
  51. Metronidazole
    DNA REPLICATION

    Reduction of the nitro group on antibiotic causes toxic intermediate in bacteria - distrupts DNA

    ANEROBIC ONLY

    INTESTINAL PROTAZOA (GIARDIA AND HISTOLYTICA) AND ANAEROBIC BACTERIA

    ex METRONIDAZOLE
  52. FOSFOMYCIN
    UTI - INHIBITS PROTEIN SYNTH

    G+ & G-
  53. Polyenes
    ANTI-FUNGAL

    binds to ergosterol in fungal cell membrane - osmotic instability and loss of membrane integrity

    ONLY FOR VERY SERIOUS FUNGAL INFECTION -- TOXIC

    ex AMPHOTERICIN B
  54. Azoles
    ANTI-FUNGAL

    interfere with fungal cell membrane ergosterol synthesis

    NON-TOXIC, IV OR ORAL

    • Fluconazole,
    • itraconazole,
    • voriconazole,
    • posaconazole
  55. Echinocandins
    ANTI-FUNGAL

    inhibit glucan synthesis in cell wall of yeasts and some mold fungi

    IV

    • Caspofungin,
    • micafungin,
    • anidulofungin
  56. Flucytosine
    ANTI-FUNGAL

    inhibits DNA and RNA synthesis of some fungi

    orally, bone marrow toxicity - only for serious infections

    Flucytosine or 5FC

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