ANTIMICROBIAL AGENTS

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					        ANTIMICROBIAL AGENTS

ANTIBIOTICS:

   NATURAL    COMPOUNDS    PRODUCED    BY
    MICROORGANISM WHICH INHIBIT THE GROWTH
    OF OTHER .

CHEMOTHERAPY:


   SYNTHETIC COMPOUNDS.
SELECTIVE TOXICITY:

   THE ABILITY TO KILL OR INHIBIT THE
    GROWTH OF MICROORGANISM WITHOUT
    HARMING THE HOST CELLS.
BACTERICIDAL: KILLS BACTERIA
BACTERIOSTATIC: PREVENTS MULTIPLICATION.

SPECTRIM OF ACTIVITY:

   BROAD SPECTRUM: G+VE& G-VE
   NARROW SPECTRUM: SELECTIVE ORGANISM.
THERAPEUTIC INDEX:

   THE RATIO OF THE DOSE TOXIC TO THE HOST TO
    THE EFFECTIVE THERAPEUTIC DOSE.

EXAMPLES:

     PENICILLIN: HIGH
     AMINOGLYCOSIDES: LOW
     POLYMYXIN B: THE LOWEST
        MECHANISMS OF ACTION OF
            ANTIMICROBIALS

1) INHIBITION OF CELL WALL SYNTHESIS.

2) ALTERATION OF CELL MEMBRANES

3) INHIBITION OF PROTEIN SYNTHSIS

4) INHIBITION OF NUCLEIC ACID

5) ANTIMETABOLIC OR COMPETITEVE ANTAGONISM.
MECHANISMS OF ACTION
ANTIMICROBIALS THAT INHIBIT CELL
        WALL SYNTHESIS
   BETA LACTAMS


       PENICILLINS
       CEPHALOSPORINS
       CARBAPENEMS
       MONOBACTAM


 VANCOMYCIN
 BACITRACIN
FIG. 1
 - LACTAM ANTIBIOTICS:

 BETA LACTAM RING &ORGANIC ACID.
 NATURAL &SEMISYNTHETIC
 CIDAL ACTION
 BIND TO PBP, INTERFERES WITH TRANSPEPTIDATION
  REACTION
TOXICITY:
     HYPERSENS.
     ANAPHYLAXIS,
     DIARRHOEA, ..ETC.
PENICILLINS:
BENZYLE PENICILLIN:

   PENIC. V,
   PROCAINE PEN.,
   BENZATHIN PEN.


6-AMINOPENICILLANIC ACID:

 CLOXACILLIN          STAPH.
 AMOXYCILLIN          ENTEROBACTERIA
 PIPERACILLIN         PSEUDOMONAS
CEPHALOSPORINS:

FIRST GENERATIONS:
                         THIRD GEN:
CEPHRADINE
                         GRAM –VE ONLY
SECOND GENERATIONS:      CEFTRIAXONE
CEFUROXIME ,CEFOXITIN    CEFTAZIDIME
THIRD GENERATIONS:      FOURTH GEN:
                         CEFEPIM
EXPANDED SPECTRUM
                           CEFEXIME
    VANCOMYCIN:
   GLYCOPEPTIDE

   CIDAL ON G +VE BACTERIA ONLY.

   INHIBIT CELL WALL SYNTHESIS

   INJ. ONLY.

   USED FOR MRSA S.EDIDER. PESUDOMEM.COLITIS.

   NEPHROTOXIC & OTOTOXIC.
       ANTIBIOTICS THAT ALTER CELL
               MEMBRANES
   POLYMYXIN B

   PEPTIDE ACTIVE AGAINST G –VE

   BACTERICIDAL

   ONLY USED LOCALLY DUE TO SERIOUS
    NEPHROTOXICITY
     ANTIBIOTICS THAT INHIBIT PROTIEN
                SYNTHESIS

   AMINOGLYCOSIDES

   TETRACYCLINES

   CHLORAMPHENICOL

   MACROLIDES
AMINOGLYCOSIDES:

   BACTERICIDAL

   GRAM –VE BACTERIA

   SRTEPT.& ANAEROBES RESISTANT

   ACTION: INTERFER WITH BINDING OF t RNA TO 30 S SUBUNIT

   GENTAMICIN, AMIKACIN, NEOMYCIN

   INJECTABLE

   NEPHROTOXIC& OTOTOXIC -DOSE RELATED
TETRACYCLINES

 BROAD SPECTRUM, STATIC
 ORAL ABSORPTION
 INTRACELLULAR EG. MYCOPLASMA, CHLAMYDIA
  BRUCELLA ALSO FOR CHOLERA NOCARDIA

TWO CLASSES:
 SHORT ACTING: TETRACYCLINE
 LONG ACTING: MINOCYCLIN ,DOXY.


SIDE EFFECTS:
 TEETH DISCOLORATION, GIT DISTURBANCE
CHLORAMPHENICOL

   BROAD SPECTRUM, CIDAL

   BIND TO 50 s RIBOSOMAL SUBUNIT

   AFFECT BONE MARROW CELLS AND CAUSE
    APLASTIC ANAEMIA

   SEVERE INFECTIONS: TYPHOID FEVER, HI
    MENINGITIS, RICKETSIA…ETC.
MACROLIDES:
   ERYTHROMYCIN & CLINDAMYCIN

   BACTERIOSTATIC

   LEGIONELLA, CAMPYLOBACTER, G +VE INFECTIONS IN PTS.
    ALLERGIC TO PEN.

   CLINDAMYCIN ACT ON ANAEROBES

   GIT DISTURBANCE, PMC (CLIND)

   NEW MACROLIDES:

   AZITHROMYCIN , CLARITHRIMYCIN
ANTIMICROBIALS THAT ACT ON NUCLEIC ACID

    RIFAMOICIN

    QUINOLONES

    METRONIDAZOLE
RIFAMPICIN:
   SEMISYNTHETIC , CIDAL G +VE COCCI

   RESERVED FOR TB

   INHIBIT DNA DEP.RNA POLYMERASE

   RESISTANCE DEVELOP QUICKLY

   USED IN COMBINATION

   DISCOLORATION OF BODY FLUIDS

   HEPATOTOXIC
QUINOLONES:

   SYNTHETIC ,CIDAL, INHIBIT DNA GYRASE

   NALIDIXIC ACID : OLD,G _VE ONLY

   FLOUROQUINOLONES: CIPROFLOXACIN, NORFLOXACIN

   SYSTEMIC INFECTIONS, UTI

   BROAD EPECTRUM

   BETTER PHARMACOLOGICALLY

   AFFECT CARTILAGE IN ANIMALS
Fig. 3
ANTIMETABOLITES:

   SULFONAMIDES

   TRIMETHOPRIM

   COMBINATION: BACTRIM/ SEPTRIN

   BLOCK SEQUENTIAL STEPS IN FOLIC ACID SYNTHESIS

   NOCARDIA,CHLAMYDIA,PROTOZOA,P.CRANII

   UTI LRTI, OM..

   GIT.HEPATITIS, BM DEPRESSIN, HYPERSENSITIVITY
 ANTITUBERCULOUS AGENTS
FIRST LINE: INH   SECOND LINE:
 RIFAMPICIN      STREPTOMYCIN
 ETHAMBUTOL      PASA
 PYRAZINAMIDE    CYCLOSERINE,
                  CAPREOMYCIN
ISONIAZIDE (INH)

   BATERICIDAL

   INTRA& EXTRA CELLULAR MYCOBACTERIA

   TREATMENT & PROPHYLAXIS

   PREPHERAL NEURITIS
                     PYRAZINAMIDE
ETHAMBUTOL
                      ACID
 CIDAL
                       ENVIRONMENT OF
 CONC.IN              MACROPHAGES
  PHAGOLYSOSOME OF    HEPATITIS &
  ALVEOLI              ARTHRALGIA
 OPTIC NEURITIS
ANTIBIOTIC RESISTANCE IN BACTERIA


 INDISCRIMINATE USE OF ANTIMICROBIALS
 SELECTIVE ADVANTAGE OF ANTIBIOTICS

TYPES OF RESISTANCE:
PRIMARY:

 INNATE eg. STREPT. &ANAEROBES RESISTANT TO
  GENTAMICIN
ANTIBIOTIC RESISTANCE IN BACTERIA (Continue)

AQUIRED:
 1-MUTATION: MTB R TO SRTEPTOMYCIN
 2- GENE TRANSFER: PLASMID MEDIATED OR
  TRANSPOSONES
CROSS RESISTANCE:
 R TO ONE GROUP CONFER R TO OTHER OF THE
  SAME GROUP
 EG ERYTHROMYCIN & CLINDAMYCIN
DISSOCIATE R:
 R TO GENTA. DOES NOT CONFER R .TO
  TOBRAMYCIN
MECHANISMS OR RESISTANCE

1-PERMIABILITY CANGED

2-MODIFICATION OF SITE OF ACTION, EG. MUTATION

3-INACTIVATION BY ENZYMES.EG. BETA
   LACTAMASE, AMINOGLYCOSIDES INACTIVATING
   ENZYMES

BYPASSING BLOCKED METABOLIC REACTION EG.
PABA      FOILC ACID BY PLASMID MEDIATED
  DFR.
PRINCIPLES OF ANTIMICROBIAL THERAPY:


   INDICATION       SHORT TERM:
   CHOICE OF DRUG    MENINGITIS
   ROUTE            LONG TERM:
   DOSAGE            TB, UTI , RHEUMATIC
   DURATION           FEVER
   DISTRIBUTION
   EXCRETION
   TOXICITY
   COMBINATION
   PROPHYLAXIS:
CRITERIA FOR IDEAL ANTIMICROBIAL:

   SELECTIVE TOXICITY

   NO HYPERSENSITIVITY

   PENETERATE TISSUES QUICKLY

   RESISTANCE NOT DEVELOP QUICKLY

   NO EFFECT ON NORMAL FLORA

   BROAD SPECTRUM
ANTIFUNGAL AGENTS:

   NYSTATIN         LOCAL
   AMPHOTERICIN B       SYSTEMIC

ANTIVIRAL AGENTS
  IODOXURIDINE
  VIDARABINE
  AMANTADINE
  INTERFERON

				
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posted:5/15/2013
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