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    10 Control of Microbe in The BODY

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    10 Control of Microbe in The BODY

    Uploaded by

    isa masias
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    Original Title

    10-Control-of-Microbe-in-the-BODY

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    © All Rights Reserved
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    4 views51 pages

    10 Control of Microbe in The BODY

    Uploaded by

    isa masias

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 51

    CONTROL OF

    MICROBE IN THE
    BODY
    Loading…
    Clinical Considerations in Prescribing Antimicrobial Drugs

    1. Readily available 4. Easily administered


    2. Inexpensive 5. Nontoxic and non-allergenic
    3. Chemically stable 6. Selectively toxic
    Loading…
    Loading…
    Spectrum of Action
    - is the no. of different kinds of pathogens a drug acts against
    a. narrow-spectrum drugs
    b. broad-spectrum drugs
    Efficacy
    a. Diffusion Susceptibility Test (Kirby-Bauer Method)

    b. Minimum Inhibitory Concentration (MIC)

    - is the smallest amount of drug that will inhibit growth and


    reproduction of the pathogen

    - determine via a broth dilution test (turbidity)

    c. Minimum Bactericidal Concentration (MBC) Test


    - the lowest concentration of drug for which no growth
    occurs in the Subcultures
    Safety and Side Effects
    a. Toxicity
    b. Allergies
    c. Disruption of normal microbiota

    “
    Characteristics of Chemotherapeutic Agents

    1. Highly toxic to a large number of pathogens.

    2. No toxicity to the host.

    3. Does not induce the development of antibiotic resistance in mutant


    MQs.

    “ 4. Will not induce hypersensitivity in the host.

    5. Does not interfere with the host’s normal defense mechanism.


    Factors Influencing Therapeutic Value

    1. The susceptibility of the pathogen to the chemotherapeutic agent.

    2. The drugs spectrum of activity.

    3. Possible adverse reactions to the drug.

    “
    4. The drugs distribution within the body.

    5. Metabolism of the drug in the body.

    6. Duration of treatment.

    7. Interactions with other drugs the patient maybe taking.


    1. The Development of Resistance in Populations
    a. new mutations of chromosomal genes
    b. by acquiring resistance genes on extra-chromosomal pieces of
    DNA called R-plasmids or R-factors via transformation,
    transduction, or conjugation.

    “
    2. Mechanisms of Resistance

    a. Resistant bacteria may produce an enzyme that destroys or deactivates the


    drug. (e.g. penicillinase)

    b. Resistant pathogens may slow or prevent the entry of the drug into the
    cell. (e.g. altered porins)

    “ Loading…
    c. Resistant cells may alter the receptor for the drug so that it either
    cannot attach to or binds less effectively to its target.
    (sulfonamides, erythromycin)

    d. Resistant cells may alter their metabolic chemistry or they may


    abandon the susceptible and then metabolic chemistry stops
    altogether.

    e. Resistant cells may pump the drug out of the cell before the drug
    can act.
    “
    Multiple Resistance and Cross Resistance

    - multiple resistance is resistance to more than one drug at a time


    - cross resistance is resistance to one drug, and confers resistance to similar drugs
    Retarding Resistance

    1. First, sufficiently high concentrations of the drug can be maintained in a patient’s


    body for long, enough time to kill all susceptible cells and inhibit others long enough for

    “
    the body’s defenses to defeat them.

    2. Then, use antimicrobial agent in combination so that pathogens resistant to one drug
    will be killed by the second, and vice versa.

    Synergism – one drug enhances the effect of the second drug; e.g. penicillin and
    streptomycin
    Antagonistic – interfering with each other

    3. Lastly, is to limit the use of antimicrobial agent to necessary cases.


    “
    Thank you for
    your kind
    attention !

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