Antimicrobial agent in vivo vivo inside the body vitro out side the body

Chemotherapeutic agent use chemical to treat any disease or condition. Antimicrobial agent drugs used to treat an infections disease either by inhibiting or killing Pathogens in vivo. Antibacterial Anti protozoa Anti virus Anti fungal some antimicrobial are antibiotic antibiotic is substance produced by microorganisms that is effective in killing or inhibiting the growth of other microorganism. all antibiotic are antimicrobial agent, but not all antimicrobial agent are antibiotic.

1928 Alexander Fleming a scotch bacteriologist discover the first antibiotic when notice the grout of penicillium mold colonies on the culture plates were inhibiting the growth of staphylococcus bacteria.

IDEAL QUALITY OF Antimicrobial AGENT: Kill or inhibit the growth of pathogens Cause no damage to the host . Cause no allergic reaction in the host. Be stable when stored in solid or liquid form . Remain in specific tissues in the body long enough to be effective. Kill the pathogens before they mutate and become resistant to it.

HOW ANTIMICROBIAL AGENT WORK: inhibit of the cell wall synthesis. damage to cell membranes. Inhibition of protein synthesis . Inhibition of enzyme activity. Inhibition of nucleic acid synthesis.(either DNA or RNA)

In most of gram positive bacteria including streptococci and staphylococcus penicillin interfere with the synthesis and cross – linking of peptidoglycan , a competent of bacterial cell wall . Thus, by inhibiting cell wall synthesis, penicillin destroy the bacteria . Narrow spectrum antibiotics: those antibiotics that is destructive to Gram positive (vancomycine) or Gram negative bacteria (colistin and nalidixic acid). Broad spectrum antibiotics : those that are destructive to both Gram positive and Gram negative bacteria ( ampicillin-chloramphenicol-trtracycline).

Synergism versus antagonism The use of two antimicrobial agent to treat an infectious disease some times produces a degree of pathogen killing that is far greater than that achieved by either drug alone .this is called synergism. Where a combination of two drug work against each other called antagonism.

Intrinsic resistant : some bacteria are naturally resistant to a particular antimicrobial agent because they lack the specific target site for the drug ( e.g. mycoplasma have no cell and are ,there fore, resistant to any drugs that interfere with the cell wall synthesis). Acquired resistant : bacteria were susceptible to type of antibiotic and become resistant to this type of antibiotic by one of this mechanisms :

A chromosomal mutation that causes a change in the structure of the drug so the drug cannot bind to the bacterial sites A chromosomal mutation that causes a change in cell membrane permeability.-the drug cannot pass through the cell membrane and thus cannot enter the cell. Acquisition a gene that enable the bacterium to produce an enzyme that destroys or inactivates the drug .- the drug is destroyed or inactivated by the enzyme-. Acquisition a gene that enable the bacterium to produce an multidrug resistant (MDR) pump.- the drug is pumped OUT of the cell before it can damage or kill the cell.