Page 21 - MNU-PM502- Pharmaeutical Microbiology Theoritical Book

Pharm D- Clinical Pharmacy Program Third Level Pharmaceutical Microbiology& Antimicrobials (PM 502)

• Cell wall is damaged, it makes a cell susceptible to lysis.
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• When plasma membrane is disrupted, the cell loses its selective

2 permeability & leads to the death of the cell.

• When a protein’s shape is changed it is called denaturing & loses its
3 function; inhibition or elimination of function can result in cell death.

• Nucleic acids are required for cell survival: Some agents can bind
irreversibly to DNA. This prevents gene expression. Others are
4 mutagenic and cause lethal mutations.

Factors that affect the rate at which microbes are killed

1) Exposure time to method or agent

More contact times are more effective than shorter contact times.

2) Number of microbes present (microbial load)

The more microbial contamination on a surface,
the longer it will take to disinfect or sterilize it.

3) Amount of organic debris on surface
The organic material (blood, mucus, pus, feces) should be
mechanically removed before chemical sterilization or
disinfection.

Organic debris will inhibit accessibility of the antimicrobial agent
to the organism (physical barrier).

4) Types of organisms
• More time will be required to treat microbes that have high levels of resistance.

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