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Chapter 18

MCB 3020L Chapter Notes - Chapter 18: Antibiotics, Peptidoglycan, Streptomycin


Department
Microbiology
Course Code
MCB 3020L
Professor
Scheurle Daniela
Chapter
18

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Chapter 18
Chapter 18: Antiseptics, Disinfectants, and Antibiotics
Antiseptics and disinfectants are both types of methods to reduce the numbers of
bacteria, but generally do not result in total sterilization
o Both are also forms of chemical bacterial control
Disinfectants: chemicals applied to surfaces of inanimate objects
Antiseptics: chemicals applied to the surfaces of tissues
Diffferent chemicals have different effects on bacteria
o Some attack the peptidoglycan layers of the cell wall and the cell membrane,
leading to the lysis of the cells
Bactericidal: chemical agents that are able to cause total cell death of the bacteria; KILLS
the bacteria like straight up
Bacteriostatic agents: are able to temporarily inhibit the growth of certain bacteria, but
are not able to kill the cells
CONCENTRATION is very important
o Too low bacteria may be effected
o Too high May be toxic to the user, cause damage to the surface treated, or
prohibitively expensive
LENGTH of time it takes is also very important
o This length of time that it takes to be effective is the time is measured as the
decimal reduction time (DRT)
o DRT is the amount of time it takes a particular chemical at a certain
concentration to kill 90% of the bacteria that had been present at the time of
application for the agent being measured
Chemotherapeutic agents: agents required for the control of bacterial populations (or
bacterial growth) within living tissues
o Can be natural or synthetically produced
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