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Flashcards in The Control of Microbial Growth Deck (24):

Roughly when did the control of microbial growth begin?

Around 100 years ago


What were the initial methods of controlling microbial growth around 100 years ago?

Washing hands with chloride of lime
Techniques of aseptic surgery


What does sterilisation mean?

The removal or destruction of all microbial life/living microorganisms


What is a sterilising agent called?

A sterilant


Why is complete sterilisation in commercial sterilisation not often required?

The body's natural defences can cope


What does commercial sterilisation involve?

Heated enough to destroy endospores of clostridium botulinum which can produce a deadly toxin


Limited heat treatment in commerce is referred to as

Commercial sterilisation


What does disinfection mean?

To remove pathogens - the control is directed at destroying harmful microorganisms


What can be used as a disinfectant?

Chemicals, ultraviolet radiation, boiling water or steam


What is antisepsis?

When the disinfectant treatment is directed at living tissue it is termed antisepsis


What is a chemical that is directed at living tissue called?

An antiseptic


What is degerming?

Removing microbes from a limited area - such as when someone is receiving an injection the area is wiped with an alcohol swab


What is sanitization?

The lowering of microbial counts on eating utensils


What is a biocide/germicide?

Biocides/germicides kill microbes


What does the term bacteriostasis mean?

Inhibiting the growth of microbes (not killing)


What does sepsis mean?

Refers to microbial contamination


What does asepsis mean?

An object/area is free of pathogens / the absence of significant contamination


What is the goal os aseptic surgery techniques?

To prevent the microbial contamination of wounds


When bacterial populations are heated or treated with antimicrobial chemical, describe how they die.

They usually die at a constant rate. If plotted logarithmically, the death rate is constant as shown with a straight line.


If there are 1 million bacteria being treated with an antimicrobial, how many will be left after one minute, two minutes? Say about 90% of the bacteria die each time

One minute, 90% die to 100,000
two minutes, 90% die to 10,000


The rate of microbial death depends on four factors. List these.

1. The number of microbes
2. Environmental influences
3. Time of exposure
4. Microbial characteristics


How does the number of microbes present affect the rate of microbial death?

The greater the number of microbes there are to begin with, the longer it takes to eliminate the entire population


How does the environment play a role in the rate of microbial death?

1. Microbes in biofilms may be difficult to reach
2. Presence of organic matter can inhibit action of chemical antimicrobials


Microbial control agents act in three ways. List them.

1. Alteration of membrane permeability
2. Damage to proteins
3. Damage to nucleic acids