Microbial Growth

Topics: Bacteria, Microorganism, Water Pages: 7 (1536 words) Published: August 31, 2013
* Jamshoro college of Nursing jamshoro
* Turn off your mobile.
* If you have any problem or urgency you can leave class without any disturbance. * Questioning and answering are asked at the end of presentation. * Don't discuses during presentation each other.

* ten minutes for Q&A

* objective
At the end of presentation learner will be able
* Introduction of control of microbial growth
* Define term related to control of microbial growth
* Describe physical method of microbial growth


Control of Microbial Growth
Control of Microbial Growth:
* Early civilizations practiced salting, smoking, pickling, drying, and exposure of food and clothing to sunlight to control microbial growth. * Use of spices in cooking was to mask taste of spoiled food. Some spices prevented spoilage. * In mid 1800s Semmelweiss and Lister helped developed aseptic techniques to prevent contamination of surgical wounds. Before then: * Nosocomial infections caused death in 10% of surgeries. * Up to 25% mothers delivering in hospitals died due to infection Control of Microbial Growth:

Sterilization: Killing or removing all forms of microbial life (including endospores) in a material or an object.
Heating is the most commonly used method of sterilization.
Commercial Sterilization: Heat treatment that kills endospores of Clostridium botulinum the causative agent of botulism, in canned food.
Does not kill endospores of thermophiles, which are not pathogens and may grow at temperatures above 45oC. Control of Microbial Growth:
Disinfection: Reducing the number of pathogenic microorganismsto the point where they no longer cause diseases. Usually involves the removal of vegetative or non-endospore forming pathogens.
May use physical or chemical methods.
* Disinfectant: Applied to inanimate objects.
* Antiseptic: Applied to living tissue (antisepsis).
* Degerming: Mechanical removal of most microbes in a limited area. Example: Alcohol swab on skin. * Sanitization: Use of chemical agent on food-handling equipment to meet public health standards and minimize chances of disease transmission. E.g: Hot soap & water. Control of Microbial Growth:

Sepsis: Comes from Greek for decay or putrid. Indicates bacterial contamination.
Asepsis: Absence of significant contamination.
Aseptic techniques are used to prevent contamination of surgical instruments, medical personnel, and the patient during surgery.
Aseptic techniques are also used to prevent bacterial contamination in food industry. Control of Microbial Growth:
Bacteriostatic Agent: An agent that inhibits the growth of bacteria, but does not necessarily kill them. Suffix stasis: To stop or steady.
Germicide: An agent that kills certain microorganisms.
* Bactericide: An agent that kills bacteria. Most do not kill endospores. * Viricide: An agent that inactivates viruses.
* Fungicide: An agent that kills fungi.
* Sporicide: An agent that kills bacterial endospores of fungal spores.

Control of Microbial Growth:
Rate of Microbial Death
When bacterial populations are heated or treated antimicrobial chemicals, they usually die at a constant rate. Control of Microbial Growth:
Rate of Microbial Death
Several factors influence the effectiveness of antimicrobial treatment.
1. Number of Microbes: The more microbes present, the more time it takes to eliminate population.
2. Type of Microbes: Endospores are very difficult to destroy. Vegetative pathogens vary widely in susceptibility to different methods of microbial control.
3. Environmental influences: Presence of organic material (blood, feces, saliva) tends to inhibit antimicrobials, pH etc.
4. Time of Exposure: Chemical antimicrobials and radiation treatments are more effective at longer times. In heat treatments, longer...

References: * Black, J.G. (1996). Microbiology. Principles and Applications. Third Edition. Prentice Hall. Upper Saddle River, New Jersey. pp. 136-140, 151-153.
* Tortora, G.J., Funke, B.R., Case, C.L. (1995). Microbiology. An Introduction. Fifth Edition. The Benjamin/Cummings Publishing, Co., Inc., Redwood City, CA, pp. 155-158
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