Chapter 7 2270 key concepts

Sterilization

The process of killing ALL microbes, including bacteria, viruses, fungi, and endospores.

Disinfection

The process of killing or removing microbes from an inanimate object, but it does not achieve sterilization. For example, wiping a table surface with a cleaner.

Antisepsis

The process of killing or removing pathogens from living tissue. Sterilization is typically too damaging for living tissues.

Sanitation

The process of reducing microbial populations to safe levels, often used in public health and food safety contexts.

Death Curve

A graphical representation that charts the rate of microbial demise over time when exposed to a microbial control agent.

D-value (Decimal Reduction Time)

The time required to reduce a microbial population by 90%. The death rate slows down as dead cells can protect the living cells from the antimicrobial agent. For example, when using antibiotics, dead cells still absorb the antibiotic, reducing its effectiveness on living cells.

Dry Heat

Not very effective at killing microbes, as it takes a long time.

Moist Heat

More effective than dry heat. Boiling water at 100°C kills most vegetative cells but does not kill viruses, thermophiles, or spores.

Steam Autoclaves

Use pressurized superheated steam at 121°C for 20 minutes to sterilize materials. This method is effective for heat- and moisture-resistant items like glassware, surgical equipment, and agar.

Limitations

Autoclaving is not suitable for items that cannot get wet or would melt, such as electronics, most plastics, and paper.

Pasteurization

A process used to kill microbes in food products. It is non-sterilizing but reduces microbial populations without cooking the food.

Cold

Low temperatures are never sterilizing, but they slow bacterial growth. At temperatures below -70°C, bacterial growth essentially ceases.

Filtration

A method of removing microbes by restricting their flow using a filter.

Irradiation

Uses high-energy particles or photons to damage microbial cells by mutating their DNA. Not very damaging to inanimate objects.