chap 27

Comprehensive vocabulary flashcards covering the physical, chemical, and biological methods of microbial control, including mechanisms of action and specific sterilized conditions as detailed in the lecture.

Sterilization

The process by which all living cells, spores, and viruses are destroyed on an object.

Disinfection

The killing or removal of disease-producing organisms from inanimate surfaces, which does not necessarily result in sterilization.

Antisepsis

The removal of pathogens from the surface of living tissues, such as the skin.

Sanitation

Reducing the microbial population to safe levels, usually involving both cleaning and disinfecting an object.

Chemotherapy

The use of chemicals to kill or inhibit the growth of microorganisms within host tissue.

Cidal agents

Chemical or physical agents that act by killing cells.

Static agents

Chemical or physical agents that inhibit growth but do not kill cells.

Germicidal

Agents that kill pathogens and many nonpathogens, but do not necessarily kill spores.

D-value ($D_{100}$)

The time required for an agent or condition to kill $90\%$ of cells, representing the time it takes for the viable cell count to drop by one $\log_{10}$ unit.

Boiling

A physical method using $100\,^\circ\text{C}$ at sea level to denature proteins and alter membranes.

Dry-heat oven

A physical method set at $170\,^\circ\text{C}$ for $2\,\text{hours}$ that denatures proteins, alters membranes, and causes dehydration and desiccation.

Incineration

A method of dry heat control involving exposure to flame, such as a flaming loop or microincinerator, to destroy by burning.

Autoclave

A sterilization method typically set at $121\,^\circ\text{C}$ for $15\,\text{minutes}$ at $15\,\text{pounds per square inch (psi)}$ to denature proteins and alter membranes.

LTLT Pasteurization

Low temperature, long time method involving heating at $63\,^\circ\text{C}$ for $30\,\text{minutes}$.

HTST Pasteurization

High temperature, short time (flash) pasteurization involving heating at $72\,^\circ\text{C}$ for $15\,\text{seconds}$.

UHT Pasteurization

Ultra high temperature method involving heating at $138\,^\circ\text{C}$ for $1\text{--}2\,\text{seconds}$, producing nearly sterile milk with a shelf life up to $6\,\text{months}$.

Refrigeration

Physical control at $0\,^\circ\text{C}$ to $7\,^\circ\text{C}$ that inhibits metabolism and slows or arrests cell division.

Freezing

Physical control below $-2\,^\circ\text{C}$ that stops metabolism and may kill microbes.

High-pressure processing

The use of $100\text{--}800\,\text{MPa}$ to denature proteins and cause cell lysis.

Hyperbaric oxygen therapy

A treatment using air pressure three times higher than normal to inhibit the metabolism and growth of anaerobic microbes.

Lyophilization

The rapid freezing of materials under a vacuum to inhibit metabolism for the preservation of food or laboratory cultures.

Ionizing Radiation

Radiation (gamma and beta) that penetrates deep into objects to destroy bacterial endospores; used for cold sterilization of medical supplies and food.

UV radiation

Nonionizing radiation that causes the formation of thymine dimers in DNA, leading to lethal mutations in exposed microbes.

Sonication

The use of ultrasonic waves to cause cavitation, creating empty spaces that disrupt and lyse cells.

HEPA filtration

High-efficiency particulate air filtration using a $0.3\,\mu\text{m}$ pore size to physically remove microbes from air.

Membrane filtration

The use of a filter with $0.2\,\mu\text{m}$ or smaller pore size to physically remove microbes from heat-sensitive liquid solutions.

Phenol coefficient

A measure determined by comparing the highest dilution of a test agent capable of killing pathogens to that of phenol.

Phenolics

Chemical disinfectants like Cresols or Triclosan that denature proteins and disrupt membranes.

Metals (Mechanism)

Chemical agents such as Mercury, Silver, and Copper that bind to proteins and inhibit enzyme activity.

Halogens

Chemical agents including Iodine, Chlorine, and Fluorine that act by oxidation and destabilization of cellular macromolecules.

Alcohols

Ethanol and Isopropanol used as disinfectants or antiseptics to denature proteins and disrupt membranes.

Surfactants

Soaps and detergents that lower the surface tension of water and disrupt cell membranes.

Bisbiguanides

Chemicals such as Chlorhexidine and Alexidine that act by the disruption of cell membranes.

Alkylating Agents (Aldehydes)

Chemicals like Formaldehyde and Glutaraldehyde that inactivate enzymes and nucleic acids.

Peroxygens

Strong oxidants like Hydrogen peroxide and Benzoyl peroxide that destabilize cellular macromolecules.

Supercritical Carbon Dioxide ($CO_2$)

A gas that penetrates cells to form carbonic acid and lower intracellular pH for food preservation and medical sterilization.

Ethylene oxide

A sterilizing gas that acts as an alkylating agent to sterilize heat-sensitive materials; it is microbicidal and sporicidal.

Nisin

A natural food preservative that acts by the inhibition of cell wall synthesis.

Probiotics

A biological method of microbial control based on the use of microbial competition.

Phage Therapy

A biological method of control using viruses as a possible alternative to antibiotics.