Control of Microbial Growth Flashcards

Vocabulary flashcards covering physical and chemical control methods of microbial growth, biological safety levels, clinical cleanliness classifications, and disinfectant effectiveness testing.

Sterilization

The complete removal or killing of all vegetative cells, endospores, and viruses from an inanimate item or organism.

Disinfection

The inactivation or killing of microbes on inanimate surfaces (fomites) using heat or antimicrobial chemicals, which does not guarantee the destruction of all endospores.

Sanitization

The reduction of microbial load on an inanimate item to safe public health levels through heat or chemical application.

Antisepsis

The reduction of microbial load on living tissue or skin through the application of an antimicrobial chemical.

Degerming

The reduction of microbial load on skin or tissue through gentle to firm scrubbing combined with the use of mild chemicals, such as handwashing.

Critical Items

Medical items that must be sterile because they come into direct contact with sterile tissue or enter the bloodstream.

Semicritical Items

Medical items that require high disinfection rather than sterilization because they contact non-sterile tissue or mucous membranes without penetrating tissue.

Noncritical Items

Medical items that contact intact skin without penetrating tissue and do not require sterilization, such as stethoscopes.

Bactericidal

An agent or treatment that results in the direct killing of bacteria.

Bacteriostatic

An agent or treatment that inhibits or stops the growth and division of bacteria without directly killing them.

Decimal Reduction Time (DRT)

The amount of time in minutes required to kill $90\%$ (a $1\text{-log}$ reduction) of a population of microbes under a specific condition.

Thermal Death Point (TDP)

The lowest temperature required to kill all microorganisms in a liquid sample in $10\,\text{minutes}$.

Thermal Death Time (TDT)

The length of time required to kill all microorganisms in a sample at a specified temperature.

Autoclave

A sterilization device that uses pressurized steam, typically set to $121\,^\circ\text{C}$ at $15\,\text{psi}$ for roughly $20\,\text{minutes}$, to kill endospores and viruses.

HTST Pasteurization

High-Temperature Short-Time pasteurization, where milk is heated at $72\,^\circ\text{C}$ for $15\,\text{seconds}$ and then bottled and refrigerated.

UHT Pasteurization

Ultra-High-Temperature pasteurization, where milk is heated at $138\,^\circ\text{C}$ for $2\,\text{or more seconds}$ and sealed in airtight containers for storage up to $90\,\text{days}$ without refrigeration.

Pascalization

A high-pressure physical control method ($100\text{--}800\,\text{MPa}$) used in food processing to denature proteins and induce cell lysis.

Lyophilization

A desiccation process involving rapid freezing under vacuum to inhibit metabolism, used for long-term preservation of foods, laboratory cultures, or reagents.

Ionizing Radiation

High-energy radiation (X-rays and gamma rays) that penetrates cells, alters molecular structures, and introduces double-strand breaks into DNA.

Nonionizing Radiation

Radiation such as ultraviolet light that does not deeply penetrate surfaces but damages exposed cells by forming thymine dimers in DNA, leading to lethal mutations.

Sonication

The use of high-frequency sound waves to induce bubble formation inside cells, leading to cellular lysis.

HEPA Filter

High-efficiency particulate air filter designed with physical pore barriers (usually $0.2\,\mu\text{m}$ or smaller) capable of trapping microbes and viruses.

Phenolics

Chemical disinfectants featuring a benzene ring with an $-\text{OH}$ group (e.g., cresols, triclosan) that denature proteins and disrupt cell membranes.

Iodophor

A complex of iodine bound to an organic molecule, increasing iodine stability and providing slow, continuous release.

Surfactants

Chemical compounds (such as soaps and detergents) that lower the surface tension of water to assist in mechanical removal of microbes or cell membrane disruption.

Quaternary Ammonium Compounds (Quats)

Cationic detergents that mimic phospholipids and insert into bacterial cell membranes, causing membrane disruption.

Bisbiguanides

Cationic antiseptic molecules (e.g., chlorhexidine, alexidine) that disrupt microbial cell membranes and are used for surgical hand scrubs.

Alkylating Agents

Chemical disinfectants and sterilants (e.g., formaldehyde, glutaraldehyde, ethylene oxide) that replace hydrogen atoms with alkyl groups, inactivating enzymes and nucleic acids.

Peroxygens

Strong oxidizing agents (e.g., hydrogen peroxide, benzoyl peroxide, ozone gas) that produce oxygen free radicals to disrupt cellular macromolecules.

Supercritical Fluid

A state of a chemical (such as supercritical $\text{CO}_2$) brought above its critical temperature and pressure to exhibit properties between a liquid and a gas, penetrating cells and lowering intracellular pH.

Phenol Coefficient

A historical standard measuring the efficacy of a disinfectant relative to that of phenol.

In-Use Test

A clinical assay used to determine whether an actively used disinfectant solution in a facility has become contaminated with microorganisms.