Control of Microbes Flashcards

Flashcards covering the control of microbes, including sterilization methods, physical and chemical controls, and evaluation of effectiveness.

Sterilization

The complete removal or destruction of all microbes, including even spores and viruses.

Disinfection

The killing, inhibition, or removal of disease-causing microbes, usually on inanimate objects.

Sanitization

The reduction of microbial populations to levels deemed "acceptable."

Antisepsis

The prevention of infection of living tissue by microorganisms using chemical agents.

Germicides

Agents which kill pathogens but not endospores.

Statics

Agents which prevent growth; if the agent is removed, microbial growth continues.

Microbial Death

The state where microorganisms are unable to reproduce in conditions that normally support their reproduction.

Moist Heat

Physical control method that degrades nucleic acids, denatures proteins, and disrupts membranes.

Dry Heat Sterilization

Method that oxidizes cell constituents and denatures proteins; it requires higher temperatures and longer exposure times than moist heat.

Thermal death time (TDT)

The shortest time needed to kill all microbes in a suspension at a specific temperature and under defined conditions.

Decimal reduction time (D value)

The time required to kill $90\%$ of microbes or spores in a sample at a specific temperature.

Z value

The increase in temperature required to reduce the D value by $1/10$.

F value

The time in minutes at a specific temperature needed to kill a population of cells or spores.

Autoclaves

Devices that use saturated steam under pressure to reach temperatures above boiling to kill endospores efficiently.

Flash pasteurization

A high temperature short-term (HTST) process involving heating at $72^\circ\text{C}$ for $15$ seconds followed by rapid cooling.

Ultrahigh-temperature (UHT) sterilization

A process using temperatures of $140$ to $150^\circ\text{C}$ for $1$ to $3$ seconds.

Depth filters

Thick fibrous or granular filters that remove microorganisms by physical screening, entrapment, and/or adsorption.

Membrane filters

Porous membranes with defined pore sizes that remove microorganisms primarily by physical screening.

HEPA filters

High-efficiency particulate air filters used for large volumes of air, such as in laminar flow biological safety cabinets.

UV radiation

A radiation method limited to surface sterilization because it does not penetrate glass, dirt films, water, and other substances.

Ionizing radiation

Radiation that penetrates deep into objects to destroy bacterial endospores; gamma radiation is used for food and plastic supplies.

Phenolics

Disinfectants that act by denaturing proteins and disrupting cell membranes; they are tuberculocidal and effective in the presence of organic material.

Iodophore

A complex of iodine with an organic carrier used as a skin antiseptic.

Quaternary Ammonium Compounds

Detergents with hydrophilic and hydrophobic ends; cationic versions are effective disinfectants that kill most bacteria but not M. tuberculosis or endospores.

Phenol coefficient test

A test where the potency of a disinfectant is compared to that of phenol; values $>1$ are more effective than phenol.

High-level disinfectants

Germicides that destroy vegetative bacterial cells including M. tuberculosis, bacterial endospores, fungi, and viruses.

Intermediate-level disinfectants

Germicides that destroy vegetative bacterial cells, M. tuberculosis, fungi, and viruses, but not endospores.