methods of microbial control Flashcards
process that destroys less than 100% of microbes on non-living surfaces. Unable to kill endospores which are the most difficult type of microbe to treat. Examples include applying 5% bleach soln to an operating table and boiling eating utensils after use by sick patients
Disinfection
Process that destroys 100% of microbes (even endospores) on non-living surfaces.
Sterilization
process that destroys less than 100 % of microbes on living surfaces. Examples include swabbing skin with iodide prior to surgery and washing your hands with soap.
Antisepsis
any process that removes microbes and other debris or contaminants to “safe levels.” Examples include washing plates and cups.
Decontamination
Microbicidal/microbistatic:
agents that kill microbes
Microbicidal
Microbicidal/microbistatic:
agents that temporarily inhibit the reproduction of microbes, but do not kill them.
Microbistatic
Factors that affect the rate at which microbes are killed include:
ENARA
1) exposure time to agent (the longer the material is exposed to agent, the more microbes will be killed)
2) number of microbes present on surface (the more microbial contamination, the longer it will take to disinfect it)
3) amt of organic debris or contaminants
4) resistance level of microbes (endospores vs non-endospores);
5) activity level of the agent (cidal versus static).
Category of microbial control methods:
Include heat, filtration, UV radiation and US vibration
Physical control method
Category of microbial control methods:
Include the use of sterilants, disinfectants, antiseptics and sanitizers
Chemical control method
Category of microbial control methods:
Include filtration and US vibration
Mechanical control method
Antimicrobial agents damage microbes by disrupting the:
1) cell wall;
2) cell membrane;
3) proteins;
4) NA (DNA or RNA).
T or F:Mechanical agents (filtration) physically remove microbes but do not kill them.
True
Non-ionizing/ionizing radiation:
causes breakage in microbial DNA.
Ionizing radiation
Non-ionizing/ionizing radiation:
uses ultraviolet light to form dimers between neighboring thymines in the DNA.
Non-ionizing radiation
effective physical control agent that can be delivered in both moist (steam sterilization, pasteurization) and dry (bacti-cinerators and ovens) forms.
Heat
Heat helps control microbial growth by…
Destroying or denaturing structural and regulatory proteins.
Chemical antimicrobials range from low-level disinfectants, to intermediate-level disinfectants, to high-level sterilants. Antimicrobial chemicals include:
SCHHAAPPP
1) halogens;
2) phenolics;
3) chlorhexidine;
4) alcohols;
5) peroxides;
6) soaps and detergents;
7) heavy metals;
8) aldehydes; and
9) preservatives.
Microbial control (reduction and elimination) methods can be classified based upon their level of effectiveness against different types of microbes: Treatment include bacterial endospores, which form a 3-layer coat of protection, and acid-fast Mycobacteria which have a waxy cell wall.
Highest level of resistance
Microbial control (reduction and elimination) methods can be classified based upon their level of effectiveness against different types of microbes: Treatment include protozoans in both cyst and vegetative form, Gram-negative bacteria, which have an outer membrane, porins and drugs pumps, as well as fungi, which have a cell wall made of chitin.
Intermediate level resistance
Microbial control (reduction and elimination) methods can be classified based upon their level of effectiveness against different types of microbes: Treatment include naked viruses, Gram-positive bacteria, and enveloped viruses.
Low level resistance
Microbes that grow best at cooler temperatures ranging from -5°C to 20°Celsius.
Psychrophiles and psychrotrophs
Microbes that include most disease-causing forms of bacteria, grow best at temperatures ranging from 20°C to 40°C.
Mesophiles
Microbes that include bacteria growing in hot springs and deserts, prefer warmer temperatures ranging from 40°C to 80°C.
Thermophiles
Microbes that can be found in geysers and volcanoes, grow best at temperatures above 80°C.
Hyperthermophiles