Microbiology 251- Ch. 13

Explain how critical items are used:

-Inside the body; penetrates body tissues
-Must be sterile
-(surgical instruments, caths, IV)

Explain how semicritical items are used:

-Contacts mucous membranes; non-intact skin; does not penetrate body tissues
-(GI endoscopes, respiratory therapy equipment)

Explain how non-critical items are used:

-Contacts unbroken skin; must be clean
-(bed linens, furniture, stethoscopes, etc.)

What is sterilization?

Eliminates all forms of life (not prions)

How is sterilization achieved?

-Physical: High heat, pressure or filtration
-Chemical: sterilants

Can boiling achieve sterilization?

No

What is aseptic technique?

Procedure used to avoid contamination of sterile surfaces

What is disinfection?

Inactivating most microbes on fomites using antimicrobial chemicals or heat (not sterile)

What is pasteurization?

Reduces the number of spoilage organisms (such as milk); extends shelf life

What conditions are necessary for high-temperature short-time (HTST) pasteurization?

72°C for 15 seconds (for regular milk)

What conditions are necessary for ultra high-temperature (UHT) pasteurization?

138°C for 2 or more seconds (for non-refrigerated milk)

What is decontamination?

Reduces pathogens to a level considered "safe"

What is sanitation?

Reduces microbial populations to levels acceptable for public health

What is degerming?

Significantly reducing microbial numbers (handwashing)

What are antiseptics?

Antimicrobial chemicals safe for use on skin surfaces (hydrogen peroxide, isopropyl alch.)

What is preservation?

Slowing/inhibiting growth of microbes in food/other products

What is the risk of breaking aseptic technique?

Patient infection; sepsis (systemic infection that can be fatal)

Does sterilization remove all vegetative cells, endospores, and viruses?

Yes

What are the main uses for sterilization?

Laboratory, medial, manufacturing, food industry settings

What is commercial sterilization?

Uses heat at low enough temperature to preserve food quality, but high enough to destroy common pathogens

-Ex: Destroying endospores like C. botulimum

What autoclave conditions result in sterilization?

121°C, 15min, 15psi (steam)

What method is necessary to destroy endospores?

Sterilization

What is the "moist heat" method of microbial control?

-Denatures proteins
-Widely used; cheap, safe, effective

What is the "boiling" method of microbial control?

-@ least 5mins; destroys most microorganisms including viruses (NOT endospores)
-Used to treat drinking water

What is the "dry heat ovens" method of microbial control?

-Destroys cell components and denatures proteins; less efficient than moist heat methods takes longer and higher heat)
-Used for laboratory glassware, powders, oils, and dry material

What is the "incinerating" method of microbial control?

-Burns cell components to ashes
-Used for inoculating loops, medical wastes, animal carcasses

What is the radiation method of microbial control?

-Used to sterilize heat-sensitive materials
-Three sources: gamma, x-rays, electron accelerators
-Some endospores can be resistant

What pore size filter does a HEPA filter use to remove microbes from the air?

0.3um

What are the types of microbe filtration?

-Air filtration
-Membrane filtration
-Liquid filtration (for heat-sensitive fluids)

What are the germicidal chemicals considered sterilants used for?

Heat-sensitive critical instruments

What are the germicidal chemicals considered high-level disinfectants used for?

To treat semi-critical items (e.g., GI endoscopes)

What are the germicidal chemicals considered intermediate-level disinfectants used for?

Disinfects non-critical instruments (e.g., stethoscopes)

What are the germicidal chemicals considered low-level disinfectants used for?

General purpose; disinfects furniture, floors, walls, etc.

Which of the germicidal chemicals eliminate endospores?

Sterilants and some high-level disinfectants

What are high-level germicides effective on?

Vegetative cells, fungi, viruses, endospores (sterilization)

What are intermediate-level germicides effective on?

Less effective on endospores and viruses

What are low-level germicides effective on?

Kills only vegetative cells and certain enveloped viruses; ineffective against endospores

What are alcohols used for as a germicidal chemical?

-Antiseptics (used on skin)

SARS-CoV-2 is an enveloped virus that may be inactivated by what germicidal chemical product?

Alcohol

The CDC recommends using hand sanitizer with ___% - ___% alcohol and rubbing hands together for at least ____ seconds?

60% - 90% ; 20 seconds

What are aldehydes used for as a germicidal chemical?

-Chemical sterilant
-Good alternative when something cannot be autoclaved (heat-sensitive)

What is the aldehyde Formalin used for?

To kill bacteria in vaccines and inactivate viruses (makes vaccines safer)

Are aldehydes used as antiseptic?

No; they are irritating to skin

What is ethylene oxide used for as a germicidal chemical?

-Sterilizes items within plastic bags
-"cold sterilization" which is gaseous
-Good alternative for heat-sensitive materials

What are bisbiguanides used for as a germicidal chemical?

-Broad spectrum antiseptic (not sterilization)
-Does not eliminate pseudomonas or mycobacterium
-Used as pre-surgery antiseptic (surgeons)
-Chlorhexidine: common ingredient in skin creams, disinfectants, mouthwash/oral rinses

What are halogens used for as a germicidal chemical?

-Commonly disinfects water (Bleach)
-Some protozoan cysts are resistant
-Betadine: medical hand scrub prior to surgery

What are heavy metals used for as a germicidal chemical?

-Bind to proteins to inhibit enzymatic activity
-Silvers: used as antiseptic (silvadene cream for burns, some catheters and bandaids)

What are phenolics used for as a germicidal chemical?

-Compound in mouthwashes and throat lozenges ( less toxic than phenols)
-Lysterine, Lysol

Who developed phenolics?

Joseph Lister: Began w/ carbolic acid (phenol) as disinfectant for surgical woulds

Why was Triclosan banned by the FDA?

The chemicals were found to not be any more effective than regular soaps

What are the bacterial cell targets of germicidal chemicals?

-DNA
-Cytoplasmic membrane
-Proteins (denaturing)

What is the purpose of assay testing for germicidal chemicals?

Similar to Kirby-Bauer; tests chemical efficacy agasint specific bacteria