Microbial Control and Biosafety

• destruction of all forms of life including bacterial spores

• chemical or physical methods

• destruction of some forms of life except bacterial spores

• chemical or physical methods

applied to inanimate objects

applied to skin; cannot be used as disinfectants

• presents variability to withstand chemical and physical treatment

• biochemical composition and mechanisms to protect themselves

• rich in proteins, lipids, and carbohydrates

• rich in dipicolinic acid and calcium

bacterial spores are rich in?

Cell walls of mycobacteria are rich in?

total number of organisms present

• most likely composed of organisms with varying degrees of susceptibility to killing agents

• not all the organisms die at the same time

higher number of organisms require?

• amount of disinfectant needed to destroy microorganisms

• varies with the different agents

___ affects killing activity by inactivating the disinfecting agent

examples of organic materials are?

easily inactivated by organic material

• amount of time a disinfectant or sterilant is in contact with the object

• Advantages: reliable effects, ease of use, shorter time and cost effective

• most common method of disinfection and sterilization

heat under steam pressure

application of autoclave

autoclave is the sterilization/disinfection method for?

• longer exposure times & higher temperature

• Sterilization method for heat-stable substances that are not penetrated by moist heat

Dry heat is the sterilization method for?

Boiling kills most microorganisms in approximately ___ minutes

• eliminates food-borne pathogens & organisms responsible for food spoilage

• reduces spoilage of food without affecting its taste

Pasteurization is done at ___ and ___ C

Autoclave temperature

Duration time of autoclave

Temperature of oven (dry heat)

duration time of oven

Temperature of Boiling

duration time of boiling

temperature of pasteurization (flash method)

temperature of pasteurization (batch method)

Duration time of pasteurization (flash method)

Duration time of pasteurization (batch method)

Does an autoclave application sterilize or disinfect?

Dry oven application

Boiling steam application

Pasteurization flash method application is a form of?

Pasteurization batch method application is a form of?

thin membrane filters composed of plastic polymers or cellulose esters containing pores

pore size for bacteria, yeasts, and molds

pore size for critical sterilizing

pore sizes for small viruses

Liquid filtration is the sterilization method for?

• use of high-efficiency particulate air (HEPA) filters

• used in laboratory hoods and in air systems

air filtration removes microorganisms larger than?

• short wavelength and high energy

Gamma rays or electron beam

Radiation is the sterilizing method for?

UV rays are?

long wavelength and low energy

non-ionizing is the sterilization method for?

• for sterilization

• used mainly as disinfectants

chemical agents that may be used to sterilize

Denatures proteins; makes proteins soluble

Skin disinfectants (iodophor)

Used to disinfect drinking water and surface disinfectants

Inactivates proteins

Reacts with water to form hyperchlorous acid (HClO); oxidizing agent

• Precipitates Proteins

• Eyedrops (1% Solution)

• Reacts with -SH group; lyses cell membrane

• Disinfectant; toxic at high concentrations

• Skin Antiseptics; disinfectants

• Disrupt cell membrane

• Disinfectant at high concentrations; used in soap at lower concentration

• Denatures proteins; disrupt cell membranes

• Sterilization of heat-sensitive objects

• Alkylating agent

• antiseptics and disinfectants

• principle: inactivate microorganisms by denaturing protein

• disadvantage: inactivated by organic materials

Alcohol used for disinfection/antiseptic?

• principle: Reaction with the thiol (–SH) groups of enzymes

• disadvantage: carcinogenic agent

• not recommended (in any form) be used as a disinfectant or sterilant on a routine basis

Formaldehyde used?

Formaldehyde is the sterilization method for?

• principle: inactivation of DNA and RNA through alkylation of sulfhydryl and amino groups

• advantage: rapid killing action; remains active in the presence of organic materials (active at alkaline)

• disadvantage: extremely susceptible to pH changes

glutaraldehyde disinfectant uses ___% of solution for ___ mins

glutaraldehyde sterilant solution?

glutaraldehyde is used as sterilant for?

• principle: degrades microbial cell walls and cytoplasm, denatures enzymes, and coagulates chromosomal material

• antiseptic

• advantage: less irritating, nonstaining, and more stable

Iodine can be used in two forms as antiseptics:

Contact time for iodophors

iodophor solution?

forms of hypochlorite

• principle: oxidative effects of hypochlorous acid

• disadvantages: long exposure time required for sporicidal action; inactivated by organic materials

hypochlorite disinfectant

contact time for hypochlorite

recommendation of CDC for blood spills

Hypochlorite is the disinfection method for?

• principles: reducing the surface tension of molecules in a liquid; disruption of the cellular membrane, resulting in leakage of cell contents

• disadvantages: effectiveness is reduced by hard water & soap; inactivated by organic materials

Quarternary Ammonium Compound is the disinfection method for?

principle: disruption of cell walls leading to precipitation of proteins

• commonly found as ingredients of germicidal soaps

disruption of enzyme system

Phenolics disinfects?

• topical antiseptic

• principle: disrupts the microbial cell membrane and precipitates cellular contents

• advantages: strong affinity to the skin and mucous membranes; not significantly affected by organic materials

• disadvantage: affected by pH

Chlorhexidine Gluconate is used to disinfect?

• effective against gram-positive bacteria (3% for 15-30 seconds)

• principle: interrupts bacterial electron transport

inhibits membrane-bound enzymes

ruptures bacterial membranes

• principle: microbial cell wall disruption and enzyme inactivation

• advantage: unaffected by organic materials

• disadvantage: neutralized by nonionic surfactants andpolyethylene glycol

** low antimicrobial efficacy compared with iodines, iodophors, and CHG in reducing skin flora

Chloroxylenol is the disinfection method for?

• advantage: not significantly affected by organic materials

• disadvantage:

• affected by pH, surfactants and emollients

• formulation significantly affects activity

• absorbed through intact skin

• consumer and professional health care products

Triclosan good activity

Triclosan has fair activity on?

Triclosan poor activity