OCTC-Micro-Chapter 9

Reduction in the number of microorganisms and viruses, particularly potential pathogens on living tissue.
EX: iodine, alchool
Antiseptics are frequently_________ whose strength has been ________ to make them safe for living tissues.
disinfectants, reduced
Aspetic refers to an environment or procedure free of ______.
pathogenic contaminants.
Examples of aseptic
prep of surgical field, hand washing, flame sterilization of laboratory equipment.
Scientists, laboratory technicians and health care workers routinely follow standardized _______ techniques
suffixes indicating destruction of a type of microbe.
Example of
Bactericide, fungicide, germicide, virucide
Germicides include_____ oxide, ____oxide &_____.
ethylene, propylene, aldehydes
Degerming is the
removal of microbes by mechanical means
Examples of degerming
Hand washing, alcohol swabbing at site of infection and skin scrubbing
Destruction of most microorganims and viruses on nonliving tissue
Examples of disinfectants
Phenolics, alcohols, aldehydes and soaps
The term disinfection is primarily used in relation to _____.
use of heat to destroy pathogens and reduce the number of spoilage microorganisms in food and beverages
Examples of Pasturization
milk, fruit juices, wine, and beer
in pasteurization, heat treatment is _____ to reduce alteration of taste and nutrients.
in pasteurization,______ microbes still remain and eventually cause _______.
non pathogenic, spoilage
removal of pathogen from objects to meet public health standards.
Washing tableware in scalding hot water in restaurants is an example of?
Standards of _____vary among governmental jurisdictions.
What is the only difference of disinfecting dishes at home and sanitizing dishes at a restaurant?
public (sanitization) vs. private (disinfection).
suffixes indicating inhibition, but not complete destruction of a type of microbe
What are some examples of -statis &
Bacteriostatic, fungistatic, virustatc
______ agents include some chemicals, refrigeration and freezing.
Destruction (complete removal) of ALL microorganims and viruses in or on an object
Preparation of microbial culture media and canned food is an example of what?
How is sterilization typically achieved?
by steam, under pressure, incineration,or ethylene oxide gas.
Sterilization does not apply to _____.
prions(infectious proteins that cause mad cow disease)
Only _____ destroys prions.
Commercial Sterilizationis defined as?
sufficient heat treatment to kill endospores of Clostridium botulinum in canned food.
Vegetables are available in _____ packaging
What is the use of chemical methods for eliminating or reducing microbes and viruses (particularly pathogens) on the skin or living tissue?
Antisepsis is a modification of _____?
Disinfectants destroy vegetative pathogens but not ______?
all viruses and bacterial endospores.
Unlike sterilization, disinfection suggests that
some viable microbes may persist.
Disinfectants are_____concentrated and left on the surface of _______ longer.
more inanimate objects
Antiseptic are disinfectants whose strength is ______ to make them _______?
reduced, safe for living tissue
Examples of disinfection:
1.applying a 5% solution of bleach to examining table
2.boiling eating utensils used by a sick person
3.immersing thermometers in iodine solution between use
4.combs soaked in ammonia solutions at barber shop.
What is the term that refers to microbial contamination and growth of microorganisms in blood and tissues (think septic tank)?
Process of rendering an object, person, or area free of a substance
Such as:Bacteria, poison gas, radioactive substance
Cide and cidal: Virucides
inactivate viruses
Cide and cidal: Bactericides
kill bacteria
Cide and cidal: Fungicides
kill fungal hyphae, spores, yeast.
Cide and cidal: Germicides
are chemical agents kill pathogens in general.
What is Microbial death?
permanent loss of Reproductive ability of microbes under ideal environmental conditions.
What is one way to evaluate the efficiency of an antimicrobial agent (chemical or physical)?
calculate the microbial death RATE.
What is Microbial Death Rate?
the time it takes for heat or chemicals to kill a population of microorganism under certain conditions.
Ex. Boil (212 ?F) water 10 minutes
Microbial death rate is usually ____ over time for a _____ pathogen under a ______ set of conditions.
constant, particular, particular
For example: 90% of a population of microbes is killed per minute.
In the death phase of cell population growth curve The cells die at a _____ rate. They die ______.
constant, exponentially.
The Viral envelop surrounds a _____
viral protein.
Viral Envelop is made up of proteins and phospholipids that are
Responsible for attachment of virus to target cell.
Damage to the viral envelop does what? Why?
Fatally interrupts viral replication Because the enveloped virus is now unable to attach to the host cell.
Non-enveloped viruses have _____tolerance of harsh conditions and antimicrobial agents because they do not _____ on the envelop to attach to the target cell.
greater, depend
Protein function depends on it specific _____ shape.
Microbial life depends on continuous supply of _____ to function as _____ and structural molecules.
proteins, enzymes
A perfect antimicrobial agent or method would be
1.Inexpensive and fast-acting
2.Stable during storage
3.Control all microbial growth while being harmless to humans, animals, and objects
Factors affecting Efficacy of Antimicobial methods
1.What area is to be treated?
2.How susceptible or resistant is the microbe?
3.What are the Environmental conditions?
1.What area is to be treated?
Harsh chemicals and extreme heat cannot be used on humans, animals and fragile objects.
Needles and scalpels carry a greater potential for infection so they must be sterilized.
Items that contact the skin may be disinfected
2.How susceptible or resistant is the microbe?
Select a method to kill the hardiest microbes present and Assume that more fragile microbes are killed as well.
The three most resistant microbes are:
1.Bacterial endosproes
2.Species of Mycobacterium
3.Cysts of protozoa
The Hardest Microbes to Treat (1)
1. Bacterial Endospores
Endospores of Bacillus and Clostridium are the most resistant life forms
Bacillus and Clostridium can survive in _______of temperature, chemicals, and acidity
The Hardest Microbes to Treat (2)
cell walls have a waxy coat that prevents:
1.The entrance of water based chemical
The Hardest Microbes to Treat (3)
3. Protozoal cysts wall prevents entry of:
Most disinfectants
Protects protozoa against drying
Shields protozoa against heat, and radiation
The effectiveness of germicides can be classified as _____ or ______.
high or low
_____ level germicides kill all pathogens, including bacterial endospores.
3.Environmental Conditions affect ______ of antimicrobials
High temperatures and extremely low or high pH usually ____ the effectiveness of antimicrobial agents.
Biofilms, and fat, feces, emesis, and blood usually _______ the effectiveness of antimicrobial agents. Therefore, It is very important to ______ objects before using disinfectants or sterilization.
decrease, clean
What are the four Methods for Testing or Evaluating the Effectiveness Disinfectants and Antiseptics?
1.Phenol Coefficient
2.Use-Dilution Test
3.Disk-Diffusion Method
4.In-Use Test.
1. Phenol Coefficient Test (Carbolic acid)
Phenol (carbolic acid or benzene) was used by Lister in late 1850s
Phenol was the standard to test all other disinfectants and antiseptics.
1.Phenol Coefficient Test (Carbolic acid)
Researchers evaluated the efficiency of disinfectants and antiseptics when compared to phenol (carbolic acid).
Phenol Coefficient Test has been replaced by newer methods because we
no longer extensively use phenol as a antiseptic.
2. Use-Dilution Test
Use-dilution test is another method of evaluating efficacy of disinfectants and antiseptics.
What is the first step used in the Use-dilution test?
1.Metal rings dipped into broth cultures of bacteria are dried at 37C.
What is the 2nd step used in the Use-dilution test?
2. Rings with dried cultures are placed in different dilutions of a disinfectant:
Example: control (distilled water), 2%, 5%, 15% of Clorox solution.
What is the 3rd step used in the Use-dilution test?
3. Rings stay in solution for 10 min at 20°C (68F) and rinsed.
What is the 4th step used in the Use-dilution test?
4. Rings are transferred to nutrient agar and incubated to determine whether bacteria survived disinfectant treatment
What is the 5th step used in the Use-dilution test?
5. Look for growth on agar plate. The most effective agent is the one that entirely prevents microbial growth at the highest dilution.
3.Kelsey-Sykes Capacity Test
is the standard alernative assessment approved by the European Union to determine the capacity of a given chemical to inhibit bacterial growth.
3.Kelsey-Sykes Capacity Test step 1
1. Researchers add a suspension P. aeruginosa or S. aureus to different concentrations of chemical being tested
3.Kelsey-Sykes Capacity Test step 2
2.After predetermined time, move the mixture into broth with a disinfectant deactivator
3.Kelsey-Sykes Capacity Test step 3
3.Incubate for 48 hours
3.Kelsey-Sykes Capacity Test step 4
4.Measure turbidity
3.Kelsey-Sykes Capacity Test step 5
5.Lack of turbidity indicates lack of bacterial reproduction
3. Disk-Diffusion Method aka Kirby-Bauer Method
demonstrates the effectiveness of disinfectants and antiseptics on pathogens.
Procedure for Disk-Diffusion Method
A disk of filter paper is soaked in different chemical agents and then placed on an agar plate just previously inoculated with bacteria.
Bacteria are incubated and then observed.
Disk-Diffusion Method results
A clear zone around the disk indicates inhibition called zone of inhibition.
The visible area around disk is where bacteria did not grow.
In Disk-Diffusion Method the ______
are measured to determine the microorganism’s sensitivity to the disinfectants, antiseptic or antibiotic.
zones of inhibition
The disk with the _____ zone of inhibition is the best agent to use against that particular pathogen.
4.In-Use Test
The In-Use Test is a more realistic method for determining the effectiveness of a disinfectant or antiseptic.
In The In-Use Test Swabs are taken from ______before and after application of disinfectant or antiseptic.
actual objects (operating room equipment)
Describe what happens in the In-Use Test
The swabs are inoculated onto nutrient agar plates and incubated.
The plates are monitored for growth before and after the disinfectant was used.
List the 10 types of Physical Methods of Microbial Control (Table 9.4 pg. 270)
1.Moist Heat = Boiling, Autoclaving (pressure cooking), Pasteurization and Ultrahigh-temperature sterilization.
2.Dry Heat = Hot air and Incineration
5.Desiccation (drying)
6.Lyophilization (freeze drying)
8.Osmotic Pressure
9.Ionizing radiation (electron beams, gamma rays, X rays)
10.Nonionizing radiation (ultraviolet light)
Heat = one of the older and more common means of _______.
microbial control
High Temperatures = ______ proteins, interfere with cell walls and cytoplasmic membranes, and disrupt function and structure of ______.
denature, nucleic acids
Thermal death point is
lowest temperature required to kill bacteria in a broth in 10 minutes.
Thermal death time is
the time required to kill all bacteria in a broth at a given temperature.
Decimal reduction time (D time) is the
time required to kill 90% of the population of bacteria in a sample at a given temperature
Researchers measure the effectiveness of heat sterilization by calculating the
decimal reduction time.
Thermal death time is the time it takes to completely _____ a particular volume of liquid at a set_______.
sterilize, temperature
How does high temperature control microbes in the environment?
High temperatures denatures proteins, interferes with the integrity of cytoplasmic cell walls and disrupts the function and structure of nucleic acids.
List 6 heat-related methods used in microbial control.
1.Moist heat
5.Ultrahigh-temperature sterilization
6.Dry heat
Moist Heat is used to do what 4 things?
disinfect, sanitize, sterilize, pasteurize.
4 Types of Moist heat
Ultrahigh-Temperature Sterilization
Boiling (100?C) kills _______ cells of bacteria and fungi, protozoan trophozoites, and most viruses within
vegetative, 10 minutes at sea level.
Boiling does not kill which 3 things and why?
endospores, protozoan cysts, and some viruses. because they can survive boiling for 10 minutes at sea level
Will it require longer boiling time in Denver or Los Angeles?
It takes a longer boiling time in Denver.
Why does it require longer boiling time in Denver or Los Angeles?
Water boils at lower temperatures at higher elevations because there is less air pressure and steam escapes more quickly and pulls of excess heat.
When is an autoclave required?
An autoclave is used when sterilization is required.
Autoclaving does not let the ____escape and water will boil at a ____temperature.
steam , higher
Autoclaves are used to sterilize ____?
medical and laboratory supplies that can tolerate heat and moisture.
The Autoclave conditions are?
121?C, 15 psi, 15 minutes.
what are used to check for sterility of the items being autoclaved.
Bacillus stearothermophilus endospores
Pasteurization is a method of _____ & ______Without altering the quality of the food
Heating foods to kill pathogens
Control spoilage organisms
Pasteurization is used for:
Ice cream
Fruit juices
Beer and Wine
Pasteurization is not
Dairy industry and other food processors use:Ultrahigh-temperature sterilization
To rid liquids of
all living microbes.
Liquids are passed through super heated steam at 140?C (284?F) for 1-3 second, then rapidly cooled. What is this?
Ultrahigh-temperature sterilization
milk and other liquid products passed through Ultrahigh-temperature sterilization can be
stored indefinitely at room temperature.
What is a better conductor of heat… water or air?
What is more effective in controlling microbes in the environment… moist heat or dry heat?
Moist heat is more effective than dry heat because water is better conductor of heat than air.
At sea level, what does boiling at 100C kill? What does it not kill?
Boiling (100?C) kills vegetative cells of bacteria and fungi, protozoan trophozoites, and most viruses not kill endospores, protozoan cysts, and some viruses
In Denver, will water boil at a greater than 100C or less than 100C?
less then because Water boils at lower temperatures at higher elevations because there is less air pressure and steam escapes more quickly and pulls of excess heat.
Will it take longer or less time to boil water for 10 minutes to kill microbes in Los Angeles as compared to Denver?
less time because there is more pressure
device that uses steam heat under pressure to sterilize chemicals and objects that can tolerate moist heat.
Autoclaving needs less than _____to sterilize an object at _______.
15 mins, 121 C
Autoclaving denatures______ and destroys______.
proteins, membranes
the use of heat to kill pathogens and reduce the number of spoilage microorganisms in dairy products, fruit juices, beer, and wine
4 types of pasteurization of milk:
1.Historical (batch) pasteurization
2.Flash pasteurization
3.Ultrahigh-temperature pasteurization
4.Ultrahigh- temperature sterilization:
Categories: Microbiology