Lecture 5 Flashcards
HD
Containment required for Risk group 1
Good industrial large scale practices(image gilespy bowler)
Containment required for Risk group 2
Level 1 containment
Containment required for Risk group 3
Level 2 containment
Containment required for Risk group 4
Level 3 containment
What risk group is: Low individual and community risk. A microorganism that is unlikely to cause human disease or animal disease of veterinary importance
Risk Group 1 - open lab
What risk group is: Moderate individual risk, limted community risk. Can cause human disease but is unlikely to be a serious hazard to laboratory workers. Eg: Salmonella food poisoning.
Risk group 2 - aseptic lab practises
What risk group is: High individual risk, low community risk. A pathogen that usually causes serious human disease, but does not orinarily spread from one infected individual to another. Prophylaxis and treatment may be available
Risk group 3 - fume hood practises
What risk group is: High individual and community risk. A pathogen that usually causes serious human or animal disease and may be readily transmitted from one individual to another. No effective prophylaxis or treatment is available eg. Ebola virus
Risk group 4 - space suit y’all
What is prophylaxis
Measure taken to prevent the occurrence of disease - e.g. disinfection, immunization
What are 2 varieties of methods used to control microbial growth?
Physical methods and Chemical agents
What are 6 types of physical methods used to control microbial growth?
DHORFL
- Desiccation
- Heat
- Osmotic Pressure
- Radiation
- Filtration
- Low Heat
Define Sterilization
The destruction of all forms of microbial life, including most resistant forms.
What is the most common method used for sterilization?
Heating
Term for heat treatment when food is subjected to only enough heat to destroy the endospores of Clostridium botulinum, which can produce deadly toxins.
commercial sterilization
Define Disinfection
Control directed at destroying harmful microorganisms . It usually refers to the destruction of vegetative (non-endospore forming) pathogens.
True or False - Disinfection is the use of a chemical (a disinfectant) to treat an inert surface or substance.
True
When this treatment is directed at a living tissue, it is called ___________and the chemical is then called an ______________.
antisepsis, antiseptic.
When your skin is swabbed with alcohol before a jab what is that process called?
Degerming - removing not killing
Referring to disinfection and antisepsis when it comes to restaurant glassware, china, and tableware are subjected to ______
Sanitization
Names of treatments that cause the outright death of microbes have the suffix _____meaning kill
cide
What is an endospore?
Type of spore formed intracellularly by the parent cell or hyph
What would fungicide do?
Kill fungi
What would virucide do?
inactivate viruses
What would biocide and germicide do?
Kill microorganisms
The suffix -stat or -statis, means to
stop or to steady
Bateriostatis
Temporarily stop growth
Sepsis indicates?
bacterial contamination
Asepsis is?
absence of signification contamination - like aseptic techniques
If the death curve is plotted logarithmically, the death rate is
constant
What are 4 factors influence the effectiveness of antimicrobial treatments?
- The number of microbes
- Environmental influences
- Time of exposure
- Microbial characteristics
What are two of the earliest techniques used for microbial control?
Drying (desiccation) and salting (osmotic pressure)
Define Thermal death point (TDP)
the lowest temperature at which all microorganisms in a liquid suspension will be killed in 10 minutes.
Define Thermal death time (TDT)
the minimal length of time for all bacteria in a liquid culture to be killed at a given temperature.
Define Decimal Reduction time (DRT or D value)
DRT is the time, in minutes, in which 90% of a population of a given bacteria at a given temperature will be killed.
Autoclaving like boiling is a moist heat microbial control what 2 factors are involved in this method of control?
Steam and pressure
What are 2 ways to check that an autoclave sterilization has worked?
Colour changing tape, and endospore impregnated strips
Thermoduric refers to …..
Heat resistant bacteria - duric - durable
HTST pasteurization heat and time is
135C, 1-2 sec
UHT milk pasteurization heat and time is
72C- 85C for 15sec
Dry Heat kills by _________ effects.
oxidation
Simplest form of dry heat sterilization is
direct flaming incineration
During dry heat sterilisation, items are place in a _______ and set to _____C for nearly _____ hours
oven, 170C, 2
Why is slow freezing more harmful to bacteria?
the ice crystals that form disrupt the cellular and molecular structure of the bacteria.
What is Lyphilization
Freeze-Drying - quickly and water removed via high vacuum
What is the temperature range used for Lyphilization ?
-54C - 72C
Can organisms that have undergone lyphilization be revived at any time by hydration with a suitable liquid nutrient medium.
yes
In the absence of water, a condition known as __________ where microorganisms cannot grow or reproduce but can remain viable for years.
desiccation
The use of high concentrations of salts and sugars to preserve food is based on the effects of ___
osmotic pressure
What are two types of radiation?
Ionizing and Non-Ionizing
The vegetative stage in organisms life cycle where______
nutrition and growth predominate as opposed to sexual reproduction or dormancy.
The three bacteria used in the use-dilution test are?
Salmonella choleraensuis, Staphylococcus aureus and Pseudomonas aeruginosa
What are two types of Evaluating Disinfectant
Use-dilution test andThe disk-diffusion test
In the disk diffusion test - Disks containing antibiotics are commercially available and used to determine what?
microbial susceptibility to antibiotics.
Alcohols effectively kill bacteria and fungi but not
endospores and non-enveloped viruses.
Two of the most commonly used alcohols are
ethanol and isopropanol
The recommended optimum concentration of alcohol is 70%, but concentrations between 60-95% seem to kill as fast. Why is pure ethanol less effective than aqueous solution? (ethanol mixed with water)
because denaturation requires water
Define Fomites
Inanimate objects that may be contaminated with infectious organisms and serve in their transmission.
Rodac agar plates are when Agar fills the entire dish to produce a ______ surface, which is then______
Convex, pressed against the surface to be sampled
Swab-rinse technique is where?
A sterile cotton swab is moistened with a buffer or other solution and rubbed over the surface to be sampled
