Control of Microbial growth Flashcards
Infectious microorganisms
microorganisms that are capable of causing dz
Contaminant
microbes are present that are undesirable or wanted
Nosocomial infection
hospital acquired infection
Describe levels of contamination controls in normal house hold conditions vs general medical conditions
household =general cleanliness
general medical = general cleanliness plus greater stringency through the routine use of chemical disinfectants
Describe levels of contamination controls of strict transmission control conditions
general cleanliness plus, routine use of chemical disinfectants, and greater attention to minimizing transmission of infectious microbes by using PPE, sterile equipment, and air particle control
Describe Biosafety level 1
- No infectious microbes handled
- general good lab technique
- think highschool/college lab
Describe Biosafety level 2
- common clinical samples and several unusual pathogens
- access to lab is limited
- requires special training
Describe Biosafety level 3
- more unusual or highly transmissible pathogens, like TB
- Level 2 precautions and routine use of Biosafety Cabinet
- HEPA filter mask
- Engineering features in lab, that help contain dangerous materials
Describe Biosafety level 4
- highly infectious, exotic microbes and toxin which there is no vaccine or effective treatment
- highest levels of special protective equipment
Sterile/sterilization
sterile= free of all microbes sterilization= techniques to achieve sterilization
Disinfect/Decontamination
use of physical procedures or chemical agents to destroy, inhibit, neutralize or remove at least most infectious organisms on an objects surface
Disinfectant
agent or method used to carry out disinfection
-high, intermediate and low levels
Antiseptic
use of mild disinfectant on skin or other living tissue
Aseptic
usually refers to a technique free from contamination or infectious microorganisms
Pasteurization
applying heat to kill or significantly reduce the numbers of microbes which can causes spoilage
cide/cidal
kills`
state/static
inhibit growth
Thermolabile
altered or destroyed by heat
Thermostable
not easily altered by heat
Rank hardest to kill microbes to easiest to kill.
- Bacterial endospores
- Mycobacterium
- Protozoan cysts
- Non-enveloped viruses
- Vegetative bacteria
- Fungi
- Non-enveloped viruses
True or False Microbes are killed instantly when exposed to lethal agents
False, the become dysfunctional and die over a period of time
How does the presence of organic matter affect microbial killing
this material can protect or inactivate disinfectants, and protect microbes from heating or cooling
What does cold do to microbes
slows metabolism but does not kill most microbes
What does heat do to microbes
disrupts cell membrane making it more fluid an losing selective permeability, denatures proteins, and inactivates nucleic acids
What is more effective moist or dry heat
moist heat
What are the conditions for dry heat disinfection
160-180 C for 2 hours
What are the disadvantages to dry heat
liquids cannot be heated above boiling and organic compounds may denature
What are the conditions for moist heat disinfection
121 C for 15 minutes, large loads may require longer
What are the advantages of using an autoclave
pressure counteracts boiling
What are the conditions for autoclave disinfectant
121 C, 15 lbs or pressure, and 15 minutes
True or False pressure in the autoclave helps kills microbes
False
What are the disadvantages of using moist heat/autoclave
-Cannot be used substances that are adversely affected by heat and moisture ie dry chemicals, thermolabile substances
Define incineration and when it is used
burning or organic material, used for small metal or glass instruments in lab or to destroy medical waste
How does gamma radiation kill microbes
Nonspecifically alters cellular proteins and nucleic acids
Where is gamma radiation used for sterilization
Rx, and medical/dental supplies
How does electron beam radiation kill microbes
alters nucleic acids
Where is electron beam radiation used for sterilization
to decontaminate packages
True or False electron beam and gamma radiation are both ionizing radiation
True
How does ultraviolet radiation kill microbes
Damages nucleic acids and causes mutations
What is the optimum wave length for UV sterilizations
UV-c rays in the 240-280 nm range, best is 254 nm
What is a good source of UV-c radiation
Pulsed Xenon
What are the disadvantages of UV radiation for sterilization
-low penetrating power, and can require exposures ranging from 10 seconds to 30 minutes
Describe filtration sterilization
use of a 3D matrix membrane that has complex pores that trap microbes.
When is filtration sterilization used
used for sterilization of thermolabile liquids
What is HEPA filtration
- High-Efficiency Particulate Air filter, that uses randomly orientated glass and polymer fibers (non woven)
- traps 99.97*
How does HEPA filters capture microbes
through electrostatic interception (most impactful) and the sieve
What is a PAPR
Powered Air Purifying Respirator, includes HEPA filter, blower and hood
What is an N95
mask consisting of HEPA oven filters, 90-99% effective
What is a biological safety cabinet
a contained work area designed to prevent exposure to infectious aerosols. Airflow carries particulate from the user into an area of filtration
How does a detergent work
They dissolve weak bonds that hold the microbes together
They also loosen the adherence to skin allowing them to be washed off the skin
How long do you have to wash your hands w/ detergents to be effective
20 secs
What is cold plasma ion disinfection
an electromagnetic energy field that dissociates molecular bonds creating ions used in HVAC systems
What percentage of Glutaraldehyde is needed as a disinfectant and what is it mode of action
2-5%
-disrupts structural proteins
What percentage of H2O2 is needed as a disinfectant, what is it mode of action, how long does it work
Vaporized= 25% works in 6 hrs,
Aqueous=3% works in 2-30 minutes
-formation of free radicals, which are toxic to cells
What percentage of Phenolic compounds is needed as a disinfectant and what is it mode of action
- 4-0.5% works in 2-30 minutes
- disrupts cell walls and membranes and precipitates proteins
What is a common phenolic compound
Lysol
What percentage of Chlorine compounds is needed as a disinfectant and what is it mode of action
Gaseous-100 to 1000 ppm
Hypochlorite= 1:10 dilution of bleach
Inactivates enzymes/damages membranes
2-30 minutes
What percentage of Alcohol is needed as a disinfectant and what is it mode of action
70% most effective
dissolves membrane lipids and coagulates protein
1-10 minutes
