Which are ways that infection may spread in a dental clinic
- airborne organisms
- improper sterilization
- Direct contact
- Indirect contact
According to Spauldings classifications, When is an instrument needing critical disinfection? and what is the process of disinfection
Critical is when equipment has entered sterile tissues, including the vascular system
They need cleaning followed by sterilization
According to Spauldings classifications, When is an instrument needing Semi-critical disinfection? and what is the process of disinfection
Semi-critical is when equipment comes into contact with non-intact skin or mucus membranes, but hasn’t penetrated them
They need cleaning, with high level disinfection as a minimum. (sterilization is preferred)
According to Spauldings classifications, When is an instrument needing non-critical disinfection? and what is the process of disinfection
Equipment that touches intact skin, or doesn’t touch the patient
the need cleaning, followed by low level disinfection (some cases cleaning alone is acceptable)
What is sterilization
the complete absence of life
what is disinfection
destruction of vegetative pathogens, usually on inanimate objects
What does the suffix - cides mean
agents that kill
what does the suffix - static mean
agents which prevent growth
What is sepsis
bacterial contamination and growth
What is antiseptic
agent which destroys vegetative pathogens (usually on living tissue)
What is sanitation
Lowering bacterial counts to safe public health levels
is the death rate of microbes log linear
yes, a certain percentage of the bacteria die over time
what is D-value (death of microbes)
the time required to kill 90% of bacteria (1 log) at a specific temperature
How do log reduction and percent kill relate
for each log reduction 90% of the bacteria are killed 1 log = 90% 2 log = 99% 3 log = 99.9% 4 log = 99.99%
Which is better at disinfecting, sanitizing, and sterilizing: Moist heat or Dry heat
moist heat (dry heat requires longer time, and higher temperatures)
how does heat kill bacteria
by denaturing proteins and destroying cytoplasmic membranes
What are the four methods of microbial control that use moist heat
- boiling
- autoclaving
- pasteurization
- Ultra-high temperature sterilization
What can boiling kill in terms of microbes
vegetative cells of bacteria and fungi
viruses
protozoan trophozoites
What is important to consider when boiling to kill microbes
the boiling time (more time if at higher locations
What can’t boiling kill in terms of microbes
endospores
protozoan cysts
prions
What is autoclaving
when pressure is applied to boiling water, which prevents the escape of steam. this leads to increased temperature (121 C)
Does autoclaving kill endospores
yes
What is historical (batch) pasteurizaition
heating up something to 63 degrees celcius for 30 minutes
What is flash pasteurization
72 degrees celcius for 15 seconds
When do you use dry heat to sterilize
when you have materials that will be damaged by moist heat, or those that can’t be sterilized with moist heat
what is the ultimate means of sterilization
incineration
What is membrane filtration
running a liquid medium through a filter with specific pore sizes to trap desired organisms
What is ionizing radiation, and how does it kill bacteria
shooting wavelengths of less than 1nm, it disrupts bonding, and creates ions that denature DNA and other molecules
how effective is ionizing radiation against bacteria
it isn’t very effective, it is more lethal to humans than to bacteria
what is non-ionizing radiation
radiation with wavelengths greater than 1 nm.
what is non-ionizing radiation used for
disinfecting air, transparent fluids, and surfaces of objects
How does contact time affect disinfection
longer time = more effective
how is disinfection affected by Temperature
hotter = more effective
how is disinfection affected by pH
dependent on each chemical
how is disinfection affected by Bioburden
more microbes = need a longer time
how is disinfection affected by Extraneous matter
organic matter inhibits many disinfectants
how is disinfection affected by proper exposure
it insures the agent gets in
how is disinfection affected by disinfectant concentration
higher = better, with alcohols as the exception
List these from least to most resistant to disinfection spores fungi mycobacteria non-enveloped viruses enveloped viruses gram positive bacteria gram negative bacteria prions
envelopped viruses and gram positive bacteria fungi and gram negative bacteria non-enveloped viruses spores and mycobacteria prions
What are the characteristics in the disinfectants with phenol (phenolics)
- intermediate to low level disinfectants
- Denatures proteins and disrupt cell membranes
- remain active for a long time
- ineffective against many naked viruses
What are the characteristics of alcoholic disinfectants
- intermediate level disinfectants
- denature proteins and disrupt cytoplasmic membranes
- evaporate rapidly
- good surface disenfectants
- no activity on spores
do alcohols have activity against spores
nope
do isopropyl alcohol inactivate naked viruses
nope
What are the characteristics of halogen disinfectants
intermediate-level antimicrobial chemicals
damage via oxidation, or denaturing proteins
iodine tablets, iodophors, chlorine, bromine
What easily inactivates halogen disinfectants
organic material
What are the characteristics of oxidizing agents as disinfectants
high-level disinfectants
kill via oxidation
hydrogen peroxide, ozone, peracetic acid
what is peracetic acid particularly effective against
spores, used to sterilize equipment
What are the characteristics of surfactants as disinfectants
reduce surface tension of solvents to make them better at dissolving solutes
soaps, detergents, and quats
Where are quats used, and what type of disinfectant are they
they are surfactants, and they are used in medical, food, and industrial applications
What are the characteristics of heavy metals as disinfectants
alter the 3-D shape of proteins
low level bacteriostatic and fungistic agents
1% silver nitrate used to prevent blindness (gonorrhea)
copper used to control algal growth
What are the characteristics of aldehydes as disinfectants
cross link groups to denature proteins and inactivate nucleic acids
glutaraldehyde both disinfects, and sterillizes (long exposure)
formalin used in embalming and disinfection
What are the characteristics of gaseus agents as disinfectants
denature proteins by cross linking functional groups
used in hospitals and dental offices
can be hazardous, carcinogenic, poisonous, and flammable
Does cellulose in paper towels inactivate iodophores
Yes
Does the glutaraldehyde used in hospitals do a good job of killing HPV
nope
What kind of filters are used to filter microbes out of the air
HEPA filters
What is the air sampling device that mirrors the human respiratory system
the Anderson sampler
how long can airborne microbes stay in the air
hours
What type of handwash seems to be the best and killing microbes
chlorhexidine
What are HAI’s
Hospital acquired infections
what is the best disinfectant for countertops
70-80% ethanol
What is the best disinfectant for large areas (floors)
substituted phenols or quats
what is the best disinfectant for semicritical instruments
steriplex SD
what is the best disinfectant for sterilization of heat-labile instruments
H2O2 Gas plasma
What does HEPA filter stand for
High Efficiency Particulate Air Filter
