Hygiene and disinfection Flashcards
What are examples of infectious agents?
bacteria
viruses
fungi
prions
What is vegetative bacteria?
where bacteria grow and reproduce
What is spore bacteria?
in a form of hybernation
What are examples of spore bacteria?
clostridium and bacillus spp.
What is the chain of infection?
What is a bacterial infectious agent?
staphlococcus aureus
What is the reservoir for S. aureus?
The nasal vestibule
What is the portal of exit for S. aureus?
draining a wound
sneezing
What is the portal of entry for S. aureus?
skin and intravascular devices
mode of transmission of S. aureus?
contaminated hands
Who is a susceptible host for S. aureus?
chronic conditions…
diabetes
cancer
eczema
lung disease
What are the steps in the decontamination cycle?
When is the decontamination cycle important?
for not single use items
Decontamination definition
the combination of processes including cleaning, disinfection and/or sterilisation , used to render a re-usable item for further use
What are the overall aims of decontamination?
- make the item safe for staff to handle without presenting an infection hazard
- make the item safe to use on a patient
Cleaning definition
the process that physically removes soiling including large numbers of micro-organisms and the organic material on which they thrive
Is there a standard methodology for cleaning procedure?
yes
Disinfection definition
reduction i the number of viable micro-organisms on a product to a level previously specified as appropriate for its intended further handling or use
What is a cidal effect of microorganisms?
killing of organisms
What is a static effect on microorganisms?
reduction in reproduction of organisms
What are disinfectants often?
chemicals
What are the main ways chemicals can cause a static effect?
modification of proteins
What are the main ways chemicals cause a cidal effect?
disruption of cell membrane
What are example of chemicals causing a cidal effect by disruption of the cell membrane?
alcohol
detergents
phenol (rarely used)
What are examples of chemicals causing a static effect by modification of proteins?
chlorine
iodine
heavy metals
hydrogen peroxide
formaldehyde
string acids/alkalis
What chemicals are used to modify the nucleic acids of bacteria?
dyes e.g. crystal violet
Other than chemical disinfection, what else can be used?
thermal disinfection
e.g. washer-disinfector
What are the 3 things you should consider when carrying out the risk assessment of a disinfective agent?
toxicity
shelf-life
ease of use
Sterile definition
the process to render a product sterile
subject to a sterilisation process there is less than 1 in a million chance probability of a surviving organism
What are the 4 methods of sterilisation?
heat
chemical
radiation
filtration
How does heat sterilise?
destruction of micro-organisms by denaturing proteins
What are 3 types of heat sterilisation?
dry heat
moist heat
pasteurisation
What is the most common type of heat sterilisation in dentistry?
moist heat
What temperature is dry heat sterilisation carried out and for how long?
180 d.c.
2 hours
What can sterilise at a lower temperature; moist or dry heat?
moist heat
steam
What is the most common form of moist heat sterilisation?
autoclave
What should be carried out before autoclave sterilisation?
items must be
cleaned
rinsed
dried
Can instruments in an autoclave be touching?
no
Wat are the 2 types of autoclave?
non-vacuum (type N)
Vacuum (type B)
How does the non-vacuum autoclave (Type N) sterilise?
bench top autoclave
do not have a vacuum
rely on gravity displacement
instruments not wrapped up
How does the vacuum autoclave (Type B) sterilise?
Forced air removal for porous loads and wrapped instruments.
What is the advantage of a type B autoclave?
the instruments come out already wrapped
What is the temperature, pressure and time required to safely sterilise dental equipment?
pressure: 2.25 bars
temp: 134 d.c.
time: 3 mins
For some plastics/instruments, what is the alternative to autoclave sterilisation?
chemical gas
ethylene oxide (most common)
alkylates and nucleic acids
UV
x-rays
filtration
Can radiation be used for sterilisation?
yes
Do spores need a higher dose of UV radiation for sterilisation?
yes
x10 higher dose to kill spores
What can X-ray sterilisation kill and not kill?
kill vegetative cells
spores more resistant
When would you use filtration for sterilisation?
useful for liquids such as IV infusion
air in hospitals theatres
What is used for filtration sterilisation?
membrane filter, different sizes depending on what microorganism you want to filter out
What constitutes high risk category?
items which penetrate skin
enter sterile body areas
contact with severely ulcerated mucous membranes
How would you decontaminate high risk category instruments?
sterilisation
(autoclave, EO etc)
What constitutes intermediate category?
contact with intact mucous membranes or non-intact skin
How would you decontaminate intermediate risk instruments?
sterilisation/ disinfection (heat, chemical)
What constitutes low risk category?
contact with intact skin or not in contact with patient
How would you decontaminate low risk category instruments?
cleaning (general-purpose detergent)
