Transmission of infection Flashcards
What is virulence
The ability of the microbe to cause disease
What is dose
The number of microbes entering the body
What is ID50
Infectious dose 50 (how an infectous dose is expressed)
What is the infectios dose of TB
1 bacillus
What is the infectous dose of Syphilis
57 bacteria
What is the incectious dose of E. coli 0157
<10 cfu
What is the infectious dose of influenxa virus
<10 (tissue culture ID50)
What does a low ID50 indicate
More infectious
What makes a device/instrument critical (high risk)
Items in contact with normally sterile body sites
What are examples of high risk instruments
foreceps, periodontal scaler
Why is an instrument semi critical (spaulding clacification)
It has been in contact with intact mucous membrane
What is an example of a semi critical device/instrument
Dental handpiece
What does the title noncritical (low risk) indicate
The object has been in contact with intact skin
What is a non-critical object
light cure
What does minimal risk indicate
Items not normally in contact with intact skin
What is a minimal risk object in the dental setting
Dental chair
How are minimal risk objects cleaned
Decontaminated using detergent/antibacterial wipes
How are low riskobjects cleaned
Some are placed in a washer disinfector with the semi-critical and critical instruments however some, such as light cure, can be decontaminated using antibac wipes etc
What is a non-critical environment surface called
Housekeeping surfaces
What are examples of household surfaces (not directly touched suring treatment)
Walls
Hand sink
Floor
What is the definition of clinical contact surfaces
Contaminated area from patient materials either by direct spray or splatter generated during dental procedures
OR
By contact with gloved hands of dental health care personnel
What are examples of clinical contact surfaces
Light handle
Worktop
Spitoon and tubing
Drawer handles
What is the most common pathway of indirect transmission
Through poor hand hygeine
-Touching contaminated surface and then the susceptible patient
What is the definition of cleaning
A process which physically removes infectious agents and the organic matter on which they thrive but does not necessarily destroy infectious agents
The reduction of microbial contamination depends upon many factors, including the effectiveness of the cleaning process and the initial bioburden
Cleaning is an essential prerequisite to ensure effective disinfection or sterilisation.
Routine cleaning is regular cleaning which is carried out on a scheduled basis, not on an ad hoc basis and not in response to an outbreak
What are the common issues with surface cleaning
Visual assessment of cleanliness = poor measure of invisible soiling
Visual clean can = large numbers of bugs and residues
Body fluids form films which then makes it easier for bugs to attach themselves to. This then makes surface cleaning more difficult.
What is detergent
Body fluids form films which then makes it easier for bugs to attach themselves to. This then makes surface cleaning more difficult.
What is the difference between high and low level disinfectant
High level disinfectant
-Kills all microbes (including mycobacteria) but not large numbers of bacterial spores
-Usually require longer contact time (hours)
Low level disinfectant
-Kill most vegetative bacteria, some fungi and some viruses in a practical period of time (<10 mins)
What factors compromise the efficacy of detergents
Organic matter
When dried or coagulated matter
Time of exposure
Coverage of large or irregular areas
How can we break each linkin the chain of infection
Infectious Agent – ?
Reservoir – Surface design, Surface material, Cleaning, Role of detergents
Portal of exit – Aerosol control
Mode of Transmission – Hands, fomites (objects or materials)
Portal of entry – PPE
Susceptible Host – Vaccinations
