Welcome to my blog about life in Valencia! This is something that I have wanted to do for a while but I have been so busy I haven’t had chance/ I’ve been too lazy to try and work out how on earth to set up a blog page. But starting something late is better than never I suppose!
I am 20 years old and in what would be my third year at Leeds University studying Sociology. However, this year I am on Erasmus (erasmoooose) teaching English, doing some marketing work at a small law firm and going to the beach whenever the sun is shining, so a lot! I have been lucky enough to move in with Giles (my boyfriend) who is studying his whole degree in Valencia for 5 years (currently fourth year and counting wooo) as we have been in a long distance relationship since the beginning whilst both studying…
Here is a video demonstrating the process of cleaning the dental chair. It shows all of the different areas that have to be cleaning in order for the chair to be ready for the next patient.
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Below is a second video which shows you how you should clean, package, log and sterilise the instruments used in the dental clinic.
There are two main types of Autoclave used in steam sterilisation, the first is the Gravity displacement autoclave and the second is the High speed pre-vacuum steriliser.
Gravity Displacement Autoclave
In this type of autoclave, steam enters into the top or the sides of the sterilising chamber and because the steam is lighter than air, it forces the air out of the bottom of the chamber through a drain vent.
It is mainly used in:
Processing of laboratory media
Pharmaceutical products
Regulated medical waste
Non-porous articles whose surface have direct steam contact
The time that it takes for the steam to penetrate into porous items is prolonged due to incomplete elimination of air.
High Speed Pre-Vacuum steriliser
These work in a similar way to gravity displacement sterilisers apart from the fact that they are fitted with a vacuum pump which ensures the air is removed from the sterilising chamber and the load before the steam is admitted
This has an advantage over gravity displacement because there is almost instant steam penetration, even into porous loads.
The Bowie-dick test can be used to detect if there are any air leaks which would lead to inadequate air removal from the chamber:
It involves folded 100% cotton surgical towels which are cleaned & preconditioned
They are placed horizontally in the front bottom section of the sterilisation rack, over the drain in an otherwise empty chamber
It is run at 134 degrees for 3.5 mins
This test is run each day before the first load is processed
Air which is not removed from the chamber will interfere with steam contact
Smaller disposable test packs have been designed to replace surgical towels in the testing of efficacy of the vacuum system
These test packs ‘Simulate the product to be sterilised and constitute a defined challenge to the sterilisation process”
They should be representative of the load and simulate the greatest challenge to the load
Steriliser vacuum performance is acceptable if the sheet inside the test pack shows a uniform colour change
Entrapped air will cause a spot to appear on the test sheet because the steam cant reach the chemical indicator
If it fails the Bowie-dick test then you cannot use the steriliser until it is inspected by steriliser maintenance personnel
Above is an example of a test pack that can be used for the Bowie-Dick test. It also shows the colour change after a successful test.
Sterilisation is a method used to destroy all microorganisms on the surface of and article // in a fluid to prevent disease transmission associated with use of the item.
All critical items must be sterilised
The goal in steam sterilisation is to expose each item to direct stream contact at the required temperature & pressure for a specified time
It is a non-toxic, inexpensive, rapid microbicidal, sporicidal and rapidly heats and penetrates fabrics
Autoclave Parameters
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Steam — Should be dry saturated steam & entrained water
Dryness fraction >97%
Pressure — Used to obtain the high temperatures needed to quickly kill microorganisms
Temperature — Specific temperatures must be obtained to ensure microbicidal activity
The most common sterilising temperatures are 121oC (250oF) and 132oC (270oF)
Time — The specific temperature must be maintained for a minimal time to kill microorganisms
the minimum exposure period for sterilisation of wrapped healthcare supplies is 30 mins at 121 degrees in a gravity displacement steriliser
In a prevacuum steriliser only 4 minutes is needed at 132 degrees
At constant temperatures the sterilisation times will vary depending on:
The type of item (metal Vs rubber OR plastic OR items with a lumen)
Various factors affect the effectiveness of a germicide against microorganisms. Some of these factors are intrinsic qualities of the organism while others are due to the chemical and physical environment.
Number & Location of Microorganisms
The larger the number of microbes, the more time it takes for a germicide to destroy them all. That is the reason why thorough cleaning of medical devices is necessary before disinfection & sterilisation — to reduce the number of microorganism that need to be inactivated. Proper cleaning increase the margin of safety along with reducing the exposure time necessary to kill all the microbes present.
With regards to location, medical devices with multiple devices must be disassembled because only surfaces that are directly in contact with the germicide will be disinfected. There must be no air pockets and the equipment must be completely immersed for the entire exposure period.
Innate resistance of Microorganisms
The resistance of microorganisms to chemical germicides and sterilisation varies greatly. For example, spores are resistant to disinfectants because the spore coat and cortex act as a barrier; mycobacteria have a waxy cell wall that prevents disinfectant entry; gram-negative bacteria possess an outer membrane which acts as a barrier to the uptake of disinfectants.
The order of innate resistance to chemical germicides is as follows:
Prions (most resistant)
Bacterial spores
Coccidia — e.g Cryptosporidium
Mycobacteria — e.g. M. tuberculosis
Non lipid // small viruses — e.g. Poliovirus
Fungi — e.g. Candida
Vegetative bacteria — e.g. Staphylococcus
Lipid // medium sized viruses — e.g Herpes & HIV
Germicidal resistance of Gram-positive and Gram-negative bacteria is similar with some exceptions — e.g. P. aeruginosa shows greater resistance to some disinfectants.
Concentration and Potency of Disinfectants
The more concentrated the disinfectant, the greater its efficacy and the shorter the time necessary to achieve microbial kill, with the exception of iodophors. Different disinfectants aren’t all affected in the same way with regards to concentration adjustments. For example, Quaternary ammonium compounds and phenol have concentration exponents of 1 and 6 respectively. Therefore if we halve the concentration of Quaternary ammonium compounds we must double the disinfecting time, but if we halved the concentration of phenol we must increase the disinfecting time by 64-fold.
Physical and Chemical Factors
Temperature — The activity of most disinfectants increases as the temperature increases (with some exceptions)
Too great an increase in temperature causes the disinfectant to degrade & weakens its germicidal activity.
pH — Influences the antimicrobial activity by altering the disinfectant molecule or the cell surface.
An increase in pH improves the antimicrobial activity of some disinfectants — e.g qluteraldehyde & quaternary ammonium compounds
A decrease in pH improves the antimicrobial activity of others — e.g. phenols, hypochlorites & iodine
Relative humidity — Most important factor in influencing the activity of gaseous disinfectants/sterilants — e.g. EtO, Chlorine Dioxide & Formaldehyde
Water hardness (the concentration of divalent cations)Reduces the rate of kill of certain disinfectants
Divalent cations (e.g. Magnesium & Calcium) in hard water interact with the disinfectant to form insoluble precipitates.
Both the images above show the type of water present in different regions of Spain & the UK. You can see if you lived in Valencia, the south of England or in Ireland that Hard water could be a problem when using disinfectants.
Above you can find the link to the peppermint castile soap that was used in the video to test the hardness of water. Alternatively you can use test strips to test the hardness of your water, found here on amazon:
Organic matter such as Serum, Blood, Pus, Faecal, Lubricant material can all interfere with antimicrobial activity of disinfectants in two ways:
The first is a chemical reaction between the germicide & organic matter resulting in a complex which is less germicidal // non-germicidal.
This leaves less active germicide available for attacking microorganisms.
Chlorine & Iodine disinfectants are most prone to interactions like this.
The second way, organic material protects microorganisms from attack by acting as a physical barrier.
Inorganic contaminants can protect microorganisms from all sterilisation process via occlusion to salt crystals.
Both Organic & Inorganic material can easily be removed by washing which emphasises the importance of thorough cleaning of medical devices before sterilisation.
Duration of Exposure
Items must be exposed to the germicide for the appropriate minimum time contact time as stated on the label instructions of EPA-registered products.
If the user selects exposure conditions different to those stated on the EPA-registered product label then the user accepts liability for any injuries resulting from the instruments use — The user could be subject to enforcement action under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA).
The exact times for disinfecting medical items are somewhat elusive due to the effects of the perviously mentioned factors on disinfection efficiency.
In general Longer contact times are more effective than shorter contact times.
Biofilms
Biofilms are microbial communities which are tightly attached to surfaces & can’t easily be removed. Microbes that reside within the biofilms can be resistant to disinfectants by a few different mechanisms:
Physical characteristics of older biofilms
Genotypic variation of the bacteria
Microbial production of neutralising enzymes
Physiologic gradients within the biofilm
Bacteria within a biofilm are 1,000 times more resistant to antimicrobials than bacteria in suspension.
Biofilms can be found in whirlpools, dental unit waterlines, and many different medical devices.
Presence of biofilms can have serious consequences for immunocompromised patients & for patients with medical devices permanently fixed into them.
Some enzymes & detergents can degrade biofilms // reduce the numbers of viable bacteria within the biofilm — None of theses such products are currently EPA-registered or FDA-cleared for their use against biofilms.
objects and surfaces.
Giles Jones' Blog 