Posted by Animal1852:
Ok here’s the micro bio lesson
Sterilization is defined as the complete killing of all living organisms. Key Word there living, virus are not living organisms.
The pore size of a .2micron filter is too large. The smallest virus is the poliovirus at 28 nanometers much much smaller than the pore size. Viruses range from 28nm to 200nm (smallpox). Prokaryotes (Bacteria) range from .1 to 50um which means most bacteria will in fact be filtered out. Also bacteria in aquatic environments do something called reductive cell division to increase cell surface to volume ratio in which case they can reach sizes smaller than .2um.
In regards, to sterility, sterility is achieved at a 121 degrees Celsius at 1.1 kg/cm^2 for 15 minutes for 500ml of solution. If you throw your vial in the oven you can certainly reach the temperature but you have to pin the vial to prevent it from bursting, the vial does not reach a pressure of 1.1kg/cm^2 and it specifications don’t allow it to. It’s not sterilization but a means of reducing bacterial count.
Also bacteria can survive at temps up to 380 degrees Celsius in thermal vents but I doubt those bacteria will be encountered in environments we live in. However, bacteria do participate in something called Transformation. This a process in which live bacteria can pick up the contents of a dead bacterial cell. How is this relevant to this? When you kill the bacteria in your vial those bacteria are now burst cells with small constituents floating in your vials. Those DNA sequences can be picked up by the live bacteria (normal flora of your skin) that may get into you when you inject/ puncture your skin. Those normal flora will then be transformed into possibly deadly bacteria. When you alcohol swab your skin it does not sterilize your skin but rather acts as a disinfectant – the killing of most but not all living organisms.
Finally, the most dangerous bacteria, anthrax and clostridium are found commonly in soil. Dirty hands can transfer this to preparation solutions. These bacteria produce spores which are much smaller than the bacterial cell and can resist alcohol, antibiotics, and high temperatures, these are a very real possibility considering their diversity and ease of contractibility (soil) and the environments many ugls operate in. So in conclusion, the oven method or syringe filters are not means of cleaning gear 100% but rather a means of prevention.
With that said, I still firmly believe that sterile filters should be used with the knowledge that they are a means of prevention. (kinda like condoms not 100% effective haha)
Animal
1.What do you suggest for syringe filters size?
2. If I vent my gear whilst its baking in the oven. Won't that defeat the purpose? I don't think the air in the oven is sterilized
I dont think green soap sterilizes I think its a disinfectant not sure on that
1 - .22um sterile syringe filters are standard for sterilizing water based substances, thats why its a little hard to use them on oil based gear but they work.
2- Thats what I was getting at the common person does not have the materials to achieve sterilization. There are methods (heating, adding ba, and using filters) to try and achieve sterility but these methods are more precautionary uses, Your oven like I said will reduce the bacteria count from the high temp but by lab standards it will not be considered sterilized.
In addition I forgot to mention. If you are sure your gear is dirty I wouldn't use it even if you run it through a filter. This is because what gets you sick often from bacteria is their toxins or by products they produce. These toxins and by products can often remain stable at temperatures higher than what conventional kitchen ovens can achieve. So even if you kill the microbes their products can remain active in your gear.
The point of my post was to encourage the use of syringe filters as a means of precaution rather than assuming that if some gear is giving you infections you can just run it through a syringe filter and you will be fine, not true. Also its commonly believed that ba will kill anything that is not true either. BA prevents the growth of organisms does not kill most organisms. BA can be tolerated esp at the concentration found in gear by many microbes. There are common methods used to achieve the reduction of growth among microbes, many food are preserved by introducing high concentrations of salt or sugar in the solution to prevent growth of microbes (ex can of beans high in salt) but even they can become contaminated eventually. ba slows growth and may kill certain microbes but it does not kill all microbes.
Animal
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