Talk:Sterilization (microbiology)

Wiki Education Foundation-supported course assignment
This article was the subject of a Wiki Education Foundation-supported course assignment, between 27 August 2019 and 21 December 2019. Further details are available on the course page. Student editor(s): Chdiaz10. Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 10:13, 17 January 2022 (UTC)

Wiki Education Foundation-supported course assignment
This article was the subject of a Wiki Education Foundation-supported course assignment, between 25 October 2020 and 12 December 2020. Further details are available on the course page. Student editor(s): Aasif24350. Peer reviewers: Conghuiw.

Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 10:13, 17 January 2022 (UTC) == at 2.2.1 ethylene dioxide this sentence simply makes no logical sense "Besides moist heat and irradiation, ethylene oxide is the most common sterilization method, used for over 70% of total sterilizations"== Danieledalpra (talk) 21:22, 9 December 2012 (UTC)

Merge or Remove Incineration/Flaming/Glass Beads
These are all really variants on dry heat sterilization. The exact methods vary, but the underlying mechanism is the same. I would propose that we expand the dry heat sterilization section to cover these methods and remove them as their own sections. TaylorJO (talk) 20:43, 3 August 2016 (UTC)

Section on the sterilization effect of negative air ionization?
Does anyone have any info on this? The USDA has a great photo of it that is in the public domain, found here:. Thanks! TeamZissou (talk) 20:11, 7 May 2010 (UTC)

Spaulding Classification System
Someone should add information about what needs which level of sterilization. Include critical, semi-critical, and non-critical items used in surgery. —Preceding unsigned comment added by 70.225.67.1 (talk) 20:06, 12 July 2009 (UTC)

Medicine and Surgery
Sterile parts of the body? Are there sterile parts of the body? Thirty to forty years ago blood was thought to be sterile. Bloodborne pathogens were unheard of. —Preceding unsigned comment added by 63.117.126.2 (talk) 13:26, 26 March 2008 (UTC)

Microwaves
University of Florida engineering researchers have found that microwaving kitchen sponges and plastic scrubbers — known to be common carriers of the bacteria and viruses that cause food-borne illnesses – sterilizes them rapidly and effectively. Brian Pearson 02:53, 23 January 2007 (UTC)  Microwave Sterilization and Microwave Sterilizer are well established technologies. Microwave disinfection is sometimes used. Please reference electroporation or electropermeabilisation or electropermeabilization or permeabilization.

Filtration
Shouldn't there be a section about sterilization by filtration, which is extensively used to sterilize, for example, heat sensitive protein solutions in biology research? --mglg(talk) 23:09, 12 February 2007 (UTC)
 * Well, why not. If you know that, write it there.--Juan de Vojníkov 14:59, 14 February 2007 (UTC)

Kill Rate
I found the text below the middle of the Wikipedia article - I think it doesn't belong there; it belongs here, or perhaps on a page about the term kill rate in general. Jutta 17:43, 27 February 2007 (UTC)

NB #1: Unfortunately it is common diction to say "the kill rate is log6" or "the germ reduction is log6", which strictly speaking is not only wrong but nonsensical. By saying this one means that the germ reduction is 6 orders of magnitude or the survival probability of each single germ is 10-6. (This wrong diction originates from a misunderstanding of the mathematical expression log 106 = 6)

NB #2: Strictly speaking it is also wrong to talk about single germs or the like. It's correct to use the item cfu or colony forming unit. The main problem is not inevitably the presence of germs (bacteria, spores, ...) but their ability of fast fissiparous, which gives an exponential increase of the number of the germs with time. If one tries to count "a number of germs" one has to, simply spoken, cultivate them on an agar plate, let them grow for a few days and count the macroscopic colonies which have formed. Each of these colonies is resulting from 1 cfu (= 1 "augmentable germ").

Example #1: One item which has to be sterilized carries a contamination of 107 germs prior to sterilisation. The germ reduction capability of the sterilisation process is 6 orders of magnitude (=106 or "log 6"), which means the survival probability of the germs is 10-6. If such items are sterilised the average number of "surviving germs" or, correctly spoken, cfu's which are found on the items after sterilisation is: 107 / 106 = 10 or 107 * 10-6 = 10.

Example #2 (statistically equivalent to #1): A lot of items which have to be sterilized are carrying a contamination of 10 germs each prior to sterilization. The germ reduction capability of the sterilisation process is 6 orders of magnitude (=106 or "log 6"), which means the survival probability of the germs is 10-6. If one sterilises a statistically significant number of these items the average number of cfu's which is found on the items after sterilisation is: 10 / 106 = 10-5 or 10 * 10-6 = 10-5. This means that, in average 1 cfu is found per 105 = 100.000 items.


 * Jutta, I agree. I just started a Sterility assurance level page for this specific topic. --Microbiojen 01:59, 28 February 2007 (UTC)

Alcohol
Isn't alcohol used for sterilization? Puddytang 02:06, 5 June 2007 (UTC)
 * My question exactly. This university course states the following:


 * (a) Alcohols work best as 70 to 99% mixtures with water


 * (b) Alcohol-water mixtures are additionally more penetrating than pure alcohols


 * (c)                   Either ethanol or isopropyl (rubbing) alcohol may be employed for disinfecting


 * (d)                   Alcohols are especially appropriate for application to sites in which their propensity to evaporate away is convenient (e.g., to disinfect skin prior to injection)


 * (e)                   The down side of alcohols is that they are not terribly penetrating nor capable of killing endospores or other resistant cells


 * (f)                     Alcohols should not be applied to wounds since they can cause tissue damage


 * --Ty580 04:49, 3 July 2007 (UTC)

Alcohols are not sporicidal, and therefore are not sterilants. Best to not list them.

TaylorJO (talk) 22:02, 24 March 2015 (UTC)

To reiterate, alcohols do not sterilize--they can clean and disinfect.

Alcohols have limited affect on spores and prions, to name at least two pathogens alcohols fail to deactivate.

--scaraway (talk) 12:48, 31 May 2016 (UTC)

Dry and Moist heat
Do not support the merger.

These articles dry heat and moist heat:


 * 1. do add more information
 * 2. provide a point to link to
 * 3. are important individual entities and are one of the foundations of sterilization, and need special mention.

—Preceding unsigned comment added by Sarindam7 (talk • contribs) 19:15, 30 April 2008 (UTC)


 * I will not interfere any more, this is not my domain of expertise. But please be careful of not duplicating/repeating stuff that is in this article. If the other articles merits it then obviously this article may have to be split. Regards. --Triwbe (talk) 19:55, 30 April 2008 (UTC)


 * Discussion closed. Proposition withdrawn.sarindam7 (talk) 09:51, 3 June 2008 (UTC)

Bleach
Sodium hypochlorite (chlorine bleach) is not a sterilizing agent. It is a disinfectant and decontaminant only. As a reference, see the "Biosafety in Microbiological and Biomedical Laboratories" manual referenced in this very section. Since bleach is not a method of sterilization, this section should be removed from the article entirely. Keenspotter (talk) 22:42, 19 March 2009 (UTC)

Chlorine bleach should never have been removed from the main article. I believe the above opinion is mistaken--and the opinion represents a common misconception that seems to even be present in much of academia I've sampled (based on my anecdotal first-hand experience at multiple schools, as well as reviewing some biology and micro-biology text books). Chlorine and NaOH are often noted as being some of the best sterilizing chemicals, yet chlorine bleach is often discounted as "ineffective" without a fair scientific assessment based on comparing efficacy of various chemicals/methods.

I assert that common household bleach is a better sterilizing agent then AT LEAST 1/2 of the methods currently listed in the article. But like all methods, bleach must be used properly for meaningful results. It must be in the proper concentration and be in contact with the contaminated area for the proper time.

Chlorine bleach is one of the few avenues available for sterility for most homes, small businesses, etc. In addition, although toxic, chlorine bleach probably has the greatest ratio of efficacy to safety of any option (although it is dangerous, but not as dangerous as the other methods for most common scenarios). And, it's the least expensive option for many situations.

Is chlorine bleach used in hospitals throughout the world, including when there's an outbreak of a highly-resistant strain of bacteria, such as MRSA?

Is chlorine bleach often the 1st choice to spray on people who have died from highly infectious fatal diseases, such as Ebola?

In the case of the recent Ebola outbreak, I consistently saw chlorine bleach being sprayed on dead bodies, then on the outside of the sealed body-bags, then on the ground (even dirt) where infected people had been.

I recall seeing scientific research that indicated Chlorine bleach is somewhat effective in deactivating prions, whereas most things are not.

The CDC recommends using chlorine bleach to turn contaminated water into drinking water.

Does chlorine bleach denature proteins as a generality?

Is chlorine bleach a strong oxidizing agent?

I once had a bottle of common household chlorine bleach sitting on my tile floor, and it developed a pin-hole leak. Thinking I was smart, I put the bleach in the kitchen sink, which was made of stainless steel, and left the house for a few days. When I returned, the bleach had eaten a small hole all the way through the metal sink, and it had corroded the drain and all other metal that it had been allowed to contact as it slowly drained away over those days. Thesis: chlorine bleach should always be taken seriously!

I don't have the time right now to do the research to find all the answers and sources (if I did, I would simply be modifying the main article instead of this talk page), but I do want to get this discussion started for when I (or someone) finds the time to properly re-include Sodium hypochlorite as a useful chemical for sterilizing in many situations.

For those who disagree or are skeptical, I ask these questions: 1) If you want to sterilize a surface in your home--say a counter-top--what do you propose is more effective then chlorine bleach? 2) If you found a water leak in your home or business, and found that mold had developed there, what do you propose is more effective then chlorine bleach? 3) If someone had a deadly and highly-contagious disease, such as Ebola, and was sitting on your porch, after you got them off your porch (or they died there), what do you propose is more effective than chlorine bleach for cleaning your porch, concrete, outdoor furniture, etc.?

There are smart people who assert that the development of chlorine bleach is the most important human development when it comes to how much it has protected human life from disease and death.

Please consider all this with an open mind.

Thank you, scaraway (talk) 15:37, 1 June 2016 (UTC)

Removed "Spore Testing" section
I removed the entire section on spore testing, as it appears as though the person who added it simply copied and pasted an academic paper. Additionally, the section heading was vague and the section itself seemed to go well beyond the scope of the article. If someone disagrees with me feel free to check the archived page in the history, clean it up to meet Wikipedia standards, and re-insert it into the article. As it was, it did not come anywhere close to meeting Wikipedia standards and even referenced this article as a source (in what appeared to be a "works cited" page) material inserted into the article. I'm not entirely sure how an article can reference itself. In short, thanks for contributing, but please read over the Wikipedia standards next time. Chrisbrl88 (talk) 08:25, 22 May 2010 (UTC)

Things that don't work
I removed subsections "Food utensils" and "Bathing" from the "Heat sterilization" section because it was frankly ridiculous to list methods that clearly don't sterilize, and it was stated in those subsections that they don't sterilize. To keep something to clear up misconceptions, I added a section at the bottom called "Cleaning methods that do not achieve sterilization" which is meant to be a BRIEF list of methods Danieledalpra (talk) 21:22, 9 December 2012 (UTC)which laypersons think "kill germs", not a long discussion of why they don't achieve sterilization. So far I listed dishwashers, bathing, disinfectants, antiseptics, and pasteurization with links to the respective articles. Hope this is helpful. Xenobiologista (talk) 03:09, 2 July 2010 (UTC) I added parts of this section to the page header to clarify what sterilization is, then removed all references to things that are not sterilization. Should be much more clear now. TaylorJO (talk) 05:18, 25 March 2015 (UTC)

"Cellulostics"
If you Google "cellulostics peroxide," the only results appear to be pages that (presumably) plagiarize this Wikipedia article, including a patent that plagiarizes a large proportion of the article. It is not clear that any source not plagiarizing Wikipedia has ever used this term. 18.93.4.100 (talk) 00:36, 28 February 2015 (UTC)

Tyndallization
Tyndallization has its own page, should this be merged? In addition, this is an obsolete method. TaylorJO (talk) 22:14, 24 March 2015 (UTC)

Good points.

Maybe it should be mentioned in a section on outdated, obsolete, and/or no longer considered effective methods.

Beyond being obsolete, I assert this isn't truly a method of sterilizing based on current science.

Even IF this method DID kill most forms of life (such as bacteria, molds, spores, Eukaryotes, etc.), I believe that boiling (without high pressure), even repeatedly, is not an effective method for deactivating viruses or prions.

--scaraway (talk) 15:58, 1 June 2016 (UTC)

Prions
There are several references to prions in the page, do they belong here? Since they are not living, I would argue that they don't belong with sterilization. Listing parameters for destroying prions seems to be outside of the scope of the page. TaylorJO (talk) 05:22, 25 March 2015 (UTC)

YES, they absolutely belong here!

Any life or biological agent that causes disease must be deactivated and/or removed for sterility. I'm flabbergasted by this question, and the ongoing confusion about sterilization generally, and less commonly thought of pathogens (like prions) specifically!

Prions are pathogens, they are disease causing, they are biological agents.

To reiterate, you MUST remove or deactivate (kill) all life AND biological disease-causing agents for something to be sterile.

If a surgeon uses a scalpel with any prions on it, do you consider it sterile?

Would meat that was devoid of all other pathogens EXCEPT prions be sterile? Would you eat it?

If you don't believe sterilization refers to prions, what words would you use to describe it? You will need to create new words to indicate the same concepts for prions that we have for other pathogens. In such a case, communication will become more cumbersome, confusing, and less concise as we have to start saying things like "sterilize the scalpel AND remove and/or deactivate all prions AND remove and/or deactivate all other biological agents."

Why would a word refer to a broad range of pathogens (like bacteria, viruses, spores, molds, small organisms, etc.) yet exclude prions? What logic would there be? Is your logic that prions are not alive? If so, then what about viruses, which many scientists do not consider to be alive or life?

The point of sterilization is SAFETY from disease-causing bio-agents (and POTENTIAL disease causing agents that are not yet known).

(And by the way, if you look at "biological agents" on wikipedia, it is incorrect and needs updating badly--it incorrectly is a page about biological WARFARE agents.)

--scaraway (talk) 13:16, 31 May 2016 (UTC)

UV light
Removed the sentence that said that "glass for example completely absorbs all UV light.". This needs elaboration and clarification- if this is true, then UV bulbs would be pointless because the glass of the bulb would absorb all the light and none would get out, and they would only emit heat. (Unless this person is implying that UV bulbs have been made out of plastic only for the last hundred years) — Preceding unsigned comment added by 173.69.187.16 (talk) 03:59, 31 March 2015 (UTC)

Regarding above, good points--in reality, SOME glass absorbs or reflects SOME % of SOME bands of UV light. This is something I had to research myself to answer some questions about glass blocking/absorbing UV light for a research project I was part of.

--scaraway (talk) 16:17, 1 June 2016 (UTC)

UV light bulbs generally come in two types: "blacklights" which output UV-A (around 350nm wavelength, light just shorter in wavelength than humans can see), and "germicidal lamps" which output mainly UV-C (around 200nm, which is much more ionizing and usually even turns some of the oxygen in the air into ozone). Blacklights usually use ordinary glass, with a dark tint to it to cut down on residual visible light which would otherwise be emitted. Ordinary glass passes 350nm light fairly well. Germicidal lamps have quartz bulbs or envelopes. Like glass, quartz is silicon dioxide, but quartz is almost pure SiO2, whereas glass contains other chemicals, called fluxes, which reduce its melting point and make it easier to shape. It is these fluxes which are responsible for the UV-filtering effect of ordinary glass. Sbreheny (talk) 07:19, 24 February 2020 (UTC)

New topic: I assert that UV light is not a true sterilization method.

My understanding is that UV light has limited efficacy killing many bacteria and fungi, and deactivating some viruses.

Although many hoods in biology labs have UV lights as part of their "sterilizing" protocol, I know many tend to FIRST wipe down the surfaces with alcohol, THEN use the UV light. In addition, what they are calling "sterilizing" tends to really be concerned with eliminating as much DNA/RNA prior to the next DNA extraction.

If my understanding is correct, this isn't sterilization--it's decontaminating an area "good enough" for the next experiment. I wouldn't want to lick anything inside these hoods after the supposed sterilization, or keep my food in the hood.

Thesis: I believe the sterilizing efficacy of UV light has been grossly misunderstood and overstated.

--scaraway (talk) 16:17, 1 June 2016 (UTC)


 * Hi User:Scaraway, I've also heard some skepticism surrounding how effective the UV lights in biosafety cabinets are at sterilizing surfaces, but I've not really looked into it. Do you have any references to back up your thesis? Thanks Ajpolino (talk) 17:36, 1 June 2016 (UTC)


 * Hi Ajpolino. Currently I don't have references as I haven't yet researched to find papers/sources on this topic (if I had, I would have just modified the main article instead of discussing it here), but I intend to do that investigation someday when I have time to really look into it.

What my thesis is based on thus far is based on my understanding of biology, physics, logic, some limited experience with research about UV-light killing extromophile bacteria, and 1st hand (therefore anecdotal) experience with some microbiology labs in academia.

I might also mention that upon reviewing some CDC resources for sterilization and cleaning health-care facilities, I don't remember seeing UV light mentioned in my reading so far.

If someone else decides to do some research on UV light, that would be cool.

Thank you, scaraway (talk) 10:10, 3 June 2016 (UTC)