# Hygiene hypothesis

The clinical building at my institute has always been very conscientious about infection control. They’ve had hand sanitiser dispensers for years, but in the last few months (before swine flu!) they’ve begun to supplement them with large numbers of new signs exhorting people to “stop the spread!”.
They’re also using a series of new stickers. Here’s the one on the outside of the ladies’ loo next to a seminar room:

I’d noticed that this number did not increase during the week since I was last in the building, a rather surprising turn of events given the amount of caffeine required to get through some seminars. But it was my colleagues who noticed that something much more sinister seems to be going on. As soon as I heard, I immediately dashed in there, personal safety be damned and iPhone in hand, to document these shenanigans for the benefit of my readers.
[cont]

This is the inside of the same door. The door opens inwards, meaning that the only way to leave the room is to use the handle.

Wormhole? Rabid toilet beast that pulls its prey into the sewers by the thousands?

Previously documented inhabitant of Vancouver’s sewer system
Or are 82.7% of all users too freaked out by the stickers to touch the handle, and can only leave the room when someone else opens the door from the outside? It’s a fine line between good hygiene and germophobia after all. Must get pretty crowded in that room at times.
Maybe the answer lies inside the stalls. I chose one of the three and ventured in, wary of rabid toilet beasts, but trying hard to visualise the first Pulitzer to be won by a random person with a crappy camera.

But

Hypotheses:

• 3,321 out of 5,499 users chose this stall, with 71.3% of them meeting an untimely demise some time between flushing and exiting the stall. This would suggest either a rabid toilet beast, or an unnecessarily strong flush, causing a powerful vacuum that sucks people into the sewers. Either way, we should check those feet.
• 953 out of 5,499 users chose this stall, and flushed an average of 3.84 times each, perhaps to banish the rabid toilet beast.

Either way, it appears that only the survivors of this one stall made it out of the room alive. Pulitzer Schmulitzer, I got the hell out of there without further journalistic investigation.
Any other ideas?

"one of the sillier science bloggers [...] I thought I should give a warning to the more staid members of the community." - Bob O'Hara, December 2010
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### 31 Responses to Hygiene hypothesis

1. Richard Wintle says:

Some possibilities:
1) People are using (clean, I hope) toilet paper to grab the handles and let themselves out.
2) People are, as you say, using their feet, not touching with their hands.
3) People are taking lab gloves in for the sole purpose of opening/closing stall and door handles.
4) Telekinesis.
Also, this reminds me of the often-seen chestnut of washroom graffiti: Everyone with sh** on their hands has touched this handle. Your occ health and safety folks are just saying the same thing, in a nicer way.

2. Sabine Hossenfelder says:

Our building suddenly features omnipresent hand-sanitizers. So does my dentist’s office. Everybody is supposed to clean their hands before entering. But then the dentist’s receptionist has the flu. And is at work! Telling everybody no, its not the swine flu. Swine or not swine, I think there’s something wrong with a system where people think they have to work even when they are sick.

3. Cath Ennis says:

Richard, either that or the stickers themselves are full of sh**.
Sabine, it really is terrible that people do that. My whole family got taken out by a norovirus at Christmas, after my sister picked it up from someone at her office. I’ll usually go in with a cold, but if I have a fever, forget it, I’m not getting out of bed!

4. Kyrsten Jensen says:

I had to start stifling laughter when the only non-scientist in our building started putting up signs about washing our hands and how to avoid swine flu.
At my partner’s workplace (where there are no scientists), they “quarantined” one guy at home who had come back from Mexico for 5 days. Apparently the OPS manager had read somewhere that 5 days was sufficient. To which I started laughing manically because my best friend is an infectious diseases expert (PhD and MD) who was front-line working on the swine flu epidemic in Halifax, and she proved (in a journal article to come out very soon) that it’s more like 3 weeks.
The stupidity surrounding this pandemic causes me to go “GAH!” regularly, especially because people die from regular flu with far higher regularity.

5. Cath Ennis says:

I’ll work from home for 3 weeks quite happily!
We got the hand sanitiser dispensers in our building last week, but apparently that was planned before the aporkalypse / snoutbreak

6. Eric Michael Johnson says:

Well, it appears that slightly more people (2368 out of 5499) disappear between flushing the toilet and touching the inside of the door to their stall. 2178 people vanish between entering the bathroom and flushing. There is no evidence of how many people touch the outside of the stall door, but the best hypothesis seems to be that the culprit is inside the toilet. I’m thinking alligators. Those that aren’t already waiting beneath the lid are probably allerted by the sound of flushing and rush in from an adjoining stall. A well-respected documentary highlighted this very thing. Be warned.

7. Åsa Karlström says:

I’m still not getting it… if you consider that there probably aren’t any sinks inside the stalls right? So, what you want them to do is to open the door fro mthe stall, doesn’t matter if you are germy or not, and then go and wash your hands before you open the outer door.
Oh my, I really don’t have any humour… sorry.
And I think if people could refraining from sneezing in their hands and rather sneeze towards the arm like my granny told me when I was a kid some of this might not be a problem. The problem about not washing hands after going to the loo is still a mystery for me…. why wouldn’t you?! Ah well, i’ll take some hand sanitizer now before gloves “since that is obviously not over careful… duh”

8. Cath Ennis says:

Eric, I have not seen that documentary, but I will have to obtain a copy forthwith. It looks most illuminating.
Åsa, yeah, no sinks inside the stalls. At the compulsory staff orientation (which I’ve now had to do twice, having worked elsewhere for 2 years before returning with a new name, new job and new employee number), they tell us to wash your hands, take your paper towel, and then use the paper towel to turn off the tap and open the door. But there are no bins within accurate throwing range of the door… so you have to either throw it in the right general direction and hope for the best, or wander the corridors looking for another bin to put your towel in.

9. Åsa Karlström says:

they tell us to wash your hands, take your paper towel, and then use the paper towel to turn off the tap and open the door
Cath> So they assume not everyone will wash their hand then? Because if everyone did, it would be safe to touch the handle with your hand?!
I personally don’t get why it is such a panic attack about touchign the handle. It is only a problem if you put your hands in your face/mouth a lot afterwards… (or have wounds on your hands) otherwise the skin protects very well from getting “sickness” from your hands. But what do I know, I am just a simple microbiologist 😉

10. Eva Amsen says:

They probably slid under the stall door and opened the outside door with their elbows. It’s the only logical explanation!

11. Cath Ennis says:

Åsa, I think it’s always safe to assume that a certain percentage of people in any building are just nasty.
Eva, I’ll keep an eye out for such behavior from now on!

12. Tom Hennessy says:

Quote:
“I personally don’t get why it is such a panic attack about touchign the handle. It is only a problem if you put your hands in your face/mouth a lot afterwards… (or have wounds on your hands) otherwise the skin protects very well from getting “sickness” from your hands. But what do I know, I am just a simple microbiologist ;)”
Well if you are such a .. simple microbiologist .. in a world of simple biologists .. why then .. microbiologist .. explain WHY all surfaces in the hospital are covered with metal / steel which is KNOWN to be a haven for .. coincidentally .. bacteria .. ?
You microbiologists have NO IDEA how bacteria works obviously and VOILA we have bacteria running rampant in the hospitals and YOU say .. ? .. “don’t worry about it your skin will protect YOU” .. ?
It’s the spreading of the germs OUT of the washroom ONTO the steel door handles .. FROM .. your hands .. that it is all about.
YOU guys should know better but it has been shown medical people was LESS than the general population.
It is to curb the SPREAD of the bacteria OUT of the bathroom.
THAT’s why it is ON the handle .. it is made out of steel ..
Understand .. microbiologist .. ?
The bacteria FEED on steel ..
“Metal chelator 1,000-fold greater killing / infection”
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1393226
Chelator-Induced Dispersal and Killing of Pseudomonas aeruginosa Cells
in a Biofilm.
Banin E, Brady KM, Greenberg EP
Appl Environ Microbiol. 2006 Mar ; 72(3): 2064-9
Biofilms consist of groups of bacteria attached to surfaces and encased
in a hydrated polymeric matrix.
Bacteria in biofilms are more resistant to the immune system and to antibiotics than their free-living planktonic counterparts.
Thus, biofilm-related infections are persistent and often show recurrent symptoms.
The metal chelator EDTA is known to have activity against biofilms of gram-positive bacteria such as Staphylococcus aureus.
EDTA can also kill planktonic cells of Proteobacteria like Pseudomonas aeruginosa.
In this study we demonstrate that EDTA is a potent P. aeruginosa biofilm disrupter.
In Tris buffer, EDTA treatment of P. aeruginosa biofilms results in
1,000-fold greater killing than treatment with the P. aeruginosa
antibiotic gentamicin.
Furthermore, a combination of EDTA and gentamicin results in complete killing of biofilm cells. P. aeruginosa biofilms can form structured mushroom-like entities when grown under flow on a glass surface.
Time lapse confocal scanning laser microscopy shows that EDTA causes a dispersal of P. aeruginosa cells from biofilms and killing of biofilm cells within the mushroom-like structures.
An examination of the influence of several divalent cations on the
antibiofilm activity of EDTA indicates that magnesium, calcium, and
iron protect P. aeruginosa biofilms against EDTA treatment.
Our results are consistent with a mechanism whereby EDTA causes detachment and killing of biofilm cells.

13. Cath Ennis says:

Dude. Chill. If you’d like to discuss infection control in hospitals, I suggest you
a) find a forum that is actually discussing it seriously, instead of providing a fun Friday comment thread
and
b) lose the personal attacks.

14. Tom Hennessy says:

It may not be a good idea to touch ANY metal in a hospital.
Maybe if it was painted with good old fashioned starch based paint.
Phytic acid in the starch binds any metal.
The same paint they use for lead contaminated houses.
http://cat.inist.fr/?aModele=afficheN&cpsidt=19112861
The role of iron in Mycobacterium smegmatis biofilm formation: the
exochelin siderophore is essential in limiting iron conditions for
biofilm formation but not for planktonic growth.
Ojha A, Hatfull GF.
Department of Biological Sciences, University of Pittsburgh,
Pittsburgh, PA 15260, USA.
Mol Microbiol. 2007 Oct;66(2):468-83. Epub 2007 Sep 14.
M. smegmatis surface motility is similarly dependent on iron availability, requiring both supplemental iron and the exochelin pathway to acquire it.
PMID: 1785440
Which leads to flesh eating disease found coincidentally in iron overloaded people .. ‘iron and fasciitis’ ..
It has been shown that iron from our food accumulates in the body over the years and is now named age-related iron accumulation.
http://www.ncbi.nlm.nih.gov/pubmed/18682742
Below shows fasciitis appears in older people and those with iron excess.
Both coincidentally iron related.
“Necrotizing fasciitis”
“Almost exclusively in males over the age of 50 years”
“Elevated serum iron levels (e.g. liver cirrhosis, chronic hepatitis, haemochromatosis)”
Wound infections caused by Vibrio vulnificus and other marine bacteria.
Epidemiol Infect. 2005 Jun;133(3):383-91.
Oliver JD.
Department of Biology, University of North Carolina at Charlotte, 9201 University City Blvd, Charlotte, NC 28223, USA. jdoliver@uncc.edu
Infections caused by Vibrio vulnificus were first reported in 1979 by Blake et al. of the US Centers for Disease Control.
At that time described as a ‘rare, unnamed halophilic lactose-fermenting Vibrio species’, V. vulnificus has emerged as the most virulent foodborne pathogen in the United States with a hospitalization rate of 0.910 and a case-fatality rate of 0.390.
It is in addition a significant cause of potentially life-threatening wound infections.
Infections following ingestion of raw or undercooked seafood, commonly raw oysters, can lead to a primary septicaemia with a fatality rate of 50-60%.
An unusual symptom, occurring in 69% of 274 cases reviewed by Oliver, is the development of secondary lesions, typically on the extremities, which are generally severe (often a necrotizing fasciitis) and require tissue debridement or amputation.
These cases occur almost exclusively in males over the age of 50 years. Interestingly, this gender specificity has been found to be due to the female hormone oestrogen, which in some manner provides protection against the lethal V. vulnificus endotoxin.
Further, most cases occur in persons with certain underlying diseases which are either immunocompromising or which lead to elevated serum iron levels (e.g. liver cirrhosis, chronic hepatitis, haemochromatosis).
V. vulnificus infections resulting in primary septicaemia have been extensively studied, and the subject of several reviews.
This review concentrates on the wound infections caused by this marine bacterial pathogen, including the more recently described biotypes 2 and 3, with brief discussions of those caused by other marine vibrios, and the increasingly reported wound/skin infections caused by Mycobacterium marinum, Erysipelothrix rhusiopathiae, and Aeromnonas hydrophila.
PMID: 15962544

15. Tom Hennessy says:

Dude. Chill. If you’d like to discuss infection control in hospitals, I suggest you
a) find a forum that is actually discussing it seriously, instead of providing a fun Friday comment thread
and
b) lose the personal attacks.
I thought that it may come off as an attack .. but .. it wasn’t meant to be ..
It was at the .. microbiologist .. persay .. NOT the ‘individual’ microbiologist ..
You are what you have learned or taught .. and like I said .. obviously .. the profession .. has been found wanting in that they have NO IDEA of how bacteria work .. evidenced .. BY .. ? .. as mentioned the number of metal surfaces in hospitals which NEED NOT BE .. metal.
One cleaning woman was caught for going from the toilet to the table with her cleaning cloth and when one has a surface which FEEDS an infection .. that is not a good thing.

16. Cath Ennis says:

People, don’t eat oysters in hospitals, especially not with a metal fork

17. Cath Ennis says:

Well, OK. But that did come across as a personal attack on Åsa, and I don’t have much tolerance for personal attacks on my friends.
Infection control obviously is a problem, but as you can hopefully tell from my post, my facility is one of the ones taking it very seriously.
Having said that, I really do think that this is the wrong forum for your arguments as most people here are not microbiologists, but are here for the silly conversation about people disappearing through worm holes in bathrooms.

18. Tom Hennessy says:

Oh .. you do know about .. iron and how by removal of it you have much better recovery as opposed to those who do not.
I forgot the forks ..
Chop sticks for everyone ..

19. Henry Gee says:

Gee Minor spun out of school yesterday in a characteristically cheerful manner, waving her fingers before her mouth and saying that she was pretending to be a microbe. Bless.

20. Cath Ennis says:

Cool! At that age I was probably pretending to be a cat or a horse, she’s obviously light years ahead of me.
Any idea what kind of microbe?

21. Sabbi Lall says:

So odd (maybe the person who posted them confused the stickers?)! I never touch a handle in the restroom. Maybe I telekinese, maybe I’m a better climber or jumper than I appear to be, I’m not telling.
Noone’s taken a sharpie to a sticker and added “+1”? Not that I’d encourage that type of behaviour of course- I’m simply surprised it hasn’t happened.

22. David Whitlock says:

I think there are better ways of preventing disease transmission than by attempting Domainicide (completely killing all members of the Domains Archaea and Bacteria while leaving Eukarya). Much of what suppresses pathogenic bacteria and prevents infection are non-pathogenic commensal bacteria. This is why secondary infections often follow treatment with antibiotics. The antibiotics knock-out the good bacteria, leaving the niche open for the bad bacteria (which are all around anyway).
If you have a biofilm that is keeping you healthy and suppressing potential pathogens, I think it may be better to leave it in place and not mess with a good thing. I particularly like the ammonia oxidizing bacteria which should be particularly effective in places where there is a lot of ammonia. I think these bacteria are behind some of the effects of the hygiene hypothesis.
Microbes with wiggling appendages are in their planktonic form. The state they are in until they meet up with enough others of their kind to detect quorum sensing and switch on virulence factors. I would be very careful about letting children be sufficiently unsupervised in large groups that they begin to express virulence factors. In a sense that is what happened in Lord of the Flies.

23. Bob O'Hara says:

May I suggest an alternative hypothesis? The sign is not pointing at the door handle, but at the piece of door just below it. Feel sorry for the poor soul who had to place that sign at exactly the right place.

24. Åsa Karlström says:

Cath> thanks.

25. Eva Amsen says:

Oh, wow, the comments… At least now we know who’s sliding underneath the stall doors.

26. Cath Ennis says:

Sarbjit, paper towel? How are your throwing skills?
David, excellent points, and your Lord of the Flies comment made me giggle!
Bob, if our infection control people have nothing better to do than to tally touches to specific parts of doors (presumably through a hidden camera – creepy!), then I assume that the battle against swine flu has already been won! You heard it here first!
Åsa, you’re welcome!
Eva, yeah, I didn’t expect the attack of the amazing metal-feeding bacteria. It’s amazing that any metal structures still exist at all, if bacteria are feeding on them at such an alarming rate!

27. Kyrsten Jensen says:

Have we told the architects of the world about the metal-eating bacteria? because they should know!
But if you want to know about strange bacteria, how about the ones you can pick up with a magnet?

28. Cath Ennis says:

Well, obviously they know about it, but there’s a vast conspiracy to cover it up. They just call it “metal fatigue”.

29. Richard Wintle says:

@Eva – one word. Levitation.

30. Unbalanced Reaction says:

Ack! The wormhole dweller picture gets me every time! I’ll bet that whoever put the stickers up did that on purpose just to mess with your (and, erm, MY) head.

31. Cath Ennis says:

Hee hee! Sorry!
Classic episode though.