Science Buddies: "Ask an Expert"

my problem/question is: What is the best hand hygiene method for a school setting? I have swabbed many hands and grown great cultures on my agar petri dishes. I do not have access to a lab so am sealing the petri dishes and using a grid count instead. My first set of controls ( blanks) have some kind of wierd diffuse, flat, opaque growth that is not seen in any of my other samples. My mom thinks its a fungi/yeast but we can't seem to find any reference to this kind of problem in the lit review/sites we have accessed. The rest of my controls have no or almost no growth, my petri dishes have all kinds of white/yellow/orange round bacteria so there is a defintie difference. Can you advise or direct me to info on another site?
Thanks for your help and the time you give to young scientists like me.

Hi,

I volunteer in a hospital setting, and they are nearly paranoid about hand hygene to prevent spreading infections. Their recommendations are to wash your hands frequently with soap and water. The secondary recommendation is to use an alcohol gel on the hands ( They use a gel called Endure). No matter how frequently you use these methods your hands will be recontaminated the next time you touch a germy surface.

Hope this helps!

Barrett Tomlinson

Welcome to the Ask an Expert forum. It seems you might also have a question about your control, but I'm not exactly sure what that question is. Can you clarify what sort of advice you want? If you want to identify the growth on your control, would it be possible to post a photograph?
Looking forward to hearing more.
Chris

Thanks for the replies to date. I need to be clearer. My project is entitled " what is the best hand hygiene strategy in a school setting" I have done 3 trials, the first one without telling the kids anything just seeing what their normal hand hygiene grows on the petri dishes, the second is with half assigned to wash with soap and half assigned to use hand sanitizer, the third with the same groups being coached by the school nurse and myself to use hand washing or hand sanitizer properly. In all three samples I had ten controls which I did nothing to.I have done all of my testing and am now analysing results.
Yes my control is my concern. Some of the controls in the first trial have grown a diffuse growth that my mom thinks is a yeast. Here is a photo of one of the controls labelled C6; below it is an example of one of the trial one petri dishes labelled 40. ( none of the controls in the other 2 trials had this problem so I am a little stumped)
My question is- can you tell me what the control is growing? I know it is difficult to tell without a microscope but a guess would be helpful too!
Next question- can you hazard a guess as to some of the things growing on my #40 sample?
As I don't have access to a lab I will be counting growth using a grid instead of identifying the individual bacteria growing- but... I am already getting questions from people as I show them how gross some of the samples are about what kinds of things might be growing.
Thanks again for answering our science questions.

Hi,
Thanks for the additional info. My main experience with growing cultures on agar has been with fungus, and C6 does resemble some kind of fungus. I'd guess a mold, because that's what I spent most of my time trying to keep out of my own agar plates. Of course, that's just a guess, and it's hard to know for sure just by seeing the photo. Have any of those diffuse cultures started to change color to green, black, or some dark shade that would suggest production of mold spores?

It's interesting that you only see that diffuse growth on your controls. Perhaps the control plates were optimal for growing mold because of the absence of other competing organisms like bacteria.

I don't work much in the laboratory. Hopefully the lab microbiologists will chime in with some of their expert advice!

Chris

Thanks for the replies to date. Does anyone else have any ideas what I grew on my controls? or on my other petri dish? ( see pic attached to my second last post) I don't have access to a lab so am using counts of growth on the petri dishes to compare mty trials. But I think people will want to know what the growth is, so far I think I've identified e coli, strep, fecal colliforms and some mold.
L

Hi,
What methods are you using for identification? Has the appearance of the diffuse growth on your controls changed at all? Have you had a chance to examine it under a microscope?
If you are not able to definitively identify particular genus or species, it would still be informative to show people the general types of microbes that exist in our living environment.
Chris