Science Buddies: "Ask an Expert"

I'm doing research on how to test for staphylococcus aureus (S. aureus) on tur fields. I'm running into a problem because nothing spells out how to test for it. Most things just say that S. aureus was found but nothing actually says how to test for it. any help on where to find this would be much appreciated.

Hello, there are tests that can be done to identify S. aureus, but you have to remember, when you take a culture of the turf fields, you must likely going to grow a mixture of bacteria, you will see colonies of bacteria with different size, shape and hemolysis. It might difficult for you to pick out S. aureus from a mix culture. In general S. aureus take 18-24 hours to grow, colonies is beta-hemolytic (zone of clearing around the colonies), creamy, buttery-looking on blood agar plate.

Here is some basic about S. aureus:

Gram Stain: Gram positive cocci in clusters
Catalase test: Positive
Coagulase test: Positive

In another word, if you identify a colony of gram positive cocci in clusters, and it shows a positive catalase and coagulase reaction, then you can identify that colony as S. aureus. There are also rapid test kits (kind of like a pregnancy test kit) on the market that can test for S.aureus in minutes, but its use in general is limited to clinical setting (hospitals and clinics).

The Catalase test is easy to perform, and all you need is one drop of hydrogen peroxide. You can find the instructions on Catalase test in this website: http://www2.austin.cc.tx.us/microbugz/h ... ndout.html

The Coagulase test is more difficult to perform and it utilize either human/animal plasma (blood) as reagent, you should check with your teacher for this procedure.

Here is a Penn State study "A Survey of Microbial Populations in Infilled Synthetic Turf Fields" that might be of interest to you.

http://cropsoil.psu.edu/mcnitt/microbial/discussion.cfm

Michael

I agree with the assessment of Michael's response.

However, I would add just one more thing.

Please be careful when you obtain S aureus cultures. There are MRSA strains present in the environment. In fact, several students at a nearby high school (from where I live) that installed turf on their football field recently were admitted to the hospital with MRSA infections on their skin wounds. If you don't know about MRSA (methicillin resistant S aureus), I highly suggest you do some reading. Otherwise, good luck.

James