Tuesday, March 02, 2010

Strep tease

Last week in the college biology class I'm teaching a couple of nights per week here, I had the students doing some basic microbiology. Not bad for having no lab equipment, supplies, or support from the University, I'd say.

Fortunately, I'd been able to sweet-talk my way into snagging some bacteriological petri plates from the Post hospital's laboratory department. Those plates were (just) beyond their expiration dates, and were going to be trashed anyway.

They'd work just fine for what I had in mind.

I directed the students to use a sterile swab to gather up the sample they wanted to test, and then to inoculate four different growth media (those petri dishes) with the same swab. We'd see what grew on which medium, and perhaps be able to draw some conclusions as to which bacteria could grow on which plates.

The good folks in the hospital lab agreed to let me incubate the plates in their body-temperature incubator for the requisite amount of time, and then store them in their biohazard refrigerator until my next class.

We examined the specimens last night. I'm very grateful to the hospital laboratory staff for their assistance with this endeavor!

Everyone managed to plate out samples that grew differentially on the various growth media. Most of my students had never worked with bacteriological samples before, and they were more than a little off-put by the smells coming from some of the cultures. I was delighted to see those Soldiers comparing results while attempting to make sense of the data they'd gathered.

Bacterial cultures can present with quite varied colony sizes, morphologies, textures, colors, smells, and interactions with the media upon which they're growing. The students appeared both fascinated and appalled at the diversity of the organisms they grew.

They had a good time, and were really into it. A couple said they were going to start carrying Purell around with them at all times, however. One said he really felt the need to go back to his barracks and shower, for a long time.

I love science!

One of the most disturbing results was the many different kinds of bacteria, including Streptococcus pyogenes (the causative agent of strep throat), which were cultured from a sink in the latrine just down the building from our classroom, and the many and varied bacteria from the open storm sewer which flows among the barracks here where we live.... Ain't science grand?

Now, if only we had a *real* lab in which to conduct some experiments...

Blessings and peace to one and all,

Fr. Tim, SJ

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