When the CSI television show kicks off each episode with The Who singing “Who are you? Who-ooh Who-ooh?”, I’m often reminded that some of the most satisfying moments in science come when a mystery is solved and we come to understand something that was beyond our knowing. In the TV show, the discovery is often the identity of a killer. In the microbiology lab, it is often the identity of a microbe. Sometimes, that microbe can also be a killer!
The traditional way for identifying bacteria is through completion of a series of biochemical tests conducted using tubes and plates of special growth media. That was one of the things that drew me to microbiology – instead of trying to provide names to structures penetrated by pins stuck through cat muscles or plant leaves, test results in the micro lab were unambiguously black and white, or at least red and yellow. I may nothave been sure whether the pin was in the semimembranosus or the pectineus, but I sure could tell the difference between red and yellow!
Today microbiologists still conduct the tests using tubes and plates, especially in the typical college teaching lab. But the BIMS program is committed to exposing students to the tools that are used in hospitals and research labs to do things more quickly and accurately. So, once students believe they know the identity of the bacteria they have isolated from nature, we follow up to confirm identity using a rapid ID system like those used in clinical labs. This approach comes at a cost, but the experience is worth every penny.
There are many to choose from, and those schools exposing students to rapid ID systems typically choose to use either Enterotubes or API strips, which are on the “lower-tech” end of the spectrum. We have decided to go a bit more high-tech and use the BD-BBL Crystal Rapid ID system. Students place a colony or two of their purified unknown into the dilution broth and fill all 30 wells with inoculum. A panel of 30 dehydrated media is snapped into place, enabling the inoculum to rehydrate the media, and the panels are tossed into an incubator overnight. Ten-digit numerical codes are derived from the results and fed into a computer that spits out an identity. Most recently, my students have used the panels for identifying bacteria contaminating foods – meats, fresh fruits and vegetables.
Who are you? When our students look at their plates of unknown bacteria and ask that question, they will find the answer is easy to determine using Crystal panels. We fully believe by the time they graduate, BIMS students will be capable of answering the same question for CSI. All it takes is the right tools, methods, and skills – something we are committed to providing.