On Bacterial Taxonomists

Ed Uthman, MD

Diplomate, American Board of Pathology

What is it with these bacterial taxonomists? Every once on a while, a quiet little fellow shows up to "update" the Vitek software. He never stops by and says hello to me, but I always know when he has been here from the stream of phone calls from befuddled clinicians who have received reports on organisms they have never heard of. Neither I nor the clinicians ever get any warning of this. I realize that these name changes are proposed in the International Journal of Systematic Bacteriology, and someone reprints them in micro journals, but no one bothers to tell regular ol' docs about it, and they are the ones who are using the data for the benefit of individual patients.

Oh, yes, and I used to buy into that claim that certain name changes are only "proposed," i.e., may be subject to review and rejection by those if us out in the hinterlands. Well, it is clear to me now that when they say a name change is "proposed," you can put your money on it that it's a done deal. The taxonomists have already gotten together in their dingy CO2-filled rooms and hashed out the details and decided what kind of spin to put on to give it the veneer of collegial democratic consensus. The next we hear about it, Streptococcus pyogenes has been changed to Anotherdeadmicrobiologistella shamelesslygushedoveri. Fait accompli.

We who teach med students have a hard enough time getting them to memorize all the trivia it takes to become a doctor without taxonomists continually repainting the stripes on the playing field. For instance, it used to be easy to teach rickettsia. You had Rickettsia this and Rickettsia that and Rickettisia somethingelse, and they all were arthropod-vectored, caused a skin rash, and could not survive outside an animal host or vector. The only exception was Coxiella burnetii, which is not arthropod-vectored, does not cause a skin rash, and can live outside a host (thus transmissible by aerosol). You just had to tell the med students, "Sure there're a bunch of rickettsiae, but, see, all the ones of genus Rickettsia have all this in common, and the odd man out, Coxiella, is just the opposite!" This is the essence of good teaching, making something complicated into something simple. But no, the taxonomists have to take us in the opposite direction: I now read that there is a "proposal" (nudge, nudge! wink, wink!) to put Rickettsia tsutsugumushi into the genus Orientia, which screws up the whole pedagogic approach.

It seems to me that bacterial taxonomy was at one time prepared to take its rightful place alongside gross anatomy among the dusty tomes of fully developed biological knowledge which only needed a swipe with a featherduster now and then. Then, someone figured out how to do DNA homology studies, and, pointing gleefully to their new toy like a child on Christmas morning, the taxonomists went berserk, summarily throwing out volumes of the work of those who gave their careers, and even their lives (e.g., Ricketts, Prowazek, Carrion) to the development of classification of microbes under the Linnaean system.

I say let the taxonomists do DNA homology studies out the wazoo if they want to, but use some sort of numerical hierarchical system to define new species and reclassify old ones, something that would fit well with the "cluster diagrams" they love so much. But this does not fit well at all with the Linnaean system, which was originally published in 1735, over two centuries before Watson, Crick, and Wilkins lifted the secret of the double helix off Rosalind Franklin's desk while she wasn't looking. Let us footsoldiers keep the traditional Linnaean nicknames for our most respected adversaries in the microbial world. If we really want to know what flavor of DNA they have, we'll give the taxonomists a call. You can count on it.

But this will never happen. The taxonomists will not give up the Linnaean system, no matter how inappropriate it is to modern techniques. After all, we all know that each taxonomist secretly harbors the hope that someday his or her name will appear in italics in the pages of IJSB with the suffix "-ella" after it.

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