As “medical” readers might have guessed from the title, this post concerns the nomenclature of microbial resistance testing. For those unfamiliar, panels of antimicrobial compounds are tested against a sample of microbial pathogens (often cultured) from a patient. Technical specifics aside, when this sort of testing is ordered, the managing physician gets a report back that will often divide the tested drugs into groups, with (hopefully) some that will effective against the pathogen on one end of the spectrum, some that would do little to nothing on the other end, and some in the middle ground. Intuitively, these results are used to help guide treatment of infectious diseases.
Unlike the opening sentence of this post, “resistance” is seldom the term used in labelling these sorts of tests, and instead they are often called either “sensitivities” or “susceptibilities” (e.g., a blood culture is ordered with these to be reported). The choice of terminology seems to vary by location and organization unpredictably, but my purpose in writing this post is to argue that “sensitivity” (when used to mean “microbial sensitivity”) should be abandoned in favor of “susceptibility.”
The best reason I can offer is clarity: “sensitivity” is already a pervasive term used to refer to a diagnostic performance characteristic of a test, and using it in reference to a test in a different manner is an invitation for confusion. If it seems like I’m exaggerating, just know that I’ve actually been in a conversation where my mention of the “sensitivity” of a urine culture resulted in exactly this sort of confusion. On the other hand, “susceptibility” is unambiguous, as it is implausible that it refers to anything but the microbes’ resistance profile when used in the context of a microbial culture.
Further, “susceptibility” seems to better connote the intended message, conveying a sense of disposition to potential harm (that is, to the microbes) beyond that which could reasonably be inferred from the property of “sensitivity.”
Though the impact may be minor, a conscious choice to use better terminology is easy in this case, where (to my knowledge) no camps exist favoring one term or another. At least from my perspective, the choice is easy.