{"id":2820,"date":"2012-06-12T21:00:44","date_gmt":"2012-06-13T01:00:44","guid":{"rendered":"http:\/\/blogs.nejm.org\/?p=2820"},"modified":"2023-12-28T07:08:07","modified_gmt":"2023-12-28T12:08:07","slug":"id-learning-unit-the-etest","status":"publish","type":"post","link":"https:\/\/blogs.nejm.org\/hiv-id-observations\/index.php\/id-learning-unit-the-etest\/2012\/06\/12\/","title":{"rendered":"ID Learning Unit — The Etest"},"content":{"rendered":"

\"\"<\/a>Every year I attend on the general medical service, so it gives me a chance to work directly with the medical residents — and to brush up on my non-ID-related Internal Medicine.<\/p>\n

In exchange for what they teach me, each day on rounds I try to tell them about at least one ID-related thing that they may not know. Since I do this in the spring, they’re awfully sharp. Fortunately, I’ve been doing this ID stuff a long<\/em> time, so can usually find something.<\/p>\n

Today’s learning unit was the “Epsilometer Test, or “Etest” — that brilliantly simple way of estimating the MIC of an antibiotic to an organism, by using a drug-impregnated strip that has a gradient of concentration, from high to low. Find where the “elipse” of inhibition crosses the strip, and presto! There’s your MIC.<\/p>\n

We take for granted that this method is readily available and, for the most part, clinically valid. It’s worth remembering, however, that when it debuted in the late 1980s\/early 1990s, it was considered pretty slick and not entirely trustworthy.<\/p>\n

And there’s still some debate about how reliable it is, especially with MRSA<\/a>.<\/p>\n

If you want to learn how to do it, watch this movie.<\/p>\n