Antibiogramm

An Antibiogramm is the second step in the laboratory, because the work happens in a fixed order:

1. The laboratory first identifies the pathogen in the sample, which answers what the infection is.
2. It then tests that pathogen against a panel of antibiotics, to see which of them still stop it.

Those are two different questions and they are answered at two different times. Resistance is the reason the second step exists at all, because the obvious substance is no longer reliably the working substance. For a given isolate the only way to find out is to test the candidates against it, which is also why the answer cannot be looked up in advance from the name of the organism alone.

The timing follows from the method, because something has to grow before anything can be read. An Antibiogramm therefore takes days instead of minutes and it can never be a Point-of-Care-Test. When a customer asks at the counter why the result is not back, the honest answer is that a culture has to grow first and that no amount of pressure shortens it.

Everything before the laboratory still decides the outcome, because a urine sample kept warm grows the wrong organisms while a swab that dries out grows nothing. The result therefore depends on Präanalytik and Probenlogistik instead of on the analysis itself. The akkreditiertes Labor states the container, the temperature and the transport window for each sample type, and those instructions are not open to local improvisation.

The boundary here is unusually clean, because an Antibiogramm describes what happened in a laboratory dish under laboratory conditions. Which antibiotic a person should take, at what dose and for how long, is a prescribing decision that also depends on the person in front of the prescriber, so the report belongs to the prescriber. A pharmacy team can explain what the report is for and why the wait was necessary, though reading a recommendation out of it is somebody else's work.