I'm guessing that "organic screen" doesn't currently usually include antibody testing of CSF from a lumbar puncture since the article implies that only a limited number places do that screening currently.

> To find psychiatric patients who might benefit from immunotherapy, researchers have set up centers, roughly similar to the one at Columbia, at Baylor University Medical Center, in Texas; King’s College London; Uppsala University, in Sweden; and the University of Freiburg, in Germany, among other places. Some of the best research into the phenomenon has been conducted in Germany, where it’s more common for patients in a first episode of psychosis to have lumbar punctures to access their spinal fluid, which can reveal the presence of antibodies.