Various devices, systems and methods for detecting a susceptibility of an infectious agent to an anti-infective are described herein. A method comprises introducing a fluid sample to a first surface and a second surface; exposing the first surface to a first solution; exposing, the second surface to a second solution, wherein the second surface comprises an anti-infective; sampling the first solution after exposing the first solution to the first surface; sampling the second solution after exposing the second solution to the second surface; monitoring a first electrical characteristic of a first electrolyte-insulator-semiconductor (EIS) sensor exposed to the first solution sampled; monitoring a second electrical characteristic of a second EIS sensor exposed to the second solution sampled; and comparing the first electrical characteristic and the second electrical characteristic to assess the susceptibility of the infectious agent to the anti-infective.