Electrochemical immunosensing devices for detection of microbial agents are briefly reviewed. The practical results describe amperometric immunosensors based on screen-printed electrodes as a general platform for sandwich-based assay of microbes. The examples are focused on the determination of Francisella, Salmonella, Escherichia and Bacillus species. The achieved analytical parameters seem promising for real applications. In particular, combination of the immunosensor with cyclone device allowed fully automated testing of the system for detection of bioaerosols of E. coli as a model agent; the preliminary results confirm that levels below 100 CFU/L in air can be detected within 20 min.