The invention provides systems and methods for rapid automated identification of microbes and antimicrobial susceptibility testing (AST) directly from a patient specimen, without specimen preparation. Specimens are loaded into an analytical cartridge for processing. Analytical cartridges are preloaded with species-specific labels that are used to identify and enumerate microbes in the specimen. Instruments, such as analyzers can be used to interact with analytical cartridges to carry out methods of the invention all within the cartridge.