Infections caused by the highly pathogenic bacterium Yersinia pestis are rare, however, the pathogen still pose a major biosecurity risk due to the potential misuse for biological warfare or bioterrorism. In contrast, the massive emergence of multi-drug-resistant (MDR) bacteria, such as Klebsiella pneumoniae, constitutes an enormous threat to global health as MDR-associated treatment failure causes high mortality rates in nosocomial infections. In both cases, rapid pathogen detection and antibiotic resistance screening are crucial for successful therapy and thus patient survival. Reporter phage-based diagnostics offer an avenue to expedite pathogen identification and resistance testing. Reporter phages feature integrated reporter genes that enable real-time detection of living target bacteria upon infection. Here, we developed and engineered highly specific reporter phages which produce nanoluciferase (nLuc) as a reporter enzyme upon host infection that enable rapid detection of K. pneumoniae or Y. pestis cells in clinical matrices within a few hours. At the same time, these reporter phage assays can be utilized in real-time antibiotic susceptibility testing to provide rapid identification of suitable antibiotic treatment options.