Abstract: The present invention relates to novel diagnostic tools including system, method and kit for determining antibiotic susceptibility in microorganisms directly in a clinical sample. Specifically, the present invention relates to a diagnostic system and method for testing antibiotic susceptibility based on a phenotypic screening of the microorganisms in the presence of major antibiotics being used currently. The present invention can be used directly on the clinical samples and obliterates the need for prior culturing. The present invention is convenient, rapid, cost-effective, does not need prior expertise to handle, has excellent selectivity and sensitivity. The present invention has the potential to improve patient outcomes and help reduce further evolution of antimicrobial resistant microorganisms.