A Microbiology Spectrum study shows that two concentration-adjusted disk diffusion methods enable accurate direct antibiotic susceptibility testing from urine for suspected UTIs. By accounting for the inoculum effect, these methods achieved high agreement with standard AST (>93% for a threshold-adapted approach; ~88%–100% with regression modeling, depending on antibiotic and class) and allow culture, identification, and AST to proceed in parallel. This approach could deliver targeted susceptibility results up to 24 hours earlier, supporting earlier optimization of therapy and improved antimicrobial stewardship, though further validation and refinement are needed.

Source: Microbiology Spectrum