Bacteria isolated from diagnostic and surveillance specimens are becoming increasingly resistant to antimicrobial agents. Organisms resistant to key agents in multiple antimicrobial classes commonly used for treatment are referred to as multi-drug resistant organisms (MDRO). MDRO that are uncommon and/or have unusual types of resistance are labeled novel MDRO (nMDRO) and these are typically more difficult to treat (fewer therapeutic options). Identification of both MDRO and nMDRO starts in the diagnostic laboratory where it is essential to use reliable methods for testing and reporting. This session will cover definitions of MDRO and nMDRO and what clinical and public health microbiologists must do to help clinicians identify treatment options and help infection prevention and public health professionals minimize their spread.