Rationale for a Neisseria gonorrhoeae Susceptible Only Interpretive Breakpoint for Azithromycin

BACKGROUND: Azithromycin (AZI) is recommended with ceftriaxone (CRO) for treatment of uncomplicated gonococcal urethritis and cervicitis in the United States, and an AZI-susceptibility breakpoint is needed. Neither the Food and Drug Administration (FDA) nor the Clinical and Laboratory Standards Institute (CLSI) has set interpretive breakpoints for AZI susceptibility. As a result, AZI antimicrobial susceptibility testing (AST) cannot be interpreted using recognized standards. This has contributed to increasingly unavailable clinical laboratory AST, although gonorrhea is on the rise with >550 000 US gonorrhea cases reported to the Centers for Disease Control and Prevention in 2017, the highest number of cases since 1991. METHODS: This article summarizes the rationale data reviewed by the CLSI in June 2018. RESULTS: The CLSI decided to set a susceptible-only interpretive breakpoint at the minimum inhibitory concentration of