An outbreak of shigellosis that occurred in Los Angeles last year is the first known transmission in the U.S. of Shigella sonnei with resistance to azithromycin, according to MMWR.

Of 43 cases of shigellosis associated with a private bridge club, 14 were confirmed by culture. Four isolates had elevated azithromycin minimum inhibitory concentrations (MICs) of >16 μg/mL and a plasmid-encoded macrolide resistance gene.

The authors write: “Guidelines for azithromycin susceptibility testing and criteria for interpretation of MICs for Shigella species have not been published. Clinicians are urged to report azithromycin treatment failure among shigellosis patients to public health authorities and to retain Shigella isolates from such cases for further analysis.”

Source: MMWR