(P61) Azithromycin use and antimicrobial resistance in Neisseria gonorrhoeae before and after a national treatment guideline change, King County, WA, USA, 2017-2022

Background

In December 2020, the rising prevalence of azithromycin-resistant (AZM-R) Neisseria gonorrhoeae (NG) prompted a change in U.S. treatment guidelines to stop using AZM in the treatment of NG. We evaluated trends in NG treatment and antimicrobial susceptibility test (AST) results in the period before and after the treatment guideline change.



Methods

NG cultures were collected from patients at a sexual health clinic (SHC) and eight clinics in King County, Washington, 2017-2022. We used E-tests to define antimicrobial susceptibility in NG isolates; we defined AZM-R as a minimum inhibitory concentration (MIC) ≥2.0 µg/mL and cephalosporin resistance (CEPH-R) as a ceftriaxone MIC ≥ 0.125 µg/ml or cefixime MIC ≥ 0.25 µg/ml. Clinical data on cases with AST were obtained from laboratory requisition forms and medical records; antimicrobial use data were derived from population-based case-surveillance and SHC medical records. We calculated the proportion of NG patient-cases in King County and of SHC patients who were prescribed AZM, and the proportion of NG isolates with AZI-R and CEPH-R by patient population and site of infection, using chi-square or Fisher’s exact tests to evaluate trends in antimicrobial use and AST results.



Results

A total of 26,235 NG patient-cases in King County were reported over the 6-year study period. The percentage of King County NG patient-cases treated with AZM declined from 83% in 2017 to 8% in 2022 (p< 0. 0001); the percentage of SHC visits during which patients received AZM declined from 20% to 1% (p< 0. 0001). Overall, 3,218 NG isolates from 2,882 patient-cases were available for AST. The annual proportion of patient-cases with AZI-R increased from 6% (2017) to 17% (2022), while CEPH-R prevalence remained stable at ≤1%. The prevalence of AZM-R increased from 10% before the guideline update (2019-2020) to 16% after the update (2021-2022, p=0.0001). This increase occurred across all population subgroups examined and among isolates from all anatomic sites (Table).



Conclusion

Despite a decrease in AZM use for treating gonococcal infections and among SHC patients overall, the proportion of King County NG isolates that are AZI-R continued to rise in the two years following the change in U.S. gonorrhea treatment guidelines.