Azithromycin Susceptibility Among Neisseria gonorrhoeae Isolates and Seasonal Macrolide Use

Abstract

Rising azithromycin nonsusceptibility among Neisseria gonorrhoeae isolates threatens current treatment recommendations, but the cause of this rise is not well understood. We performed an ecological study of seasonal patterns in macrolide use and azithromycin resistance in N. gonorrhoeae, finding that population-wide macrolide use is associated with increased azithromycin nonsusceptibility. These results, indicative of bystander selection, have implications for antibiotic prescribing guidelines.

Figure 1.

Seasonality in macrolide use among MarketScan members, 2011–2015. Points indicate monthly macrolide use among all included members, by year (A); among members in each age group in 2015 (B); and among members in each US Census region in 2015 (C).

Figure 2.

Seasonality in Neisseria gonorrhoeae azithromycin minimum inhibitory concentrations (MICs) among GISP isolates, 2005–2015. Points indicate monthly means of the seasonal deviates; error bars show standard errors of the mean. The line indicates the point estimate for the seasonal amplitude and phase from the sinusoidal model; the gray area shows the 95% confidence interval for the amplitude. MICs (left axis) were computed using seasonal deviates from year-clinic regressions (right axis) on a baseline MIC of 0.2 μg/mL.