Analysis of Neisseria gonorrhoeae Azithromycin Susceptibility in the United States by the Gonococcal Isolate Surveillance Project, 2005 to 2013

Abstract

e Azithromycin, administered with ceftriaxone, is recommended by the CDC for the treatment of gonorrhea. Many experts have expressed concern about the ease with which Neisseria gonorrhoeae can acquire macrolide resistance. We sought to describe gonococcal azithromycin susceptibility in the United States and to determine whether azithromycin susceptibility has changed over time. We analyzed data from 2005 to 2013 from the Gonococcal Isolate Surveillance Project, a CDC-supported sentinel surveillance network that monitors gonococcal antimicrobial susceptibility. A total of 44,144 N. gonorrhoeae isolates were tested for azithromycin susceptibility by agar dilution methods. The overall azithromycin MIC 50 was 0.25 g/ml, and the MIC 90 was 0.5 g/ml. There were no overall temporal trends in geometric means. Isolates from men who had sex with men had significantly higher geometric mean MICs than isolates from men who had sex exclusively with women. The overall prevalence of reduced azithromycin susceptibility (MIC, >2 g/ml) was 0.4% and varied by year from 0.3% (2006 and 2009) to 0.6% (2013). We did not find a clear temporal trend in gonococcal azithromycin MICs in the United States, and the prevalence of reduced azithromycin susceptibility remains low. These findings support the continued use of azithromycin in a combination therapy regimen for gonorrhea.

Association between intensity of STI screening and development of antimicrobial resistance in N. gonorrhoeae in 12 cities in the USA: An ecological study

“…Reply: There were small changes in the laboratory protocol used. The protocol used and these changes are detailed in the Kirkcaldy et al report as follows [1]: "Gonococcal isolates collected at each sentinel clinic are subcultured at the clinic's local public health laboratory on supplemented chocolate medium and frozen in Trypticase soy broth containing 20% glycerol.…”

“…Currently, only 9 cities are used in the correlation analysis, as far as the reviewer could see. The paper under review studies the association between the frequency of STI screening in MSM 1 The paper under review studies the association between the frequency of STI screening in MSM and changes in geometric mean MICs for certain antibiotics in samples in select N. gonorrhoeae US cities. An important potential source of bias in such analysis could be reverse causality, namely places with higher prevalence of drug resistance for gonorrhea, as well as syphilis in MSM may initiate more STI screening efforts.…”

“…In the United States (USA) the prevalence of antimicrobial resistance in Neisseria gonorrhoeae has typically been higher in men who have sex with men (MSM) than men who have sex with women (MSW) and women 1,2 . It has also frequently been noted to be highest in the West and lowest in the South [1][2][3] .…”

“…It has also frequently been noted to be highest in the West and lowest in the South [1][2][3] . Resistance has characteristically emerged in the West Coast and Hawaii and then spread eastward [1][2][3] .…”

“…It has also frequently been noted to be highest in the West and lowest in the South [1][2][3] . Resistance has characteristically emerged in the West Coast and Hawaii and then spread eastward [1][2][3] . This patterning of spread has led to the view that a primary driver of resistance is the import of resistant gonococci from eastern Asia and other world regions 3 .…”