Trends and determinants of antimicrobial susceptibility of Neisseria gonorrhoeae in the Netherlands, 2007 to 2015

Background: Neisseria gonorrhoeae antibiotic resistance surveillance is important to maintain adequate treatment. We analysed 2007-15 data from the Gonococcal Resistance to Antimicrobials Surveillance (GRAS), which currently includes 19 of 25 sexually transmitted infection (STI) centres in the Netherlands. Methods: From each patient with a gonorrhoea culture, the minimum inhibitory concentration (MIC) for several antibiotics was determined. Time trends were assessed by geometric means and linear regression of logarithmic MIC. Determinants for decreased susceptibility to ceftriaxone (MIC>0.032mg/L) and resistance to cefotaxime (MIC > 0.125 mg/L) and azithromycin (MIC>0.5mg/L) were assessed using stratified logistic regression. Results: 11,768 isolates were analysed. No ceftriaxone resistance was found. In 2015, 27 of 1,425 isolates (1.9%) were resistant to cefotaxime and 176 of 1,623 (10.9%) to azithromycin. Ceftriaxone susceptibility showed no trend (p =0.96) during the study period, but cefotaxime MIC decreased (p< 0.0001) and azithromycin MIC increased (p< 0.0001) significantly. Concerning ceftriaxone, isolates of men who have sex with men (MSM) from 2013 (p=0.0005) and 2014 (p=0.0004) were significantly associated with decreased susceptibility. Significant determinants for cefotaxime resistance were having >= 6 partners for women (p = 0.0006). For azithromycin,isolates from MSM collected in 2012 (p=0.0035), 2013 (p=0.012), and 2014 (p=0.013), or from non-Dutch (p<0.0001) or older >= 35 years; p= 0.01) MSM were significantly associated with susceptibility. Resistance in heterosexual men was significantly associated with being >= 25 years-old (p=0.0049) or having 3-5 partners (p=0.01). Conclusions: No ceftriaxone resistance was found, but azithromycin MIC increased in 2007-15. Resistance determinants could help with focused intervention strategies.