Objectives Antimicrobial resistance in Neisseria gonorrhoeae is a major public health problem worldwide. Slovenia is among the countries with highest prevalence of decreased susceptibility and resistance to extended-spectrum cephalosporins (ESCs) in Europe. Herein, the phenotypic and molecular characterization of Slovenian N. gonorrhoeae strains from 2008–2012 is presented.

Methods N. gonorrhoeae isolates cultured 2008–2012 in Slovenia (n = 138) were examined for antimicrobial susceptibility with Etest methodology for 8 antimicrobials (cefixime, ceftriaxone, penicillin, ciprofloxacin, azithromycin, tetracycline, gentamicin and spectinomycin). Furthermore, all isolates were investigated with Neisseria gonorrhoeae multi-antigen sequence typing (NG-MAST) for molecular epidemiology, and sequencing of major ESC resistance determinants; penA, mtrR and penB.

Results The overall prevalence of resistance and decreased susceptibility to cefixime and ceftriaxone (MIC≥ 0.125 mg/L) was 16% and 7%, respectively. The resistance and decreased susceptibility showed an epidemic peak during 2009–2011 when it reached 28% for cefixime and 12% for ceftriaxone, however, the prevalence subsequently decreased to 6% and 4%, respectively, in the year 2012. NG-MAST sequence types 1407 (13% of all isolates), 21 (8%) and 225 (6%) were the most common STs during 2008–2012. ST1407, previously stated as an internationally spread successful clone with resistance or decreased susceptibility to ESCs, was most prevalent in 2009 (43%). However, the ST1407 prevalence declined in 2010 (15%) and 2011 (11%) and the clone was rare in 2012 (4%). Instead, in 2012 the ESC susceptible ST21 was the predominant ST (21%). During 2008–2012, a penA mosaic allele (mainly penA XXXIV, associated with ST1407) was detected in 25% of isolates.

Conclusion The prevalence of gonococcal resistance to ESC in Slovenia has fluctuated, which is mainly due to the longitudinal prevalence of a few gonococcal clones. Fortunately, some ESC susceptible clones, such as ST21, now appear to replace the main ESC resistant clone ST1407, a replacement that is indicated in several European countries.