Azithromycin-resistant Neisseria gonorrhoeae strains recently isolated in Italy

The aim of this study was to characterize 22 azithromycin-resistant Neisseria gonorrhoeae isolates, collected in Italy from January 2007 through June 2008, during a study of the prevalence of antibiotic resistance.

MICs of azithromycin, ciprofloxacin, ceftriaxone, penicillin and tetracycline were determined by the Etest method. Azithromycin-resistant strains (MIC > or = 1 mg/L) were genetically analysed by N. gonorrhoeae multi-antigen sequence typing (NG-MAST) and PFGE.

A total of 22 azithromycin-resistant isolates were found among the 219 collected. Five of the 22 isolates showed high-level azithromycin resistance (MICs of 128 or 256 mg/L). Sixteen of the 22 were isolated from men who have sex with men. Among the 14 sequence types (STs) found by NG-MAST, 5 STs, containing clusters of two, three or four strains, were homogeneous with respect to epidemiology and/or antibiotic susceptibility. PFGE divided the 22 strains into two main groups that were possibly related.

This is the first report of gonococci with high-level resistance to azithromycin circulating in Italy. Correlation between NG-MAST results and epidemiological data for some of the analysed strains and patients could be established. This study represents a reference point for future surveillance in Italy and suggests the need to add azithromycin to the antibiotic susceptibility panel for gonococci.