Background Molecular surveillance of Neisseria gonorrhoeae will help in understanding the transmission patterns of the infection and the acquisition/development of antibiotic resistant strains. We aimed to determine the antimicrobial resistance (AMR) and the genotypes of the N. gonorrhoeae isolates.
Methods Of a total of 287 N. gonorrhoeae isolates the minimal inhibitory concentration (MIC; mg/L) of penicillin, tetracycline, ciprofloxacin, ceftriaxone, azithromycin, spectinomycin and cefixime was determined employing the gold standard agar dilution method. β-lactamase production was detected using nitrocefin solution. The sequence types (STs) of the isolates was obtained using the NG-Multi Antigen Sequence Typing (NG-MAST) method.
Results All isolates were susceptible to ceftriaxone, spectinomycin, and cefixime. Resistance to ciprofloxacin, tetracycline, penicillin, and azithromycin was 50.9%, 46.3%, 26.5%, and 2.4% respectively. A total of 10.8% of the strains produced β-lactamase. Overall 74 STs were determined. Five STs made up for 50.3% of all the isolates: ST2992 (19.8%); ST1407 (9.7%); ST2400 (7.6%); ST387 (7.3%); ST2212(5.9%). ST387 was isolated in heterosexuals only and ST2400 and ST2992 in mainly men having sex with men. All ST387 were susceptible to all tested antibiotics with 95.2% of the strains having a MIC of 0.001 mg/L for ceftriaxone. All ST2992 were susceptible to ciprofloxacin and all ST1407, ST2212, and ST2400 were resistant. The median MICs for ceftriaxone were 0.03 µg/ml for ST1407, ST2212, and ST2400 and 0.008 µg/ml for ST2292. None of the five STs showed β-lactamase activity.
Conclusions Associations were found between antibiotic susceptibility and sequence type. The most important finding is the absolute susceptibility to the tested antibiotics of ST387, which was identified in heterosexuals only. Our preliminary results are very promising. However, more research is needed to further optimise the NG-MAST method for its use in predicting AMR and in molecular surveillance. Ultimately the method should be applicable directly on biological specimens.
Disclosure of interest Nothing to declare.
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