Epidemiological characteristics and antibiotic susceptibility of Neisseria gonorrhoeae isolates from Greece during 2009-2023

Abstract

Objectives: To monitor epidemiological characteristics and antibiotic susceptibility trends of Neisseria gonorrhoeae in Greece during 2009-2023.

Methods: Microbiological and epidemiological data for 1756 gonococci received by the Greek National Reference Centre for Neisseria gonorrhoeae were evaluated. Strains were isolated consecutively from gonorrhoea cases in hospitals throughout Greece. Minimum inhibitory concetrations of antibiotics were determined by E-test. Plasmid content analysis was performed for penicillinase-producing isolates (PPNG) and for isolates exhibiting tetracycline resistance (TRNG). tetM, penA, gyrA and parC genes were identified by PCR and RFLP/sequencing. Isolates were subjected to serotyping. Genomic analysis by pulsed-field gel electrophoresis (PFGE) was performed for extended-spectrum cephalosporin (ESC)-resistant isolates.

Results: Only 2.8% of the isolates were fully susceptible to all antibiotics. High rates of resistance were observed for penicillin G (27.5%), tetracycline (59.2%) and ciprofloxacin (68.8%). PPNG and/or TRNG isolates accounted for 26% of the total sample, the majority (81.6%) being simultaneously quinolone-resistant (QRNG). The isolation frequency of QRNG isolates was stably high as in previous years. Interestingly, a proportion of QRNG isolates exhibited cross-resistance to all antibiotics except spectinomycin. Azithromycin resistance is showing an increasing trend since 2021 at alarming levels (32.7% in 2023). The percentage of isolates exhibiting decreased susceptibility to ESCs (CDS) remained stable until 2019, whereas no CDS strains were isolated from 2020 to 2023. Spectinomycin was active against all isolates. Serotyping results revealed a strong association of quinolone resistance with Bpyut, Bpyust and Bropyst serovars and I/S phenotypes with Bpyvut and Byut serovars. PFGE showed that CDS isolates were classified into eight groups, with the majority clustered in three main clones including the predominant CDS clone isolated during 2001-2008.

Conclusions: The gonococcal population showed a continuous change in the resistance phenotypes and predominating clones during 2009-2023 underlining the need for continuous monitoring of the traits of this pathogen.

Keywords: Neisseria gonorrhoeae; antibiotic resistance; epidemiology.