Update on antimicrobial susceptibility and genotype of Neisseria gonorrhoeae isolated in Italy

Neisseria gonorrhoeae molecular typing for understanding sexual networks and antimicrobial resistance transmission: A systematic review

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Combined molecular and epidemiological data can describe the spread of gonorrhoea.

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Sexual networks can be inferred from molecular clusters of infection.

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Gender and sexual orientation are commonly used to characterise these networks.

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Application of these data within gonorrhoea control interventions is limited.

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Future studies should focus on evaluating molecular typing data in practice.

Objectives

Neisseria gonorrhoeae (NG) is a significant global public health concern due to rising diagnoses rates and antimicrobial resistance. Molecular combined with epidemiological data have been used to understand the distribution and spread of NG, as well as relationships between cases in sexual networks, but the public health value gained from these studies is unclear. We conducted a systematic review to examine how molecular epidemiological studies have informed understanding of sexual networks and NG transmission, and subsequent public health interventions.

Methods

Five research databases were systematically searched up to 31st March 2017 for studies that used sequence-based DNA typing methods, including whole genome sequencing, and linked molecular data to patient-level epidemiological data. Data were extracted and summarised to identify common themes.

Results

Of the 49 studies included, 82% used NG Multi-antigen Sequence Typing. Gender and sexual orientation were commonly used to characterise sexual networks that were inferred using molecular clusters; clusters predominantly of one patient group often contained a small number of isolates from other patient groups. Suggested public health applications included using these data to target interventions at specific populations, confirm outbreaks, and inform partner management, but these were mainly untested.

Conclusions

Combining molecular and epidemiological data has provided insight into sexual mixing patterns, and dissemination of NG, but few studies have applied these findings to design or evaluate public health interventions. Future studies should focus on the application of molecular epidemiology in public health practice to provide evidence for how to prevent and control NG.

Molecular Characterization of Penicillinase-Producing Neisseria gonorrhoeae Isolated in Two Time Periods, 2003-2004 and 2014-2015, in Italy

The emergence of antibiotic resistant strains poses a great concern for gonorrhea treatment. The aim of this study was to characterize penicillinase-producing Neisseria gonorrhoeae (PPNG) isolates collected in Italy in two time frames, 2003-2004 and 2014-2015. A total of 80 PPNG were characterized for the bla_TEM gene variant and the plasmid type. Furthermore, gonococci were typed using Neisseria gonorrhoeae multiantigen sequence typing. Antibiotic susceptibility assay was performed for penicillin, ciprofloxacin, ceftriaxone, and spectinomycin by Etest and minimum inhibitory concentration (MIC) test strip methods. The β-lactamase production was detected using nitrocefin test. Among PPNG isolates, four bla_TEM alleles were identified as follows: bla_TEM-1, bla_TEM-228, bla_TEMP14S, and bla_TEM-135. The African plasmid possessed the bla_TEM-1, bla_TEM-228, and bla_TEMP14S, whereas bla_TEM-135 was identified in Toronto/Rio and Asian plasmids. The percentage of isolates with the bla_TEM-1-carrying African plasmid increased from 42.5% in 2003-2004 to 55% in 2014-2015; conversely, the isolates with bla_TEM-135-carrying Toronto/Rio plasmid decreased from 57.5% to 35%. Among the isolates carrying the Toronto/Rio plasmids possessing bla_TEM-135, sequence type (ST)661 and ST5624 were found to be the predominant STs in both periods 2003-2004 and 2014-2015, respectively. More than half of the PPNG isolates were resistant to ciprofloxacin. Increase in the isolates carrying the African plasmid possessing bla_TEM-1 and a parallel decrease of the bla_TEM-135-carrying Toronto/Rio plasmid was observed. Moreover, PPNG isolate harbored Toronto/Rio plasmid with bla_TEM-135 belonged mainly to two major STs (ST661 and ST5624). Given the possible role of a mutated bla_TEM gene as an additional mechanism to extended spectrum β-lactamase resistance, it is crucial to monitor gonococci carrying these resistance genes.

Changing antimicrobial resistance profiles among Neisseria gonorrhoeae isolates in Italy, 2003 to 2012

The emergence of Neisseria gonorrhoeae isolates displaying resistance to antimicrobial agents is a major public health concern and a serious issue related to the occurrence of further untreatable gonorrhea infections. A retrospective analysis on 1,430 N. gonorrhoeae isolates, collected from 2003 through 2012, for antimicrobial susceptibility by Etest and molecular characterization by Neisseria gonorrhoeae multiantigen sequence typing (NG-MAST) was carried out in Italy. Azithromycin-resistant gonococci decreased from 14% in 2007 to 2.2% in 2012. Similarly, isolates with high MICs to cefixime (>0.125 mg/liter) decreased from 11% in 2008 to 3.3% in 2012. The ciprofloxacin resistance rate remains quite stable, following an increasing trend up to 64% in 2012. The percentage of penicillinase-producing N. gonorrhoeae (PPNG) significantly declined from 77% in 2003 to 7% in 2012. A total of 81 multidrug-resistant (MDR) gonococci were identified, showing 11 different antimicrobial resistance patterns. These were isolated from men who have sex with men (MSM) and from heterosexual patients. Two sequence types (STs), ST661 and ST1407, were the most common. Genogroup 1407, which included cefixime-, ciprofloxacin-, and azithromycin-resistant isolates, was found. In conclusion, a change in the antimicrobial resistance profiles among gonococci was identified in Italy together with a percentage of MDR isolates.

[What's new in the diagnosis and treatment of Neisseria gonorrhoeae]

Bacterial culture remains the gold standard for symptomatic infection. Nucleic Acid Amplification Tests (NAATs) have better sensitivity and specificity for rectal and pharyngeal specimens. A bacterial culture with antibiogram must be done for all NAAT positive specimens in order to modify antibiotics prescription if needed. We must fear a diffusion of extensively drug-resistant Neisseria gonorrhoeae in the future. Nevertheless, ceftriaxone 500 mg intramuscular with 1 g of azithromycin against Chlamydia trachomatis remains the treatment of N. gonorrhoeae infections. Screening of partners of identified cases and other STDs is the main measure to add to the treatment of gonorrhea.