Whole-genome sequencing of Shigella for surveillance purposes shows (inter)national relatedness and multidrug resistance in isolates from men who have sex with men.

In the Netherlands, more than half of domestic shigellosis cases are among men who have sex with men (MSM), particularly in the Amsterdam region. However, there is limited insight into which Shigella strains circulate in the Netherlands. Our objective was to assess the added value of whole-genome sequencing (WGS)-based surveillance for Shigella. To this end, we determined the relatedness among Shigella spp. isolates from patients in the Amsterdam region, as well as in an international context, including antimicrobial resistance markers, using WGS. The following criteria were used: it should provide insight into (1) clustering of shigellosis cases and the affected population, (2) the extent of admixture of MSM-associated isolates with those from the broader population and (3) the presence of antimicrobial resistance. It should then lead to more opportunities for targeted control measures. For this study, Shigella isolates from three laboratories in the Amsterdam region obtained between February 2019 and October 2021 were subjected to Illumina WGS at the National Institute for Public Health and the Environment (RIVM). Raw data were quality-checked and assembled, the Shigella serotype was determined with ShigaTyper, and antimicrobial resistance markers were detected using ResFinder and PointFinder. For Shigella sonnei, subclades were determined using Mykrobe. Relatedness of isolates, including 21 international reference genomes, was assessed with core genome multilocus sequence typing. In total, 109 isolates were included, of which 27 were from females (25 %) and 66 were from males (61 %), with which the majority (n=48, 73 %) being from MSM. No information on sex was available for the remaining 16 cases. The WGS data for all isolates, comprising 55 S. sonnei, 52 Shigella flexneri, 1 Shigella boydii and 1 Shigella dysenteriae, met the quality criteria. In total, 14 clusters containing 51 isolates (49 %) were identified, with a median cluster size of 2.5 cases (range: 2-15). Nine out of 14 clusters were MSM-associated, and 8 clusters (57 %) were travel-related. Six of the MSM clusters were related to international reference genomes. The prevalence of antimicrobial resistance markers was higher among isolates from MSM than non-MSM patients, particularly for ciprofloxacin (89 vs 33 %) and azithromycin (58 vs 17 %). In conclusion, about half of Shigella spp. patients were part of a cluster, of which a substantial part were related to international reference genomes, particularly among MSM, and a high prevalence of antimicrobial resistance markers was found. These findings indicate widespread international circulation of Shigella spp., particularly among MSM, with multidrug resistance that hampers treatment of patients. Moreover, the results of this study led to the implementation of a national WGS-based laboratory surveillance programme for Shigella spp. that started in April 2022.

High carriage of ESBL-producing Enterobacteriaceae associated with sexual activity among men who have sex with men.

BACKGROUND: Extended-spectrum ß-lactamase Enterobacteriaceae (ESBL-E) may be sexually transmitted. Men who have sex with men (MSM) have different sexual behaviour than the general population, and thus may be at risk for ESBL-E carriage. This study determined the prevalence of ESBL-E carriage and its association with sexual behaviour among MSM in Amsterdam, The Netherlands. MATERIALS AND METHODS: In total, 583 HIV-positive and HIV-negative MSM from the Amsterdam Cohort Study were screened for rectal ESBL-E carriage between April and December 2018. Participants completed a self-administered questionnaire on (sexual) behaviour and risk factors for antimicrobial resistance. The proportion of the study population with ESBL-E carriage was compared by number of sexual partners using logistic regression, and across clusters of sexual behaviours with steady and casual partners, separately, using latent class analyses; all results were adjusted for recent use of antibiotics, travel and hospitalization. RESULTS: Overall, 16.3% [95% confidence interval (CI) 13.4-19.5] of the study population tested positive for ESBL-E. The odds of ESBL-E carriage increased as number of sexual partners increased [adjusted odds ratio per ln(partner+1), 1.57, 95% CI 1.26-1.94; P<0.001]. There was no association between ESBL-E carriage and sexual behaviour with steady partner(s). Compared with participants in the 'no sex with casual partner(s)' cluster, adjusted odds of being ESBL-E positive were 2.95-fold higher (95% CI 1.52-5.80) for participants in the 'rimming and frottage' cluster (P=0.001) and 2.28-fold higher (95% CI 0.98-5.31) for participants in the 'toy use and fisting' cluster (P=0.056). CONCLUSIONS: The prevalence of ESBL-E in MSM is higher compared with the overall Dutch population, likely due to sexual transmission with casual partners. This implies that sexually active MSM should be considered a risk group for ESBL-E carriage.

Ten years of external quality assessment (EQA) of Neisseria gonorrhoeae antimicrobial susceptibility testing in Europe elucidate high reliability of data.

BACKGROUND: Confidence in any diagnostic and antimicrobial susceptibility testing data is provided by appropriate and regular quality assurance (QA) procedures. In Europe, the European Gonococcal Antimicrobial Susceptibility Programme (Euro-GASP) has been monitoring the antimicrobial susceptibility in Neisseria gonorrhoeae since 2004. Euro-GASP includes an external quality assessment (EQA) scheme as an essential component for a quality-assured laboratory-based surveillance programme. Participation in the EQA scheme enables any problems with the performed antimicrobial susceptibility testing to be identified and addressed, feeds into the curricula of laboratory training organised by the Euro-GASP network, and assesses the capacity of individual laboratories to detect emerging new, rare and increasing antimicrobial resistance phenotypes. Participant performance in the Euro-GASP EQA scheme over a 10 year period (2007 to 2016, no EQA in 2013) was evaluated. METHODS: Antimicrobial susceptibility category and MIC results from the first 5 years (2007-2011) of the Euro-GASP EQA were compared with the latter 5 years (2012-2016). These time periods were selected to assess the impact of the 2012 European Union case definitions for the reporting of antimicrobial susceptibility. RESULTS: Antimicrobial susceptibility category agreement in each year was ≥91%. Discrepancies in susceptibility categories were generally because the MICs for EQA panel isolates were on or very close to the susceptibility or resistance breakpoints. A high proportion of isolates tested over the 10 years were within one (≥90%) or two (≥97%) MIC log2 dilutions of the modal MIC, respectively. The most common method used was Etest on GC agar base. There was a shift to using breakpoints published by the European Committee on Antimicrobial Susceptibility Testing (EUCAST) in the latter 5 years, however overall impact on the validity of results was limited, as the percentage categorical agreement and MIC concordance changed very little between the two five-year periods. CONCLUSIONS: The high level of comparability of results in this EQA scheme indicates that high quality data are produced by the Euro-GASP participants and gives confidence in susceptibility and resistance data generated by laboratories performing decentralised testing.

Characterization of Bordetella holmesii isolates from patients with pertussis-like illness in The Netherlands.

Bordetella holmesii is a recently described human pathogen mainly isolated from blood. However, in the US and Canada, B. holmesii has also been cultured from the nasopharynx of patients with pertussis-like symptoms. To the best of our knowledge, respiratory isolates from Europe have not been characterized. Here, we report the isolation and characterization of B. holmesii from Dutch patients with pertussis-like illness. Species determination was confirmed by 16S rRNA gene sequencing and detection by PCR of IS481 and bhoE, a gene not found in Bordetella pertussis but present in B. holmesii. Comparative genomic hybridization (CGH) with microarrays revealed that the Dutch isolates formed a cluster distinct from isolates from the US and UK suggesting a distinct population or an epidemiological relationship between the Dutch isolates. All isolates contained a locus involved in iron uptake, previously suggested to originate from B. pertussis. The causes for the apparent increase in the isolation of B. holmesii are discussed.