Epidemiology of Campylobacter infections in Ireland 2004–2016: What has changed?

Seek and you shall find: Yersinia enterocolitica in Ireland's drinking water

INTRODUCTION

Three Yersinia species were identified from samples of drinking water from diverse geographic regions of Ireland. Conventional commercial biochemical identification systems classified them as Yersinia enterocolitica. Since this organism is the most common cause of bacterial gastroenteritis in some countries, further investigation was warranted. The aim of the study was to provide a microbial characterisation of three Yersinia species, to determine their pathogenicity, and to review the incidence rate of Yersinia enterocolitica detection in our region.

METHODS

Organism identification was performed using conventional commercial diagnostic systems MALDI-TOF, API 20E, API 50CHE, TREK Sensititre GNID and Vitek 2 GN, and whole genome sequencing (WGS) was performed. Historical data for detections was extracted from the lab system for 2008 to 2023.

RESULTS

All three isolates gave "good" identifications of Yersinia enterocolitica on conventional systems. Further analysis by WGS matched two of the isolates with recently described Yersinia proxima, and the third was a member of the non-pathogenic Yersinia enterocolitica clade 1Aa.

DISCUSSION

Our analysis of these three isolates deemed them to be Yersinia species not known currently to be pathogenic, but determining this necessitated the use of next-generation sequencing and advanced bioinformatics. Our work highlights the importance of having this technology available to public laboratories, either locally or in a national reference laboratory. The introduction of molecular technologies for the detection of Yersinia species may increase the rate of detections. Accurate identification of significant pathogens in environmental, public health and clinical microbiology laboratories is critically important for the protection of society.

An ecological study of the spatiotemporal dynamics and drivers of domestically acquired campylobacteriosis in Ireland, 2011-2018

In 2021, Campylobacteriosis was the main gastrointestinal disease in the European Union since 2007 according to the European Centre for Disease Prevention and Control. In the Republic of Ireland, the incidence of the disease is particularly high with approximately 3,000 cases per annum, raising significant concerns for national health authorities with an expected increase in the number of cases in the light of climate change. The current study sought to assess the spatio-temporal patterns of campylobacteriosis in the Republic of Ireland using 20,391 cases from January 2011 to December 2018. An ensemble of spatial statistics techniques including seasonal decomposition, spatial clustering and space-time scanning, were used to elucidate the main individual and spatio-temporal characteristics of the disease in the country. Findings revealed that cases from the paediatric age group (i.e., under 5 years old) were more likely to occur in rural areas (aOR: 1.1.27, CI 95% 1.14-1.41) while cases from the intermediate age group (i.e., >5 & <65 years old) were associated with urban living (aOR: 1.30, CI 95% 1.21-1.4). The disease exhibited a peak during Irish summer, with a stronger seasonal signal reported in counties located on the Western part of the country. Infection hotspots were more likely to occur in urban areas, and more particularly on the Southern part of the island and around the main metropolitan areas. Overall, research findings pointed out the influence of local and spatio-temporally specific socio-demographic and environmental risk factors (i.e., cooking habits, local weather, dietary types) therefore highlighting the need for initiating spatio-temporally targeted health management and surveillance strategies.

Establishment of sentinel surveillance of human clinical campylobacteriosis in Ireland

The aim of this work was the establishment of a national laboratory sentinel surveillance service for human clinical Campylobacter in Ireland. This included detailed genomic molecular epidemiology of Campylobacter for 2019. For February-December 2019, 24 clinical microbiology laboratories in Ireland submitted all PCR/culture-positive clinical Campylobacter spp. specimens to Public Health Laboratory (PHL) Dublin one week out of every four. Antimicrobial susceptibility testing (AST) according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria was carried out for Campylobacter spp. isolates for ciprofloxacin, tetracycline and erythromycin. Batch whole genome sequencing (WGS) was carried out on cultures and analysis was performed to determine species, genotype, identify antimicrobial resistance (AMR) and virulence determinants and identify clusters. A total of 75 isolates and 366 PCR-positive stools were received, and 277 isolates recovered (55.7% recovery from stools). Of 257 isolates characterized by WGS, 86.4% (n = 222) were Campylobacter jejuni, 11.7% (n = 30) Campylobacter coli and 1.9% (n = 5) Campylobacter lari. There were 20 clonal complexes with ST-21 clonal complex most prevalent at 26.8% (n = 69). 50.5% (n = 140) of isolates were susceptible to all three antimicrobials tested. 39.3% (n = 109) isolates were ciprofloxacin resistant, 26.3% (n = 73) tetracycline resistant and two isolates erythromycin resistant. Congruence between phenotypic and genotypic AST was observed. There was 95.9% and 95.6% sensitivity and specificity for WGS to predict ciprofloxacin sensitivity and 98.6% and 99.5% sensitivity and specificity for WGS to predict tetracycline sensitivity. Virulence factors flaA, racR, ciaB and cdtB were detected in all isolates. WGS identified 31 potential clusters for public health alert. This sentinel surveillance of human campylobacteriosis in Ireland establishes the basis for a national reference service. Linking with other partners in a 'One Health' framework will help us better understand sources of infection to reduce disease burden and the threat of AMR.