Epidemiological, Genomic and In Vitro Insights into the Clinical Significance of Yersinia enterocolitica Biotype 1A

Yersiniosis is a notifiable disease in Aotearoa|New Zealand, which includes Yersinia enterocolitica (YE) Biotype (BT) 1A, whose pathogenicity and clinical significance has been questioned. An analysis of yersiniosis cases with different YE biotypes (BTs) notified between 2018 and 2022 identified that YE BT 1A and YE BT 2/3 were more frequently observed among adults of European or Other ethnicity and young children of Asian ethnicity, respectively. A comparison of virulence-associated genes detected using whole-genome sequencing data from YE isolates confirmed that YE BT 1A lacked several recognized virulence genes. In vitro two-dimensional intestinal (Caco-2) cell assays showed that YE BT 1A (n = 4) from clinical cases attached and invaded at significantly lower levels than YE BT 2/3 and 4 (n = 3). Gut three-dimensional organ-on-a-chip infections performed using single isolates of YE BTs 2/3, 5, and 1A showed that the YE BT 1A isolate elicited a significantly larger interleukin-8 inflammatory response than the YE BT 2/3 or 5 isolates, which may suggest an acute inflammatory-mediated intestinal disease mechanism. While further work is required to elucidate the role of YE BT 1A in causing gastrointestinal illness, these findings highlight the need to distinguish cases infected with YE BT 1A from those infected with other YE BTs.