Oral Presentation Australian Society for Microbiology Annual Scientific Meeting 2021

Comparative genomics of Chinese and international isolates of Escherichia albertii: population structure and evolution of virulence and antimicrobial resistance (#30)

Lijuan Luo 1 , Hong Wang 2 , Michael Payne 1 , chelsea Liang 1 , Li Bai 3 , Han Zheng 4 , Yanwen Xiong 4 , Qun Li 2 , Ruiting Lan 1
  1. University of New South Wales, Randwick, NSW, Australia
  2. Zigong Center for Disease Control and Prevention, Zigong, Sichuan, China
  3. Food Safety Research Unit, China National Center for Food Safety Risk Assessment, Beijing, China
  4. National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China

Escherichia albertii is a newly recognized species in the genus Escherichia that causes diarrhea. The population structure, genetic diversity and genomic features have not been fully examined. Here, 169 E. albertii isolates from different sources and regions in China were sequenced and combined with 312 publicly available genomes (from additional 14 countries) for genomic analyses. The E. albertii population was divided into 2 clades and 8 lineages, with lineage 3 (L3), L5 and L8 more common in China. Clinical isolates were observed in all clades/lineages. Virulence genes were found to be distributed differently among lineages: subtypes of the intimin encoding gene eae and the cytolethal distending toxin (Cdt) gene cdtB were lineage associated, the second type three secretion system (ETT2) island was truncated in L3 and L6. Seven new eae subtypes and 1 new cdtB subtype (cdtB-VI) were found. Alarmingly, 85.9% of the Chinese E. albertii isolates were predicted to be multidrug resistant (MDR) with 35.9% harboured genes capable of conferring resistance to 10 to 14 different drug classes. By in silico multi-locus sequence typing, majority of the MDR isolates belonged to 4 STs (ST4638, ST4479, ST4633 and ST4488). Thirty-four intact plasmids carrying MDR and virulence genes, and 130 intact prophages were identified from 17 complete E. albertii genomes. Ten plasmid replicon types were found to be significantly associated with MDR. The 130 intact prophages were clustered into 5 groups, with group 5 prophages harbouring more virulence genes. Our findings provided fundamental insights into the population structure, virulence variation and MDR of E. albertii.