Epidemic Potential of Escherichia coli O16:H41-ST131: Compared with Pandemic O25b:H30-ST131 Lineage.

Background O16:H41 is an important subclone among Escherichia coli (E. coli) sequence type (ST) 131, which has risen dramatically in recent years. However, reasons for the rapid increase of E. coli O16:H41-ST131 remain unclear. The aim of this study was to compare the pathogenicity and survivability features of E. coli O16:H41-ST131 with global epidemic O25b:H30-ST131 lineage. Methods Sixteen E. coli ST131 were divided into two groups: group O16:H41-ST131 (n=6) and group O25b:H30-ST131 (n=10). Adhesion and invasion activity of different isolates were measured using human T24 cells. Biofilm production was quantified by crystal violet staining. Fifty percent human serum was used to detect serum sensitivity. Resistance to hydrogen peroxide was detected by broth microdilution method, and anti-phagocytic function was determined by phagocytosis experiments. Results E. coli O16:H41-ST131 and O25b:H30-ST131 lineage showed similar biofilm formation, adhesion and invasion abilities. In terms of survivability, resistance to serum and hydrogen peroxide of E. coli O16:H41-ST131 was similar as that of E. coli O25b:H30-ST131. But anti-phagocytic function of E. coli O16:H41-ST131 was significantly weaker than that of E. coli O25b:H30-ST131. Conclusion The pathogenicity and survivability of E. coli O16:H41-ST131 were similar to those of E. coli O25b:H30-ST131, which may be important reasons for its increasing prevalence. Our study may contribute to a better understanding of the prevalence of E. coli O16:H41-ST131.