Surface properties of Enterococcus faecalis cells isolated from chicken hearts determine their low ability to form biofilms

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.

A Comparative Study of Fluoroquinolone-Resistant Escherichia coli Lineages Portrays Indistinguishable Pathogenicity- and Survivability-Associated Phenotypic Characteristics Between ST1193 and ST131

Background

Sequence type 1193 is a new such lineage among fluoroquinolone-resistant Escherichia coli, which has risen dramatically within the last several years. However, reasons for rapid emergence and successful spread of E. coli ST1193 remain unclear. The aim of this study was to compare the pathogenicity and survivability features of E. coli ST1193 with global epidemic lineage, ST131.

Methods

A total of 30 E. coli were used in this study. Isolates were divided into two groups, ST1193 (n=15) and ST131 (n=15). Adhesion and invasion to T24 cells and resistance to serum were quantified and compared among two groups. Biofilm formation capacity was assessed by crystal violet assay. Macrocolony formation was assessed on macrocolony formation plates. Resistance to hydrogen peroxide was performed by broth microdilution. RAW264.7 cells were used to assess the anti-phagocytic function of different isolates.

Results

Adhesion and invasion assays revealed that E. coli ST1193 could adhere and invade T24 cells (p <0.05). 93.3% of E. coli ST1193 could form biofilms. The majority of E. coli ST1193 (66.7%) possessed no curli/no cellulose on macrocolony formation plates. E. coli ST1193 showed significant growth in serum and hydrogen peroxide and illustrated higher anti-phagocytic function to RAW264.7 cells (p <0.05). Group analysis showed that E. coli ST1193 was similar to ST131 in pathogenicity- and survivability-associated phenotypic characteristics (p >0.05).

Conclusion

Our study provided more insights into pathogenicity and survivability features of E. coli ST1193, which was similar to ST131. Our study could be of great importance in understanding the emergence of global spread E. coli ST1193. Strategic and continued surveillance should be carried out to prevent the infections caused by E. coli ST1193.