A Comparative Study of Fluoroquinolone-Resistant 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 , which has risen dramatically within the last several years. However, reasons for rapid emergence and successful spread of ST1193 remain unclear. The aim of this study was to compare the pathogenicity and survivability features of ST1193 with global epidemic lineage, ST131.

Methods: A total of 30 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 ST1193 could adhere and invade T24 cells ( <0.05). 93.3% of ST1193 could form biofilms. The majority of ST1193 (66.7%) possessed no curli/no cellulose on macrocolony formation plates. ST1193 showed significant growth in serum and hydrogen peroxide and illustrated higher anti-phagocytic function to RAW264.7 cells ( <0.05). Group analysis showed that ST1193 was similar to ST131 in pathogenicity- and survivability-associated phenotypic characteristics ( >0.05).

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