In an effort to search for more potent antibacterial drugs, the minimum inhibitory concentrations (MIC) of fifteen fosfomycin derivatives at 35℃ for 24h against S. aureus, Enterococcus, P.aeruginosa and Eschericha coli were determined, respectively. Preliminary antibacterial results showed that five derivatives of them were more potent than reference substance (Ⅳa) against some bacteria. Take compound Ⅳg for example, its antibacterial activity was three times as potent as that of compound Ⅳa against S.aureus. The structure-activity relationship of fosfomycin derivatives was investigated according to the mechanism of fosfomycin antibacterial action at molecular level which was pointed by Smeyers et al.

Objective: To analyze the prevalence of severe fever with thrombocytopenia syndrome virus(SFTSV)infection in Zhoushan island of Zhejiang province and the duration of serum positive IgG antibody in patients infected with SFTSV. Methods: One thousand one hundred and twenty-two healthy people from Zhoushan island of Zhejiang province were recruited for cross-sectional study in August 2019, including 641 from non-epidemic areas and 481 from epidemic areas. The serum SFTSV-IgG antibody was detected by enzyme-linked immunosorbent assay (ELISA), and the positive rates of SFTSV-IgG antibody were compared between people from the epidemic areas and non epidemic areas. Meanwhile, the antibody titer of SFTSV-IgG in 19 patients confirmed between July 2011 and June 2018 was detected by indirect ELISA. SPSS 17.0 software was used to analyze data. Results: The positive rate of SFTSV-IgG antibody was 1.5% (7/481) in the epidemic area, which was higher than that in the non-epidemic area (0/641) (χ²=7.187, P<0.01). The positive rates of SFTSV-IgG antibody in 2019 were lower than those in the epidemic area (11.7%) and non-epidemic area (2.5%) in 2013 (χ²=22.556 and 10.352, both P<0.01). The serum SFTSV-IgG antibody of 18 patients with previous infection was still positive, and the longest one lasted for 8 years. Conclusions There is a SFTSV latent infection in population from epidemic area of Zhoushan island. The SFTSV-IgG antibody can last for a long time in patients with SFTS and it may have certain protective effect.