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Background: Norovirus (NoV) GII.4 is the most common genotype for norovirus gastroenteritis worldwide. New variants or subgenotypes are continuously emerging, thus posing a serious threat to child health. Methods: We compared retrospectively the clinical manifestations and complications of norovirus gastroenteritis in children from April, 2004 through December, 2012. NoV variants were analyzed to investigate the association of circulating viral strains with the complications. A modified disease severity score system based on Vesikari score system was devised and to evaluate disease severity. Results: Compared to the outbreak in 2004/2005 winter, significant higher incidence of complications in the later periods are: convulsive disorder (ρ < 0.001) in 2006/2007 winter gastrointestinal hemorrhage (ρ = 0.047) and severe abdominal pain or irritability (ρ = 0.033) in 2008/09/10 winter; gastrointestinal hemorrhage (ρ = 0.030), severe abdominal pain or irritability (ρ = 0.014), and prominent hyperthermia (fever >39 °C, p = 0.001) in 2011/2012 winter. GII.4 Den_Haag_2006b, GII.4 2010, GII.4 Sydney 2012, and GII.4 2012b were the predominant strains in the outbreaks after 2006. By the modified severity score system, severe norovirus disease occurred in 28.5 %, 32 %, 33.3 %, and 30. 2 % of the patients in the four periods. A longer duration of hospitalization (ρ = 0.02) were found in those with high score irrespective of the year of admission. Conclusions: Our study demonstrated NoV outbreaks in northern Taiwan caused by different GII.4 variants that were associated with specific complications and uncommon clinical presentations. A modified severity score system first proposed in this study was able to identify severe cases with a longer hospital stay in NoV-infected children. [ABSTRACT FROM AUTHOR]

Background The green fluorescence protein (GFP)-associated fluorescence method and the luciferaseassociated bioluminescence method are the two major methods for IVIS imaging system to investigate the bacterial infection in animal models. The aim of this study was to evaluate the infection route of Gram-negative bacteria carrying a stable and broad range of conjugative bioluminescence plasmid pSE-Lux1 in a mouse model. Results Both encapsulated and non-encapsulated Gram-negative bacteria were used as hosts to evaluate conjugation efficiency and plasmid stability of pSE-Lux1, a recombinant of pSE34 and luxABCDE operon. The plasmid conjugation efficiencies of pSE-Lux1 ranged from 10-3 to 10-7 in various Gram-negative bacteria. Plasmid pSE-Lux1 maintained in Escherichia coli, Klebsiella pneumoniae, and Salmonella enterica serovars Choleraesues (abbreviated S. Choleraesuis) and Typhimurium (S. Typhimurium), than in Acinetobacter baumannii and Serratia marcescens, was shown to be of better stability for at least four days. To investigate systemic bacterial infections, K. pneumoniae T strain CG354 was intravenous injected and was non-pathogenic to Balb/c mice for a long-term bioluminescence monitoring for 6 days. For examining dynamic distributions of gastrointestinal tract infection, the invasion protein SipB-deficient mutant OU5045ΔsipB and OU5046ΔsipB of Salmonella enterica serovar Typhimurium constructed in this study, compared to wild-type strain OU5045 and its virulence plasmid-less strain OU5046, were of less virulence to mice. Conclusions This is the first study to evaluate the conjugative and stable bioluminescence vehicle system of pSE-Lux1 in a wide range of Gram-negative bacteria, which system can provide a useful reporter approach to trace systemic and gastrointestinal bacterial infections in a mouse model. [ABSTRACT FROM AUTHOR]