Virulence Changes between EF A7 and EF A7 cyl Mutant in the Mouse Peritonitis Models / 现代检验医学杂志

ABSTRACT

Objective The purpose of this study was to understand the pathogenic mechanisms of enterococcal hemolysin and establish the foundation to diagnose and control relevant diseases.Methods Take 30 clean grade ICR mice were randomly divided into ten groups,each 6,1 to 4 groups according to 10-fold gradient amount per 1 ml intraperitoneal injection of 5× 107 cfu/ml~5×1010 cfu/ml of EF A7,group 5 as a control group injected 0.5 ml saline,take another 30 clean grade ICR mice,intraperitoneal injection of 5×107 cfu/ml~5×1010 cfu/ml of EF A7 cyl mutant by the same measures,compared to the original strains of mice infected with mutant strain LD50,and a week after infection mortality was observed in mice daily. Another seven groups of mice with the same bacterial concentration (5×109 cfu/ml)were injected intraperitoneally EF A7 and EF A7 cyl mutant,after infection 6 h,12 h and 24 h comparing the number of leukocytes in peripheral blood of mice,re-spectively,the concentration of TNF-αin the acute phase of cytokines.Results In the mouse peritonitis models the 50% le-thal dose (LD50)of EF A7 cyl mutant was 100 times lower than enterococcus faecalis EF A7.The differences of the survival percentage of EF A7 cyl mutant groups and EF A7 groups have significance (P<0.05).As the changes in boold leukocytes numbers and the TNF-αlevel.Conclusion Cyl gene is probably a major virulence factor of Enterococcus and plays an impor-tant role in the mouse peritonitis model.