| Objective To observe the expression of ST-239-type MRSA virulence factors in different immune status,it can provide a new basis for the combination of the host immune status of Staphylococcus aureus virulence factor in gene expression.Method The rats were randomly divided into control group and model group,using40mg/kg intramuscular injection of cyclophosphamide three days in a row,then drip a high concentration of low-dose fresh MRSA bacterial suspension,continuous infusion of three days,causing immunosuppression MRSA colonization model.The control group directly drip the high concentration of fresh MRSA bacterial suspension.After a period of colonization,we extract of rat nasal tissue,using real-time quantitative PCR analysis the virulence factors gene level, which is isolated from different immune status rat in vivo experiments.At the same time,when the animals in each group were sacrificed,add different groups peripheral blood to TSB medium.Ordinary TSB medium as a control,using real-time PCR technology to analysis the virulence factors gene expression level in different culture conditions and different culture time points.Result 1.Compared with normal immune status rats,MRSA colonizes easier in immunosuppressed rats. 2.Compared with the previous intramuscular cyclophosphamide,after injection of cyclophosphamide 3 days and 7 days,the WBC and PLT in peripheral blood are declining rapidly,while RBC, HGB also significantly lower(P <0.01);CD3+T, CD3+CD4+ T,CD3+CD8+T lymphocyte ratio was significantly decreased and the proportion of B lymphocytes and NK cells was significantly reduced(P <0.01); Immunoglobulin G, M, A levels decreased significantly(P <0.01); 3.Drip small doses of high concentrations of fresh MRSA bacterial suspension three times,it can presence inside and outside the nasal tissue stablely after a period of colonization. 4.Detection of virulence factors in vivo test showed that model group MRSA virulence factor expression levels is higher then the control group(P<0.05), in which the level of target spa gene expression was significantly increased(P <0.01);5.It shows that the expression of bacterial virulence factors are different,after culturing at different times and different contexts in vitro;At 90 min,expression of virulence factor hla and spa have no change,which is compared with 0min(P>0.05);However,when culture to120 min,expression of hla in model group is significantly higher than the control group(P<0.01),and the expression of spa is also increased(P<0.05).Conclusion 1.When the host is in a state of immunosuppression,it maybe stimulate the expression of virulence factors of S. Aureus. 2.When MRSA infected host, the growth of bacteria is completely different in the medium, there are some differences could lead to the expression of different virulence factors of S. Aureus. |
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