Reserch On Epidemiology And Resistant To Antibiotics Of Stapylococus Aureus And The Isolation Of Hetero-VISA Strains

Objective To investigate the isolation and antibiotic resistance of stapylococus aureus from2008to201l,so as to provide a guidance for using antibiotics properly.To investigate the prevalence rate of heterogeneous vancomycin resistant stapylococus aureus and develop a new test method for hetero-VISA isolation.Methods1096staphylococcus aureus were isolated and cultured from our hospital from2008to2011. The data of susceptibility tests result and departmental resource was analysised. The infection situation and antibiotics-resistance patterns and distribution of staphylococcus aureus was received.113strains of staphylococcus aureus from2010to2011were screened by agar dilution method and E-test method.The resistant strains were confirmed by population analysis.Results In number of1096strains of stapylococus aureus were isolated from50774samples,the detected rate accounted for2.16%.694strains of1032strains were MRSA,the proportion of MRSA was67.25%.The proportion of MRSA of2008was74.40%and the same proportion was50.00%of2011,the tendency of MRSA isolated rate was descended.The detected rate of Staphylococcus epidermidis ascended from0.09%of2008to0.87%of2011,and in the mean time the proportion of Staphylococcus saprophyticus rised from0.00%to0.05%.The non-susceptibility rate to vancomycin was0.21%in the four years and three strains of SA reduced susceptibility to vancomycin were isolated through the part Ⅱ experment,To isolate hetero-VISA from Stapylococus aureus and screening a new method for hetero-VISA strains.MIC of one strain was3μg/ml,and MIC of two strains were4μg/ml.One of the4μg/ml strains performed heterogeneously vancomycin-resistant,and was confirmed by population analysis finally.Of113strains of SA,1strains was detected as herero-VISA,the positive rate was0.88%.Conclusion1.The detected rate of stapylococus aureus strains presented an decreasing tendency,the main reason was the accretion of specimen quantity and decrement of isolated stapylococus aureus except2009at the same time.But the detected rate of Staphylococcus epidermidis and Staphylococcus saprophyticus isolates performed an increasing tendency.2.The constituent ratio of MRS A in stapylococus aureus represented an descendent trend in the four year,from74.40%of2008to50.00%of2011.But the majority of stapylococus aureus were MRSA overview.3.Two VRSA strains were isolated from stapylococus aureus in2008and2009severally,and never find after that. However, a strain of h-VISA was screened by the part II of exeperiment.The h-VISA could sudden change to VISA with the compressive stress of Vancomycin,and VISA could change back to h-VISA without this stress.Because this kind of stable drug resistance, h-VISA could disperse between patients and lead to grievous endanger. The emerge of the strains with reduced susceptibility to vancomycin and herero-VISA should be paid attention to.4.The population analysis are more effective than the method of disc agar diffusion for h-VISA identification and the former has a good sensitivity as10-8. The detected rate of h-VISA of population analysis was8.3%.5.This reserch isolated a h-VISA strain with4μg/ml.The strain could not be selected by BHI-vancomycin selective culture media with6μg/ml. We still need more penetrating observation for the effect of6μg/ml BHI-vancomycin selective culture media.