Study On Drug Resistance Of Nosocomial Respiratory MRSA Tract And Vancomycin Alone Or Combined With Tanreqing Against MRSA

Objective: The incidence of nosocomial infections are increasing gradually in recent years,which has become a serious global issue.It is particularly important to disclose the epidemic state as well as the trend of drug resistance and the sensitivity of certain drugs of MRSA.The aim of this study was to evaluate the effect of vancomycin combined with Tanreqing and the ability to prevent mutant resistance,We detected the minimum inhibitory concentration(MIC),mutant prevention concentration(MPC)of vancomycin(VAN),Tanreqing monotherapy,combination therapy in quality controlled MRSA strains ATCC 43300 via static methods respectively.Methods:The bacterial strains used in this study was obtained from the isolated respiratory tract MRSA strains from inpatients in our hospital from January 2014 to December 2014 as the study object,used the method recommended by 2014 Clinical Laboratory Standards Institute(CLSI)were exeacted to identify and analyze the pure isolated bacteria,to measure the MIC of the clinical isolated strains,and to calculate the drug resistant ratio;We screened 30 trains with no repetition among isolated MRSA strains collected from respiratory tract from patients definitely diagnosed as MRSA pneumonia,and then we measured the MIC and MPC of quality controlled strain ATCC43300 and clinical isolated strains against Tanreqing or vancomycin combined with Tanreqing by two-folds agar dilution method;We compared the effect of VAN monotherapy or Tanreqing combination therapy of on selectivity index(SI)and Mutant selection window(MSW),then calculated the fraction inhibitory concentration(FICI)to evaluate the effect of combination therapy.Results:Analysis of the resistance of MRSA strains isolated from respiratory tract in Henan Province People's Hospital hospital against antibiotics shows that the resistant rate of each drug is: tobramycin(77.5%),gentamicin(70.8%),erythromycin(75.3%),Amikacin(59.6%),clindamycin(59.6%),compound sulfamethoxazole(6.7%);and vancomycin,teicoplanin,linezolid resistance show no resistance;The MIC of vancomycin alone against 30 clinical isolated strains is0.50~100?g/m L,while after combined with Tanreqing,the MIC is 0.12~0.50?g/m L.The lowest MICcombined is reduced by 4-folds compared with corresponding MICmonotherapy,28 strains(93.33%)shows significant reduction with 2 strains(6.66%)showing no reduction;The MPC of vancomycin alone against 30 clinical isolated strains is 2.00~16.00?g/m L,while after combined with Tanreqing the MPC is 1.00~4.00?g/m L.The lowest MPCcombined is reduced by 16-folds compared with corresponding MPCmonotherapy,30 strains show significant reduction(100%);The upper limit of MSW of vancomycin alone against 30 clinical isolated strains is 0.50~16.00?g/m L,and the lower limit is 0.50~2.00?g/m L;while after combined with Tanreqing the upper limit of MSW is 0.25~4.00?g/m L,and the lower limit of MSW is 0.12~1.00?g/m L.30 strains show significant reduction,and some strains even show that MSW is closed;The SI of vancomycin alone against 30 clinical isolated strains is 4~32;while the SI of vancomycin combined with Tanreqing is 2-16?g/m L,22 strains(73.33%)show reduction,with 7 strains(23.33%)no changes and 1 strain(3.33)increase;The MIC of tanreqing alone against 30 clinical isolated strains is 16-125?l/ml,the MPC of tanreqing alone against 30 clinical isolated strains is 64-500?l/ml.while after combined with vancomycin the MIC is4-32?l/ml,the MPC of vancomycin combined against 30 clinical isolated strains is 16-250?l/ml.The Fraction Inhibitory Concentration index of vancomycin combined with Tan re qing is 0~0.5,strains(16.66%)show synergiristic effect,23 strains(76.66%)with FICI between 0.5 to 1 show additive effect,2 strains(6.66%)with FICI between 1 to 2show no indifferent effect.Conclusion:1.The proportion of MRSA among all staphylococcus aureus attained from respiratory specises was 69.53%,and no vancomycin intermediate staphylococcus aureus(VISA),vancomycin resistant staphylococcus aureus(VRSA)and heterogeneous vancomycin-resistant staphylococcus aureus(h VISR)strains were detected,and all strains are susceptible to vancomycin,teicoplanin or linezolid was not detected;2.Tanreqing,a Chinese patent medicine shows certain inhibitory effect on MRSA in vitro,and the administration of Vancomycin combined with Tanreqing decrease MPC,narrow MSW and sometimes even close the MSW;can increase the sensitivity of both drugs with MRSA synergiristic effect,which may provide theoretical basis for combine from therapy VAN and Tanreqing against MRSA.