Study On The Epidemiological Of Disinfectant-resistant Gene QacA/B In MRSA And It’s Resistance Of Disinfectant And Mechanisims Research

Objecctive:1. To investigate the disinfectant-resistant gene qacA/B in meticillin-resisitantStaphylococcus aureus isolated from xi’an’s hospital in January2011to June2011, inorder to know the aureus’s sensitivityofdisinfectant.2. By testing the resistance of methicillin Staphylococcus aureus to usualdisinfectants (iodophor and84chlorine disinfectant) to understand theresistance and to guide the rational use of disinfectants; Discuss the relationshipbetween methicillin-resistant Staphylococcus aureus which carrying geneqacA/B and the resistance to iodophor and84chlorine disinfectant. In that caseto provide clinical data for further study on bacterial resistance mechanisms.Methods:1. Experimental strains are continuously isolated from clinical collection of152methicillin-resistant Staphylococcus aureus strains. QacA/B gene is testedby PCR method;According to whether having the qacA/B genes to divide twogroups, and test the minimum inhibitory concentration and minimal baeterieidaconcentration of each strain by broth dilution method.At last, making acomparisonwith the standard strains’s MIC and MBC.2. We use the Mann-Whiteney U test on the minimum inhibitory experiments and the minimum bactericidal experimental data, and chi-square test on theconfrontational rate.Results:1. In the investigation of the research,152methicillin-resistant Staphylococcusaureus strains are isolated from four hospitals of Xi’an in January2011toJune.In those strains,11strains have the qacA/B gene, the positive rate is7.2%.2. The experimental strains’s MIC of povidone-iodine eight strains’s MICare100mg/L, two strains in positive gene group,six in negative gene group. Tenstrains’s MIC are200mg/L, five strains in positive gene group; four strains’sMIC are300mg/L, all of them are bigger than standard strains’s MIC,and all ofthem have qacA/B gene. Making a comparison with the standard strain’sMIC,the resistant rate is18.2%.After all,MRSA’s MIC of positive gene group ismuch bigger than in negative gene group by stamasticly analizing P<0.05）. Thedifference between the twogroups is statistically significant.3. The experimental strains’s MBC of povidone-iodine One positive genegroup strain’s MBC are100mg/L; three strains’s MBC are200mg/L,one strainin positive gene group, two in negative gene group; eleven strains’s MBC are300mg/L, four strains in positive gene group, seven in negative gene group; sixstrains’s MIC are400mg/L,five strains in positive gene group, one in negativegene group; One positive gene group strain’s MBC are500mg/L; Sevenstrains’sMBC are bigger than standard strain,the resistant rate is31.8%. MRSA’s MBCof positive gene group is much bigger than in negative gene group bystamasticly analizing P<0.05）. The difference between the two groups is alsostatistically significant.4. The experimental strains’s MIC of84chlorine disinfectant Fifteenstrains’sMIC are250mg/L, six strains in positive gene group, nine in negative genegroup;seven strains’s MIC are500mg/L,five strains in positive gene group, twoin negative gene group. Seven strains’s MIC are bigger than standard strain’s,the resistant rate is31.8%. The difference between the positive gene group and negative gene group is not statistically significant.5. The experimental strains’s MBC of84chlorine disinfectant Seven strains’sMBC are250mg/L,two strains in positive gene group,five in negative genegroup; nine strains’s MBC are500mg/L,four strains in positive gene group,fivein negative gene group; six strains’s MBC are1000mg/L,five strains in positivegene group,one in negative gene group; all of them are bigger than standardstrains’s MBC, the resistant rate is27.3%. The difference between the positivegene group and negative gene group is not statistically significant.Conclusions：We collected152MRSA,11of which were detected with qacA/B gene.This gene has the carrier rate of7.2%,we forecast that MRSA quaternaryammonium disinfectant resistance in this region is relatively lower than in otherregions.It have not appearred a large number of MRSA-qacA/B epidemic strains.MRSA disinfectant resistance to iodophor and84chlorine enhanced in varyingdegrees compared to standard strains,We proposed to increase the clinical useof povidone-iodine and84chlorine disinfectant concentration of the disinfectionor extend the duration of action. Results of the determination of MIC and MBCgroups speculate that the qacA/B gene may be one of the reasons resistant onMRSA, it provides a reliable reference value for further study about iodophordisinfectant and bacterial resistance.mechanism.