定植压力与耐甲氧西林金黄色葡萄球菌医院内交叉传播相关性研究

目的通过动态监测患者住院期间MRSA携带情况,分析在未实施严格接触隔离措施的情况下,CP与MRSA交叉传播之间的相关性,进而评估CP在预测MRSA交叉传播中的作用.方法分别对2009年3-12月间我院急诊病房240例患者和RICU 94例患者进行动态MRSA定植调查.MRSA菌株经rep-PCR方法进行同源性分析.计算MRSA的WCP、CP界值和交叉传播率.分析患者暴露于不同CP时,MRSA交叉传播的相对危险度.结果急诊病房和RICU的MRSA入院携带率分别为6.25%(15/240)和13.83%(13/94),分别在13周和14周出现MRSA交叉传播;两个病房CP界值分别为6.49%和17.66%.高CP作用下,急诊病房MRSA交叉传播率(6.674‰)显著高于低CP时的交叉传播率(0.694‰,x2=7.10,P＜0.01),MRSA交叉传播RR为9.61(95%CI:1.25～74.00),RICU的MRSA交叉传播率(4.710%)显著高于低CP时的交叉传播率(0.297%,x2=12.60,P＜0.01),交叉传播RR为15.87(95%CI:2.06～122.10).结论高CP是MRSA交叉传播的重要危险因素,平均CP可作为预测MRSA交叉传播或加强隔离防控措施的指标.

Study on the relationship between colonization pressure and MRSA cross transmission among hospitalized patients

Objective Based on active monitoring MRSA carriage for hospitalized patients, the relationship between colonization pressure and MRSA cross transmission in wards without rigorous contactisolation measures was analyzed, and the role of colonization pressure in predicting MRSA cross transmission was further evaluated. Methods From March to December 2009, active MRSA colonization screening was performed for 240 hospitalized patients in emergency ward and 94 cases in RICU in our hospital. rep-PCR method was employed to do homology analysis on MRSA strains obtained in this study. MRSA weekly colonization pressure, threshold colonization pressure ,cross transmission rate were calculated respectively. RR of MRSA cross transmission under higher level of colonization pressure and lower level of colonization pressure was analyzed. Results MRSA carriage rates on admission for patients in emergency wards and RICU were 6. 25% (15/2A0) and 13. 83 % (13/94) ,and MRSA cross transmission occurred in 13 weeks and 14 weeks in above two units, respectively. Threshold colonization pressures for above two units were 6. 49%and 17. 66%, respectively. For emergency ward, the MRSA cross transmission rate under higher level of colonization pressure was significantly higher than that under lower level of colonization pressure (x2 = 7. 10,P＜0. 01), the RR of MRSA transmission was 9. 61 (95% CI:1. 25-74.00). For RICU, the MRSA cross transmission rate under higher level of colonization pressure was significantly higher than that under lower level of colonization pressure(x2 = 12. 60, P＜0. 01 ), the RR of MRSA transmission was 15.87 (95% CI:2. 06-122. 10). Conclusions Higher level of colonization pressure is an important risk factor for MRSA transmission, and average colonization pressure can be used as a prediction index for MRSA transmission and strengthening prevention and control measures.