艰难梭菌实验室快速鉴定方法检验效能的比较

Laboratory methods for rapid identification of Clostridium difficile: a comparison of the test efficiency

目的评价3种艰难梭菌实验室鉴定方法的快速性及准确性。方法 2013年6月至2013年11月,收集136名ICU患者共248份标本进行24 h、48 h厌氧培养,并进行鉴定,同时对大便标本提取DNA进行tcd B毒素基因检测。以48 h培养结果为参考标准,评价24小时培养法和PCR扩增tcd B基因法鉴定艰难梭菌的灵敏度、特异度、阳性预测值和阴性预测值。结果 136名ICU发生腹泻的患者中,11名患者共有12份标本48 h培养为艰难梭菌阳性,艰难梭菌感染率为8.09%(11/136),标本阳性率为4.84%(12/248)。24小时培养法及PCR扩增tcd B基因法的灵敏度、特异度、阳性预测值、阴性预测值分别为75.00%、100%、100%、98.74%和83.33%、99.15%、83.33%、99.15%。结论提取大便DNA tcd B毒素基因是最快速、灵敏度和特异度均较高的方法;48小时培养法时间相对较长,但稳定可靠,并可以保留菌株进行后续试验;24小时培养法,时间短、简便但会漏诊某些阳性病例。

Objective To identify the fastest and most accurate method among three laboratory methods for identification of Clostridium difficile. Methods 248 stool specimens from 136 ICU inpatients during June and November2013 were collected and cultured for anaerobic bacteria for 24 hours and 48 hours respectively. DNA was extracted from the stool specimens for tcd B gene detection. Based on the result of 48-hour culture method,the sensitivity,specificity and positive and negative predictive values of 24-hour culture and those of PCR amplification of tcd B gene were evaluated. Results Among the 136 ICU patients with diarrhea,11 patients with a total of 12 specimens were found positive for Clostridium difficile after 48 hours. The rate of Clostridium difficile infection（ CDI） was8. 09%（ 11 /136）; 4. 84%（ 12 /248） of the stool specimens were found positive for Clostridium difficile. The sensitivity,specificity,positive predictive value and negative predictive value were 75. 00%,100%,100% and98. 74% for the 24-hour culture method and 83. 33%,99. 15%,83. 33%,99. 15% for tcd B gene PCR amplification method. Conclusion The stool DNA extraction for tcd B testing is the most rapid method with higher sensitivity and specificity. The 48-hour culture medthod takes more time but the results are consistent and reliable,and the strains can be preserved for following experiments. The 24-hour culture method is simple and takes less time,but may miss some positive cases.