Division of Epidemiology, Tel-Aviv Sourasky Medical Center, Tel-Aviv, Israel.
J Clin Microbiol. 2009 Oct;47(10):3261-5. doi: 10.1128/JCM.02368-08. Epub 2009 Aug 12.
The spread of carbapenem-resistant members of the Enterobacteriaceae family (CRE) harboring carbapenemases is an emerging public health threat. As KPC-producing Klebsiella species are endemic in our tertiary care hospital, we aimed to evaluate a PCR-based surveillance test for identification of rectal carriage of KPC-producing CRE. We conducted a surveillance study between May and December 2007. Rectal swabs were collected from patients known to harbor CRE and from contacts of newly discovered patients harboring CRE. Specimens were evaluated by culture and by PCR analysis for blaKPC and were defined as positive if CRE was cultured and blaKPC was identified. Discrepant results between the culture and PCR analysis were resolved by subculturing, repeating the PCR, and performing a hydrolysis assay. Positive CRE cultures prior or subsequent to the time of sampling for the study were also taken into consideration. Sensitivity, specificity, and time to result were calculated. A total of 755 swabs were included. Concordant results were documented for 735 specimens; 51 were positive as determined by both PCR and culture. Discrepancies existed for 20 swabs; 9 were blaKPC negative and CRE culture positive, and 11 were blaKPC positive and CRE culture negative. After repeat testing, a total of 64 samples were classified as blaKPC-positive CRE. The sensitivity and specificity of the PCR analysis were 92.2% and 99.6%, respectively, and those of the culture were 87.5% and 99.4%, respectively. Over the last 3 months of the study, the sensitivity of the PCR improved to 96.3%, versus 77.8% for culture. Time to result was 30 h for the PCR and 60 h (negative) and 75 h (positive) for the CRE culture. blaKPC PCR-based testing is a useful method for the surveillance of KPC-producing CRE. Its main advantage over culturing is a shorter time to result, and it may prove to be more sensitive.
产碳青霉烯酶的肠杆菌科（CRE）成员的传播是一种新出现的公共卫生威胁。由于产 KPC 的肺炎克雷伯菌在我们的三级保健医院中普遍存在，我们旨在评估一种基于 PCR 的监测试验，以鉴定产 KPC 的 CRE 的直肠携带情况。我们在 2007 年 5 月至 12 月期间进行了一项监测研究。从已知携带 CRE 的患者和新发现携带 CRE 的患者的接触者中采集直肠拭子。通过培养和 blaKPC 的 PCR 分析评估标本，如果培养出 CRE 并鉴定出 blaKPC，则将其定义为阳性。培养和 PCR 分析之间的不一致结果通过传代培养、重复 PCR 和进行水解试验来解决。在进行研究之前或之后采集的阳性 CRE 培养物也被考虑在内。计算了敏感性、特异性和结果时间。共纳入 755 个拭子。735 个标本的结果一致；51 个标本通过 PCR 和培养均为阳性。20 个拭子存在差异；9 个 blaKPC 阴性且 CRE 培养阳性，11 个 blaKPC 阳性且 CRE 培养阴性。重复检测后，共有 64 个样本被归类为 blaKPC 阳性 CRE。PCR 分析的敏感性和特异性分别为 92.2%和 99.6%，培养的敏感性和特异性分别为 87.5%和 99.4%。在研究的最后 3 个月，PCR 的敏感性提高到 96.3%，而培养的敏感性为 77.8%。PCR 的结果时间为 30 小时，而 CRE 培养的结果时间为 60 小时（阴性）和 75 小时（阳性）。基于 blaKPC 的 PCR 检测是一种用于监测产 KPC 的 CRE 的有用方法。与培养相比，其主要优势在于结果时间更短，并且可能更敏感。
