National Institute for Antibiotic Resistance and Infection Control, Ministry of Health, Tel Aviv, Israel.
Adelson School of Medicine, Ariel University, Ariel, Israel.
Microbiol Spectr. 2024 Apr 2;12(4):e0406223. doi: 10.1128/spectrum.04062-23. Epub 2024 Mar 1.
Timely detection of carbapenem-resistant (CRAB) carriers is essential to direct infection control measures. In this work, we aimed to develop a practical protocol to detect CRAB from screening samples. To choose a selective medium that detects CRAB with high sensitivity and specificity, 111 . clinical isolates were inoculated on three types of agar: mSuperCARBA (SC), CHROMagar Acinetobacter (CaA), and modified CHROMagar Acinetobacter (mCaA) containing 4.5 mg/mL meropenem. SC was non-selective, CaA was the most sensitive (100%), but only moderately specific (72%), and mCaA was highly specific (97%) and sensitive (98%). Confirmation of the carbapenem-resistant phenotype using PCR-based detection of , , and genes was specific but not sensitive, detecting only 58% of CRAB isolates. Identification of using either or PCR was excellent. Next, we used the same methodology in routine screening for CRAB carriage. mCaA had the best yield, with high sensitivity but moderate specificity to differentiate between CRAB and other carbapenem-resistant organisms. Skin sampling using sponges and 6 hour enrichment was highly sensitive (98%), while other body sites had poor sensitivity (27%- 41%). Shorter incubation had slightly lower yield, and longer incubation did not improve the detection. Performing PCR for and on colonies growing on modified mCaA differentiated between CRAB and other species with high accuracy (98% and 99%, respectively). Based on our results, we present a procedure for easy and reliable detection of CRAB carriage using skin sampling, short enrichment, selection on mCaA, and PCR-based identification.
Carbapenem-resistant (CRAB) is a substantial cause of nosocomial infections, classified among the most significant multidrug-resistant pathogens by the World Health Organization and by the US Centers for Disease Control. Limiting the spread of CRAB is an important goal of infection control, but laboratory methods for identification of CRAB carriers are not standardized. In this work, we compared different selective agar plates, tested the efficiency of identification by PCR for species-specific genes, and used PCR-based detection of common resistance genes to confirm the carbapenem-resistant phenotype. During a prospective study, we also determined the optimal sample enrichment time. Based on our results, we propose a simple and efficient protocol for the detection of CRAB carriage using skin sampling, short enrichment, selection on appropriate agar plates, and PCR-based identification, resulting in a turn-around time of 24 hours.
及时发现耐碳青霉烯类肠杆菌科细菌（CRAB）携带者对于直接实施感染控制措施至关重要。本研究旨在制定一种实用方案，从筛查样本中检测出 CRAB。为了选择一种具有高灵敏度和特异性的选择性培养基来检测 CRAB，我们将 111 株临床分离株接种于三种琼脂平板上：mSuperCARBA（SC）、显色头孢菌素琼脂（CaA）和含 4.5mg/mL 美罗培南的改良显色头孢菌素琼脂（mCaA）。SC 是非选择性的，CaA 的敏感性最高（100%），但特异性仅为 72%，而 mCaA 的特异性（97%）和敏感性（98%）均较高。使用基于 PCR 的检测方法对 、 和 基因进行碳青霉烯耐药表型的确认特异性高但灵敏度低，仅能检测出 58%的 CRAB 分离株。使用 或 PCR 对 进行鉴定的效果非常好。然后，我们在常规筛查 CRAB 携带情况中使用相同的方法。mCaA 的产率最高，对区分 CRAB 和其他耐碳青霉烯类药物的细菌具有高灵敏度和适度特异性。使用海绵和 6 小时富集的皮肤采样具有很高的灵敏度（98%），而其他部位的采样灵敏度较低（27%-41%）。缩短孵育时间会略微降低产率，而延长孵育时间不会提高检测效果。在改良 mCaA 上生长的菌落上进行针对 和 的 PCR 检测可高度准确地区分 CRAB 和其他种属（分别为 98%和 99%）。基于我们的研究结果，我们提出了一种简便可靠的检测方法，使用皮肤采样、短时间富集、在 mCaA 上选择以及基于 PCR 的鉴定，可检测出 CRAB 携带者。
耐碳青霉烯类肠杆菌科细菌（CRAB）是医院获得性感染的一个重要原因，被世界卫生组织和美国疾病控制与预防中心列为最重要的多重耐药病原体之一。限制 CRAB 的传播是感染控制的一个重要目标，但鉴定 CRAB 携带者的实验室方法尚未标准化。在这项工作中，我们比较了不同的选择性琼脂平板，测试了基于 PCR 的种特异性基因鉴定对 鉴定的效率，并使用基于 PCR 的常见耐药基因检测来确认碳青霉烯耐药表型。在一项前瞻性研究中，我们还确定了最佳的样本富集时间。基于我们的研究结果，我们提出了一种简单而高效的方案，使用皮肤采样、短时间富集、在适当的琼脂平板上选择以及基于 PCR 的鉴定来检测 CRAB 携带情况，总检测时间为 24 小时。
