Microbiology and Immunology Department, Faculty of Pharmacy (Girls), Al-Azhar University, Cairo, Egypt.
Microbiology and Immunology Department, Faculty of Pharmacy (Boys), Al-Azhar University, Cairo, Egypt.
Eur J Clin Microbiol Infect Dis. 2018 Sep;37(9):1647-1652. doi: 10.1007/s10096-018-3294-7. Epub 2018 Jun 23.
We aimed to identify the carbapenem-resistant Gram-negative bacteria (GNB) causing catheter-related bloodstream infections (CRBSI) in intensive care units (ICU) in a tertiary care Egyptian hospital, to study their resistance mechanisms by phenotypic and genetic tests, and to use ERIC-PCR for assessing their relatedness. The study was conducted over 2 years in three ICUs in a tertiary care hospital in Egypt during 2015-2016. We identified 194 bloodstream infections (BSIs); 130 (67.01%) were caused by GNB, of which 57 were isolated from CRBSI patients (73.84%). Identification of isolates was performed using conventional methods and MALDI-TOF MS. Antimicrobial susceptibility testing (AST) was done by disc diffusion following CLSI guidelines. Phenotypic detection of carbapenemases enzymes activity was by modified Hodge test and the Carba-NP method. Isolates were investigated for the most common carbapenemases encoding genes bla, bla, and bla using multiplex PCR. Molecular typing of carbapenem-resistant isolates was done by ERIC-PCR followed by sequencing of common resistance genes. The overall rate of CRBSI in our study was 3.6 per 1000 central venous catheter (CVC) days. Among 57 Gram-negative CRBSI isolates, Klebsiella pneumoniae (K. pneumoniae) was the most frequently isolated (27/57; 47.4%), of which more than 70% were resistant to Meropenem. Phenotypic tests for carbapenemases showed that 37.9% of isolates were positive by modified Hodge test and 63.8% by Carba-NP detection. Multiplex PCR assay detected the bla in 28.6% of the isolates and bla in 26.8%, bla and bla were detected together in the same isolate in 5.6%, while bla-like were not detected. ERIC-PCR detected limited genetic relatedness between K. pneumoniae isolates. Elevated resistance rates were observed to all antibiotics including carbapenems among K. pneumoniae isolates causing CRBSI. ERIC-PCR showed that the resistant isolates were mainly polyclonal. Our results call for reinforcement of antimicrobial stewardship and measures to prevent CRBSI.
我们旨在鉴定引起埃及一家三级护理医院重症监护病房（ICU）导管相关血流感染（CRBSI）的耐碳青霉烯类革兰氏阴性菌（GNB），通过表型和基因检测研究其耐药机制，并使用 ERIC-PCR 评估其相关性。该研究于 2015-2016 年在埃及一家三级护理医院的三个 ICU 进行了 2 年。我们鉴定了 194 例血流感染（BSI）；130 例（67.01%）由 GNB 引起，其中 57 例从 CRBSI 患者中分离（73.84%）。使用常规方法和 MALDI-TOF MS 进行分离物鉴定。根据 CLSI 指南进行药敏试验（AST）。通过改良 Hodge 试验和 Carba-NP 方法检测碳青霉烯酶活性。使用多重 PCR 检测最常见的碳青霉烯酶编码基因 bla、bla 和 bla。对耐碳青霉烯的分离株进行 ERIC-PCR 分子分型，然后对常见耐药基因进行测序。耐碳青霉烯分离株的总体 CRBSI 发生率为每 1000 个中心静脉导管（CVC）天 3.6 例。在 57 株革兰氏阴性 CRBSI 分离株中，肺炎克雷伯菌（K. pneumoniae）是最常分离的（27/57；47.4%），其中超过 70%对美罗培南耐药。碳青霉烯酶表型检测显示，改良 Hodge 试验阳性率为 37.9%，Carba-NP 检测阳性率为 63.8%。多重 PCR 检测发现 28.6%的分离株携带 bla，26.8%的分离株携带 bla，同一分离株同时携带 bla 和 bla 的比例为 5.6%，而 bla 样基因未检出。ERIC-PCR 检测到肺炎克雷伯菌分离株之间遗传相关性有限。引起 CRBSI 的肺炎克雷伯菌对所有抗生素包括碳青霉烯类的耐药率均升高。ERIC-PCR 显示，耐药分离株主要为多克隆。我们的结果呼吁加强抗菌药物管理和预防 CRBSI 的措施。
