Department of Pharmaceutics, College of Pharmacy, King Saud University, 11451 Riyadh 2457, Saudi Arabia.
Microbiology and Immunology Department, Faculty of Pharmacy, Al-Azhar University, Nasr City, Cairo, Egypt.
Biomed Res Int. 2019 Jul 29;2019:6736897. doi: 10.1155/2019/6736897. eCollection 2019.
The aim of this study was to investigate the mechanisms responsible for resistance to antimicrobials in a collection of enterobacterial isolates recovered from two hospitals in Saudi Arabia. A total of six strains isolated from different patients showing high resistance to carbapenems was recovered in 2015 from two different hospitals, with four being and two All isolates except one were resistant to tigecycline, but only one was resistant to colistin. All produced a carbapenemase according to the Carba NP test, and all were positive for the EDTA-disk synergy test for detection of MBL. Using PCR followed by sequencing, the four isolates produced the carbapenemase NDM-1, while the two isolates produced the carbapenemase VIM-1. Genotyping analysis by Multilocus Sequence Typing (MLST) showed that three out of the four isolates were clonally related. They had been recovered from the same hospital and belonged to Sequence Type (ST) ST152. In contrast, the fourth isolate belonged to ST572. Noticeably, the NDM-1-producing additionally produced an extended-spectrum ß-lactamase (ESBL) of the CTX-M type, together with OXA-1 and TEM-1. Surprisingly, the three clonally related isolates produced different CTX-M variants, namely, CTX-M-3, CTX-M-57, and CTX-M-82, and coproduced QnrB, which confers quinolone resistance, and the 16S rRNA methylase RmtC, which confers high resistance to all aminoglycosides. The AAC(6')-Ib acetyltransferase was detected in both and . Mating-out assays using as recipient were successful for all isolates. The gene was always identified on a 70-kb plasmid, whereas the gene was located on either a 60-kb or a 150-kb plasmid the two isolates, respectively. To the best of our knowledge, this is the first report of the coexistence of an MBL (NDM-1), an ESBL (CTX-M), a 16S rRNA methylase (RmtC), an acetyltransferase (AAC[6']-Ib), and a quinolone resistance enzyme (QnrB) in isolates recovered from different patients during an outbreak in a Saudi Arabian hospital.
本研究旨在探讨从沙特阿拉伯两家医院采集的肠杆菌分离株对抗菌药物耐药的机制。2015 年，从两家不同医院的不同患者中分离出 6 株对碳青霉烯类药物高度耐药的菌株，其中 4 株为 ，2 株为 。除一株外，所有分离株均对替加环素耐药，但仅有一株对黏菌素耐药。所有分离株均根据 Carba NP 试验产生碳青霉烯酶，且所有分离株均对 EDTA 纸片协同试验检测金属β-内酰胺酶（MBL）呈阳性。通过 PCR 测序，4 株 产生碳青霉烯酶 NDM-1，而 2 株 产生碳青霉烯酶 VIM-1。多位点序列分型（MLST）基因分型分析显示，4 株 中的 3 株具有克隆相关性。它们均来自同一家医院，属于序列型（ST）ST152。相比之下，第四株 属于 ST572。值得注意的是，产 NDM-1 的 还产生了 CTX-M 型超广谱β-内酰胺酶（ESBL），同时还产生了 OXA-1 和 TEM-1。令人惊讶的是，这 3 株具有克隆相关性的分离株产生了不同的 CTX-M 变体，分别为 CTX-M-3、CTX-M-57 和 CTX-M-82，并且共同产生了赋予喹诺酮类耐药性的 QnrB 和赋予所有氨基糖苷类药物高耐药性的 16S rRNA 甲基化酶 RmtC。在 和 中均检测到 AAC(6')-Ib 乙酰转移酶。使用 作为供体的接合实验对所有分离株均成功。 基因总是在 70kb 质粒上被鉴定到，而 基因则分别位于 60kb 或 150kb 质粒上——这两种情况均发生在两株 中。据我们所知，这是首次在沙特阿拉伯一家医院的暴发中从不同患者中分离出的 中同时存在 MBL（NDM-1）、ESBL（CTX-M）、16S rRNA 甲基化酶（RmtC）、乙酰转移酶（AAC[6']-Ib）和喹诺酮类耐药酶（QnrB）的报道。
