目的：本研究旨在分析从白血病患者血液中分离的产生NDM-1（新德里金属-β-内酰胺酶-1）的肺炎克雷伯菌的临床资料和特征。
方法：对患者的临床资料进行回顾性分析。采用改良Hodge试验(MHT)和乙二胺四乙酸(EDTA)-圆片协同试验检测金属β-内酰胺酶。使用琼脂稀释法测定抗生素抗性。PCR用于鉴定抗性基因。进行S1-PFGE(S1核酸酶/脉冲场凝胶电泳)和Southern印迹杂交以确定blaNDM-1的位置。使用缀合实验来确认抗性基因的可转移特征。还进行了多位点序列分型(MLST)。
结果：患者出现由产生NDM-1的菌株引起的血流感染，并因病情恶化而死亡。该菌株对β-内酰胺类抗生素具有高度抗性，并包含blaNDM-1，qnrB，和blaCTX-M-9基因.Southern印迹证实blaNDM-1位于约55kb的质粒上并且可以转移到大肠杆菌J53中。MLST分析表明，该菌株属于不常见的序列类型ST1224。
结论：多种耐药基因共存是大多数抗生素耐药的机制。此外,由多重耐药细菌引起的感染增加了免疫缺陷患者的死亡率，提醒临床医生建立合理有效的联合药物治疗。
OBJECTIVE: This study aimed to analyze the clinical data and characteristics of an NDM-1 (New Delhi metallo-β-lactamase-1)-producing Klebsiella pneumoniae isolated from the bloodstream of a leukemia patient.
METHODS: A retrospective analysis was used for the clinical data of the patient. The modified Hodge test (MHT) and ethylenediaminetetraacetic acid (EDTA)-disk synergy test were used for detecting metallo-β-lactamase. Antibiotic resistance was determined using the agar dilution method. PCR was used to identify resistance genes. S1-PFGE (S1 nuclease/pulsed-field gel electrophoresis) and Southern blot hybridization were performed to determine the location of blaNDM-1. A conjugation experiment was used to confirm the transferable characteristics of the resistant genes. Multilocus sequence typing (MLST) was also performed.
RESULTS: The patient developed bloodstream infections caused by this NDM-1-producing strain and died due to worsening of the condition. The strain was highly resistant to β-lactam antibiotics and coharbored blaNDM-1, qnrB, and blaCTX-M-9 genes. Southern blot confirmed that blaNDM-1 was located on a plasmid of approximately 55 kb and could be transferred to Escherichia coli J53. MLST analysis showed that this strain belonged to an uncommon sequence type
ST1224.
CONCLUSIONS: The coexistence of various resistant genes is the mechanism for resistance to most antibiotics. Additionally, infections caused by multi-drug resistant bacteria increase the mortality of patients with immunodeficiency, which alerts clinicians to establish a rational and effective combination drug therapy.
