Objectives To investigate the blaNDM-1 gene of 30 CRE isolates recovered from April 2013 to March 2014 in our hospital,and the clinical characteristics of patients with CRE infections,as well as its relationship to antibiotic resistance.Methods Identification and drug resistance were tested by the BD Phoenix-100 system.Modified Hodge Test was used for the screening of carbapenemase.EDTA-synergy test was used for the detection of metallo-β-lactamases.PCR was performed for blaNDM-1 and the positive products were sequenced and analyzed with BLAST.Results (1) The distribution of isolates:the 30 CRE isolates from the clinical specimens of patients in our hospital between April 2013 and March 2014,including 16 isolates of Klebsiella pneumoniae (53.3％),12 isolates of Enterobacter cloacae (40％),one isolate of Citrobacter brinell,and one isolate of Citrobacterfreundii.These isolates were mainly collected from the intensive care unit (15/30,50.0％),and neurological intensive care unit (8/30,26.7％).Most of them were isolated from the sputum sample (12/30,66.7％),followed by the urine (5/30,16.7％),the blood (4/30,13.3％),and the drainage fluid (1/30,3.3％).The five blaNDM-1 gene carrying isolates were recovered from four patients with an average age of 73,and the average hospitalization time lasted 10 months;among these,three isolates were collected from urine,and two from sputum;two patients survived and two patients died.(2) The results of the drug resistance test:the resistance rates of 30 CRE to imipenem and meropenem were 100％ and 86.7％,respectively;the resistance rates to the other β-lactam antibiotics were 100％.The resistance rates to chloramphenicol,gentamicin,levofloxacin,and ciprofloxacin were among 66.7％～93.3％.All of them were most sensitive to colistin and tigecycline,the sensitive rates were 100％;followed by trimethoprim/sulfamethoxazole and amikacin,the sensitive rates were 66.7％ and 46.7％.All of the five NDM-l-producing isolates were sensitive to colistin and tigecycline;three isolates were sensitive to trimethoprim/sulfamethoxazole,and two isolates were sensitive to amikacin.All of the five NDM-1-producing isolates were resistant to β-lactam antibiotics,quinolones,and chloramphenicols.Conclusion 30 CRE isolates in our hospital were mainly collected from ICU and NICU,and were highly resistant to multiple antibiotics.The NDM-1-producing isolates were mainly recovered from long-term hospitalized senile patients with a high mortality rate.Therefore,we should investigate the risk factors of infections,and take effective measures to control infections.%目的 了解我院2013年4月—2014年3月临床分离的30株耐碳青霉烯类肠杆菌科(carbapenem-resistant Enterobacteriaceae,CRE)菌株blaNDM-1基因型检出情况,感染患者的临床特征,以及对常用抗菌药物的耐药特点.方法 临床分离菌株由美国BD公司生产的Phoenix-100全自动细菌鉴定/药敏系统进行菌株鉴定和药敏试验.改良Hodge试验检测产碳青霉烯酶,EDTA协同试验筛查金属β-内酰胺酶.利用特异性引物进行blaNDM-1基因PCR扩增,采用双脱氧末端终止法进行DNA测序,所测序列与GenBank基因库中的已知序列进行BLAST比对.结果 (1)菌株分布情况:我院2013年4月—2014年3月临床标本中分离出对碳青霉烯类抗生素耐药肠杆菌科细菌共30株,其中肺炎克雷伯菌16株,占53.3％;阴沟肠杆菌12株,占40.0％;布氏柠檬酸杆菌和弗氏柠檬酸杆菌各1株,blaNDM-1基因确证,共有5株为产NDM-1酶菌株,5株菌包括肺炎克雷伯菌2株,阴沟肠杆菌2株,布氏柠檬酸杆菌l株,这些细菌来自不同的科室,但主要分布在重症医学科(15/30,50.0％),神经内科重症病房(8/30,26.7％).标本主要来源于痰(20/30,66.7％),其次为尿液(5/30,16.7％),血液4株(13.3％),引流液1株(3.3％).5株产NDM-1酶菌株分离自4例患者,3株分离自患者尿液标本,2株分离自患者痰标本;感染患者平均年龄为73岁,平均住院时间10个月,2例死亡.(2)药物敏感性试验结果:30株CRE对碳青霉烯类抗生素亚胺培南和美罗培南的耐药率分别为100％和86.7％,对其他β-内酰胺类抗生素耐药率均为100％;对氯霉素、庆大霉素、左氧氟沙星、环丙沙星的耐药率在76.7％～93.3％之间;对多黏菌素和替加环素敏感率高达100％,其次为复方磺胺甲噁唑和阿米卡星,敏感率分别为66.7％和46.7％.5株产NDM-1酶菌株对多黏菌素和替加环素均敏感,3株对复方磺胺甲噁唑敏感,2株对阿米卡星敏感;而对β-内酰胺类抗生素以及喹诺酮类、氯霉素类等均耐药.结论 我院流行的CRE菌株主要分离自重症医学科和神经内科重症病房患者,对多种抗生素呈高度耐药,其中产NDM-1酶菌株主要来自长期住院的高龄患者,且死亡率较高,应对其感染的风险因素进行调查,并有针对性的采取感染预防措施进行防控.
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