Fernández-Baca V, Ballesteros F, Hervás J A, Villalón P, Domínguez M A, Benedí V J, Albertí S
Servicio de Microbiología, Hospital Universitario Son Dureta, Palma de Mallorca, Spain.
J Hosp Infect. 2001 Nov;49(3):173-82. doi: 10.1053/jhin.2001.1053.
Since 1992, there has been an increase in the incidence of Enterobacter sepsis in the neonatal intensive care unit (NICU) of the authors' hospital. From 1995 to 1997, a prospective molecular epidemiological survey of the colonizing and infecting strains isolated from neonates was conducted. Enterobacter cloacae was the most frequent cause of neonatal sepsis, accounting for 19.2% of all neonatal infections, reaching a peak incidence of 2.2/1000 during 1996. Fifty isolates from the NICU and four epidemiologically unrelated strains were characterized by pulse-field gel electrophoresis (PFGE), ribotyping, enterobacterial repetitive intergenic consensus (ERIC)-PCR and plasmid profiling. PFGE was the most discriminatory technique and identified 13 types (two of them classified into two and three subtypes) compared with ERIC-PCR, plasmid profiling and ribotyping that identified 11, 11 and seven types, respectively. A good correlation was found between all techniques. Five different clones caused 15 cases of sepsis. Clones A and B were prevalent in 1995 and 1996, but they were not isolated in 1997. An outbreak caused by clone G in 1997 was controlled by cohort nursing and hygienic measures, without changing the antibiotic policy. Strains were characterized by their antibiotic resistance pattern and divided into three groups. Group I correlated with PFGE types A, B1 and B2, which hyperproduced Bush type 1 chromosomal beta-lactamase and expressed extended-spectrum ?-lactamases (ESBLs). Group II only hyperproduced Bush type 1 chromosomal beta-lactamase and correlated with PFGE-types D1, D2, D3 and I. Finally, Group III, with inducible beta-lactamases, correlated with the rest of PFGE types. The sudden disappearance of E. cloacae after reinforcement of hygienic measures confirms the importance of patient-to-patient transmission.
自1992年以来，作者所在医院的新生儿重症监护病房（NICU）中阴沟肠杆菌败血症的发病率有所上升。1995年至1997年，对从新生儿中分离出的定植菌和感染菌进行了前瞻性分子流行病学调查。阴沟肠杆菌是新生儿败血症最常见的病因，占所有新生儿感染的19.2%，在1996年发病率达到峰值2.2/1000。采用脉冲场凝胶电泳（PFGE）、核糖体分型、肠杆菌重复基因间共有序列（ERIC）-PCR和质粒图谱分析对50株来自NICU的菌株和4株流行病学上无关的菌株进行了特征分析。PFGE是最具鉴别力的技术，鉴定出13种类型（其中两种又分为两个和三个亚型），而ERIC-PCR、质粒图谱分析和核糖体分型分别鉴定出11种、11种和7种类型。所有技术之间均发现有良好的相关性。5个不同的克隆导致了15例败血症病例。克隆A和B在1995年和1996年流行，但在1997年未分离到。1997年由克隆G引起的一次暴发通过分组护理和卫生措施得到了控制，且未改变抗生素使用策略。菌株根据其抗生素耐药模式进行分类，分为三组。第一组与PFGE类型A、B1和B2相关，这些菌株超产布什1型染色体β-内酰胺酶并表达超广谱β-内酰胺酶（ESBLs）。第二组仅超产布什1型染色体β-内酰胺酶，与PFGE类型D1、D2、D3和I相关。最后，第三组具有诱导性β-内酰胺酶，与其余PFGE类型相关。加强卫生措施后阴沟肠杆菌的突然消失证实了患者间传播的重要性。
