Sáez-López Emma, Bosch Jordi, Salvia Maria Dolors, Fernández-Orth Dietmar, Cepas Virginio, Ferrer-Navarro Mario, Figueras-Aloy Josep, Vila Jordi, Soto Sara M
*ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic-Universitat de Barcelona, †Department of Microbiology, Hospital Clínic-Universitat de Barcelona, and ‡Department of Neonatology, Center of Medicine Maternofetal and Neonatology (BCNatal) Hospital Clínic (ICGON) and Hospital Sant Joan de Déu, Universitat de Barcelona, Barcelona, Spain.
Pediatr Infect Dis J. 2017 Nov;36(11):1079-1086. doi: 10.1097/INF.0000000000001652.
Escherichia coli is one of the most frequent causes of late-onset neonatal sepsis. The aim of this study was to characterize an outbreak of neonatal sepsis occurring in the neonatal intensive care unit of the Hospital Clinic of Barcelona from April to August 2013.
After presentation of the index case, all E. coli isolates from previously hospitalized neonates, health-care workers and neonates admitted to the neonatal intensive care unit from April to October 2013 were tested for K1 antigen positivity and epidemiologically compared by pulse-field gel electrophoresis. Furthermore, the E. coli K1 strains collected from neonates during this period were analyzed by different methods (serotyping, phylotyping, polymerase chain reaction of virulence factors, antimicrobial resistance and "in vitro" assays in Human Brain Microvascular Endothelial Cells (HBMEC)).
An E. coli O18:K1:H7 sequence type 95 and phylogenetic group B2 strain was the cause of the outbreak involving 6 preterm neonates: 1 with late septicemia because of a urinary focus and 5 with late-onset septicemia and meningitis, 3 of whom died. All showed the same pulsotype, full resistance to ampicillin and intermediate resistance to gentamicin. The outbreak strain carried the pathogenicity island (PAI) IIJ96-like domain that could explain the high-grade bacteremia necessary to develop meningitis.
All the E. coli isolates responsible for this outbreak belonged to a single clone suggesting a common source of infection, and it was categorized as O18:K1:H7. Despite the bacteria's pathogenicity has an important role in the severity of infection, the host-associated factors were crucial for the fatal outcomes.
大肠杆菌是晚发型新生儿败血症最常见的病因之一。本研究的目的是对2013年4月至8月在巴塞罗那医院诊所新生儿重症监护病房发生的新生儿败血症暴发进行特征描述。
在首例病例出现后，对2013年4月至10月期间曾住院的新生儿、医护人员以及入住新生儿重症监护病房的新生儿所分离出的所有大肠杆菌菌株进行K1抗原阳性检测，并通过脉冲场凝胶电泳进行流行病学比较。此外，采用不同方法（血清分型、系统发育分型、毒力因子聚合酶链反应、抗菌药物耐药性以及在人脑微血管内皮细胞（HBMEC）中进行的“体外”试验）对在此期间从新生儿中收集的大肠杆菌K1菌株进行分析。
一株大肠杆菌O18:K1:H7序列型95且属于系统发育组B2的菌株是此次暴发的病因，涉及6名早产儿：1名因泌尿系统感染源导致晚发性败血症，5名患有晚发型败血症和脑膜炎，其中3名死亡。所有菌株均显示相同的脉冲型，对氨苄西林完全耐药，对庆大霉素中度耐药。暴发菌株携带致病岛（PAI）IIJ96样结构域，这可以解释发生脑膜炎所需的严重菌血症。
此次暴发所涉及的所有大肠杆菌分离株均属于单一克隆，提示存在共同感染源，且被归类为O18:K1:H7。尽管细菌的致病性在感染严重程度中起重要作用，但宿主相关因素对致命结局至关重要。
