从儿童分离的产超广谱β-内酰胺酶大肠埃希菌的耐药特征及毒力因子分析。
Characterization of the extended-spectrum β-lactamases and determination of the virulence factors of uropathogenic Escherichia coli strains isolated from children.
机构信息
Department of Microbiology, School of Medicine, University of Zagreb, Salata 3, 10000, Zagreb, Croatia.
出版信息
Wien Klin Wochenschr. 2012 Aug;124(15-16):504-15. doi: 10.1007/s00508-012-0210-5. Epub 2012 Aug 16.
BACKGROUND AND AIM
The aim of the study was to characterize ESBL-producing uropathogenic Escherichia coli (UPEC) strains isolated in children. That included the investigation of virulence factors and the analysis of the types of β-lactamases at the molecular genetic level.
MATERIAL AND METHODS
During the 2-year study period, 77 ESBL-producing E. coli strains were recovered from urine samples of febrile children with significant bacteriuria hospitalized at one Croatian hospital. Susceptibility of isolates to bactericidal serum activity was tested by Shiller and Hatch method, while adhesin expression was determined by agglutination methods. Characterization of ESBLs was performed by PCR with specific primers for ESBLs and by sequencing of bla (ESBL) genes. Genotyping of the E. coli isolates was performed by pulsed-field gel electrophoresis (PFGE).
RESULTS
Twenty-seven (35.1 %) and 50 (64.9 %) ESBL-producing UPEC strains were isolated in neonates and infants, respectively. Of 70 strains investigated for the presence of virulence factors, adhesins were detected in 48.6 % strains (8.6 % in the neonate and 40 % in the infants group) giving a statistically significant difference in adhesin expression between the two groups (p < 0.01). Hemolysin was produced by 84.3 %, whereas 70 % of strains were serum-resistant. The bla (TEM) gene was detected in 22 (28 %) and bla (SHV) gene in 57 strains (74 %), whereas bla (CTX-M) gene was detected in only two isolates (2.5%). In ten isolates, bla (TEM) and bla (SHV) were simultaneously detected. Sequencing of bla (SHV) genes revealed that SHV-5 β-lactamase was by far the most prevalent and was found in 51 strains (66 %). The strains were clonally related as demonstrated by PFGE and assigned into ten clusters.
CONCLUSIONS
Infection control measures should be employed and the consumption of expanded-spectrum cephalosporins in the hospital should be restricted.
背景与目的
本研究旨在对儿童尿路感染产 ESBL 大肠埃希菌（UPEC）分离株进行特征分析，包括对毒力因子进行研究，并在分子遗传水平上对β-内酰胺酶的类型进行分析。
材料与方法
在为期 2 年的研究期间，从克罗地亚一家医院住院的严重菌尿症发热儿童的尿液样本中分离出 77 株产 ESBL 的大肠埃希菌。通过 Shiller 和 Hatch 法检测分离株对杀菌血清活性的敏感性，通过凝集法检测黏附素的表达。通过针对 ESBL 的 PCR 及 bla（ESBL）基因测序对 ESBL 进行特征分析。采用脉冲场凝胶电泳（PFGE）对大肠埃希菌分离株进行基因分型。
结果
分别有 27（35.1%）和 50（64.9%）株产 ESBL 的 UPEC 分离株在新生儿和婴儿中被分离。在对 70 株菌株进行毒力因子检测中，黏附素在 48.6%的菌株中被检出（新生儿组为 8.6%，婴儿组为 40%），两组间黏附素表达存在统计学差异（p<0.01）。84.3%的菌株产生溶血素，70%的菌株对血清具有抗性。在 22（28%）株菌中检测到 bla（TEM）基因，在 57 株菌（74%）中检测到 bla（SHV）基因，而仅在 2 株菌（2.5%）中检测到 bla（CTX-M）基因。在 10 株菌中同时检测到 bla（TEM）和 bla（SHV）。bla（SHV）基因测序结果显示，SHV-5 型β-内酰胺酶最为普遍，共在 51 株菌（66%）中被检出。PFGE 结果显示菌株间具有克隆相关性，可分为 10 个聚类。
结论
应采取感染控制措施，并限制医院内广谱头孢菌素的使用。
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