French National Reference Center for Bacterial Resistance in Commensal Flora, Laboratory of Bacteriology, Bichat-Claude Bernard Hospital, Assistance Publique-Hôpitaux de Paris.
Clin Infect Dis. 2011 Oct;53(7):677-85. doi: 10.1093/cid/cir522.
From the time of CTX-M emergence, extended-spectrum β-lactamase-producing enterobacteria (ESBL-E) have spread worldwide in community settings as well as in hospitals, particularly in developing countries. Although their dissemination appears linked to Escherichia coli intestinal carriage, precise paths of this dynamic are largely unknown.
Children from a pediatric renutrition center were prospectively enrolled in a fecal carriage study. Antibiotic exposure was recorded. ESBL-E strains were isolated using selective media from fecal samples obtained at admission and, when negative, also at discharge. ESBL-encoding genes were identified, their environments and plasmids were characterized, and clonality was assessed with polymerase chain reaction-based methods and pulsed-field gel electrophoresis for E. coli and Klebsiella pneumoniae. E. coli strains were subjected to multilocus sequence typing.
The ESBL-E carriage rate was 31% at admission in the 55 children enrolled. All children enrolled received antibiotics during hospitalization. Among the ESBL-E-negative children, 16 were resampled at discharge, and the acquisition rate was 94%. The bla(CTX-M-15) gene was found in >90% of the carriers. Genetic environments and plasmid characterization evidenced the roles of a worldwide, previously described, multidrug-resistant region and of IncF plasmids in CTX-M-15 E. coli dissemination. Diversity of CTX-M-15-carrying genetic structures and clonality of acquired ESBL E. coli suggested horizontal genetic transfer and underlined the potential of some ST types for nosocomial cross-transmission.
Cross-transmission and high selective pressure lead to very high acquisition of ESBL-E carriage, contributing to dissemination in the community. Strict hygiene measures as well as careful balancing of benefit-risk ratio of current antibiotic policies need to be reevaluated.
CTX-M 型超广谱β-内酰胺酶（ESBL）产生肠杆菌自出现以来，已在社区环境以及医院中在全球范围内传播，尤其是在发展中国家。尽管它们的传播似乎与大肠埃希菌的肠道携带有关，但这种动态的具体途径在很大程度上仍是未知的。
前瞻性地招募了一家儿科营养中心的儿童进行粪便携带研究。记录抗生素暴露情况。从入院时以及阴性时（即出院时）获得的粪便样本中使用选择性培养基分离 ESBL-E 菌株。鉴定 ESBL 编码基因，对其环境和质粒进行特征分析，并通过聚合酶链反应（PCR）方法和脉冲场凝胶电泳对大肠埃希菌和肺炎克雷伯菌进行克隆性评估。对大肠埃希菌菌株进行多位点序列分型。
55 名入组儿童中，入院时 ESBL-E 携带率为 31%。所有入组儿童在住院期间均接受了抗生素治疗。在 ESBL-E 阴性的儿童中，有 16 名在出院时再次采样，其获得率为 94%。>90%的携带者携带 bla(CTX-M-15)基因。遗传环境和质粒特征表明，一个广泛存在的、先前描述的多药耐药区域和 IncF 质粒在 CTX-M-15 大肠埃希菌的传播中发挥了作用。CTX-M-15 携带基因结构的多样性和获得的 ESBL 大肠埃希菌的克隆性表明了水平基因转移的存在，并强调了某些 ST 型在医院内交叉传播的潜力。
交叉传播和高选择压力导致 ESBL-E 携带的高获得率，这有助于在社区中的传播。需要重新评估严格的卫生措施以及当前抗生素政策的获益-风险比的谨慎平衡。
