Unité des Bactéries Pathogènes Entériques, Centre National de Référence des Escherichia coli, Shigella et Salmonella, Institut Pasteur, Paris, France.
J Clin Microbiol. 2013 Mar;51(3):894-900. doi: 10.1128/JCM.03121-12. Epub 2013 Jan 2.
The performance of CHROMagar STEC and CHROMagar STEC O104 (CHROMagar Microbiology, Paris, France) media for the detection of Shiga toxin-producing Escherichia coli (STEC) was assessed with 329 stool specimens collected over 14 months from patients with suspected STEC infections (June 2011 to August 2012). The CHROMagar STEC medium, after an enrichment broth step, allowed the recovery of the STEC strain from 32 of the 39 (82.1%) Shiga toxin-positive stool specimens, whereas the standard procedure involving Drigalski agar allowed the recovery of only three additional STEC strains. The isolates that grew on CHROMagar STEC medium belonged to 15 serotypes, including the prevalent non-sorbitol-fermenting (NSF) O157:H7, O26:H11, and O104:H4 serotypes. The sensitivity, specificity, and positive and negative predictive values for the CHROMagar STEC medium were between 89.1% and 91.4%, 83.7% and 86.7%, 40% and 51.3%, and 98% and 98.8%, respectively, depending on whether or not stx-negative eae-positive E. coli was considered atypical enteropathogenic E. coli (EPEC) or STEC that had lost Shiga toxin genes during infection. In conclusion, the good performance of CHROMagar STEC agar medium, in particular, the high negative predictive value, and its capacity to identify NSF O157:H7 as well as common non-O157 STEC may be useful for clinical bacteriology, public health, and reference laboratories; it could be used in addition to a method targeting Shiga toxins (detection of stx genes by PCR, immunodetection of Shiga toxins in stool specimens, or Vero cell cytotoxicity assay) as an alternative to O157 culture medium. This combined approach should allow rapid visualization of both putative O157 and non-O157 STEC colonies for subsequent characterization, essential for real-time surveillance of STEC infections and investigations of outbreaks.
采用 329 份采集于疑似 STEC 感染患者的粪便标本（2011 年 6 月至 2012 年 8 月），评估了 CHROMagar STEC 和 CHROMagar STEC O104（CHROMagar Microbiology，巴黎，法国）培养基对产志贺毒素大肠埃希氏菌（STEC）的检测性能。经过增菌肉汤步骤，CHROMagar STEC 培养基可从 39 份志贺毒素阳性粪便标本中回收 32 株 STEC 菌株，而标准程序（含 Drigalski 琼脂）仅能额外回收 3 株 STEC 菌株。在 CHROMagar STEC 培养基上生长的分离株属于 15 种血清型，包括流行的非山梨醇发酵（NSF）O157：H7、O26：H11 和 O104：H4 血清型。CHROMagar STEC 培养基的敏感性、特异性和阳性与阴性预测值分别在 89.1%至 91.4%、83.7%至 86.7%、40%至 51.3%和 98%至 98.8%之间，具体取决于是否将stx 阴性 eae 阳性大肠埃希氏菌视为非典型肠致病性大肠埃希氏菌（EPEC）或在感染过程中丢失志贺毒素基因的 STEC。总之，CHROMagar STEC 琼脂培养基性能良好，尤其是高阴性预测值，以及其识别 NSF O157：H7 和常见非 O157 STEC 的能力，可能对临床细菌学、公共卫生和参考实验室有用；它可以替代 O157 培养基，与针对志贺毒素的方法（PCR 检测 stx 基因、粪便标本中志贺毒素的免疫检测或 Vero 细胞细胞毒性测定）结合使用，作为替代方法。这种联合方法应允许快速观察到推定的 O157 和非 O157 STEC 菌落，便于对 STEC 感染进行实时监测和暴发调查。
