Department of Clinical Microbiology, Vaasa Central Hospital, Vaasa, Finland.
J Clin Microbiol. 2012 Nov;50(11):3586-90. doi: 10.1128/JCM.01754-12. Epub 2012 Aug 29.
The performance and usability of CHROMagar STEC medium (CHROMagar Microbiology, Paris, France) for routine detection of Shiga toxin-producing Escherichia coli (STEC) strains were examined. The ability of the medium to selectively propagate STEC strains differing by their serotypes and virulence genes was studied with a collection of diarrheagenic E. coli isolates (n = 365) consisting of 49 different serotypes and with non-STEC and other bacterial isolates (n = 264). A total of 272 diarrheagenic E. coli (75.0%) isolates covering 24 different serotypes grew on CHROMagar STEC. The highest detection sensitivities were observed within the STEC serogroups O26 (90.0%), O111 (100.0%), O121 (100.0%), O145 (100.0%), and O157 (84.9%), and growth on CHROMagar STEC was highly associated with the presence of the tellurite resistance gene (terD). The specificity of the medium was 98.9%. In addition, CHROMagar STEC was used in parallel with a Shiga toxin-detecting immunoassay (Ridaquick Verotoxin/O157 Combi; R-biopharm, Darmstadt, Germany) to screen fecal specimens (n = 47) collected from patients suffering from hemorrhagic diarrhea. Positive growth on CHROMagar STEC was confirmed by the Premier EHEC enzyme immunoassay (Meridian Bioscience, Inc., Cincinnati, OH), and discrepant results between the two screening methods were confirmed by stx gene-detecting PCR. All 16 of the 47 stool samples that showed positive growth on CHROMagar STEC were also positive in the confirmatory tests. CHROMagar STEC proved to be an interesting option for STEC screening, allowing good detection sensitivity and specificity and permitting strain isolation for further outbreak investigations when required.
我们考察了 CHROMagar STEC 培养基（CHROMagar Microbiology，法国巴黎）在常规检测产志贺毒素大肠杆菌（STEC）菌株方面的性能和可用性。使用包含 365 个分离株的腹泻性大肠杆菌分离株（n=365）集，该集由 49 个不同血清型和非 STEC 及其他细菌分离株（n=264）组成，研究了该培养基选择性增殖血清型和毒力基因不同的 STEC 菌株的能力。共有 272 个腹泻性大肠杆菌（75.0%）分离株覆盖了 24 个不同血清型，在 CHROMagar STEC 上生长。在 STEC 血清群 O26（90.0%）、O111（100.0%）、O121（100.0%）、O145（100.0%）和 O157（84.9%）中观察到最高的检测敏感性，并且 CHROMagar STEC 上的生长与碲酸盐抗性基因（terD）的存在高度相关。该培养基的特异性为 98.9%。此外，CHROMagar STEC 与志贺毒素检测免疫测定（Ridaquick Verotoxin/O157 Combi；R-biopharm，达姆施塔特，德国）平行使用，筛选来自患有出血性腹泻的患者的粪便标本（n=47）。在 CHROMagar STEC 上的阳性生长通过 Premier EHEC 酶免疫测定（Meridian Bioscience，Inc.，俄亥俄州辛辛那提）得到确认，并且两种筛选方法之间的不一致结果通过stx 基因检测 PCR 得到确认。在 CHROMagar STEC 上显示阳性生长的 47 个粪便样本中的 16 个在确认测试中也呈阳性。CHROMagar STEC 被证明是一种用于 STEC 筛选的有趣选择，允许良好的检测敏感性和特异性，并允许在需要时进行菌株分离，以进行进一步的暴发调查。
