Álvarez-Suárez María-Elena, Otero Andrés, García-López María-Luisa, Dahbi Ghizlane, Blanco Miguel, Mora Azucena, Blanco Jorge, Santos Jesús A
Department of Food Hygiene and Food Technology, Veterinary Faculty, University of León, Spain.
Laboratorio de Referencia de E. coli (LREC), Department of Microbiology and Parasitology, Veterinary Faculty, University of Santiago de Compostela (USC), Lugo, Spain.
Int J Food Microbiol. 2016 Nov 7;236:148-54. doi: 10.1016/j.ijfoodmicro.2016.07.035. Epub 2016 Jul 30.
The aim of this study was to characterize a collection of 44 Shiga toxin-producing (STEC) and enteropathogenic Escherichia coli (EPEC) isolated from goat milk and goat farm environment. Of the 19 STEC isolates, five (26.3%) carried the stx1 gene, four (21.1%) the stx2 gene and 10 (52.6%) presented both stx genes. Six (31.6%) STEC strains were eae-positive and belonged to serotypes related to severe human disease (O157:H7 and O5:HNM). Another seven STEC strains were of serotype O146:H21 and three of serotype O166:H28, also linked to human disease. The STEC strains isolated from goat milk were of serotypes potentially pathogenic for humans. All the 25 EPEC isolates were considered atypical (aEPEC) and one aEPEC strain was of serotype O26:H11, a serotype frequently isolated in children with diarrhea. Multilocus sequence typing (MLST) was carried out with seven housekeeping genes and 23 sequence types (ST) were detected, 14 of them newly described. Twelve STs grouped STEC isolates and 11 STs grouped EPEC isolates. Genetic typing by pulsed field gel electrophoresis (PFGE) resulted in 38 patterns which grouped in 10 clusters. Well-defined groups were also observed for strains of pathogenic serotypes. In conclusion, strains of STEC and aEPEC belonging to serotypes related to severe human disease have been detected in goat milk and the goat farm environment. Ruminants are an important reservoir of STEC strains and the role of these animals as carriers of other pathogenic types of E. coli seems to be an emerging concern.
本研究的目的是对从山羊奶和山羊养殖场环境中分离出的44株产志贺毒素大肠杆菌（STEC）和肠致病性大肠杆菌（EPEC）进行特征分析。在19株STEC分离株中，5株（26.3%）携带stx1基因，4株（21.1%）携带stx2基因，10株（52.6%）同时携带这两种stx基因。6株（31.6%）STEC菌株eae呈阳性，属于与严重人类疾病相关的血清型（O157:H7和O5:HNM）。另外7株STEC菌株为O146:H21血清型，3株为O166:H28血清型，也与人类疾病有关。从山羊奶中分离出的STEC菌株具有对人类潜在致病的血清型。所有25株EPEC分离株均被认为是非典型的（aEPEC），其中1株aEPEC菌株为O26:H11血清型，该血清型在腹泻儿童中经常分离到。利用7个管家基因进行多位点序列分型（MLST），共检测到23种序列类型（ST），其中14种为新描述的类型。12种ST对STEC分离株进行了分组，11种ST对EPEC分离株进行了分组。通过脉冲场凝胶电泳（PFGE）进行基因分型，得到38种图谱，分为10个簇。对于致病性血清型的菌株也观察到了明确的分组。总之，在山羊奶和山羊养殖场环境中检测到了属于与严重人类疾病相关血清型的STEC和aEPEC菌株。反刍动物是STEC菌株的重要储存宿主，这些动物作为其他致病性大肠杆菌类型携带者的作用似乎是一个新出现的问题。
