从断奶后到屠宰期间，对来自牧场和饲养场的牛所排出的产志贺毒素大肠杆菌血清型O26、O45、O103、O111、O113、O121、O145和O157进行分离和鉴定。
Isolation and characterization of shiga toxin-producing escherichia coli serogroups O26, O45, O103, O111, O113, O121, O145, and O157 shed from range and feedlot cattle from postweaning to slaughter.
作者信息
Ekiri Abel B, Landblom Douglas, Doetkott Dawn, Olet Susan, Shelver Weilin L, Khaitsa Margaret L
机构信息
College of Public Health and Health Professions, University of Florida, Gainesville, Florida 32610-0136, USA; Department of Veterinary and Microbiological Sciences, North Dakota State University, Fargo, North Dakota 58108-6050, USA.
Dickinson Research Extension Center, North Dakota State University, 1041 State Avenue, Dickinson, North Dakota 58601, USA.
出版信息
J Food Prot. 2014 Jul;77(7):1052-61. doi: 10.4315/0362-028X.JFP-13-373.
Cattle are the main reservoirs for Shiga toxin-producing Escherichia coli (STEC) strains. E. coli O26, O45, O103, O111, O121, O145, and O157 are among the STEC serogroups that cause severe foodborne illness and have been declared as adulterants by the U.S. Department of Agriculture, Food Safety and Inspection Service. The objectives of this study were (i) to estimate the prevalence of non-O157 STEC and E. coli O157 in naturally infected beef cows and in steer calves at postweaning, during finishing, and at slaughter and (ii) to test non-O157 STEC isolates for the presence of virulence genes stx1, stx2, eaeA, and ehlyA. Samples were collected from study animals during multiple sampling periods and included fecal grabs, rectal swabs, and midline sponge samples. Laboratory culture, PCR, and multiplex PCR were performed to recover and identify E. coli and the virulence genes. The prevalence of non-O157 STEC (serogroups O26, O45, O103, O111, O121, O113, and O145) fecal shedding ranged from 8% (4 of 48 samples) to 39% (15 of 38 samples) in cows and 2% (1 of 47 samples) to 38% (9 of 24 samples) in steer calves. The prevalence of E. coli O157 fecal shedding ranged from 0% (0 of 38 samples) to 52% (25 of 48 samples) in cows and 2% (1 of 47 samples) to 31% (15 of 48 samples) in steer calves. In steer calves, the prevalence of non-O157 STEC and E. coli O157 was highest at postweaning, at 16% (15 of 96 samples) and 23% (22 of 96 samples), respectively. Among the 208 non-O157 STEC isolates, 79% (164 isolates) had stx1, 79% (165 isolates) had stx2, and 58% (121 isolates) had both stx1 and stx2 genes. The percentage of non-O157 STEC isolates encoding the eaeA gene was low; of the 165 isolates tested, 8 (5%) were positive for eaeA and 135 (82%) were positive for ehlyA. Findings from this study provide further evidence of non-O157 STEC shedding in beef cows and steer calves particularly at the stage of postweaning and before entry into the feedlot.
牛是产志贺毒素大肠杆菌（STEC）菌株的主要宿主。大肠杆菌O26、O45、O103、O111、O121、O145和O157属于STEC血清群，可导致严重的食源性疾病，已被美国农业部食品安全与检验局列为掺假物。本研究的目的是：（i）估计自然感染的肉牛和断奶后、育肥期及屠宰时的小公牛犊中，非O157 STEC和大肠杆菌O157的流行率；（ii）检测非O157 STEC分离株是否存在毒力基因stx1、stx2、eaeA和ehlyA。在多个采样期从研究动物采集样本，包括粪便抓取物、直肠拭子和中线海绵样本。进行实验室培养、PCR和多重PCR以回收和鉴定大肠杆菌及毒力基因。母牛中非O157 STEC（血清群O26、O45、O103、O111、O121、O113和O145）粪便排菌率在8%（48个样本中的4个）至39%（38个样本中的15个）之间，小公牛犊中为2%（47个样本中的1个）至38%（24个样本中的9个）。母牛中大肠杆菌O157粪便排菌率在0%（38个样本中的0个）至52%（48个样本中的25个）之间，小公牛犊中为2%（47个样本中的1个）至31%（48个样本中的15个）。在小公牛犊中，非O157 STEC和大肠杆菌O157的流行率在断奶后最高，分别为16%（96个样本中的15个）和23%（96个样本中的22个）。在208株非O157 STEC分离株中，79%（164株）有stx1，79%（165株）有stx2，58%（121株）同时有stx1和stx2基因。编码eaeA基因的非O157 STEC分离株比例较低；在检测的165株中，8株（5%）eaeA呈阳性，135株（82%）ehlyA呈阳性。本研究结果进一步证明了肉牛和小公牛犊，尤其是在断奶后和进入饲养场之前阶段，存在非O157 STEC排菌情况。
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