Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa (ORCID: https://orcid.org/0000-0001-9470-9421 [A.A.A.]; https://orcid.org/0000-0002-2268-9748 [P.N.T.]).
Department of Veterinary Public Health and Preventive Medicine, College of Veterinary Medicine, Michael Okpara University of Agriculture, Umudike, Abia State, Nigeria.
J Food Prot. 2020 Mar 1;83(3):476-484. doi: 10.4315/0362-028X.JFP-19-372.
A cross-sectional study was conducted to determine the prevalence of and factors associated with Shiga toxin-producing Escherichia coli (STEC) in raw beef and ready-to-eat (RTE) beef products sold in 31 retail outlets in Pretoria, South Africa, and nearby areas. A total of 463 beef and RTE samples were screened for four STEC virulence genes (stx1, stx2, eaeA, and hlyA) and seven O-serogroups (O113, O157, O26, O91, O145, O111, and O103) with a multiplex PCR assay. The total aerobic plate count (TAPC) per gram was also determined. A total of 38 STEC isolates were recovered and characterized by conventional PCR assay and serotyping. The overall prevalence of STEC in the beef and RTE samples tested was 16.4% (76 of 463 samples; 95% confidence interval, 13 to 20%). The prevalence of STEC differed significantly by product type (P < 0.0001), with the highest prevalence (35%) detected in boerewors (spicy sausage). The STEC prevalences in minced beef, brisket, RTE cold beef, and biltong were 18, 13, 9, and 5%, respectively. The most frequently detected stx gene was stx2 (13%), and STEC serogroups from recovered isolates were detected at the following prevalences: O2, 15%; O8, 12%; O13, 15%; O20, 8%; O24, 3%; O39, 3%; O41, 8%; O71, 3%; O76, 3%; O150, 12%; and O174, 3%. A high proportion (77%) of the samples had TAPCs that exceeded the South African microbiological standards for meat export (5.0 log CFU/g). The prevalence of O157 STEC (16%) and the diversity of non-O157 STEC serogroups found in five common beef-based products from retail outlets in South Africa suggest exposure of raw beef and beef products to multiple contamination sources during carcass processing and/or cutting and handling at retail outlets. These data provide direct estimates of the potential health risk to consumers from undercooked contaminated products and indicate the need to improve sanitary practices during slaughter and processing of beef and beef-based RTE products. A risk-based surveillance system for STEC may be needed.
本横断面研究旨在确定南非比勒陀利亚及周边地区 31 家零售点销售的生牛肉和即食（RTE）牛肉产品中，产志贺毒素大肠埃希氏菌（STEC）的流行情况及其相关因素。采用多重 PCR 检测法对 463 份牛肉和 RTE 样本的 4 种 STEC 毒力基因（stx1、stx2、eaeA 和 hlyA）和 7 种 O 血清群（O113、O157、O26、O91、O145、O111 和 O103）进行了筛查，并测定了每克样品的总需氧平板计数（TAPC）。通过常规 PCR 检测和血清分型，共回收并鉴定了 38 株 STEC 分离株。经检测，牛肉和 RTE 样本中 STEC 的总检出率为 16.4%（463 份样本中有 76 份；95%置信区间，13 至 20%）。不同产品类型的 STEC 检出率存在显著差异（P<0.0001），其中香肠（辣味香肠）的检出率最高（35%）。碎牛肉、胸肉、RTE 冷牛肉和比托的 STEC 检出率分别为 18%、13%、9%和 5%。检出的 stx 基因以 stx2 为主（13%），从回收的分离株中检测到的 STEC 血清群的流行率如下：O2，15%；O8，12%；O13，15%；O20，8%；O24，3%；O39，3%；O41，8%；O71，3%；O76，3%；O150，12%；O174，3%。样本中有很大一部分（77%）的 TAPC 超过了南非出口肉类的微生物标准（5.0 log CFU/g）。在南非零售商店销售的五种常见牛肉产品中，O157 STEC 的检出率（16%）和非 O157 STEC 血清群的多样性表明，在胴体加工和/或零售点切割和处理过程中，生牛肉和牛肉产品可能受到多种污染源的污染。这些数据直接估计了未经充分烹饪的污染产品对消费者造成的潜在健康风险，并表明需要改进牛肉屠宰和加工以及基于牛肉的 RTE 产品的卫生操作。可能需要建立一个基于风险的 STEC 监测系统。
