背景:产志贺毒素的大肠杆菌(STEC)是一种人畜共患病原体,它是从各种动物传播的,尤其是牛对人类的污染,水,与受感染的环境或动物接触或接触。STEC菌株在人类中引起胃肠道并发症的能力是由于志贺毒素(sxt)的产生。然而,多药耐药STEC菌株的传播与疾病结局的严重程度和耐药基因在其他病原体中的水平传播相关.其结果已成为对公众健康的重大威胁,动物健康,食品安全,和环境。因此,这项研究的目的是调查从Zagazig市的食品和牛粪便样本中分离出的肠大肠杆菌O157的抗菌谱,Al-Sharkia,埃及,并揭示志贺毒素基因stx1和stx2作为多重耐药分离株中的毒力因子。除此之外,部分16SrRNA测序用于获得的STEC分离株的鉴定和遗传编码。
结果:从Zagazig市的不同地理区域收集了总共65个样本,Al-Sharkia-埃及,分为:15鸡肉(C),10午餐会(L),10个汉堡包(H),和30头牛粪便(CF)。从65个样本中,只有10个样本(一个来自H,和9来自CF),在最可能数量(MPN)技术的最后一步,在山梨糖醇MacConkey琼脂培养基上鉴定为无色菌落的可疑大肠杆菌O157。8个分离株(全部来自CF)被鉴定为多重耐药(MDR),因为它们对三种抗生素的多重耐药(MAR)指数≥0.23,并通过标准的Kirby-Bauer圆盘扩散法评估。这八个分离株对阿莫西林/克拉维酸表现出完全抗性(100%),和高频率的电阻(90%,70%,60%,60%,和40%)对头孢西丁,Polymixin,红霉素,头孢他啶,还有哌拉西林,分别。这八个MDR大肠杆菌O157进行血清学测定以确认其血清型。只有两个分离株(CF8和CF13),都来自CF,对抗血清O157和H7显示出强烈的凝集作用,以及对MAR指数最高(0.62)的13种所用抗生素中的8种具有抗性。通过PCR技术评估毒力基因志贺毒素(stx1和stx2)的存在。证实CF8携带stx2,而CF13携带stx1和stx2两个基因。通过部分分子16SrRNA测序鉴定了两个分离株,并具有登录号(Acc。不。)的LC666912和基因库上的LC666913。系统发育分析表明,CF8和CF13与大肠杆菌H7菌株高度同源(98%),和(100%)大肠杆菌DH7。
结论:这项研究的结果为携带志贺毒素stx1和/或stx2的大肠杆菌O157:H7的发生提供了证据,对人类和兽医学中常用的抗生素耐药频率很高,在Zagazig市,Al-Sharkia,埃及。这对动物水库和食品造成了很大程度的公共卫生风险,因为容易传播,导致疫情爆发,并将抗性基因转移到动物的其他病原体,人类,和植物。因此,环境,畜牧业,和食品监控,还有,临床感染控制,必须加强以避免MDR病原体的额外传播,尤其是MDRSTEC菌株。
Shiga toxin-producing Escherichia coli (STEC) is a zoonotic pathogen, that is transmitted from a variety of animals, especially cattle to humans via contaminated food, water, feaces or contact with infected environment or animals. The ability of STEC strains to cause gastrointestinal complications in human is due to the production of Shiga toxins (sxt). However, the transmission of multidrug-resistance STEC strains are linked with a severity of disease outcomes and horizontal spread of resistance genes in other pathogens. The result of this has emerged as a significant threat to public health, animal health, food safety, and the environment. Therefore, the purpose of this study is to investigate the antibiogram profile of enteric E. coli O157 isolated from food products and cattle faeces samples in Zagazig City, Al-Sharkia, Egypt, and to reveal the presence of Shiga toxin genes stx1 and stx2 as virulence factors in multidrug-resistant isolates. In addition to this, the partial 16S rRNA sequencing was used for the identification and genetic recoding of the obtained STEC isolates.
There was a total of sixty-five samples collected from different geographical regions at Zagazig City, Al-Sharkia-Egypt, which were divided into: 15 chicken meat (C), 10 luncheon (L), 10 hamburgers (H), and 30 cattle faeces (CF). From the sixty-five samples, only 10 samples (one from H, and 9 from CF) were identified as suspicious E. coli O157 with colourless colonies on sorbitol MacConkey agar media with Cefixime- Telurite supplement at the last step of most probable number (MPN) technique. Eight isolates (all from CF) were identified as multidrug-resistant (MDR) as they showed resistance to three antibiotics with multiple antibiotic resistance (MAR) index ≥ 0.23, which were assessed by standard Kirby-Bauer disc diffusion method. These eight isolates demonstrated complete resistance (100%) against amoxicillin/clavulanic acid, and high frequencies of resistance (90%, 70%, 60%,60%, and 40%) against cefoxitin, polymixin, erythromycin, ceftazidime, and piperacillin, respectively. Those eight MDR E. coli O157 underwent serological assay to confirm their serotype. Only two isolates (CF8, and CF13), both from CF, were showed strong agglutination with antisera O157 and H7, as well as resistance against 8 out of 13 of the used antibiotics with the highest MAR index (0.62). The presence of virulence genes Shiga toxins (stx1 and stx2) was assessed by PCR technique. CF8 was confirmed for carrying stx2, while CF13 was carrying both genes stx1, and stx2. Both isolates were identified by partial molecular 16S rRNA sequencing and have an accession number (Acc. No.) of LC666912, and LC666913 on gene bank. Phylogenetic analysis showed that CF8, and CF13 were highly homologous (98%) to E. coli H7 strain, and (100%) to E. coli DH7, respectively.
The results of this study provides evidence for the occurrence of E. coli O157:H7 that carries Shiga toxins stx1 and/or stx2, with a high frequency of resistance to antibiotics commonly used in human and veterinary medicine, in Zagazig City, Al-Sharkia, Egypt. This has a high extent of public health risk posed by animal reservoirs and food products with respect to easy transmission causing outbreaks and transfer resistance genes to other pathogens in animal, human, and plants. Therefore, environmental, animal husbandry, and food product surveillance, as well as, clinical infection control, must be strengthened to avoid the extra spread of MDR pathogens, especially MDR STEC strains.