School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, Perth, Australia.
School of Veterinary Medicine, College of Science, Health, Engineering and Education, Murdoch University, Perth, Australia; Veterinary Medicine Department, College of Food and Agriculture, United Arab of Emirates University (UAEU), Al Ain, United Arab Emirates.
Int J Food Microbiol. 2019 Nov 2;308:108305. doi: 10.1016/j.ijfoodmicro.2019.108305. Epub 2019 Aug 10.
In recent years, the number of human salmonellosis cases in Western Australia (WA) has increased more dramatically than in any other Australian state. In 2017, the number of cases in WA was more than double the five-year average, and eggs had emerged as the key culprit for several Salmonella foodborne disease outbreaks. To better understand such an epidemiologically intriguing situation, our research goal was to investigate the prevalence, serovar diversity, multilocus sequence types, and antimicrobial resistance of non-typhoidal Salmonella contamination in retail eggs produced and sold in WA. A total of 200 visually clean and intact retail egg samples (each containing a dozen eggs) were purchased for one year (2017-2018) from supermarkets in metropolitan Perth, the capital of WA. For each sample, the contents and shells of the 12 eggs were separately pooled and cultured according to standard methods. Overall, Salmonella was detected in 11.5% (23/200) of the tested egg samples. Salmonella was isolated from 4.5% (9/200) and 3% (6/200) of eggshells and egg contents, respectively. In 4% (8/200) of the samples, Salmonella was recovered from both eggshell and egg contents. Isolates from positive retail egg samples were serotyped as either S. Typhimurium (52.2% [12/23]) or S. Infantis (39.1% [9/23]). Both serotypes were concurrently recovered from two different retail egg samples. We retained a set of both S. Typhimurium (n = 29) and S. Infantis (n = 12) isolates from all Salmonella-positive retail packs (n = 23) for further characterization. Only two (S. Typhimurium) isolates showed resistance to ampicillin, of which one carried β-lactamase resistance gene bla. The remaining isolates (39/41) were susceptible to all 14 antimicrobials included in the minimum inhibitory concentrations (MICs) testing panel. Multilocus sequence typing and serotyping were perfectly mirrored, as all S. Typhimurium isolates were characterized as sequence type (ST)-19, and all S. Infantis isolates were ST-32. This study points to the noteworthy Salmonella prevalence rate in retail egg samples in WA. Our results illustrate minimal public health risks arising from antimicrobial resistance Salmonella from Australian eggs.
近年来，西澳大利亚州（WA）的人类沙门氏菌病例数量增长幅度超过了澳大利亚其他任何一个州。2017 年，WA 的病例数量是五年平均水平的两倍多，鸡蛋已成为几起食源性沙门氏菌病爆发的关键罪魁祸首。为了更好地了解这种具有流行病学吸引力的情况，我们的研究目标是调查 WA 生产和销售的零售鸡蛋中非伤寒沙门氏菌污染的流行率、血清型多样性、多位点序列类型和抗药性。在 WA 首府珀斯的超市购买了 200 个外观清洁完整的零售鸡蛋样品（每个样品包含一打鸡蛋），为期一年（2017-2018 年）。对于每个样品，将 12 个鸡蛋的内容物和蛋壳分别按照标准方法进行混合和培养。总体而言，在 200 个测试的鸡蛋样品中，有 11.5%（23/200）检测到沙门氏菌。从蛋壳和鸡蛋内容物中分别分离出 4.5%（9/200）和 3%（6/200）的沙门氏菌。在 4%（8/200）的样品中，从蛋壳和鸡蛋内容物中均回收了沙门氏菌。阳性零售鸡蛋样品的分离物被定型为肠炎沙门氏菌（52.2%[12/23]）或婴儿沙门氏菌（39.1%[9/23]）。两种血清型均从两个不同的零售鸡蛋样品中同时回收。我们保留了一组来自所有沙门氏菌阳性零售包装（n=23）的肠炎沙门氏菌（n=29）和婴儿沙门氏菌（n=12）分离物，用于进一步鉴定。只有两种（肠炎沙门氏菌）分离物对氨苄西林表现出耐药性，其中一种携带β-内酰胺酶耐药基因 bla。其余分离物（39/41）对包括最低抑菌浓度（MICs）测试面板在内的 14 种抗生素均敏感。多位点序列分型和血清分型完全一致，所有肠炎沙门氏菌分离物均为 ST-19 型，所有婴儿沙门氏菌分离物均为 ST-32 型。本研究指出了 WA 零售鸡蛋样本中沙门氏菌的高流行率。我们的结果表明，澳大利亚鸡蛋中抗药性沙门氏菌对公共健康的风险很小。
