Lam Kit-Ling, Kong Wai-Po, Ling Po-Yi, Lau Tsz-Ho, Ho Kin-Hang, Lee Fred Wang-Fat, Chan Ping-Lung
Department of Science, School of Science and Technology, The Open University of Hong Kong, Ho Man Tin, Hong Kong.
Foods. 2020 Sep 21;9(9):1327. doi: 10.3390/foods9091327.
Hydroponic produce is gaining popularity due to its suitability for urban agriculture. The general public also considers that hydroponic produce is free from microbiological contamination. In this study, we compared the frequency and abundance of tetracycline-resistant and sulphadiazine-resistant bacteria and the minimal inhibitory concentration (MIC) of these isolates in conventional, organic, and hydroponic lettuce sold in retail. We also determined the frequency of samples carrying , , , , and genes by PCR and further quantified the copy number of , , and genes in samples positive for these genes using qPCR. As expected, the number of resistant bacteria and the MICs of these isolates were lowest in hydroponic lettuce and highest in organic lettuce. All tested resistant genes, except , were detected in samples of all three production methods, but no significant difference was observed between the three groups in the frequency of samples carrying the resistance genes examined or in their copy number. To the best of our knowledge, it is the first study directly reporting the existence of antibiotic-resistant bacteria and resistance genes in hydroponic vegetables sold in retail. The result highlights that the risk of antibiotic-resistant bacteria contamination in hydroponic produce should be further investigated.
水培农产品因其适合都市农业而越来越受欢迎。公众也认为水培农产品没有微生物污染。在本研究中，我们比较了零售的传统种植、有机种植和水培生菜中耐四环素和耐磺胺嘧啶细菌的频率和丰度，以及这些分离株的最低抑菌浓度（MIC）。我们还通过PCR确定了携带tet(A)、tet(B)、tet(C)、tet(D)和sul1基因的样本频率，并使用qPCR进一步定量了这些基因呈阳性的样本中tet(A)、tet(B)和sul1基因的拷贝数。正如预期的那样，这些分离株的耐药菌数量和MIC在水培生菜中最低，在有机生菜中最高。除tet(D)外，所有测试的耐药基因在所有三种生产方式的样本中均被检测到，但在携带所检测耐药基因的样本频率或其拷贝数方面，三组之间未观察到显著差异。据我们所知，这是第一项直接报道零售水培蔬菜中存在抗生素耐药菌和耐药基因的研究。结果突出表明，水培农产品中抗生素耐药菌污染的风险应进一步调查。
