摘要

       灌溉水是新鲜农产品受到包括抗药性细菌（ARB）在内的不需要的微生物污染的主要来源，受污染的新鲜农产品可以将ARB转移到消费者身上，特别是在生食时。然而，到目前为止还没有关于ARB的灌溉水质量的法律指导方针。因此，我们对主要蔬菜种植区的灌溉水进行了抗生素抗性指示菌大肠杆菌和肠球菌的检测。，包括产超广谱β-内酰胺酶（ESBL）的大肠杆菌和耐万古霉素肠球菌，比较了ARB菌株的发生率。我们根据总数对水样进行分类，发现大肠杆菌或肠球菌总数较高的水样中，ARB阳性的水样所占比例普遍增加。我们进一步检测到产ESBL大肠杆菌的高流行率，其中8个阳性样本为36个（22%），而两个推定的万古霉素耐药肠球菌在验证性试验中对万古霉素敏感。在纸片扩散试验中，所有产ESBL的大肠杆菌均为多重耐药（n=21），所选菌株的全基因组测序显示了大量的可传播耐药基因（ARG），其中blaCTX-M-1（4/11）和blaCTX-M-15（3/11）是最常见的ESBL基因。总的来说，随着指示菌总数的增加，指示菌ARB的出现率增加，这表明后者可能是对各ARB菌株存在的合适估计。最后，具有可传播ARG的ESBL产生大肠杆菌的高流行率强调了建立灌溉水中ARB的法律临界值和监测指南的必要性。

       Irrigation water is a major source of fresh produce contamination with undesired microorganisms including antibiotic-resistant bacteria (ARB), and contaminated fresh produce can transfer ARB to the consumer especially when consumed raw. Nevertheless, no legal guidelines exist so far regulating quality of irrigation water with respect to ARB. We therefore examined irrigation water from major vegetable growing areas for occurrence of antibiotic-resistant indicator bacteria Escherichia coli and Enterococcus spp., including extended-spectrum β-lactamase (ESBL)-producing E. coli and vancomycin-resistant Enterococcus spp. Occurrence of ARB strains was compared to total numbers of the respective species. We categorized water samples according to total numbers and found that categories with higher total E. coli or Enterococcus spp. numbers generally had an increased proportion of respective ARB-positive samples. We further detected high prevalence of ESBL-producing E. coli with eight positive samples of thirty-six (22%), while two presumptive vancomycin-resistant Enterococcus spp. were vancomycin-susceptible in confirmatory tests. In disk diffusion assays all ESBL-producing E. coli were multidrug-resistant (n = 21) and whole-genome sequencing of selected strains revealed a multitude of transmissible resistance genes (ARG), with blaCTX-M-1 (4 of 11) and blaCTX-M-15 (3 of 11) as the most frequent ESBL genes. Overall, the increased occurrence of indicator ARB with increased total indicator bacteria suggests that the latter might be a suitable estimate for presence of respective ARB strains. Finally, the high prevalence of ESBL-producing E. coli with transmissible ARG emphasizes the need to establish legal critical values and monitoring guidelines for ARB in irrigation water.

       https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6258136/