摘要

需要采取措施减少生蔬菜中抗生素耐药细菌（ARB），包括人类病原体，以减少耐药性感染的发生率。这项研究的目的是确定标准的收获后干预措施，消毒剂清洗和冷藏的有效性，以减少ARB，包括人类病原体大肠杆菌O15：H7的抗生素抗性菌株和常见的腐败细菌假单胞菌。萝卜。为了提供代表ARB潜在的收获前遗留物的背景接种物，将胡萝卜浸渍在奶牛粪堆肥浆料中并进一步接种已知的ARB。用三种处理之一洗涤接种的胡萝卜：次氯酸钠（50ppm游离氯），过氧乙酸（40ppm过氧乙酸; 11.2％过氧化氢），自来水（无消毒剂）或不洗涤（对照）。将洗过的胡萝卜风干，包装并在10℃下储存7天或2℃，最多60天。使用总异养平板计数（HPC），含有抗生素的培养基（“ARB”），大肠杆菌O157：H7和假单胞菌属的HPC进行计数。洗涤后（0d）和储存7d后立即进行。除培养的细菌外，通过对细菌16S rRNA基因扩增子进行测序来确定表面胡萝卜微生物群的变化，以确定消毒剂洗涤，储存温度和储存时间（0,1,7,14和60d）的影响。储存温度，在洗涤期间添加消毒剂和储存持续时间显着影响细菌微生物群（Wilcoxon，p <0.05）。在洗涤水中加入消毒剂可显着降低大肠杆菌O157：H7和假单胞菌属的log CFU / g，以及头孢噻肟 - （10μg/ ml），磺胺甲恶唑 - （100μg/ ml）所列举的HPCs与未洗涤的对照相比，补充培养基或四环素（3μg/ ml）（ANOVA，p <0.05）。然而，洗涤和储存后没有显着降低对万古霉素或克林霉素具有抗性的细菌。 Proteobactetria，Firmicutes，Actinobacteria，Planctomycetes和Acidobacteria的成员包括细菌胡萝卜微生物群。当腐败开始发生时，胡萝卜微生物群的多样性受储存温度和长期储存（60天）的显着影响。与用于洗涤的消毒剂类型相关的细菌群的相对丰度没有显着差异。这项研究的结果表明，在洗涤水中加入消毒剂，然后在2°C下储存，可能是防止致病性大肠杆菌O157：H7再生长和降低某些抗生素耐药细菌水平的有效策略。萝卜。

Strategies to mitigate antibiotic-resistant bacteria (ARB), including human pathogens, on raw vegetables are needed to reduce incidence of resistant infections. The objective of this research was to determine the effectiveness of standard post-harvest interventions, sanitizer washing and cold storage, to reduce ARB, including antibiotic resistant strains of the human pathogen E. coli O15:H7 and a common spoilage bacterium Pseudomonas, on raw carrots. To provide a background inoculum representing potential pre-harvest carryover of ARB, carrots were dip-inoculated in dairy cow manure compost slurry and further inoculated with known ARB. Inoculated carrots were washed with one of three treatments: sodium hypochlorite (50 ppm free chlorine), peroxyacetic acid (40 ppm peroxyacetic acid; 11.2% hydrogen peroxide), tap water (no sanitizer), or no washing (control). Washed carrots were air dried, packaged and stored at 10 °C for 7d or 2 °C for up to 60 d. Enumeration was performed using total heterotrophic plate counts (HPC), HPCs on antibiotic-containing media ("ARBs"), E. coli O157:H7, and Pseudomonas sp. immediately after washing (0 d) and after 7 d of storage. In addition to the cultured bacteria, changes to the surficial carrot microbiota were profiled by sequencing bacterial 16S rRNA gene amplicons to determine the effect of sanitizer wash, storage temperature, and time of storage (0, 1, 7, 14 and 60 d). Storage temperature, addition of a sanitizer during wash, and duration of storage significantly affected the bacterial microbiota (Wilcoxon, p < 0.05). Inclusion of either sanitizer in the wash water significantly reduced the log CFU/g of E. coli O157:H7 and Pseudomonas sp., as well as HPCs enumerated on cefotaxime- (10 μg/ml), sulfamethoxazole- (100 μg/ml), or tetracycline (3 μg/ml) supplemented media compared to the unwashed control (ANOVA, p < 0.05). However, no significant reductions to bacteria resistant to vancomycin or clindamycin occurred after washing and storage. Members of the Proteobactetria, Firmicutes, Actinobacteria, Planctomycetes, and Acidobacteria comprised the bacterial carrot microbiota. The diversity of the carrot microbiota was significantly affected by the temperature of storage and by extended storage (60 d), when spoilage began to occur. There were no significant differences to the relative abundance of bacterial groups associated with the type of sanitizer used for washing. Results of this study indicate that inclusion of a sanitizer in wash water, followed by storage at 2 °C, might be an effective strategy to prevent re-growth of pathogenic E. coli O157:H7 and reduce levels of bacteria resistant to certain antibiotics on carrots.

https://www.ncbi.nlm.nih.gov/pubmed/30445282