Bagged, pre-cut and prewashed lettuce products are marketed as ready to eat. This concept poses a food safety concern, due to lack of efficient hurdles to eliminate possible microbial contaminants from the fresh produce and/or the processing itself. Aeromonas spp. are potential foodborne pathogens that are frequently isolated from lettuce. High counts of, e.g., A. hydrophila have been found in retail ready-to-eat (RTE) vegetable salads. The aim of this study was to assess the general microbiological quality, the occurrence and diversity of potential human pathogenic mesophilic Aeromonas spp. of retail RTE lettuce products. Additionally, temperature-dependent growth kinetic parameters of Aerobic Plate Counts (APC) and Aeromonas spp. in one selected RTE lettuce product, rocket lettuce, were quantified by performing storage experiments at 4 °C, 8 °C and 12 °C. The Aeromonas isolates were further characterized regarding pathogenic traits and phylogenetic relationship.

The overall hygienic quality of the lettuce products was unsatisfactory, as 60% of the products had an APC level higher than 7.0 log CFU/g. Presumptive Aeromonas spp. were detected in 52% of the samples, levels ranging from approximately 2.0–6.0 log CFU/g. Significantly lower counts of APC and Aeromonas spp. were found in uncut and unwashed products.

Presumptive Aeromonas spp. were able to proliferate in rocket lettuce stored at 4 °C (μ_max = 0.39 ± 0.06/d and μ_max = 0.43 ± 0.05/d for lettuce from producers A and B, respectively), and μ_max was approximately 2× higher at 8 °C and 3× higher at 12 °C. Eighty-four percent of the collected isolates were identified as A. media, based on partial gyrB sequencing. Additionally A. salmonicida and A. bestiarum were detected. The pathogenic potential in this material was high, most of the isolates harbored at least one of the toxin genes, act, ast, alt.

袋装、预切和预洗的生菜产品以即食形式销售。由于缺乏有效的障碍来消除新鲜农产品和/或加工本身中可能存在的微生物污染物，这一概念引起了食品安全问题。气单胞菌属是经常从生菜中分离出来的潜在食源性病原体。例如，在零售即食 (RTE) 蔬菜沙拉中发现了大量的嗜水气单胞菌。本研究的目的是评估潜在人类致病性嗜温气单胞菌属的一般微生物质量、发生率和多样性。零售即食生菜产品。此外，需氧平板计数 (APC) 和气单胞菌属的温度依赖性生长动力学参数。通过在 4 °C、8 °C 和 12 °C 下进行储存实验，对一种选定的 RTE 生菜产品（火箭生菜）中的有害物质进行了定量。进一步对气单胞菌分离株的致病性状和系统发育关系进行了表征。

生菜产品的整体卫生质量不理想，60%的产品APC水平高于7.0 log CFU/g。假定的气单胞菌属。在 52% 的样品中检测到，水平范围约为 2.0–6.0 log CFU/g。 APC 和气单胞菌的数量显着降低。在未切割和未清洗的产品中发现。

假定的气单胞菌属。能够在储存于 4 °C 的火箭生菜中增殖（生产商 A 和 B 的生菜分别为 μ _max = 0.39 ± 0.06/d 和 μ _max = 0.43 ± 0.05/d），且 μ _max大约高出 2 倍8 °C，12 °C 时高出 3 倍。根据部分gyrB测序，84% 的收集分离株被鉴定为A. media 。此外还检测到了杀鲑鱼和兽类动物。该材料的致病潜力很高，大多数分离株至少含有一种毒素基因， act 、 ast 、 alt 。