NHC Key Laboratory of Food Safety Risk Assessment, China National Centre for Food Safety Risk Assessment, Beijing 100022, China.
College of Food Science and Engineering, Northwest Agriculture and Forestry Science and Technology University, Shaanxi 712100, China.
Int J Food Microbiol. 2024 Aug 16;421:110804. doi: 10.1016/j.ijfoodmicro.2024.110804. Epub 2024 Jun 17.
Pre-cut fresh fruits and vegetables are highly appealing to consumers for their convenience, however, as they are highly susceptible to microbial contamination in processing, the potential risks of foodborne illnesses to public health are not negligible. This study aimed to assess the prevalence, antibiotic susceptibility and molecular characteristics of major foodborne pathogens (Listeria monocytogenes, Escherichia coli, Staphylococcus aureus and Salmonella) isolated from fresh-cut fruits and vegetables in Beijing, China. 86 stains were isolated from 326 samples, with S. aureus being the highest prevalence (15.38 %), followed by E. coli (9.23 %) and L. monocytogenes (1.85 %), while no Salmonella was detected. The prevalence by type of food indicated that fruit trays and mixed vegetables were more susceptible to contamination by pathogens. 98 % of S. aureus were resistant to at least of one antibiotic, and showed a high resistance rate to benzylpenicillin (90 %) and oxacillin (48 %). Among 25 E. coli isolates, 57.67 % of which exhibited multi-drug resistance, with common resist to trimethoprim/sulfamethoxazole (66.67 %) and ampicillin (63.33 %). A total of 9 sequence types (STs) and 8 spa types were identified in 35 S. aureus isolates, with ST398-t34 being the predominant type (42.86 %). Additionally, analysis of 25 E. coli isolates demonstrated significant heterogeneity, characterized by 22 serotypes and 18 STs. Genomic analysis revealed that 5 and 44 distinct antibiotic resistance genes (ARGs) in S. aureus and E. coli, respectively. Seven quinolone resistance-determining regions (QRDRs) mutations were identified in E. coli isolates, of which GyrA (S83L) was the most frequently detected. All the S. aureus and E. coli isolates harbored virulence genes. ARGs in S. aureus and E. coli showed a significant positive correlation with plasmids. Furthermore, one L. monocytogenes isolate, which was ST101 and serogroupIIc from watermelon sample, harbored virulence genes (inlA and inlB) and LIPI-1 pathogenic islands (prfA, plcA, hly and actA), which posed potential risks for consumer's health. This study focused on the potential microbial risk of fresh-cut fruits and vegetables associated with foodborne diseases, improving the scientific understanding towards risk assessment related to ready-to-eat foods.
预切新鲜水果和蔬菜因其便利性而深受消费者欢迎，然而，由于它们在加工过程中极易受到微生物污染，因此食源性疾病对公众健康造成的潜在风险不容忽视。本研究旨在评估中国北京地区市售预切新鲜水果和蔬菜中主要食源性致病菌（单核细胞增生李斯特菌、大肠杆菌、金黄色葡萄球菌和沙门氏菌）的流行情况、抗生素耐药性和分子特征。从 326 份样品中分离出 86 株菌，金黄色葡萄球菌的检出率最高（15.38%），其次是大肠杆菌（9.23%）和单核细胞增生李斯特菌（1.85%），未检出沙门氏菌。按食品类型分析，表明水果拼盘和混合蔬菜更容易受到病原体污染。98%的金黄色葡萄球菌对至少一种抗生素耐药，对苯唑西林（90%）和苯唑西林（48%）的耐药率较高。在 25 株大肠杆菌分离株中，57.67%表现出多药耐药性，常见的耐药药物包括甲氧苄啶/磺胺甲恶唑（66.67%）和氨苄西林（63.33%）。35 株金黄色葡萄球菌分离株共鉴定出 9 种序列型（ST）和 8 种 spa 型，其中 ST398-t34 为优势型（42.86%）。此外，对 25 株大肠杆菌分离株的分析显示存在显著的异质性，表现为 22 种血清型和 18 种 ST。基因组分析显示，金黄色葡萄球菌和大肠杆菌分别携带 5 种和 44 种不同的抗生素耐药基因（ARGs）。在大肠杆菌分离株中发现 7 个喹诺酮类药物耐药决定区（QRDR）突变，其中 GyrA（S83L）最为常见。所有金黄色葡萄球菌和大肠杆菌分离株均携带毒力基因。金黄色葡萄球菌和大肠杆菌的 ARGs 与质粒呈显著正相关。此外，从西瓜样本中分离到的一株单核细胞增生李斯特菌，其血清型为 101 型和 IIc 群，携带毒力基因（inlA 和 inlB）和 LIPI-1 致病岛（prfA、plcA、hly 和 actA），对消费者健康构成潜在风险。本研究关注了与食源性疾病相关的预切新鲜水果和蔬菜的潜在微生物风险，提高了对即食食品相关风险评估的科学认识。
