Occurrence and antibiotic resistance of multiple Salmonella serotypes recovered from water, sediment and soil on mid-Atlantic tomato farms

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• 作者：Shirley A. Micallef^a ; ^b ; Rachel E. Rosenberg Goldstein^a ; Ashish George^a ; Lara Kleinfelter^a ; Marc S. Boyer^c ; Cristina R. McLaughlin^d ; Andrew Estrin^d ; Laura Ewing^e ; Junia Jean-Gilles Beaubrun^e ; Darcy E. Hanes^e ; Mahendra H. Kothary^e ; Ben D. Tall^e ; Jafar H. Razeq^f ; Sam W. Joseph^a ; Amy R. Sapkota^a ; ^ars@umd.edu
• 关键词：Salmonella ; Tomatoes ; Antibiotic resistance ; Immunocapture method ; Food safety
• 刊名：Environmental Research
• 出版年：2012
• 期刊代码：78_00139351
• 类别：env
• 出版时间：April, 2012
• 卷：114
• 期：Complete
• 页码：31-39
• 文件大小：269 K

摘要

Salmonella outbreaks associated with the consumption of raw tomatoes have been prevalent in recent years. However, sources of Salmonella contamination of tomatoes remain poorly understood. The objectives of this study were to identify ecological reservoirs of Salmonella on tomato farms, and to test antimicrobial susceptibilities of recovered Salmonella isolates. Fourteen Mid-Atlantic tomato farms in the U.S. were sampled in 2009 and 2010. Groundwater, irrigation pond water, pond sediment, irrigation ditch water, rhizosphere and irrigation ditch soil, leaves, tomatoes, and swabs of harvest bins and worker sanitary facilities were analyzed for Salmonella using standard culture methods and/or a flow-through immunocapture method. All presumptive Salmonella isolates (n=63) were confirmed using PCR and the Vitek^庐 2 Compact System, and serotyped using the Premi^庐Test Salmonella and a conventional serotyping method. Antimicrobial susceptibility testing was carried out using the Sensititre鈩?microbroth dilution system. Four of the 14 farms (29%) and 12 out of 1,091 samples (1.1%) were found to harbor Salmonella enterica subsp. enterica. Salmonella was isolated by the immunocapture method from soil, while the culture method recovered isolates from irrigation pond water and sediment, and irrigation ditch water. No Salmonella was detected on leaves or tomatoes. Multiple serotypes were identified from soil and water, four of which鈥?em>S. Braenderup, S. Javiana, S. Newport and S. Typhimurium鈥攈ave been previously implicated in Salmonella outbreaks associated with tomato consumption. Resistance to sulfisoxazole was prevalent and some resistance to ampicillin, cefoxitin, amoxicillin/clavulanic acid, and tetracycline was also observed. This study implicates irrigation water and soil as possible reservoirs of Salmonella on tomato farms and irrigation ditches as ephemeral habitats for Salmonella. The findings point to the potential for pre-harvest contamination of tomatoes from contaminated irrigation water or from soil or water splash from irrigation ditches onto low-lying portions of tomato plants.