| Autor: |
Bergholz PW; Department of Veterinary and Microbiological Sciences, North Dakota State University, Fargo, North Dakota 58108, USA; Department of Food Science, Cornell University, Ithaca, New York 14803, USA. peter.bergholz@ndsu.edu., Strawn LK; Department of Food Science, Cornell University, Ithaca, New York 14803, USA; Department of Food Science and Technology, Eastern Shore Agricultural Research and Extension Center, Virginia Polytechnic Institute and State University, Painter, Virginia 23420, USA., Ryan GT; Department of Food Science, Cornell University, Ithaca, New York 14803, U.S. Food and Drug Administration, College Park, Maryland 20740, USA., Warchocki S; Department of Food Science, Cornell University, Ithaca, New York 14803, USA., Wiedmann M; Department of Food Science, Cornell University, Ithaca, New York 14803, USA. |
| Abstrakt: |
Although flooding introduces microbiological, chemical, and physical hazards onto croplands, few data are available on the spatial extent, patterns, and development of contamination over time postflooding. To address this paucity of information, we conducted a spatially explicit study of Escherichia coli and Salmonella contamination prevalence and genetic diversity in produce fields after the catastrophic flooding that occurred in New England during 2011. Although no significant differences were detected between the two participating farms, both random forest and logistic regression revealed changes in the spatial pattern of E. coli contamination in drag swab samples over time. Analyses also indicated that E. coli detection was associated with changes in farm management to remediate the land after flooding. In particular, E. coli was widespread in drag swab samples at 21 days postflooding, but the spatial pattern changed by 238 days postflooding such that E. coli was then most prevalent in close proximity to surface water features. The combined results of several population genetics analyses indicated that over time postflooding E. coli populations on the farms (i) changed in composition and (ii) declined overall. Salmonella was primarily detected in surface water features, but some Salmonella strains were isolated from soil and drag swab samples at 21 and 44 days postflooding. Although postflood contamination and land management responses should always be evaluated in the context of each unique farm landscape, our results provide quantitative data on the general patterns of contamination after flooding and support the practice of establishing buffer zones between flood-contaminated cropland and harvestable crops in produce fields. |
