Elizabeth A. Bihn

Landscape and Meteorological Factors Affecting Prevalence of Three Food-Borne Pathogens in Fruit and Vegetable Farms

ABSTRACT Produce-related outbreaks have been traced back to the preharvest environment. A longitudinal study was conducted on five farms in New York State to characterize the prevalence, persistence, and diversity of food-borne pathogens in fresh produce fields and to determine landscape and meteorological factors that predict their presence. Produce fields were sampled four times per year for 2 years. A total of 588 samples were analyzed for Listeria monocytogenes, Salmonella, and Shiga toxin-producing Escherichia coli (STEC). The prevalence measures of L. monocytogenes, Salmonella, and STEC were 15.0, 4.6, and 2.7%, respectively. L. monocytogenes and Salmonella were detected more frequently in water samples, while STEC was detected with equal frequency across all sample types (soil, water, feces, and drag swabs). L. monocytogenes sigB gene allelic types 57, 58, and 61 and Salmonella enterica serovar Cerro were repeatedly isolated from water samples. Soil available water storage (AWS), temperature, and proximity to three land cover classes (water, roads and urban development, and pasture/hay grass) influenced the likelihood of detecting L. monocytogenes. Drainage class, AWS, and precipitation were identified as important factors in Salmonella detection. This information was used in a geographic information system framework to hypothesize locations of environmental reservoirs where the prevalence of food-borne pathogens may be elevated. The map indicated that not all croplands are equally likely to contain environmental reservoirs of L. monocytogenes. These findings advance recommendations to minimize the risk of preharvest contamination by enhancing models of the environmental constraints on the survival and persistence of food-borne pathogens in fields.

Risk factors associated with Salmonella and Listeria monocytogenes contamination of produce fields.

ABSTRACT Identification of management practices associated with preharvest pathogen contamination of produce fields is crucial to the development of effective Good Agricultural Practices (GAPs). A cross-sectional study was conducted to (i) determine management practices associated with a Salmonella- or Listeria monocytogenes-positive field and (ii) quantify the frequency of these pathogens in irrigation and nonirrigation water sources. Over 5 weeks, 21 produce farms in New York State were visited. Field-level management practices were recorded for 263 fields, and 600 environmental samples (soil, drag swab, and water) were collected and analyzed for Salmonella and L. monocytogenes. Management practices were evaluated for their association with the presence of a pathogen-positive field. Salmonella and L. monocytogenes were detected in 6.1% and 17.5% of fields (n = 263) and 11% and 30% of water samples (n = 74), respectively. The majority of pathogen-positive water samples were from nonirrigation surface water sources. Multivariate analysis showed that manure application within a year increased the odds of a Salmonella-positive field (odds ratio [OR], 16.7), while the presence of a buffer zone had a protective effect (OR, 0.1). Irrigation (within 3 days of sample collection) (OR, 6.0), reported wildlife observation (within 3 days of sample collection) (OR, 6.1), and soil cultivation (within 7 days of sample collection) (OR, 2.9) all increased the likelihood of an L. monocytogenes-positive field. Our findings provide new data that will assist growers with science-based evaluation of their current GAPs and implementation of preventive controls that reduce the risk of preharvest contamination.

A framework for developing research protocols for evaluation of microbial hazards and controls during production that pertain to the quality of agricultural water contacting fresh produce that may be consumed raw

Agricultural water may contact fresh produce during irrigation and/or when crop protection sprays (e.g., cooling to prevent sunburn, frost protection, and agrochemical mixtures) are applied. This document provides a framework for designing research studies that would add to our understanding of preharvest microbial food safety hazards and control measures pertaining to agricultural water. Researchers will be able to use this document to design studies, to anticipate the scope and detail of data required, and to evaluate previously published work. This document should also be useful for evaluating the strength of existing data and thus should aid in identifying future research needs. Use of this document by the research community may lead to greater consistency or comparability than currently exists among research studies, which may ultimately facilitate direct comparison of hazards and efficacy of controls among different commodities, conditions, and practices.

Recommendations to Regulations: Managing Wildlife and Produce Safety on the Farm

Successful fruit and vegetable production requires produce growers to not only have keen business acumen, but also a vast knowledge of science and agriculture, adaptability to changing farm and environmental conditions, an understanding of produce safety practices, and often times, sheer determination and dedication to rigorous labor. One long-standing and frustrating challenge for produce growers is managing wildlife on fruit and vegetable farms in an effort to protect crops from damage and preserve a full harvest to take to the market. In the last 15 years, however, focus regarding wildlife on farms has shifted to produce safety risks that may result from the presence of wildlife fecal material in produce fields and packinghouses. With buyer requirements for produce safety practices and the first-ever federal regulation of fruits and vegetables on the horizon, growers need to understand and implement food safety practices on the farm, including managing wildlife concerns to reduce risks, and make critical decisions to ensure their farm’s long-term viability.