Effective hand hygiene is essential to prevent the spread of pathogens on produce farms and reduce foodborne illness. The U.S. Food and Drug Administration Food Safety Modernization Act Proposed Rule for Produce Safety recommends the use of soap and running water for hand hygiene of produce handlers. The use of alcohol-based hand sanitizer (ABHS) may be an effective alternative hygiene intervention where access to water is limited. There are no published data on the efficacy of either soap or ABHS-based interventions to reduce microbial contamination in agricultural settings. The goal of this study was to assess the ability of two soap-based (traditional or pumice) and two ABHS-based (label-use or two-step) hygiene interventions to reduce microbes (coliforms, Escherichia coli, and Enterococcus spp.) and soil (absorbance of hand rinsate at 600 nm [A600]) on farmworker hands after harvesting produce, compared with the results for a no-hand-hygiene control. With no hand hygiene, farmworker hands were soiled (median A600, 0.48) and had high concentrations of coliforms (geometric mean, 3.4 log CFU per hand) and Enterococcus spp. (geometric mean, 5.3 log CFU per hand) after 1 to 2 h of harvesting tomatoes. Differences in microbial loads in comparison to the loads in the control group varied by indicator organism and hygiene intervention (0 to 2.3 log CFU per hand). All interventions yielded lower concentrations of Enterococcus spp. and E. coli (P < 0.05), but not of coliforms, than were found in the control group. The two-step ABHS intervention led to significantly lower concentrations of coliforms and Enterococcus spp. than the pumice soap and label-use ABHS interventions (P < 0.05) and was the only intervention to yield significantly fewer samples with E. coli than were found in the control group (P < 0.05). All interventions removed soil from hands (P < 0.05), soap-based interventions more so than ABHS-based interventions (P < 0.05). ABHS-based interventions were equally as effective as hand washing with soap at reducing indicator organisms on farmworker hands. Based on these results, ABHS is an efficacious hand hygiene solution for produce handlers, even on soiled hands.

To improve food safety on farms, it is critical to quantify the impact of environmental microbial contamination sources on fresh produce. However, studies are hampered by difficulties achieving study designs with powered sample sizes to elucidate relationships between environmental and produce contamination. Our goal was to quantify, in the agricultural production environment, the relationship between microbial contamination on hands, soil, and water and contamination on fresh produce. In 11 farms and packing facilities in northern Mexico, we applied a matched study design: composite samples (n ϭ 636, equivalent to 11,046 units) of produce rinses were matched to water, soil, and worker hand rinses during two growing seasons. Microbial indicators (coliforms, Escherichia coli, Enterococcus spp., and somatic coliphage) were quantified from composite samples. Statistical measures of association and correlations were calculated through Spearman's correlation, linear regression, and logistic regression models. The concentrations of all microbial indicators were positively correlated between produce and hands ( range, 0.41 to 0.75; P Ͻ 0.01). When E. coli was present on hands, the handled produce was nine times more likely to contain E. coli (P Ͻ 0.05). Similarly, when coliphage was present on hands, the handled produce was eight times more likely to contain coliphage (P Ͻ 0.05). There were relatively low concentrations of indicators in soil and water samples, and a few sporadic significant associations were observed between contamination of soil and water and contamination of produce. This methodology provides a foundation for future field studies, and results highlight the need for interventions surrounding farmworker hygiene and sanitation to reduce microbial contamination of farmworkers' hands.IMPORTANCE This study of the relationships between microbes on produce and in the farm environment can be used to support the design of targeted interventions to prevent or reduce microbial contamination of fresh produce with associated reductions in foodborne illness.

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In recent decades, fresh and minimally processed produce items have been associated with an increasing proportion of foodborne illnesses. Most pathogens associated with fresh produce are enteric (fecal) in origin, and contamination can occur anywhere along the farm-to-fork chain. Microbial source tracking (MST) is a tool developed in the environmental microbiology field to identify and quantify the dominant source(s) of fecal contamination. This study investigated the utility of an MST method based on Bacteroidales 16S rRNA gene sequences as a means of identifying potential fecal contamination, and its source, in the fresh produce production environment. The method was applied to rinses of fresh produce, source and irrigation waters, and harvester hand rinses collected over the course of 1 year from nine farms (growing tomatoes, jalapeño peppers, and cantaloupe) in Northern Mexico. Of 174 samples, 39% were positive for a universal Bacteroidales marker (AllBac), including 66% of samples from cantaloupe farms (3.6 log 10 genome equivalence copies [GEC]/100 ml), 31% of samples from tomato farms (1.7 log 10 GEC/100 ml), and 18% of samples from jalapeño farms (1.5 log 10 GEC/100 ml). Of 68 AllBac-positive samples, 46% were positive for one of three human-specific markers, and none were positive for a bovine-specific marker. There was no statistically significant correlation between Bacteroidales and generic Escherichia coli across all samples. This study provides evidence that Bacteroidales markers may serve as alternative indicators for fecal contamination in fresh produce production, allowing for determination of both general contamination and that derived from the human host.

A tomato (Solanum lycopersicum) foliar blight disease of unknown etiology was observed in North Carolina (NC) during 2005 to 2006. Symptoms included necrotic lesions and blighted leaves, with signs of white mycelial growth on abaxial leaf surfaces. The morphology of isolates from symptomatic leaves was consistent with that of Rhizoctonia solani. Because the pattern of symptom expression suggested that basidiospores were the primary inoculum source, Koch's postulates were fulfilled using a method to generate basidiospores in planta. Isolates were characterized by morphology, DNA sequence analysis, hyphal anastomosis, and somatic hyphal interactions. Phylogenetic analyses and hyphal anastomosis criteria support placement of the isolates in R. solani anastomosis group 3 (AG-3). Tomato foliar blight isolates from NC form a single phylogenetic group with tomato isolates of R. solani AG-3 from Japan and are more closely related to R. solani AG-3 isolates from potato than tobacco. Isolates exhibited both compatible and incompatible hyphal interactions when paired in vitro. To our knowledge, this is the first detailed report of tomato foliar blight caused by R. solani AG-3 in North America. A comprehensive description of the technique employed for producing basidiospores is presented with potential utility for understanding foliar disease etiology in other Rhizoctonia pathosystems.