Ability of Hand Hygiene Interventions Using Alcohol-Based Hand Sanitizers and Soap To Reduce Microbial Load on Farmworker Hands Soiled during Harvest

Abstract

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.

Contamination of Fresh Produce by Microbial Indicators on Farms and in Packing Facilities: Elucidation of Environmental Routes

“…These two observations together suggest that hands are a reservoir of microorganisms and an important vehicle for their transfer to fresh produce during manual production, harvesting, and/or packing (32-34), common practices in produce production in this region (32). Though no other studies to date that we know of have quantified the relationships of microbes between hands and produce in the agricultural environment, this implication is consistent with those of other studies suggesting that hands are an important vehicle of contamination of produce (13,(33)(34)(35)(36). We hypothesize that microorganisms measured in our study could have been transferred either from hands to produce or produce to hands, as has been demonstrated to occur (33,(37)(38)(39).…”

“…We hypothesize that microorganisms measured in our study could have been transferred either from hands to produce or produce to hands, as has been demonstrated to occur (33,(37)(38)(39). These findings and our hypothesis led to testing the effectiveness of hand hygiene interventions (soap, hand sanitizer) to improve the microbial quality of hands and produce (33,34). These intervention trials on farms showed that farm worker hands treated with hand hygiene products had significantly lower microbial levels immediately following hand hygiene treatment.…”

“…Furthermore, the majority of workers on study farms were temporary employees, and a transitory workforce can present unique challenges to employers in ensuring that all employees receive adequate food safety training. Lastly, as mentioned, hand hygiene interventions in the agricultural environment (33,34) result in only a transitory (Ͻ30-min) reduction in microbial load. Combined, these challenges require effective hand hygiene interventions to address the unique needs of the agricultural workforce: reduction in microbial load and persistence, accessibility of sanitary facilities, training, and facilitative labor policies to encourage hygiene practices among produce workers.…”

Evaluation of Risk of Zoonotic Pathogen Transmission in a University-Based Animal Assisted Intervention (AAI) Program

“…Hand sanitizer has been shown to be effective in reducing bacterial counts by up to 90% when used correctly in healthcare settings and still reduces bacterial counts significantly with less optimal use by >50% (11). While the effectiveness of hand sanitizer has not been specifically studied in therapy animal situations, it has been shown to be as effective as handwashing in agricultural settings such as livestock shows, petting zoos, and farm employees in reducing bacteria loads, particularly of enteric pathogens such as Escherichia coli and Salmonella (12, 13).…”

Handwashing and Ebola virus disease outbreaks: A randomized comparison of soap, hand sanitizer, and 0.05% chlorine solutions on the inactivation and removal of model organisms Phi6 and E. coli from hands and persistence in rinse water

“…Although handwashing is widely considered to be an important part of disease prevention and studies show that it is effective for preventing transmission of infection [ 20 – 23 ], studies on handwashing efficacy for the removal or inactivation of a range of organisms from hands using different protocols have shown inconsistent results. In an informal literature search, we identified 14 studies that compared the efficacy of HWWS and ABHS on the removal of organisms: of these, seven found HWWS to be more efficacious [ 24 – 30 ], five found ABHS to be more efficacious [ 31 – 35 ], and two found little difference between the methods [ 36 , 37 ]. One of these manuscripts showed that while some soaps were more efficacious than ABHS, others were not.…”