The role of hands in cross-contamination of kitchen surfaces during meal preparation.

BACKGROUND: Foodborne pathogen transmission during food preparation is a common occurrence, and cross-contamination can be a contributing factor. Behaviors that lead to cross-contamination during meal preparation have not been well characterized. The study objective was to determine how hands and food handling behaviors (with a focus on handwashing and touch-based events) affect the risk of cross-contamination of kitchen surfaces and foods during meal preparation. METHODS: Data from a prior study in which participants were observed preparing turkey burgers inoculated with bacteriophage MS2 and a salad provided the data for analysis. Cross-contamination was assessed using environmental sampling data. Behavioral coding was performed for handwashing and touch-based behaviors. Cross-contamination risk was defined as the likelihood (number of contaminated surfaces) and degree (contaminant concentration) of MS2 on surfaces. Statistical analyses were performed in R, SPSS, and SigmaPlot. RESULTS: The significantly reduced risk of cross-contamination (P.ß<.ß.0001) was observed for participants who attempted handwashing or completed more handwashing steps. Scrubbing hands for 5.ßseconds, on average, reduced the risk of cross-contamination (P.ß<.ß.05). Cross-contamination regression models created using the most significant predictor variables showed that increased handwashing attempts, completion of more handwashing steps, and average scrub times>5.ßseconds all decreased the risk of cross-contamination (P.ß<.ß.05). CONCLUSIONS: This analysis can be used in future risk assessment modeling and for informing education and outreach to reduce pathogen transmission during food preparation.

Campylobacter Colonization and Diversity in Young Turkeys in the Context of Gastrointestinal Distress and Antimicrobial Treatment.

Young turkeys are vulnerable to undifferentiated gastrointestinal distress, including "irritable and crabby syndrome" (ICS), which compromises flock performance and is typically treated with a combination of penicillin and gentamicin (P/G). However, the effects of ICS and P/G treatment on Campylobacter remain poorly understood. We investigated the impact of ICS and P/G treatment on Campylobacter levels and diversity in four flocks from three turkey farms. Cecum and jejunum samples were analyzed weekly from day of hatch to week 4-5. All four flocks became colonized with multidrug resistant (MDR) Campylobacter jejuni and C. coli by week 2-3, and two developed ICS. ICS and P/G treatment did not significantly impact total Campylobacter levels or strain genotypes but impacted species and antimicrobial resistance (AMR) profiles. One flock was raised under antibiotic-free (ABF) conditions while another flock at the same farm was raised conventionally. The ABF flock did not develop ICS while its counterpart did. However, Campylobacter strains, AMR profiles and sequence types were generally shared between these two flocks. Our findings suggest that ICS and P/G treatment impacted Campylobacter population dynamics in commercial young turkey flocks, and that ABF flocks may become readily colonized by MDR strains from non-ABF flocks at the same farm.

Cross-Contamination to Surfaces in Consumer Kitchens with MS2 as a Tracer Organism in Ground Turkey Patties.

ABSTRACT: It is estimated that one in five cases of foodborne illnesses is acquired in the home. However, how pathogens move throughout a kitchen environment when consumers are preparing food is not well characterized. The purpose of this study was to determine the prevalence and degree of cross-contamination across a variety of kitchen surfaces during a consumer meal preparation event. Consumers (n = 371) prepared a meal consisting of turkey patties containing the bacteriophage MS2 as a tracer organism and a ready-to-eat lettuce salad. Half were shown a video on proper thermometer use before the trial. After meal preparation, environmental sampling and detection were performed to assess cross-contamination with MS2. For most surfaces, positivity did not exceed 20%, with the exception of spice containers, for which 48% of the samples showed evidence of MS2 cross-contamination. Spice containers also had the highest MS2 concentrations, at a mean exceeding 6 log viral genome equivalent copies per surface. The high level of MS2 on spice containers drove the significant differences between surfaces, suggesting the significance of spice containers as a vehicle for cross-contamination, despite the absence of previous reports to this effect. The thermometer safety intervention did not affect cross-contamination. The efficiency of MS2 transfer, when expressed as a percentage, was relatively low, ranging from an average of 0.002 to 0.07%. Quantitative risk assessment work using these data would aid in further understanding the significance of cross-contamination frequency and efficiency. Overall, these data will help create more targeted consumer messaging to better influence consumer cross-contamination behaviors.

Observational Study of the Impact of a Food Safety Intervention on Consumer Poultry Washing.

ABSTRACT: This study was conducted to test the effectiveness of a consumer poultry washing educational intervention that included video observation of meal preparation with participants who self-reported washing poultry. Treatment group participants received three e-mail messages containing information that the U.S. Department of Agriculture has used on social media sites (video and infographics) related to poultry preparation, including advising against washing chicken. Participants were observed cooking chicken thighs (inoculated with traceable nonpathogenic Escherichia coli strain DH5α) and preparing a salad to determine whether they washed the chicken and the extent of cross-contamination to the salad and areas of the kitchen. After meal preparation, participants responded to an interview about food handling behaviors, including questions about the intervention for treatment group participants. Three hundred people participated in the study (158 control, 142 treatment). The intervention effectively encouraged participants not to wash chicken before cooking; 93% of treatment group participants but only 39% of control group participants did not wash the chicken (P < 0.0001). The high levels of E. coli DH5α detected in the sink and on the salad lettuce suggest that microbes transferred to the sink from the chicken, packaging, or contaminated hands are a larger cause for concern than is splashing contaminated chicken fluids onto the counter. Among chicken washers, 26 and 30% of the lettuce from the prepared salad was contaminated for the control and treatment groups, respectively. For nonwashers, 31 and 15% of the lettuce was contaminated for the control and treatment groups, respectively. Hand-facilitated cross-contamination is suspected to be a factor in explaining this resulting lettuce cross-contamination. This study demonstrates the need to change the frame of "don't wash your poultry" messaging to instead focus on preventing contamination of sinks and continuing to emphasize the importance of hand washing and cleaning and sanitizing surfaces.

Cross-Contamination on Atypical Surfaces and Venues in Food Service Environments.

ABSTRACT: Cross-contamination of raw food to other surfaces, hands, and foods is a serious issue in food service. With individuals eating more meals away from home, contracting a foodborne illness from a food service establishment is an increasing concern. However, most studies have concentrated on hands or food contact surfaces and neglected atypical and unusual surfaces (surfaces that are not typically identified as a source of cross-contamination) and venues. This review was conducted to identify atypically cross-contaminated surfaces and atypical venues where cross-contamination could occur that have not been examined thoroughly in the literature. Most surfaces that could be at risk for cross-contamination are frequently touched, are rarely cleaned and sanitized, and can support the persistence and/or growth of foodborne pathogens. These surfaces include menus, spice and condiment containers, aprons and coveralls, mobile devices and tablets, and money. Venues that are explored, such as temporary events, mobile vendors, and markets, are usually limited in space or infrastructure, have low compliance with proper hand washing, and provide the opportunity for raw and ready-to-eat foods to come into contact with one another. These factors create an environment in which cross-contamination can occur and potentially impact food safety. A more comprehensive cleaning and sanitizing regime encompassing these surfaces and venues could help mitigate cross-contamination. This review highlights key surfaces and venues that have the potential to be cross-contaminated and have been underestimated or not fully investigated. These knowledge gaps indicate where further work is needed to fully understand the role of these surfaces and venues in cross-contamination and how it can be prevented.

An Observational Study of Thermometer Use by Consumers When Preparing Ground Turkey Patties.

ABSTRACT: The purpose of this study was to test the effectiveness of an intervention for consumer thermometer use by using a randomized experimental design and direct observation of meal preparation. The study was conducted in test kitchen facilities in two locations in North Carolina (one urban and one rural). Cameras recorded participants' actions at various locations throughout the kitchen and recorded the meal preparation from beginning to end. Before preparing the meal, a randomized treatment group watched a 3-min U.S. Department of Agriculture (USDA) food safety video "The Importance of Cooking to a Safe Internal Temperature and How to Use a Food Thermometer." Participants in the control and treatment groups were observed while cooking turkey burgers and preparing a salad to determine whether a thermometer was used to check the doneness of the turkey patties. Following meal preparation, all participants responded to a postobservation interview about food handling behaviors. Treatment group participants were also asked about the intervention. A total of 383 people participated in the study (201 in the control group and 182 in the treatment group). Participants who viewed the video were twice as likely to use a thermometer to check the doneness of the turkey patties compared with the participants who were not exposed to the video (75 versus 34%) and twice as likely to place the thermometer in the correct location (52 versus 23%). Sixty-seven percent of participants who watched the video reported that it influenced their behavior in the kitchen. This study demonstrates the importance of timing and framing of a behavioral intervention for thermometer use and highlights considerations for the development of additional messages (e.g., proper insertion).

Subtyping of Salmonella enterica serovar Newport outbreak isolates by CRISPR-MVLST and determination of the relationship between CRISPR-MVLST and PFGE results.

Salmonella enterica subsp. enterica serovar Newport (S. Newport) is the third most prevalent cause of food-borne salmonellosis. Rapid, efficient, and accurate methods for identification are required to track specific strains of S. Newport during outbreaks. By exploiting the hypervariable nature of virulence genes and clustered regularly interspaced short palindromic repeats (CRISPRs), we previously developed a sequence-based subtyping approach, designated CRISPR-multi-virulence-locus sequence typing (CRISPR-MVLST). To demonstrate the applicability of this approach, we analyzed a broad set of S. Newport isolates collected over a 5-year period by using CRISPR-MVLST and pulsed-field gel electrophoresis (PFGE). Among 84 isolates, we defined 38 S. Newport sequence types (NSTs), all of which were novel compared to our previous analyses, and 62 different PFGE patterns. Our data suggest that both subtyping approaches have high discriminatory abilities (>0.95) with a potential for clustering cases with common exposures. Importantly, we found that isolates from closely related NSTs were often similar by PFGE profile as well, further corroborating the applicability of CRISPR-MVLST. In the first full application of CRISPR-MVLST, we analyzed isolates from a recent S. Newport outbreak. In this blinded study, we confirmed the utility of CRISPR-MVLST and were able to distinguish the 10 outbreak isolates, as defined by PFGE and epidemiological data, from a collection of 20 S. Newport isolates. Together, our data show that CRISPR-MVLST could be a complementary approach to PFGE subtyping for S. Newport.