Progress 10/01/07 to 09/30/12
Outputs
OUTPUTS: We compared the recoveries of an inoculation of Salmonella enterica serotype Typhimurium, fluorescent microspheres (1.0 micrometer diameter, carboxylate-modified, crimson FluoSpheres, Molecular Probes, Eugene, OR), or a combination of both from stainless steel. Three recovery methods, including a standard rinse, a one-ply composite tissue (Kimwipe), or a sonicating brush were used. Findings were used to assess the effectiveness of fluorescent microspheres as surrogates for S. Typhimurium. For each method, ten coupons (304 grade, 2.5 x 8 cm) were inoculated with either 100 microliters of a S. Typhimurium culture, or a solution of fluorescent microspheres, or both, at approximate concentrations of 106. After drying for one hour, coupons were sampled using either a rinse of 100 ml of phosphate buffered saline solution (PBS) for one min, a Kimwipe tissue method, or submerged in PBS and subjected to a sonicating brush for one min. Following treatments, PBS solutions were analyzed using duplicate plate counting (Salmonella) or hemacytometry (microspheres). Another project further evaluated the use of sonication to enhance bacterial recovery from surfaces. In this project, a hand-held ultrasonic device was evaluated for enhancing the recovery of Listeria innocua bacteria from the surface of high density polyethylene (HDPE) plastic. The ultrasonic device, commercially sold as the Black & Decker Tide Buzz, features a power source coupled with a blunt tip ultrasonic generator pen that provides a sonication frequency similar to commercial sonic toothbrushes. HDPE plastic boards were inoculated with the bacteria, and then wiped with a sterile, wetted sampling sponge. The ultrasonic device was used to contact sampling sponges in contact with the HDPE, for 30 or 60 seconds, or to contact a plastic bag containing the sample sponge and 90 mL added diluent. Sample solutions were enumerated on Tryptic Soy Agar plates. PARTICIPANTS: Mallikarjunan, K.; Williams, R.C.; Boyer, R.R. TARGET AUDIENCES: Food Safety Specialists PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The retention of pathogenic bacteria, including Salmonella spp., on food contact surfaces increases the risk of transmission to food products. In this study, data suggests a marked difference in recovery yield based on the sampling method used. A sonicating brush method was the most effective method for recovery of Salmonella Typhimurium from stainless steel coupons. The use of devices similar to a sonicating toothbrush may lead to a faster and more accurate method of enumerating surface contaminants while enhancing recovery rates. For microspheres and Salmonella, recovery by sonicating brush was the most effective, and recovery by the Kimwipe method was least effective. Additionally, the retention of microspheres on the steel ranged from 16 to 25 percent (mean from five coupons each recovery method). Microspheres yielded a significantly higher recovery rate (11 to 60 percent) than Salmonella (approximately 1 percent) for each recovery method. Since the quantitative recovery of microspheres was significantly higher than the recovery of S. Typhimurium, the microspheres used in this study, may not be appropriate surrogates for the bacteria in recovery studies on stainless steel. However, microspheres may still be useful as a surrogate for bacteria in quantitative studies since a relatively high proportion that are removed or retained may be enumerated, with an opportunity for greater precision and accuracy. In this study, data suggests a marked difference in recovery yield based on the sampling method used. For the Listeria study using the ultrasonic generator pen, the highest bacterial recovery occurred when the ultrasonic pen was applied for 60 seconds to the bag containing the sample sponge plus diluents. The differences in recovery between treatments and control were not statistically significant. Additional experiments are needed to determine the value of this device for enhancing the recovery of bacteria from food contact surfaces. The use of ultrasonic devices may lead to a faster and more accurate method of enumerating surface contaminants while enhancing recovery rates. Additionally, these studies can aid the development of sampling and testing protocols that maximize the survival and recovery of Salmonella, Listeria or other bacteria. Improved sampling and testing protocols for food processors will provide greater assurance that their sampling plans can detect the presence of, or enumerate, pathogenic microorganisms. The capacity to detect foodborne pathogens is necessary for targeting efforts to control or reduce pathogens in the food supply.
Publications
- No publications reported this period
|
Progress 10/01/10 to 09/30/11
Outputs
OUTPUTS: Food industries are increasingly using environmental sampling to determine the presence of pathogens of food and food contact surfaces. Many surface sampling methods are available for qualitative and quantitative analysis. Since most methods do not recover many of the (viable) microorganisms on the test surfaces, new and improved methods of sampling should be investigated. Sonication has been proven to be effective for destroying some microorganisms, especially when combined with a heat treatment. Additionally, under some combinations of ultrasonic frequencies (power) and treatment time, sonication can break up clusters of microorganisms and dislodge them from surfaces. In these situations, sonication could be used to enhance microbial recovery and enumeration. In this project, a hand-held ultrasonic device was evaluated for enhancing the recovery of Listeria innocua bacteria from the surface of high density polyethylene (HDPE) plastic. The ultrasonic device, commercially sold as the Black & Decker Tide Buzz, features a power source coupled with a blunt tip ultrasonic generator pen that provides a sonication frequency similar to commercial sonic toothbrushes. HDPE plastic boards were inoculated with the bacteria, and then wiped with a sterile, wetted sampling sponge. The ultrasonic device was used to contact sampling sponges in contact with the HDPE, for 30 or 60 seconds, or to contact a plastic bag containing the sample sponge and 90 mL added diluent. Sample solutions were enumerated on Tryptic Soy Agar plates. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Food Safety Professionals PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The highest bacterial recovery occurred when the ultrasonic pen was applied for 60 seconds to the bag containing the sample sponge plus diluents. The differences in recovery between treatments and control were not statistically significant. Additional experiments are needed to determine the value of this device for enhancing the recovery of bacteria from food contact surfaces. The use of ultrasonic devices may lead to a faster and more accurate method of enumerating surface contaminants while enhancing recovery rates. Additional studies can aid the development of sampling and testing protocols that maximize the survival and recovery of Listeria or other bacteria. Improved sampling and testing protocols for food processors will provide greater assurance that their sampling plans can detect the presence of or enumerate pathogenic microorganisms. The capacity to detect foodborne pathogens is necessary for targeting efforts to control or reduce pathogens in the food supply.
Publications
- No publications reported this period
|
Progress 10/01/09 to 09/30/10
Outputs
OUTPUTS: Microbiological sampling of the plant environment is an important tool that food processors use to determine the effectiveness of their sanitation practices and processes in controlling pathogens, including Salmonella and Listeria monocytogenes. Evaluation of the test results over an extended period of time can illustrate changes that should be made in test sample quantities, types, frequency, time, location or analysis. The PivotTable function in Microsoft Excel provides one method of summarizing the data sets that result from long-term sampling and analyses. Environmental and raw product samples from commercial turkey slaughter plants in five states were analyzed for Salmonella and L. monocytogenes. All samples were classified into seven sample types (drains; walls and floors; product contact surfaces and equipment; process/chilling water; workers, gloves, and boots; post-chill raw product; and fecal contamination) from one of four processing areas (transport through defeathering; evisceration; chilling; post-chill cut-up/packaging). PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
For the 1,429 samples collected, 284 (19.9 percent) were positive for Salmonella, 264 (18.5 percent) were positive for Listeria species, and 54 (3.8 percent) were positive for both. Even though the proportion of total samples positive for Salmonella and Listeria was similar, the results varied widely for each organism when sorted by sample location area, sample type, and season collected. This study can be used as a model for creating or modifying an environmental sampling plan. For example, based on this study, to maximize the chance of finding Salmonella, samples from drains should be collected most frequently, and samples from personnel (gloves, boots, etc.) the least. And, to maximize finding Salmonella, samples from the earlier operations in processing should be emphasized. Prevalence sequentially decreased from the transport through defeathering areas (highest) to the post-chill operations (lowest). In this study, 15 samples must be collected to have 95 percent confidence of finding one sample positive for Salmonella. And, a positive result for Salmonella and Listeria sp. requires 79 samples. These analyses can be used for other data sets to determine which combinations of sample location, type, quantity, and frequency will optimize identification of target microorganism(s) and niches that can be hot spots for contamination of products. Regularly modified environmental sampling plans that can identify and predict the presence of Salmonella and Listeria monocytogenes are an important way to prevent food borne illnesses
Publications
- Wright, D.J., Eifert, J.D., Bazaco, M.C., Ryser, E.T., and Kathariou, S. 2010. Optimizing environmental sampling plans for identifying sources of Salmonella: an example from a multi-state turkey processing plant study. Institute of Food Technologists (IFT) Annual Meeting Book of Abstracts, #036-02. Presentation at the IFT Annual Meeting, Chicago, IL; July 18, 2010.
|
Progress 10/01/08 to 09/30/09
Outputs
OUTPUTS: The retention of pathogenic bacteria, including Salmonella spp., on food contact surfaces increases the risk of transmission to food products. We compared the recoveries of an inoculation of Salmonella enterica serotype Typhimurium, fluorescent microspheres (1.0 micrometer diameter, carboxylate-modified, crimson FluoSpheres, Molecular Probes, Eugene, OR), or a combination of both from stainless steel. Three recovery methods, including a standard rinse, a one-ply composite tissue (Kimwipe), or a sonicating brush were used. Findings were used to assess the effectiveness of fluorescent microspheres as surrogates for S. Typhimurium. For each method, ten coupons (304 grade, 2.5 x 8 cm) were inoculated with either 100 microliters of a S. Typhimurium culture, or a solution of fluorescent microspheres, or both, at approximate concentrations of 106. After drying for one hour, coupons were sampled using either a rinse of 100 ml of phosphate buffered saline solution (PBS) for one min, a Kimwipe tissue method, or submerged in PBS and subjected to a sonicating brush for one min. Following treatments, PBS solutions were analyzed using duplicate plate counting (Salmonella) or hemacytometry (microspheres). PARTICIPANTS: Joseph Eifert (PI) and Rebecca Baker (Graduate Assistant) TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
For microspheres and Salmonella, recovery by sonicating brush was the most effective, and recovery by the Kimwipe method was least effective. Additionally, the retention of microspheres on the steel ranged from 16 to 25 percent (mean from five coupons each recovery method). Microspheres yielded a significantly higher recovery rate (11 to 60 percent) than Salmonella (approximately 1 percent) for each recovery method. Since the quantitative recovery of microspheres was significantly higher than the recovery of S. Typhimurium, the microspheres used in this study, may not be appropriate surrogates for the bacteria in recovery studies on stainless steel. However, microspheres may still be useful as a surrogate for bacteria in quantitative studies since a relatively high proportion that are removed or retained may be enumerated, with an opportunity for greater precision and accuracy. In this study, data suggests a marked difference in recovery yield based on the sampling method used. The use of devices similar to a sonicating toothbrush may lead to a faster and more accurate method of enumerating surface contaminants while enhancing recovery rates. Additionally, the results of this study will aid the development of sampling and testing protocols that maximize the survival and recovery of Salmonella bacteria. Improved sampling and testing protocols for food processors will provide greater assurance that their sampling plans can detect the presence of or enumerate these pathogenic microorganisms. The capacity to detect foodborne pathogens is necessary for targeting efforts to control or reduce pathogens in the food supply.
Publications
- No publications reported this period
|
Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: We compared the recoveries of an inoculation of Salmonella enterica serotype Typhimurium from stainless steel, using three recovery methods including a standard rinse, a one-ply composite tissue (Kimwipe), or a sonicating toothbrush. Findings were used to design an additional project to compare recovery method efficacy for a similar inoculated study with fluorescent microspheres. One student earned an M.S. degree in Food Science and Technology. PARTICIPANTS: Professional development provided for, and analytical services conducted by graduate student Rebecca Baker. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The retention of pathogenic bacteria, including Salmonella spp., on food contact surfaces increases the risk of transmission to food products. In this study, data suggests a marked difference in recovery yield based on the sampling method used. A sonicating brush method was the most effective method for recovery of Salmonella Typhimurium from stainless steel coupons. The mean percent recovery of S. Typhimurium was only 1.2% for this method, and only 0.8% for a KimWipe tissue method. A standard rinse method resulted in recovery that was significantly lower and yielded half the number of cells as the sonicating brush method. The use of devices similar to a sonicating toothbrush may lead to a faster and more accurate method of enumerating surface contaminants while enhancing recovery rates. The results of this study will aid the development of sampling and testing protocols that maximize the survival and recovery of Salmonella bacteria. Food processors will have greater assurance that their sampling plans can detect the presence of or enumerate these pathogenic microorganisms.
Publications
- Baker, R. 2008. Fluorescent Microspheres as Surrogates for Salmonella enterica serotype Typhimurium in Recovery Studies from Stainless Steel. M.S. Thesis, Virginia Tech.
|
|