Survival and Growth Characteristics of Listeria monocytogenes and Salmonella typhimurium on Stainless Steel and Buna-N Rubber

1994 ◽  
Vol 57 (11) ◽  
pp. 963-968 ◽  
Author(s):  
DAVID M. HELKE ◽  
AMY C. L. WONG
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Salmonella Typhimurium ◽  
Raw Milk ◽  
Viable Count ◽  
Food Contact Surfaces ◽  
Whole Milk ◽  
Complex Ecosystem ◽  
Survival And Growth ◽  
Phosphate Buffered Saline

Microorganisms harbored on food-contact surfaces are part of a complex ecosystem. The interactions of temperature, relative humidity (RH), soil and surface on the survival of Listeria monocytogenes and Salmonella typhimurium were studied. Survival and growth were monitored at 25°C and 6°C and 32.5% RH and 75.5% RH. Survival in phosphate-buffered saline and dilute pasteurized whole milk on both stainless steel and buna-n was highest at 6°C and 75.5% RH. Both organisms were recoverable on the two surfaces after 10 days storage at 6°C and 75.5% RH. Survival of L. monocytogenes and S. typhimurium at 25°C and 75.5% RH was increased in dilute pasteurized whole milk on stainless steel, but not on buna-n. Organisms grew in pasteurized whole milk on stainless steel at 25°C and 75.5% RH, but failed to grow on buna-n. At 25°C and 75.5% RH, S. typhimurium was not recoverable on buna-n after 10 days in whole milk; however, L. monocytogenes remained close to initial levels. The survival and growth of both organisms in raw milk soil was similar to that in pasteurized whole milk soil. Buna-n was not bacteriostatic towards all organisms, as the total viable count in raw milk increased by more than a factor of 10 after 1 day storage at 25°C and 75.5% RH. Unlike other soils tested, survival of S. typhimurium at in conditions and L. monocytogenes at 25°C and both RHs in whey was higher on buna-n than on stainless steel. At 6°C and both RHs, L. monocytogenes levels remained constant on both surfaces in whey. The bacteriostatic effect of buna-n was not affected significantly by exposure to 20 cycles of a simulated clean-in-place (CIP) process.

Attachment of Listeria monocytogenes and Salmonella typhimurium to Stainless Steel and Buna-N in the Presence of Milk and Individual Milk Components

1993 ◽  
Vol 56 (6) ◽  
pp. 479-484 ◽  
Author(s):  
DAVID M. HELKE ◽  
EILEEN B. SOMERS ◽  
AMY C. L. WONG
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Salmonella Typhimurium ◽  
Dairy Industry ◽  
Skim Milk ◽  
Whole Milk ◽  
Milk Components ◽  
Phosphate Buffered Saline ◽  
Β Lactoglobulin

The effects of milk and individual milk components on the attachment of Listeria monocytogenes and Salmonella typhimurium to two commonly used materials in the dairy industry were studied. Attachment of both organisms to stainless steel and Buna-N was significantly inhibited by the presence of skim, 2%, whole, or chocolate 2% milk compared to the phosphate-buffered saline (PBS) control. The addition of individual milk components, casein, α-lactalbumin, and β-lactoglobulin to the attachment menstruum significantly reduced attachment. Pretreating surfaces with milk and milk components for 1 h prior to attachment in PBS gave similar results. The presence of lactose did not affect attachment of either organism; however, attachment of S. typhimurium was significantly decreased on pretreated Buna-N. Cells of either organism pretreated with skim milk or β-lactoglobulin prior to attachment in PBS showed significantly less attachment than untreated cells. Pretreating S. typhimurium cells with casein had no effect on attachment to stainless steel. Pretreatment of S. typhimurium with lactose increased attachment to both surfaces while pretreatment had no effect on L. monocytogenes. Attachment of both organisms was significantly reduced in diluted whole milk. Both organisms attached significantly less to surfaces soiled with one or more layers of whole milk.

Growth Media and Surface Conditioning Influence the Adherence of Pseudomonas fragi, Salmonella typhimurium, and Listeria monocytogenes Cells to Stainless Steel

1997 ◽  
Vol 60 (9) ◽  
pp. 1034-1037 ◽  
Author(s):  
SCOTT K. HOOD ◽  
EDMUND A. ZOTTOLA
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Salmonella Typhimurium ◽  
Skim Milk ◽  
Epifluorescence Microscopy ◽  
Growth Media ◽  
Pseudomonas Fragi ◽  
Acridine Orange Staining ◽  
Surface Conditioning ◽  
Food Contact Surfaces

Microorganisms have been shown to adhere to food-contact surfaces and may provide a route for the contamination of processed food. To better understand this phenomenon, the effects of growth media and surface conditioning on the adherence of Pseudomonas fragi, Salmonella typhimurium and Listeria monocytogenes cells to stainless steel were studied. The microorganisms were grown in tryptic soy broth (TSB), 1% reconstituted skim milk (RSM) and RSM with 1% sucrose (RSM + S). Stainless-steel surfaces were conditioned by immersion in growth media for 1 h and then were rinsed in phosphate-buffered saline (PBS) prior to the adherence assay. After growing in each medium, cells were harvested, resuspended in PBS, and then allowed to contact the stainless steel for 30 min. Adherence was quantified by acridine orange-staining the cells and viewing under epifluorescence microscopy. Growth media had little influence on adherence to stainless steel that had not been preconditioned. P. fragi and L. monocytogenes cells adhered in the highest numbers when grown in RSM plus sucrose. S. typhimurium cells showed the highest level of adherence when grown in TSB. Analysis of variance yielded P values of less than 0.01, indicating that both growth media and surface conditioning were significant in the level of adherence observed.

Inhibition of Initial Attachment of Injured Salmonella Typhimurium onto Abiotic Surfaces

2017 ◽  
Vol 81 (1) ◽  
pp. 37-42 ◽  
Author(s):  
Woo-Ju Kim ◽  
Ki-Ok Jeong ◽  
Dong-Hyun Kang
Keyword(s):  
Hydrogen Peroxide ◽  
Stainless Steel ◽  
Lactic Acid ◽  
Salmonella Typhimurium ◽  
Food Processing ◽  
Food Contact ◽  
Abiotic Surfaces ◽  
Food Contact Surfaces ◽  
Contact Surfaces ◽  
Biofilm Development

ABSTRACT Following sanitation interventions in food processing facilities, sublethally injured bacterial cells can remain on food contact surfaces. We investigated whether injured Salmonella Typhimurium cells can attach onto abiotic surfaces, which is the initial stage for further biofilm development. We utilized heat, UV, hydrogen peroxide, and lactic acid treatments, which are widely utilized by the food industry. Our results showed that heat, UV, and hydrogen peroxide did not effectively change populations of attached Salmonella Typhimurium. Cells treated with hydrogen peroxide had a slightly higher tendency to adhere to abiotic surfaces, although there was no significant difference between the populations of control and hydrogen peroxide–treated cells. However, lactic acid effectively reduced the number of Salmonella Typhimurium cells attached to stainless steel. We also compared physicochemical changes of Salmonella Typhimurium after application of lactic acid and used hydrogen peroxide as a positive control because only lactic acid showed a decreased tendency for attachment and hydrogen peroxide induced slightly higher numbers of attached bacteria cells. Extracellular polymeric substance produced by Salmonella Typhimurium was not detected in any treatment. Significant differences in hydrophobicity were not observed. Surface charges of cell membranes did not show relevant correlation with numbers of attached cells, whereas autoaggregation showed a positive correlation with attachment to stainless steel. Our results highlight that when lactic acid is applied in a food processing facility, it can effectively interfere with adhesion of injured Salmonella Typhimurium cells onto food contact surfaces.

Effectiveness of a Novel Rechargeable Polycationic N-Halamine Antibacterial Coating on Listeria monocytogenes Survival in Food Processing Environments

2020 ◽  
Vol 83 (11) ◽  
pp. 1974-1982
Author(s):  
GERARDO MEDINA ◽  
HARSHITA CHAUDHARY ◽  
YANG QIU ◽  
YUCHEN NAN ◽  
ARGENIS RODAS-GONZÁLEZ ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Surface Condition ◽  
Organic Load ◽  
Log Reduction ◽  
Food Contact Surfaces ◽  
Roast Beef ◽  
Steel Surfaces ◽  
The Difference ◽  
Steel Coupon

ABSTRACT The goal of this research was to evaluate the efficacy of a novel rechargeable nonleaching polycationic N-halamine coating applied to stainless steel food contact surfaces to reduce Listeria monocytogenes contamination on ready-to-eat (RTE) foods. Four L. monocytogenes strains were inoculated onto the charged (C; chlorine activated) or noncharged (NC) N-halamine–coated steel coupon surfaces that were either intact or scratched. After inoculation, test surfaces were incubated at 2, 10, and 25°C for 0, 48, and 72 h. L. monocytogenes transfer from coated adulterated surfaces to RTE meat (beef sausages and roast beef) was also tested at 2°C. L. monocytogenes on both intact-C and scratched-C surfaces was significantly reduced at all temperatures; however, in the presence of organic material, these coatings were more effective for reducing L. monocytogenes at 2 and 10°C than at 25°C (P < 0.05). In contrast, on NC intact and scratched surfaces, reduction at 25°C increased (P < 0.05), decreasing the difference in L. monocytogenes levels between charged and noncharged intact and scratched surfaces at this temperature. Overall, greater L. monocytogenes reduction was achieved on intact-C and scratched-C (4.1 ± 0.19 log CFU/cm2) than on intact-NC and scratched-NC (2.3 ± 0.19 log CFU/cm2) surfaces at all temperatures (P < 0.05). The combination of surface condition and chlorine with coupons exposed for 2 h at 2°C in the presence of an organic load (50% meat purge) did not significantly affect the bactericidal efficacy of the N-halamine coating. Regarding transfer to RTE meat, an overall 3.7-log reduction in L. monocytogenes was observed in sausages and roast beef. These findings suggest that a novel rechargeable N-halamine coating on stainless steel surfaces can inactivate L. monocytogenes. HIGHLIGHTS

Comparison of Sampling Procedures for Recovery of Listeria monocytogenes from Stainless Steel Food Contact Surfaces

2012 ◽  
Vol 75 (6) ◽  
pp. 1077-1082 ◽  
Author(s):  
DIEGO GÓMEZ ◽  
AGUSTÍN ARIÑO ◽  
JUAN J. CARRAMIÑANA ◽  
CARMINA ROTA ◽  
JAVIER YANGÜELA
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Cost Effective ◽  
Sampling Procedure ◽  
Human Origin ◽  
Sampling Device ◽  
Food Contact ◽  
Food Contact Surfaces ◽  
Contact Surfaces ◽  
Sampling Procedures

A number of techniques exist for microbiological sampling of food processing environments in food industries. In the present study the efficacies of nine sampling procedures for the recovery of Listeria monocytogenes from food contact surfaces, including a new sampling device consisting of a miniroller, were evaluated and compared. A stainless steel table was inoculated with L. monocytogenes strain 935 (serovar 4b, human origin) and L. monocytogenes strain 437/07 (serovar 1/2b, food origin), at 105 CFU/100 cm2. L. monocytogenes strain 935 was best recovered with the minirollers (recovery of up to 6.27%), while poor recoveries (<0.30%) were obtained with the towel (one-ply composite tissue), alginate swab, metallic swab, and Petrifilm methods. In the case of L. monocytogenes strain 437/07 the replicate organism detection and counting (RODAC) ALOA contact plates yielded the best recoveries (4.15%), followed by the minirollers (up to 1.52%). Overall, recovery percentages with the minirollers were higher with stomacher homogenization than with Vibromatic agitation. The recovery percentages obtained for the Listeria strain of human origin were higher than those obtained with the food strain for all sampling procedures except Petrifilm and RODAC ALOA. With the miniroller device coated with wool fiber, the recovery of L. monocytogenes can be improved from 2 to 17 times over recoveries obtained with the sponge and cotton swab. This is the first report of a miniroller device for microbiological sampling in the available literature. The novel sampling procedure is convenient to apply on surfaces, is cost-effective, and results in better recovery of L. monocytogenes than do the conventional methods.

Biofilm Development and Sanitizer Inactivation of Listeria monocytogenes and Salmonella typhimurium on Stainless Steel and Buna-n Rubber

1993 ◽  
Vol 56 (9) ◽  
pp. 750-758 ◽  
Author(s):  
AMY B. RONNER ◽  
AMY C. L. WONG
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Salmonella Typhimurium ◽  
Biofilm Formation ◽  
Bacterial Biofilm ◽  
Extracellular Matrices ◽  
Nutrient Level ◽  
Extracellular Materials ◽  
Biofilm Development ◽  
Nutrient Conditions

Biofilm formation by seven strains of Listeria monocytogenes and one strain of Salmonella typhimurium on stainless steel and Buna-n rubber was examined under two nutrient conditions. The type of surface, nutrient level, and organism influenced biofilm development and production of extracellular materials. Buna-n had a strong bacteriostatic effect on L. monocytogenes, and biofilm formation on Buna-n under low nutrient conditions was reduced for four of the seven strains tested. Buna-n was less bacteriostatic toward S. typhimurium. It inhibited the growth of several other pathogens to varying degrees. An ethylene propylene diamine monomer rubber was less inhibitory than Buna-n, and Viton rubber had no effect. The effectiveness of sanitizers on biofilm bacteria was examined. Biofilms were challenged with four types of detergent and nondetergent sanitizers. Resistance to sanitizers was strongly influenced by the type of surface. Bacterial biofilm populations on stainless steel were reduced 3–5 log by all the sanitizers, but those on Buna-n were resistant to these sanitizers and were reduced less than 1–2 log. In contrast, planktonic (suspended) bacteria were reduced 7–8 log by these sanitizers. Chlorine and anionic acid sanitizers generally removed extracellular materials from biofilms better than iodine and quaternary ammonium detergent sanitizers. Scanning electron microscopy demonstrated that biofilm cells and extracellular matrices could remain on sanitized biofilm cells and extracellular matrices could remain surfaces from which no viable cells were recovered.

Removal of Listeria monocytogenes Biofilms from Stainless Steel by Use of Ultrasound and Ozone

2009 ◽  
Vol 72 (6) ◽  
pp. 1306-1309 ◽  
Author(s):  
ADAM R. BAUMANN ◽  
SCOTT E. MARTIN ◽  
HAO FENG
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Phosphate Buffer ◽  
Combined Treatment ◽  
Potassium Phosphate ◽  
Potassium Phosphate Buffer ◽  
Power Ultrasound ◽  
Biofilm Removal ◽  
Food Contact Surfaces ◽  
Contact Surfaces

The objective of this study was to determine the efficacy of power ultrasound and ozonation used individually, and in tandem, for the removal of Listeria monocytogenes biofilms from stainless steel chips. Stainless steel chips were inoculated with L. monocytogenes. Power ultrasound (20 kHz, 100% amplitude, 120 W) was applied for 30 or 60 s at a distance of 2.54 cm from a biofilm chip while it was submerged in 250 ml of sterile potassium phosphate buffer (pH 7.0). Ozone was cycled through the 250 ml of potassium phosphate buffer containing the biofilm chip also for 30 or 60 s at concentrations of 0.25, 0.5, or 1.0 ppm. Power ultrasound and ozonation were also used in tandem for testing of their combined effect. Each of the treatments alone resulted in a significant reduction in recoverable cells, with power ultrasound being the most effective (3.8-log CFU/ml reduction after 60 s). For the ozone in combination with power ultrasound treatment, reductions were significantly (P < 0.05) higher than by either treatment alone. There were no recoverable cells after 60 s of this combined treatment when an ozone concentration of 0.5 ppm was used (7.31-log CFU/ml reduction). These results indicated that the combination of power ultrasound and ozonation may be an effective treatment for biofilm removal from stainless steel food contact surfaces.

Evaluation of the Thermo Scientific™ SureTect™ Listeria monocytogenes Assay

2014 ◽  
Vol 97 (1) ◽  
pp. 133-154 ◽  
Author(s):  
Jonathan Cloke ◽  
Carlos Leon-Velarde ◽  
Nathan Larson ◽  
Keron Dave ◽  
Katharine Evans ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Reference Method ◽  
Ice Cream ◽  
Probability Of Detection ◽  
Specific Method ◽  
Food Contact Surfaces ◽  
Significant Difference ◽  
Thermo Fisher Scientific ◽  
Reliable Performance

Abstract The Thermo Scientific™ SureTect™Listeria monocytogenes Assay is a new real-time PCR assay for the detection of Listeria monocytogenes in food and environmental samples. This assay was validated using the AOAC Research Institute (AOAC-RI) Performance Tested MethodsSM program in comparison to the reference method detailed in International Organization for Standardization 11290-1:1996, including Amendment 1:2004 with the following foods and food contact surfaces: smoked salmon, processed cheese, fresh bagged spinach, fresh cantaloupe, cooked prawns (chilled product), cooked sliced turkey meat (chilled product), ice cream, pork frankfurters, salami, ground raw beef meat (12% fat), plastic, and stainless steel. All matrixes were tested by Thermo Fisher Scientific, Microbiology Division, Basingstoke, UK. In addition, three matrixes (pork frankfurters, bagged lettuce, and stainless steel) were analyzed independently as part of the AOAC-RI controlled laboratorystudy by the University of Guelph, Canada. Using probability of detection (POD) statistical analysis, a significant difference was demonstrated between the candidate and reference methods for salami, cooked sliced turkey and ice cream in favor of the SureTect assay. For all other matrixes, no significant difference by POD was seen between the two methods during the study. Inclusivity and exclusivity testing was also conducted with 53 and30 isolates, respectively, which demonstrated that the SureTect assay was able to detect all serotypes of L. monocytogenes. None of the exclusivity isolates analyzed were detectedby the SureTect assay. Ruggedness testing was conducted to evaluate the performance of the assay with specific method deviations outside the recommended parameters open to variation, i.e., enrichment time and temperature and lysis temperature, which demonstrated that the assay gave reliable performance. Accelerated stability testing was alsoconducted, validating the assay shelf life.

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