Transfer of Salmonella and Campylobacter from Stainless Steel to Romaine Lettuce†

2003 ◽  
Vol 66 (12) ◽  
pp. 2231-2236 ◽  
Author(s):  
CHRISTINA M. MOORE ◽  
BRIAN W. SHELDON ◽  
LEE-ANN JAYKUS
Keyword(s):  
Stainless Steel ◽  
Salmonella Typhimurium ◽  
Sampling Period ◽  
Stainless Steel Surface ◽  
Inoculum Level ◽  
Drying Time ◽  
Initial Inoculum ◽  
Significant Difference ◽  
Serovar Typhimurium ◽  
Handling Practices

The degree of transfer of Campylobacter jejuni and Salmonella enterica serovar Typhimurium was evaluated from a stainless steel contact surface to a ready-to-eat food (lettuce). Stainless steel coupons (25 cm2) were inoculated with a 20-μl drop of either C. jejuni or Salmonella Typhimurium to provide an inoculum level of ~106 CFU/28 mm2. Wet and dry lettuce (Lactuca sativa var. longifolia) pieces (9 cm2) were placed onto the inoculated stainless steel surface for 10 s after the designated inoculum drying time (0 to 80 min for C. jejuni; 0 to 120 min for Salmonella Typhimurium), which was followed by the recovery and enumeration of transferred pathogens (lettuce) and residual surface pathogens (stainless steel coupons). For transfers of Salmonella Typhimurium to dry lettuce, there was an increase from 36 to 66% in the percent transfer of the initial inoculum load during the first 60 min of sampling and then a precipitous drop from 66 to 6% in percent transfer. The transfer of Salmonella Typhimurium to wet lettuce ranged from 23 to 31%, with no statistically significant difference between recoveries over the entire 120-min sampling period. For C. jejuni, the mean percent transfer ranged from 16 to 38% for dry lettuce and from 15 to 27% for wet lettuce during the 80-min sampling period. The results of this study indicate that relatively high numbers of bacteria may be transferred to a food even 1 to 2 h after surface contamination. These findings can be used to support future projects aimed at estimating the degree of risk associated with poor handling practices of ready-to-eat foods.

3M™ Petrifilm™ Environmental Listeria Plate

2013 ◽  
Vol 96 (2) ◽  
pp. 225-228 ◽  
Author(s):  
DeAnn L Benesh ◽  
Erin S Crowley ◽  
Patrick M Bird
Keyword(s):  
Stainless Steel ◽  
Reference Method ◽  
Sampling Area ◽  
Plate Method ◽  
Inoculum Level ◽  
Environmental Surfaces ◽  
Significant Difference ◽  
Environmental Surface ◽  
High Level ◽  
Health Canada

Abstract A validation study of the 3M™ Petrifilm™ Environmental Listeria (EL) Plate (3M Food Safety, St. Paul, MN) was conducted at Q Laboratories, Inc., Cincinnati, OH. The method was compared to the Health Canada MFHPB-30 reference method for the analysis of stainless steel environmental surfaces. Twenty replicates of the environmental surface were analyzed at a low and a high inoculum level. The low-level sampling area was inoculated with 0.2–2 CFU/5 cm2, and the high-level sampling area was inoculated with 2–5 CFU/5 cm2. Five control replicates were also analyzed at 0 CFU/5 cm2. There was no significant difference in the number of positives detected by the 3M Petrifilm EL Plate method and the Health Canada MFHPB-30 reference method for the environmental surface analyzed in this study.

scholarly journals Stochasticity of Bacterial Attachment and Its Predictability by the Extended Derjaguin-Landau-Verwey-Overbeek Theory

2011 ◽  
Vol 77 (11) ◽  
pp. 3757-3764 ◽  
Author(s):  
Teck Wah R. Chia ◽  
Vu Tuan Nguyen ◽  
Thomas McMeekin ◽  
Narelle Fegan ◽  
Gary A. Dykes
Keyword(s):  
Stainless Steel ◽  
Physicochemical Properties ◽  
Surface Properties ◽  
Bacterial Attachment ◽  
Bacterial Cells ◽  
Initial Ratio ◽  
Content Type ◽  
Initial Inoculum ◽  
Serovar Typhimurium ◽  
Attachment Process

ABSTRACTBacterial attachment onto materials has been suggested to be stochastic by some authors but nonstochastic and based on surface properties by others. We investigated this by attaching pairwise combinations of twoSalmonella entericaserovar Sofia (S. Sofia) strains (with different physicochemical and attachment properties) with one strain each ofS. entericaserovar Typhimurium,S. entericaserovar Infantis, orS. entericaserovar Virchow (all with similar physicochemical and attachment abilities) in ratios of 0.428, 1, and 2.333 onto glass, stainless steel, Teflon, and polysulfone. Attached bacterial cells were recovered and counted. If the ratio of attached cells of eachSalmonellaserovar pair recovered was the same as the initial inoculum ratio, the attachment process was deemed stochastic. Experimental outcomes from the study were compared to those predicted by the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory. Significant differences (P< 0.05) between the initial and the attached ratios for serovar pairs containingS. Sofia S1296a for all different ratios were apparent for all materials. ForS. Sofia S1635-containing pairs, 7 out of 12 combinations of serovar pairs and materials had attachment ratios not significantly different (P> 0.05) from the initial ratio of 0.428. Five out of 12 and 10 out of 12 samples had attachment ratios not significantly different (P> 0.05) from the initial ratios of 1 and 2.333, respectively. These results demonstrate that bacterial attachment to different materials is likely to be nonstochastic only when the key physicochemical properties of the bacteria were significantly different (P< 0.05) from each other. XDLVO theory could successfully predict the attachment of some individual isolates to particular materials but could not be used to predict the likelihood of stochasticity in pairwise attachment experiments.

scholarly journals Removal and Transfer of Viruses on Food Contact Surfaces by Cleaning Cloths

2012 ◽  
Vol 78 (9) ◽  
pp. 3037-3044 ◽  
Author(s):  
Kristen E. Gibson ◽  
Philip G. Crandall ◽  
Steven C. Ricke
Keyword(s):  
Stainless Steel ◽  
Solid Surface ◽  
Stainless Steel Surface ◽  
Murine Norovirus ◽  
Indirect Transmission ◽  
Food Contact ◽  
Food Contact Surfaces ◽  
Significant Difference ◽  
Nonwoven Cloth ◽  
Contact Surfaces

ABSTRACTContamination of food contact surfaces with pathogens is considered an important vehicle for the indirect transmission of food-borne diseases. Five different cleaning cloths were assessed for the ability to remove viruses from food contact surfaces (stainless steel surface and nonporous solid surface) and to transfer viruses back to these surfaces. Cleaning cloths evaluated include two different cellulose/cotton cloths, one microfiber cloth, one nonwoven cloth, and one cotton terry bar towel. Four viral surrogates (murine norovirus [MNV], feline calicivirus [FCV], bacteriophages PRD1 and MS2) were included. Removal of FCV from stainless steel was significantly greater (P≤ 0.05) than that from nonporous solid surface, and overall removal of MNV from both surfaces was significantly less (P≤ 0.05) than that of FCV and PRD1. Additionally, the terry towel removed significantly fewer total viruses (P≤ 0.05) than the microfiber and one of the cotton/cellulose cloths. The cleaning cloth experiments were repeated with human norovirus. For transfer of viruses from cloth to surface, both cellulose/cotton cloths and microfiber transferred an average of 3.4 and 8.5 total PFU, respectively, to both surfaces, and the amounts transferred were significantly different (P≤ 0.05) from those for the nonwoven cloth and terry towel (309 and 331 total PFU, respectively). There was no statistically significant difference (P> 0.05) in the amount of virus transfer between surfaces. These data indicate that while the cleaning cloths assessed here can remove viruses from surfaces, some cloths may also transfer a significant amount of viruses back to food contact surfaces.

Comparison of Nucleation Site Density for Pool Boiling and Gas Nucleation

2005 ◽  
Vol 128 (1) ◽  
pp. 13-20 ◽  
Author(s):  
Yusen Qi ◽  
James F. Klausner
Keyword(s):  
Heat Transfer ◽  
Stainless Steel ◽  
Pool Boiling ◽  
Nucleation Site ◽  
Stainless Steel Surface ◽  
Distilled Water ◽  
Site Density ◽  
Significant Difference ◽  
Steel Surfaces ◽  
Nucleation Site Density

It has been well established that the rate of heat transfer associated with boiling systems is strongly dependent on the nucleation site density. Over many years attempts have been made to predict nucleation site density in boiling systems using a variety of techniques. With the exception of specially prepared surfaces, these attempts have met with little success. This paper presents an experimental investigation of nucleation site density measured on roughly polished brass and stainless steel surfaces for gas nucleation and pool boiling over a large parameter space. A statistical model used to predict the nucleation site density in saturated pool boiling is also investigated. The fluids used for this study, distilled water and ethanol, are moderately wetting and highly wetting, respectively. Using distilled water it has been observed that the trends of nucleation site density versus the inverse of the critical radius are similar for pool boiling and gas nucleation. The nucleation site density is higher for gas nucleation than for pool boiling. An unexpected result has been observed with ethanol as the heat transfer fluid, which casts doubt on the general assumption that heterogeneous nucleation in boiling systems is exclusively seeded by vapor trapping cavities. Due to flooding, few sites are active on the brass surface and at most two are active on the stainless steel surface during gas nucleation experiments. However, nucleation sites readily form in large concentration on both the brass and stainless steel surfaces during pool boiling. The pool boiling nucleation site densities for ethanol on rough and mirror polished brass surfaces are also compared. It shows that there is not a significant difference between the measured nucleation site densities on the smooth and rough surfaces. These results suggest that, in addition to vapor trapping cavities, another mechanism must exist to seed vapor bubble growth in boiling systems.

Antibacterial Activity of the Lactoperoxidase System Against Salmonella typhimurium in Trypticase Soy Broth in the Presence and Absence of a Heat Treatment

1994 ◽  
Vol 57 (5) ◽  
pp. 365-368 ◽  
Author(s):  
LISA M. WOLFSON ◽  
SUSAN S. SUMNER
Keyword(s):  
Heat Treatment ◽  
Antibacterial Activity ◽  
Salmonella Typhimurium ◽  
Thermal Inactivation ◽  
Bacteriostatic Activity ◽  
Inoculum Level ◽  
Growth And Survival ◽  
Initial Inoculum ◽  
Lactoperoxidase System ◽  
Bactericidal Activities

The antibacterial activity of the lactoperoxidase system (LP system) on the growth and survival of Salmonella typhimurium in tryptic soy broth (TSB) was determined. The LP system, consisting of lactoperoxidase (1 μg/ml), potassium thiocynante (KSCN) (5.9 mM) and H2O2 (2.5 mM), was found to have both bacteriostatic and bactericidal activities against strains of S. typhimurium. The bactericidal activity was clearly dependent on the initial inoculum level. Levels of 102 - 105 CFU/ml were killed at 37°C as opposed to the bacteriostatic activity with inoculum levels of 106 - 107 CFU/ml, which exhibited a 25-h lag. The LP system also enhanced thermal inactivation of S. typhimurium. D50°C-values were &gt; 60 min (untreated broth) and 12 min (LP system activated); corresponding D52°c-values were 20 min and 7.5 min; corresponding D55°c-values were 14 min and 4 min; corresponding D60°C -values were 5 min and 2.5 min and corresponding Devalues were .31 min and .20 min.

Effects of Domestic Storage and Thawing Practices on Salmonella in Poultry-Based Meat Preparations

2015 ◽  
Vol 78 (12) ◽  
pp. 2117-2125 ◽  
Author(s):  
ANNA ROCCATO ◽  
MIEKE UYTTENDAELE ◽  
VERONICA CIBIN ◽  
FEDERICA BARRUCCI ◽  
VERONICA CAPPA ◽  
...  
Keyword(s):  
Salmonella Typhimurium ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Most Probable Number ◽  
Probable Number ◽  
Moderate Growth ◽  
Serovar Typhimurium ◽  
Handling Practices ◽  
Food Handling Practices ◽  
Short Time ◽  
The Impact

Among consumer food handling practices, time-temperature abuse has been reported as one of the most common contributory factors in salmonellosis outbreaks where the evidence is strong. The present study performed storage tests of burgers, sausages, and kebabs and investigated (i) the effect of refrigerator temperatures (4°C versus 8 or 12°C, which were the temperatures recorded in 33 and 3%, respectively, of domestic refrigerators in Italy), with or without prior temperature abuse (25°C for 2 h, simulating transport of meats from shop to home), and (ii) the impact of the thawing method (overnight in the refrigerator at 8°C versus on the kitchen countertop at 23°C) on the presence and numbers of Salmonella bacteria. Storage tests were carried out on naturally or artificially (Salmonella enterica serovar Typhimurium at ca. 10 CFU/g) contaminated products, while freezing-thawing tests were conducted only on artificially contaminated products (Salmonella Typhimurium at ca. 10, 100, and 1,000 CFU/g). The results from the artificially contaminated products showed significant (P &lt; 0.05) growth of Salmonella Typhimurium at 12°C (i.e., from ca. 8 most probable number [MPN]/g to &gt; 710 MPN/g) in kebabs after 7 and 10 days but more moderate growth in sausages (i.e., from ca. 14 MPN/g to a maximum of 96 MPN/g after 9 days of storage). Storage of naturally contaminated burgers or sausages (contamination at or below 1 MPN/g) at 4, 8, or 12°C and a short time of temperature abuse (2 h at 25°C) did not facilitate an increase in the presence and numbers of Salmonella bacteria. Thawing overnight in the refrigerator led to either a moderate reduction or no change of Salmonella Typhimurium numbers in burgers, sausages, and kebabs. Overall, this study showed that domestic storage and thawing practices can affect food safety and that time-temperature abuse can cause a substantial increase of Salmonella numbers in some types of poultry-based meat preparations, highlighting that efforts for the dissemination of consumer guidelines on the correct storage and handling of meats need to be continued.

3M™ Tecra™ Listeria Visual Immunoassay: AOAC Official MethodsSM 995.22 and 2002.09

2013 ◽  
Vol 96 (2) ◽  
pp. 218-224
Author(s):  
DeAnn L Benesh ◽  
Erin S Crowley ◽  
Patrick M Bird
Keyword(s):  
Stainless Steel ◽  
Reference Method ◽  
Sampling Area ◽  
Inoculum Level ◽  
Fermented Sausage ◽  
High Inoculum ◽  
Significant Difference ◽  
Environmental Surface ◽  
High Level ◽  
Health Canada

Abstract A validation study of the 3M™ Tecra™ Listeria Visual Immunoassay (VIA; 3M Food Safety, St. Paul, MN) was conducted at Q Laboratories, Inc., Cincinnati, OH. The 3M Tecra Listeria VIA method was compared to the Health Canada MFHPB-30 reference method for the analysis of five ready-to-eat (RTE) meats: deli turkey, hot dogs, liver pate, raw fermented sausage, and deli ham, and on a stainless steel environmental surface. Twenty replicates of each of the five food matrixes were analyzed at a low and a high inoculum level. The low-level test portions were inoculated with 0.2–2 CFU/25 g, and the high-level test portions with 2–5 CFU/25 g. In addition, 20 replicates of one environmental surface were analyzed at a low and a high inoculum level. The low-level sampling area was inoculated with 0.2–2 CFU/5 cm2, and the high-level area with 2–5 CFU/5 cm2. Five control replicates were also analyzed at 0 CFU/25 g (uninoculated) for the foods and at 0 CFU/5 cm2 for the environmental sampling area. There was no significant difference in the number of positives detected by the 3M Tecra Listeria VIA and the Health Canada MFHPB-30 reference method for four of the RTE meats and the stainless steel environmental surface analyzed in this study. For the raw, fermented sausage, there was a significant difference in the number of positives detected for the high inoculum level by the 3M Tecra Listeria VIA and the Health Canada MFHPB-30 reference method, with the 3M Tecra Listeria VIA method detecting more positives.

Evaluation of the Thermo Scientific™ SureTect™ Listeria species Assay

2014 ◽  
Vol 97 (2) ◽  
pp. 521-538 ◽  
Author(s):  
Jonathan Cloke ◽  
Katharine Evans ◽  
David Crabtree ◽  
Annette Hughes ◽  
Helen Simpson ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Reference Method ◽  
Probability Of Detection ◽  
Stainless Steel Surface ◽  
Specific Method ◽  
Listeria Species ◽  
Smoked Salmon ◽  
Significant Difference ◽  
Thermo Fisher Scientific ◽  
High Level

Abstract The Thermo Scientific™ SureTect™ Listeria species Assay is a new real-time PCR assay for the detection of all species of Listeria in food and environmental samples. This validation study was conducted using the AOAC Research Institute (RI) Performance Tested MethodsSM program to validate the SureTect Listeria species Assay in comparison to the reference method detailed in International Organization for Standardization 11290-1:1996 including amendment 1:2004 in a variety of foods plus plastic and stainlesssteel. The food matrixes validated were smoked salmon, processed cheese, fresh bagged spinach, cantaloupe, cooked prawns, cooked sliced turkey meat, cooked sliced ham, salami, pork frankfurters, and raw ground beef. All matrixes were tested by Thermo Fisher Scientific, Microbiology Division, Basingstoke, UK. Inaddition, three matrixes (pork frankfurters, fresh bagged spinach, and stainless steel surface samples) were analyzed independently as part of the AOAC-RI-controlled independent laboratory study by the University of Guelph, Canada. Using probability of detection statistical analysis, a significant difference infavour of the SureTect assay was demonstrated between the SureTect and reference method for high level spiked samples of pork frankfurters, smoked salmon, cooked prawns, stainless steel, and low-spiked samples of salami. For all other matrixes, no significant difference was seen between the two methods during the study. Inclusivity testing was conducted with 68 different isolates of Listeria species, all of which were detected by the SureTect Listeria species Assay. None of the 33 exclusivity isolates were detected by the SureTect Listeria species Assay. Ruggedness testing was conducted to evaluate the performance of the assay with specific method deviations outside of the recommended parameters open to variation, which demonstrated that the assay gave reliable performance. Accelerated stability testing was additionally conducted, validating the assay shelf life.

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