Evaluating the Efficacy of Three U.S. Department of Agriculture–Approved Antimicrobial Sprays for Reducing Shiga Toxin–Producing Escherichia coli Surrogate Populations on Bob Veal Carcasses

2016 ◽  
Vol 79 (6) ◽  
pp. 956-962 ◽  
Author(s):  
N. J. SEVART ◽  
N. BAUMANN ◽  
H. THIPPAREDDI ◽  
T. A. HOUSER ◽  
J. B. LUCHANSKY ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Control Point ◽  
Spray Application ◽  
Department Of Agriculture ◽  
E Coli ◽  
Log Reduction ◽  
Instrumental Color ◽  
Antimicrobial Intervention ◽  
Spray Treatment

ABSTRACT Effective antimicrobial intervention strategies to reduce Shiga toxin–producing Escherichia coli (STEC) risks associated with veal are needed. This study evaluated the efficacy of lactic acid (4.5%, pH 2.0), Citrilow (pH 1.2), and Beefxide (2.25%, pH 2.3) for reducing STEC surrogates on prerigor and chilled bob veal carcasses and monitored the effects of these interventions on chilled carcass color. Dehided bob veal carcasses were inoculated with a five-strain cocktail of rifampin-resistant, surrogate E. coli bacteria. E. coli surrogates were enumerated after inoculation, after water wash, after prechill carcass antimicrobial spray application, after chilling for 24 h, and after postchill carcass antimicrobial spray application; carcass color was measured throughout the process. A standard carcass water wash (~50°C) reduced the STEC surrogate population by 0.9 log CFU/cm2 (P ≤ 0.05). All three antimicrobial sprays applied to prerigor carcasses delivered an additional ~0.5-log reduction (P ≤ 0.05) of the surrogates. Chilling of carcasses for 24 h reduced (P ≤ 0.05) the surrogate population by an additional ~0.4 log cycles. The postchill application of the antimicrobial sprays provided no further reductions. Carcass L*, a*, and b* color values were not different (P > 0.05) among carcass treatments. Generally, the types and concentrations of the antimicrobial sprays evaluated herein did not negatively impact visual or instrumental color of chilled veal carcasses. This study demonstrates that warm water washing, followed by a prechill spray treatment with a low-pH chemical intervention, can effectively reduce STEC risks associated with veal carcasses; this provides processors a validated control point in slaughter operations.

scholarly journals Seasonal prevalence and characterization of Shiga toxin-producing Escherichia coli on pork carcasses at three steps of the harvest process at two commercial processing plants in the US

2020 ◽  
Author(s):  
Ivan Nastasijevic ◽  
John W. Schmidt ◽  
Marija Boskovic ◽  
Milica Glisic ◽  
Norasak Kalchayanand ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Foodborne Pathogens ◽  
Shiga Toxin ◽  
Severe Disease ◽  
Control Point ◽  
Plate Count ◽  
Seasonal Effect ◽  
E Coli ◽  
Significant Control ◽  
Pork Products

ABSTRACTShiga toxin (stx) -producing Escherichia coli (STEC) are foodborne pathogens that have a significant impact on public health, with those possessing the attachment factor intimin (eae) referred to as enterohemorrhagic E. coli (EHEC) associated with life threatening illnesses. Cattle and beef are considered typical sources of STEC, but their presence in pork products is a growing concern. Therefore, carcasses (n=1536) at two U.S. pork processors were sampled once per season at three stages of harvest (post-stunning skins; post-scald carcasses; chilled carcasses) then examined using PCR for stx and eae, aerobic plate count (APC) and Enterobacteriaceae counts (EBC). Skins, post-scald, and chilled carcasses had prevalence of stx (85.3, 17.5, and 5.4%, respectively), with 82.3, 7.8, and 1.7% respectively, having stx and eae present. All stx positive samples were subjected to culture isolation that resulted in 368 STEC and 46 EHEC isolates. The most frequently identified STEC were serogroup O121, O8, and O91(63, 6.7, and 6.0% of total STEC, respectively). The most frequently isolated EHEC was serotype O157:H7 (63% of total EHEC). Results showed that scalding significantly reduced (P < 0.05) carcass APC and EBC by 3.00 and 2.50 log10 CFU/100 cm2 respectively. A seasonal effect was observed with STEC prevalence lower (P < 0.05) in winter. The data from this study shows significant (P < 0.05) reduction in the incidence of STEC (stx) from 85.3% to 5.4% and of EHEC (stx+eae) from 82.3% to 1.7% within slaughter-to-chilling continuum, respectively, and that potential EHEC can be confirmed present throughout using culture isolation.IMPORTANCESeven serogroups of Shiga toxin-producing Escherichia coli (STEC) are responsible for most (>75%) cases of severe illnesses caused by STEC and are considered adulterants of beef. However, some STEC outbreaks have been attributed to pork products although the same E. coli are not considered adulterants in pork because little is known of their prevalence along the pork chain. The significance of the work presented here is that it identifies disease causing STEC, enterohemorrhagic E. coli (EHEC), demonstrating that these same organisms are a food safety hazard in pork as well as beef. The results show that most STEC isolated from pork are not likely to cause severe disease in humans and that processes used in pork harvest, such as scalding, offer a significant control point to reduce contamination. The results will assist the pork processing industry and regulatory agencies to optimize interventions to improve the safety of pork products.

scholarly journals Variation in Acid Resistance among Shiga Toxin-Producing Clones of Pathogenic Escherichia coli

2005 ◽  
Vol 71 (5) ◽  
pp. 2493-2500 ◽  
Author(s):  
Teresa M. Large ◽  
Seth T. Walk ◽  
Thomas S. Whittam
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Survival Rates ◽  
Acid Resistance ◽  
Acid Decarboxylase ◽  
Infectious Dose ◽  
Clonal Group ◽  
E Coli ◽  
Log Reduction ◽  
Oxidative System

ABSTRACT Pathogenic strains of Escherichia coli, such as E. coli O157:H7, have a low infectious dose and an ability to survive in acidic foods. These bacteria have evolved at least three distinct mechanisms of acid resistance (AR), including two amino acid decarboxylase-dependent systems (arginine and glutamate) and a glucose catabolite-repressed system. We quantified the survival rates for each AR mechanism separately in clinical isolates representing three groups of Shiga toxin-producing E. coli (STEC) clones (O157:H7, O26:H11/O111:H8, and O121:H19) and six commensal strains from ECOR group A. Members of the STEC clones were not significantly more acid resistant than the commensal strains when analyzed using any individual AR mechanism. The glutamate system provided the best protection in a highly acidic environment for all groups of isolates (<0.1 log reduction in CFU/ml per hour at pH 2.0). Under these conditions, there was notable variation in survival rates among the 30 O157:H7 strains, which depended in part on Mg2+ concentration. The arginine system provided better protection at pH 2.5, with a range of 0.03 to 0.41 log reduction per hour, compared to the oxidative system, with a range of 0.13 to 0.64 log reduction per hour. The average survival rate for the O157:H7 clonal group was significantly less than that of the other STEC clones in the glutamate and arginine systems and significantly less than that of the O26/O111 clone in the oxidative system, indicating that this clonal group is not exceptionally acid resistant with these specific mechanisms.

Validation of a Sequential Hide-On Bob Veal Carcass Antimicrobial Intervention Composed of a Hot Water Wash and Lactic Acid Spray in Combination with Scalding To Control Shiga Toxin–Producing Escherichia coli Surrogates†

2018 ◽  
Vol 81 (5) ◽  
pp. 762-768
Author(s):  
JOSHUA D. HASTY ◽  
JOHN A. HENSON ◽  
GARY R. ACUFF ◽  
DENNIS E. BURSON ◽  
JOHN B. LUCHANSKY ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Lactic Acid ◽  
Ambient Temperature ◽  
Shiga Toxin ◽  
Hot Water ◽  
E Coli ◽  
Chemical Agents ◽  
Antimicrobial Interventions ◽  
Antimicrobial Intervention ◽  
Additional Reduction

ABSTRACT Scalding of hide-on bob veal carcasses with or without standard scalding chemical agents typically used for hogs, followed by an 82.2°C hot water wash and lactic acid spray (applied at ambient temperature) before chilling, was evaluated to determine its effectiveness in reducing Shiga toxin–producing Escherichia coli surrogate populations. A five-strain cocktail of rifampin-resistant, nonpathogenic E. coli surrogates was used to inoculate hides of veal carcasses immediately after exsanguination (target inoculation level of 7.0 log CFU/100 cm2). For carcasses receiving no scalding treatments, spraying with 82.2°C water as a final wash resulted in a 4.5-log CFU/100 cm2 surrogate reduction, and an additional 1.2-log CFU/100 cm2 reduction was achieved by spraying with 4.5% lactic acid before chilling. Scalding hide-on carcasses in 60°C water (no chemicals added) for 4 min in a traditional hog scalding tank resulted in a 2.1-log CFU/100 cm2 reduction in surrogate levels, and a subsequent preevisceration 82.2°C water wash provided an additional 2.9-log CFU/100 cm2 reduction. Spraying a 4.5% solution of lactic acid onto scalded, hide-on carcasses (after the 82.2°C water wash) resulted in a minimal additional reduction of 0.4 log CFU/100 cm2. Incorporation of scalding chemicals into the scald water resulted in a 4.1-log CFU/100 cm2 reduction (1.9 log CFU/100 cm2 greater than scalding without chemicals) in the surrogate population, and the first 82.2°C wash provided an additional 2.5-log CFU/100 cm2 reduction. Application of antimicrobial interventions did not affect the carcass temperature decline during chilling, the pH decline, or the color characteristics of the ribeye or the flank of the bob veal carcasses.

A Novel Selective Medium for Simultaneous Enrichment of Shiga Toxin–Producing Escherichia coli and Salmonella in Ground Beef

2018 ◽  
Vol 81 (8) ◽  
pp. 1252-1257 ◽  
Author(s):  
JOSEPH EGGERS ◽  
JOELLEN M. FEIRTAG ◽  
ALAN D. OLSTEIN ◽  
JOSEPH M. BOSILEVAC
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Ground Beef ◽  
Performance Standards ◽  
Selective Medium ◽  
Microbiological Analysis ◽  
Department Of Agriculture ◽  
Selective Enrichment ◽  
E Coli ◽  
Inspection Service

ABSTRACT Microbiological analysis of ground beef for contamination by both Salmonella and Shiga toxin–producing Escherichia coli (STEC) is performed by the U.S. Department of Agriculture, Food Safety Inspection Service (FSIS), as part of its Performance Standards Verification Testing program. FSIS has established a zero tolerance for STEC serotype O157:H7 and serogroups O26, O45, O103, O111, O121, and O145 because they are regarded as adulterants. The detection and isolation of these specific serogroups presents a technical challenge necessitating time-consuming and costly laboratory procedures that often exceed the technical capabilities of many small internal and reference laboratories. We describe here a method using a novel STEC and Salmonella selective (SSS) broth that allows for simultaneous selective enrichment of STEC and Salmonella sp., providing isolation and detection from the same broth. The method only involves direct plating from beef enrichments to detect suspect isolates that can be easily confirmed by using immunoassays or PCR, rendering the isolation simpler and less costly than the current described methods. In a side-by-side comparison with modified tryptic soy broth (mTSB), the use of SSS broth resulted in primarily isolating STEC and Salmonella sp., while substantially suppressing the growth of other gram-negative Enterobacteriacae by 90%. Significantly more (χ2 &lt; 3.84) samples containing E. coli O157:H7 and STEC O26, O111, O121, and O145 and a nondifferent (χ2 &gt; 3.84) number of samples containing STEC O103 and O45 were identified when enriching in SSS broth. Coenrichment using six different Salmonella serovars showed numerically greater but not significant (χ2 &lt; 3.84) positive samples by using SSS broth compared with mTSB for a majority of serotypes.

Evaluation of Lactic Acid as an Initial and Secondary Subprimal Intervention for Escherichia coli O157:H7, Non-O157 Shiga Toxin–Producing E. coli, and a Nonpathogenic E. coli Surrogate for E. coli O157:H7

2012 ◽  
Vol 75 (9) ◽  
pp. 1701-1708 ◽  
Author(s):  
C. I. PITTMAN ◽  
I. GEORNARAS ◽  
D. R. WOERNER ◽  
K. K. NIGHTINGALE ◽  
J. N. SOFOS ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Lactic Acid ◽  
Shiga Toxin ◽  
Hazard Analysis ◽  
Control Point ◽  
Escherichia Coli O157 ◽  
Meat Industry ◽  
Bacterial Reduction ◽  
E Coli ◽  
Critical Control Point

Lactic acid can reduce microbial contamination on beef carcass surfaces when used as a food safety intervention, but effectiveness when applied to the surface of chilled beef subprimal sections is not well documented. Studies characterizing bacterial reduction on subprimals after lactic acid treatment would be useful for validations of hazard analysis critical control point (HACCP) systems. The objective of this study was to validate initial use of lactic acid as a subprimal intervention during beef fabrication followed by a secondary application to vacuum-packaged product that was applied at industry operating parameters. Chilled beef subprimal sections (100 cm2) were either left uninoculated or were inoculated with 6 log CFU/cm2 of a 5-strain mixture of Escherichia coli O157:H7, a 12-strain mixture of non-O157 Shiga toxin–producing E. coli (STEC), or a 5-strain mixture of nonpathogenic (biotype I) E. coli that are considered surrogates for E. coli O157:H7. Uninoculated and inoculated subprimal sections received only an initial or an initial and a second “rework” application of lactic acid in a custom-built spray cabinet at 1 of 16 application parameters. After the initial spray, total inoculum counts were reduced from 6.0 log CFU/cm2 to 3.6, 4.4, and 4.4 log CFU/cm2 for the E. coli surrogates, E. coli O157:H7, and non-O157 STEC inoculation groups, respectively. After the second (rework) application, total inoculum counts were 2.6, 3.2, and 3.6 log CFU/cm2 for the E. coli surrogates, E. coli O157:H7, and non-O157 STEC inoculation groups, respectively. Both the initial and secondary lactic acid treatments effectively reduced counts of pathogenic and nonpathogenic strains of E. coli and natural microflora on beef subprimals. These data will be useful to the meat industry as part of the HACCP validation process.

Thermal Inactivation of Escherichia coli O157:H7 and Non-O157 Shiga Toxin–Producing Escherichia coli Cells in Mechanically Tenderized Veal†

2014 ◽  
Vol 77 (7) ◽  
pp. 1201-1206 ◽  
Author(s):  
JOHN B. LUCHANSKY ◽  
ANNA C. S. PORTO-FETT ◽  
BRADLEY A. SHOYER ◽  
HARSHAVARDHAN THIPPAREDDI ◽  
JESUS R. AMAYA ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Thermal Inactivation ◽  
Escherichia Coli O157 ◽  
Internal Temperature ◽  
E Coli ◽  
Log Reduction ◽  
Cooking Oil ◽  
Escherichia Coli Cells ◽  
Cooking Times

Preflattened veal cutlets (ca. 71.5 g, ca. 0.32 cm thick) were surface inoculated with ca. 6.8 log CFU/g of a multistrain cocktail of Escherichia coli O157:H7 (ECOH) or a cocktail made of single strains of serogroups O26, O45, O103, O104, O111, O121, and O145 of Shiga toxin–producing E. coli (STEC) cells and then were mechanically tenderized by passing once through a “Sir Steak” tenderizer. For each cooking time, in each of at least three trials, three inoculated and tenderized cutlets, with and without breading, were individually cooked in 15 or 30 ml of canola oil for 0.0, 0.75, 1.0, 1.25, 1.5, 1.75, or 2.25 min per side on an electric skillet set at 191.5°C. The temperatures of the meat and of the skillet were monitored and recorded using a type J thermocouple. Regardless of the breading or volume of oil used to cook the meat, the longer the cooking times, the higher was the internal temperature of the meat, along with a greater reduction of both ECOH and STEC. The average final internal temperature of the meat at the approximate geometric center ranged from 56.8 to 93.1°C. Microbial reductions of ca. 2.0 to 6.7 log CFU/g and ca. 2.6 to 6.2 log CFU/g were achieved for ECOH and STEC, respectively. Our data also revealed no differences in thermal inactivation of ECOH relative to the volume of oil used to cook nonbreaded cutlets. However, when cooking breaded cutlets, the use of more (30 ml) compared with less (15 ml) cooking oil resulted in greater reductions in pathogen numbers. To deliver about a 5.0-log reduction of ECOH and STEC, and to achieve the recommended internal temperature of 71.1°C, it was necessary to cook mechanically tenderized veal cutlets for at least 1.5 min per side on a preheated electric skillet set at 191.5°C and containing 15 ml of cooking oil. These data also established that cooking times and temperatures effective for inactivating serotype O157:H7 strains of E. coli in tenderized veal are equally effective against the additional six non-O157 Shiga toxin–producing strains investigated herein.

Efficacy of a Peroxyacetic Acid Formulation as an Antimicrobial Intervention To Reduce Levels of Inoculated Escherichia coli O157:H7 on External Carcass Surfaces of Hot-Boned Beef and Veal

2007 ◽  
Vol 70 (1) ◽  
pp. 200-203 ◽  
Author(s):  
NICK PENNEY ◽  
TERESA BIGWOOD ◽  
HAZEL BAREA ◽  
DAVID PULFORD ◽  
GUILL LeROUX ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Low Dose ◽  
High Dose ◽  
Escherichia Coli O157 ◽  
Peroxyacetic Acid ◽  
E Coli ◽  
Log Reduction ◽  
Acid Formulation ◽  
Cork Borer ◽  
Antimicrobial Intervention

The efficacy of a peroxyacetic acid formulation (POAA) at reducing Escherichia coli O157:H7 contamination on external carcass surfaces of hot-boned beef and veal with a commercial spray apparatus was determined. Hot-boned external carcass surfaces were inoculated with either a high dose (106 CFU/cm2) in fresh bovine feces or with a low dose (103 CFU/cm2)in diluent of laboratory-cultured E. coli O157:H7. Treatments included a water wash, a POAA (180 ppm) wash, or a water plus POAA wash. Samples were extracted from the external carcass surface with a cork borer to determine the numbers of viable E. coli O157:H7 remaining on the carcass surface after treatment. Although a water wash alone resulted in a 1.25 (94.4%) and a 1.31 (95.1%) mean log reduction on veal and beef inoculated with a high dose of E. coli O157:H7, the POAA treatment resulted in a substantially greater mean log reduction of 3.56 and 3.59 (&gt;99.9%). The water wash only resulted in a 33.9% reduction on veal and 62.8% on beef inoculated with a low dose of E. coli O157:H7, whereas POAA treatment greatly improved pathogen reduction to 98.9 and 97.4% on veal and beef, respectively. The combination of a water wash followed by a POAA treatment resulted in a similar E. coli O157:H7 reduction to that achieved by POAA treatment alone. In conclusion, POAA treatment significantly reduced viable E. coli O157:H7 numbers on experimentally contaminated beef and veal carcasses, which justifies its use as a chemical intervention for the removal of this human pathogen.

Inactivation of Shiga Toxin–Producing Escherichia coli in Single-Strength Lemon and Lime Juices Containing Preservatives

2011 ◽  
Vol 74 (10) ◽  
pp. 1746-1750 ◽  
Author(s):  
AI KATAOKA ◽  
ELENA ENACHE ◽  
MARIA SOHAIL ◽  
PHILIP H. ELLIOTT ◽  
D. GLENN BLACK
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Food Products ◽  
Storage Conditions ◽  
E Coli ◽  
Log Reduction ◽  
Validation Tests ◽  
Shelf Stable

The objective of this study was to determine the inactivation of non-O157 Shiga toxin–producing Escherichia coli (STEC) serotypes in comparison with O157 STEC in commercially produced, shelf-stable lemon and lime juices. The present validation tests confirmed that storage of the juices containing preservatives at room temperatures (22°C) for 3 days (72 h) ensures a &gt;6-log reduction of O26, O45, O103, O111, O121, O145, and O157 STEC. These results demonstrate that non-O157 STEC had survival abilities comparable to those of E. coli O157:H7 strains in acidic food products such as lemon and lime juices (pH 2.5 ± 0.1); therefore, the storage conditions deemed to inactivate E. coli O157:H7 similarly inactivate the non-O157 serotypes.

Efficacy of a Blend of Sulfuric Acid and Sodium Sulfate against Shiga Toxin–Producing Escherichia coli, Salmonella, and Nonpathogenic Escherichia coli Biotype I on Inoculated Prerigor Beef Surface Tissue

2017 ◽  
Vol 80 (12) ◽  
pp. 1987-1992 ◽  
Author(s):  
Britteny R. Scott-Bullard ◽  
Ifigenia Geornaras ◽  
Robert J. Delmore ◽  
Dale R. Woerner ◽  
James O. Reagan ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Sulfuric Acid ◽  
Shiga Toxin ◽  
Sodium Sulfate ◽  
Spray Application ◽  
Solution Ph ◽  
Tissue Samples ◽  
Bacterial Populations ◽  
E Coli ◽  
Main Effects

ABSTRACT A study was conducted to investigate the efficacy of a sulfuric acid–sodium sulfate blend (SSS) against Escherichia coli O157:H7, non-O157 Shiga toxin–producing E. coli (STEC), Salmonella, and nonpathogenic E. coli biotype I on prerigor beef surface tissue. The suitability of using the nonpathogenic E. coli as a surrogate for in-plant validation studies was also determined by comparing the data obtained for the nonpathogenic inoculum with those for the pathogenic inocula. Prerigor beef tissue samples (10 by 10 cm) were inoculated (ca. 6 log CFU/cm2) on the adipose side in a laboratory-scale spray cabinet with multistrain mixtures of E. coli O157:H7 (5 strains), non-O157 STEC (12 strains), Salmonella (6 strains), or E. coli biotype I (5 strains). Treatment parameters evaluated were two SSS pH values (1.5 and 1.0) and two spray application pressures (13 and 22 lb/in2). Untreated inoculated beef tissue samples served as controls for initial bacterial populations. Overall, the SSS treatments lowered inoculated (6.1 to 6.4 log CFU/cm2) bacterial populations by 0.6 to 1.5 log CFU/cm2 (P &lt; 0.05), depending on inoculum type and recovery medium. There were no main effects (P ≥ 0.05) of solution pH or spray application pressure when SSS was applied to samples inoculated with any of the tested E. coli inocula; however, solution pH did have a significant effect (P &lt; 0.05) when SSS was applied to samples inoculated with Salmonella. Results indicated that the response of the nonpathogenic E. coli inoculum to the SSS treatments was similar (P ≥ 0.05) to that of the pathogenic inocula tested, making the E. coli biotype I strains viable surrogate organisms for in-plant validation of SSS efficacy on beef. The application of SSS at the tested parameters to prerigor beef surface tissue may be an effective intervention for controlling pathogens in a commercial beef harvest process.

scholarly journals Seasonal Prevalence of Shiga Toxin-Producing Escherichia coli on Pork Carcasses for Three Steps of the Harvest Process at Two Commercial Processing Plants in the United States

2020 ◽  
Vol 87 (1) ◽  
Author(s):  
Ivan Nastasijevic ◽  
John W. Schmidt ◽  
Marija Boskovic ◽  
Milica Glisic ◽  
Norasak Kalchayanand ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Severe Disease ◽  
Control Point ◽  
The United States ◽  
Plate Count ◽  
Seasonal Effect ◽  
Content Type ◽  
E Coli ◽  
Pork Products

ABSTRACT Shiga toxin-producing Escherichia coli (STEC) is a foodborne pathogen that has a significant impact on public health, with strains possessing the attachment factor intimin referred to as enterohemorrhagic E. coli (EHEC) and associated with life-threatening illnesses. Cattle and beef are considered typical sources of STEC, but their presence in pork products is a growing concern. Therefore, carcasses (n = 1,536) at two U.S. pork processors were sampled once per season at three stages of harvest (poststunning skins, postscald carcasses, and chilled carcasses) and then examined using PCR for Shiga toxin genes (stx), intimin genes (eae), aerobic plate count (APC), and Enterobacteriaceae counts (EBC). The prevalence of stx on skins, postscald, and chilled carcasses was 85.3, 17.5, and 5.4%, respectively, with 82.3, 7.8, and 1.7% of swabs, respectively, having stx and eae present. All stx-positive samples were subjected to culture isolation that resulted in 368 STEC and 46 EHEC isolates. The most frequently identified STEC were serogroups O121, O8, and O91 (63, 6.7, and 6.0% of total STEC, respectively). The most frequently isolated EHEC was serotype O157:H7 (63% of total EHEC). Results showed that scalding significantly reduced (P < 0.05) carcass APC and EBC by 3.00- and 2.50-log10 CFU/100 cm2, respectively. A seasonal effect was observed, with STEC prevalence lower (P < 0.05) in winter. The data from this study show significant (P < 0.05) reduction in the incidence of STEC (stx) from 85.3% to 5.4% and of EHEC (stx plus eae) from 82.3% to 1.7% within the slaughter-to-chilling continuum, respectively, and that potential EHEC can be confirmed present throughout using culture isolation. IMPORTANCE Seven serogroups of STEC are responsible for most (>75%) cases of severe illnesses caused by STEC and are considered adulterants of beef. However, some STEC outbreaks have been attributed to pork products, although the same E. coli are not considered adulterants in pork because little is known of their prevalence along the pork chain. The significance of the work presented here is that it identifies disease-causing STEC, EHEC, demonstrating that these same organisms are a food safety hazard in pork as well as beef. The results show that most STEC isolated from pork are not likely to cause severe disease in humans and that processes used in pork harvest, such as scalding, offer a significant control point to reduce contamination. The results will assist the pork processing industry and regulatory agencies to optimize interventions to improve the safety of pork products.

Sign in / Sign up

Export Citation Format

Share Document