Escherichia coli O157:H7 populations in ruminants can be reduced by orange peel product feeding.

Foodborne pathogenic bacteria such as Escherichia coli O157:H7 are threats to the safety of beef. Citrus peel and dried orange pulp are by-products from citrus juice production that have natural antimicrobial effects and are often incorporated into least-cost ration formulations for beef and dairy cattle. This study was designed to determine if orange peel and pulp affected E. coli O157:H7 populations in vivo. Sheep (n = 24) were fed a cracked corn grain-based diet that was supplemented with a 50-50 mixture of dried orange pellet and fresh orange peel to achieve a final concentration (dry matter basis, wt/wt) of 0, 5, or 10% pelleted orange peel (OP) for 10 days. Sheep were artificially inoculated with 10(10) CFU of E. coli O157:H7 by oral dosing. Fecal shedding of E. coli O157:H7 was measured daily for 5 days after inoculation, after which all animals were humanely euthanized. At 96 h postinoculation, E. coli O157:H7 shedding was reduced (P < 0.05) in sheep fed 10% OP. Populations of inoculated E. coli O157:H7 were reduced by OP treatment throughout the gastrointestinal tract; however, this reduction reached significant levels in the rumen (P < 0.05) of sheep fed 10% OP diets. Cecal and rectal populations of E. coli O157:H7 were reduced (P < 0.05) by inclusion of both 5 and 10% OP diets. Our results demonstrate that orange peel products can be used as a preharvest intervention strategy as part of an integrated pathogen reduction scheme.

Orange peel products can reduce Salmonella populations in ruminants.

Salmonella can live undetected in the gut of food animals and be transmitted to humans. Animal diets can impact intestinal populations of foodborne pathogens, including Salmonella spp. Orange juice production results in a waste product, orange peel and orange pulp, which has a high nutritive value and is often included in cattle diets as a least-cost ration ingredient. Here we show that the inclusion of orange peel products reduced Salmonella Typhimurium populations in the gut of experimentally inoculated sheep. Sheep (n=24) were fed a cracked corn grain-based high grain diet that was supplemented with a 50%/50% (dry matter [DM], w/w) mixture of dried orange pellet and fresh orange peel to achieve a final concentration (DM, basis) of 0%, 10%, or 20% orange product (OP) for 10 days before inoculation with Salmonella Typhimurium. Sheep were experimentally inoculated with 10(10) colony forming units Salmonella Typhimurium, and fecal samples were collected every 24 h after inoculation. Sheep were humanely euthanized at 96 h after oral Salmonella inoculation. Populations of inoculated Salmonella Typhimurium were numerically reduced by OP treatment throughout the gastrointestinal tract, and this reduction only reached significant levels in the cecum (p<0.05) of sheep fed 10% OP diets. Apparent palatability issues decreased the consumption of OP in sheep fed 20% OP to intake levels below that of 10% OP (approximately 7% dry matter intake [DMI]/d feed refusal), thereby reducing the potential effects of OP feeding at this higher level. Our results demonstrate that orange peel and pellets are environmentally friendly and low-cost products that can be used as a pre-harvest intervention as part of an integrated pathogen reduction scheme.

Bacteriophage isolated from feedlot cattle can reduce Escherichia coli O157:H7 populations in ruminant gastrointestinal tracts.

Escherichia coli O157:H7 can live undetected in the gut of food animals and be spread to humans directly and indirectly. Bacteriophages are viruses that prey on bacteria, offering a natural, nonantibiotic method to reduce pathogens from the food supply. Here we show that a cocktail of phages isolated from commercial cattle feces reduced E. coli O157:H7 populations in the gut of experimentally inoculated sheep. A cocktail of phages was used in order to prevent the development of resistance to the phages. In our first in vivo study we found that our cocktail of phages reduced E. coli O157:H7 populations in the feces of sheep (p < 0.05) by 24 hours after phage treatment. Upon necropsy, populations of inoculated E. coli O157:H7 were reduced by phage treatment in both the cecum (p < 0.05) and rectum (p < 0.1). In our second in vivo study, several ratios of phage plaque-forming units (PFU) to E. coli O157:H7 colony-forming units (CFU) were used (0:1, 1:1, 10:1, and 100:1 PFU/CFU) to determine the most efficacious phage dose. A 1:1 ratio of phage to bacteria was found to be more effective (p < 0.05) than either of the higher ratios used (10:1 or 100:1). Ruminal levels of E. coli O157:H7 were not significantly reduced (p > 0.10) in any of the studies due to relatively low inoculated E. coli O157:H7 ruminal populations. Our results demonstrate that phage can be used as a preharvest intervention as part of an integrated pathogen reduction scheme.

Prevalence of Escherichia coli O157 and levels of aerobic bacteria and Enterobacteriaceae are reduced when hides are washed and treated with cetylpyridinium chloride at a commercial beef processing plant.

The objective of this experiment was to test the potential of a combined water wash and cetylpyridinium chloride (CPC) treatment as a hide intervention applied to cattle in the holding pens of a processing plant immediately before stunning. Over 2 processing days, 149 control and 139 treated cattle were tested. Control cattle were processed in the normal manner. The treatment group was prewashed with water the day before harvest. Immediately before stunning, these cattle were sprayed twice with 1% CPC, first for 3 min, then for 1 min. Hides and preevisceration carcasses were sampled to determine aerobic plate counts, Enterobacteriaceae counts (EBC), and Escherichia coli O157 prevalence. The treatment reduced the prevalence of E. coli O157 on hides from 56% to 34% and the prevalence on preevisceration carcasses from 23% to 3%. The treatment decreased aerobic plate counts from 4.9 log CFU/100 cm2 to 3.4 log CFU/100 cm2 and EBC from 3.1 log CFU/100 cm2 to 2.0 log CFU/100 cm2 on preevisceration carcasses. The treatment of hides did not result in any detectable CPC contamination of the chilled carcasses. These data indicated that a 1% CPC treatment preceded by a water wash was capable of reducing hide prevalence of E. coli O157 from as high as 80% to less than 50%, resulting in preevisceration carcass prevalence of 5% or less. We conclude that water washing followed by an antimicrobial treatment, such as CPC, has great potential as an effective hide intervention step and should be further evaluated for implementation as a processing step after stunning and before hide removal.

Prevalence of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella in two geographically distant commercial beef processing plants in the United States.

For two large beef processing plants, one located in the southern United States (plant A) and one located in the northern United States (plant B), prevalence of Escherichia coli O157:H7, Listeria spp., Listeria monocytogenes, and Salmonella was determined for hide, carcass, and facility environmental samples over the course of 5 months. The prevalence of E. coli O157:H7 (68.1 versus 55.9%) and Salmonella (91.8 versus 50.3%) was higher (P < 0.05), and the prevalence of Listeria spp. (37.7 versus 75.5%) and L. monocytogenes (0.8 versus 18.7%) was lower (P < 0.05) for the hides of cattle slaughtered at plant A versus plant B. Similarly, the prevalence of Salmonella (52.0 versus 25.3%) was higher (P < 0.05) and the prevalence of Listeria spp. (12.0 versus 40.0%) and L. monocytogenes (1.3 versus 14.7%) was lower (P < 0.05) for the fence panels of the holding pens of plant A versus plant B. The prevalence of E. coli O157:H7 (3.1 versus 10.9%), Listeria spp. (4.5 versus 14.6%), and L. monocytogenes (0.0 versus 1.1%) was lower (P < 0.05) for preevisceration carcasses sampled at plant A versus plant B. Salmonella (both plants), Listeria spp. (plant B), and L. monocytogenes (plant B) were detected on fabrication floor conveyor belts (product contact surfaces) late during the production day. For plant B, 21 of 148 (14.2%) late-operational fabrication floor conveyor belt samples were L. monocytogenes positive. For plant B, E. coli O157:H7 and L. monocytogenes were detected in preoperational fabrication floor conveyor belt samples. Overall results suggest that there are regional differences in the prevalence of pathogens on the hides of cattle presented for harvest at commercial beef processing plants. While hide data may reflect the regional prevalence, the carcass data is indicative of differences in harvest practices and procedures in these plants.

Protocol for evaluating the efficacy of cetylpyridinium chloride as a beef hide intervention.

The objective of this study was to establish the necessary protocols and assess the efficacy of cetylpyridinium chloride (CPC) as an antimicrobial intervention on beef cattle hides. Experiments using CPC were conducted to determine (i) the methods of neutralization needed to obtain valid efficacy measurements, (ii) the effect of concentration and dwell time after treatment, (iii) the effect of CPC on hide and carcass microbial populations when cattle were treated at a feedlot and then transported to a processing facility for harvest, and (iv) the effectiveness of spray pressure and two-spray combinations of CPC and water to reduce hide microbial populations. Residual CPC in hide sponge samples prevented bacterial growth. Dey-Engley neutralization media at 7.8% and a centrifugation step were necessary to overcome this problem. All dwell times, ranging from 30 s to 4 h, after 1% CPC application to cattle hides resulted in aerobic plate counts and Enterobacteriaceae counts 1.5 log CFU/100 cm2 lower than controls. The most effective dose of CPC was 1%, which reduced aerobic plate counts and Enterobacteriaceae counts 2 and 1 log CFU/100 cm2, respectively. Low-pressure application of 1% CPC at the feedlot, transport to the processing facility, and harvest within 5 h of application resulted in no effect on Escherichia coli O157 prevalence on hides or preevisceration carcasses. Two high-pressure CPC washes lowered aerobic plate counts and Enterobacteriaceae counts by 4 log CFU/100 cm2, and two medium-pressure CPC washes were only slightly less effective. These results indicate that under the proper conditions, CPC may still be effective for reducing microbial populations on cattle hides. Further study is warranted to determine if this effect will result in reduction of hide-to-carcass contamination during processing.