Investigation of the environmental presence of Salmonella spp. in finishing pigs at commercial swine farms in Kansas (USA).

Salmonellosis remains a major foodborne disease threat to public health worldwide. Swine are considered a reservoir for many Salmonella serotypes affecting humans; however, not all serotypes of concern in food animal products cause clinical signs of infection in swine. The objective of this study was to evaluate the presence and distribution of Salmonella spp. in finishing pigs at commercial farms across Kansas (USA). Five farms were selected and sampled when pigs weighed between 125 and 136 kg. Samples were collected and transported to the laboratory for processing following USDA-FSIS guidelines. Susceptibility and resistance profiles were also studied. Fifty-three percent (100/186) of samples were culture positive for Enterobacteriaceae, and 14% (14/100) were confirmed Salmonella positive by PCR with three of five farms having no PCR-positive samples. Salmonella serotype Braenderup was the most common serovar identified in environmental samples, while Salm. Infantis, Agona, and Montevideo were identified in fecal samples. Multidrug resistance patterns were only found in Farm 3, in fecal samples and in one floor sample. The observations reported in this study highlight areas of concern, such as locations prone to fecal contamination, to be considered when cleaning and sanitizing between groups of pigs to decrease presence of Salmonella spp. in farm environments.

Application of fly ash as an adsorbent for Estradiol in animal waste.

The contamination of agricultural ground with estrogen compounds through application of animal wastes is a present concern. At the same time, current uses for waste fly ash having high carbon content are limited. To help mitigate these problems, we examine using waste fly ash as a useful adsorbent for Estradiol in pig waste digests. In this study, Estradiol was added to vials containing water and fly ash from several different power plants. After an extraction process, the amount of Estradiol in the water was measured. Commercial activated carbon was also used for comparison purposes. Vials containing varying concentrations of Estradiol and no trapping material were used as a control. The results from this study indicate that fly ash can be used as a trapping material for Estradiol in water, but that commercially available activated carbon can trap about an order of magnitude more Estradiol than the fly ash and that the effects of the fly ash matrix can both inhibit and promote the solvation of Estradiol into water depending possibly upon pH and cation concentration effects. In addition, preliminary extraction studies using pig waste digest indicate that fly ash can be used as adsorbent for Estradiol present in pig waste.

Hypervirulent clonal complex (CC) of Listeria monocytogenes in fresh produce from urban communities.

Introduction: This study aimed to determine the prevalence and virulome of Listeria in fresh produce distributed in urban communities. Methods: A total of 432 fresh produce samples were collected from farmer's markets in Michigan and West Virginia, USA, resulting in 109 pooled samples. Listeria spp. were isolated and L. monocytogenes was subjected to genoserogrouping by PCR and genotyping by pulsed-field gel electrophoresis (PFGE). Multi-locus sequence typing (MLST) and core-genome multi-locus sequence typing (cgMLST) were conducted for clonal identification. Results: Forty-eight of 109 samples (44.0%) were contaminated with Listeria spp. L. monocytogenes serotype 1/2a and 4b were recovered from radishes, potatoes, and romaine lettuce. Four clonal complexes (CC) were identified and included hypervirulent CC1 (ST1) and CC4 (ST219) of lineage I as well as CC7 (ST7) and CC11 (ST451) of lineage II. Clones CC4 and CC7 were present in the same romaine lettuce sample. CC1 carried Listeria pathogenicity island LIPI-1 and LIPI-3 whereas CC4 contained LIPI-1, LIPI-3, and LIPI-4. CC7 and CC11 had LIPI-1 only. Discussion: Due to previous implication in outbreaks, L. monocytogenes hypervirulent clones in fresh produce pose a public health concern in urban communities.

Survival of Salmonella and the surrogate Enterococcus faecium in cooking of moisture enhanced reconstructed comminuted chicken patties by double pan-broiling.

This study compares kinetic parameters of Salmonella and Enterococcus faecium in moisture enhanced, reconstructed comminuted chicken patties prepared with different pump rates during double pan-broiling with various set-up temperatures. Fresh 1.5-kg chicken breast meat was course grounded, inoculated with S. Typhimurium and Tennessee, or E. faecium, followed by adding NaCl (2.0%) + Na-tripolyphosphate (0.5%) solutions to achieve pump rates of 1%, 5%, or 11.1%. Meat samples were manually manufactured into patties with the thickness of 2.1 cm and diameter of 10.4 cm. Patties were packaged with polyvinyl chloride films in the foam-tray stored at 4°C for 42 h before double pan-broiling set at 200°, 300°, or 425°F for 0 to 420 s. Counts of pathogens were analyzed on xylose-lysine-Tergitol-4 and bile esculin agars with tryptic soy agar layers. Microbial data and kinetic parameters (n = 9, United States Department of Agriculture [USDA]-Integrated-Predictive-Modeling-Program/USDA-Global-Fit software) were analyzed by the Mixed Model Procedure (SAS). Double pan-broiling reduced >5-log10 CFU/g (P < 0.05) of Salmonella after 360 (200°F), 180 to 225 (300°F), and 150 to 165s (425°F), and of E. faecium after 270 s (300°F), and 180 s (425°F) across all samples. D-values (Mafart-Weibull model) of Salmonella and E. faecium in 1% moisture enhanced samples cooked at 200 to 425°F (102.7-248.2 and 115.5-271.0 s) were lower (P < 0.05) than 11.1% samples (119.8-263.7 and 122.5-298.3 s). Salmonella were more susceptible (P < 0.05) to heat than E. faecium. "Shoulder-time" (Buchanan-Two-Phase model) of Salmonella cooking at 200° to 425°F increased (P < 0.05) from 82.3-229.0 to 116.6-246.2 s as pump rate increased from 1 to 11.1%, whereas this phenomenon was not shown for E. faecium. Results indicate that Salmonella were resistant to heat in chicken patties with greater pump rate. E. faecium can be used as a surrogate for Salmonella to validate thermal inactivation in chicken products.

Comparison of the Efficacy of Electrostatic versus Conventional Sprayer with Commercial Antimicrobials To Inactivate Salmonella, Listeria monocytogenes, and Campylobacter jejuni for Eggs and Economic Feasibility Analysis.

This study was conducted to compare the efficacy of antimicrobials sprayed by electrostatic versus conventional sprayer for inactivation of Salmonella, Listeria monocytogenes, and Campylobacter jejuni on eggs and to determine the economic feasibility of these treatments. Eggs were dip inoculated with overnight cultures (18 h) of Salmonella Typhimurium, Salmonella Tennessee, a two-strain mixture of L. monocytogenes, and a three-strain mixture of C. jejuni (microaerophilic condition). Inoculated eggs were then not sprayed or subjected to electrostatic and conventional spraying with peroxyacetic acid (PAA; 0.1%), lactic acid (5.0%), lactic and citric acid blend (2.5%), sodium hypochlorite (SH; 50 ppm), and SaniDate-5.0 (SD [a mixture of PAA and H2O2]; 0.25%) for 30 s (15 s each side). Surviving bacteria on eggshells were recovered on xylose lysine Tergitol 4 agar ( Salmonella), modified Oxford agar ( L. monocytogenes), or Brucella agar ( C. jejuni). Compared with conventional spraying, electrostatic spraying of PAA, SD, and SH achieved significant additional reductions ( P < 0.05) of Salmonella, L. monocytogenes, and C. jejuni of 0.96 to 3.18, 1.19 to 3.05, and 0.96 to 1.62 log CFU per egg, respectively. A simple cost comparison suggests that regardless of the antimicrobial agent used, the cost of using an electrostatic sprayer is 20 to 40% lower than that of a conventional sprayer for a small poultry farm that produces 1,500 eggs per day. Among the five antimicrobials, the total sanitizing cost was lowest for SH, followed by PAA and SD. The results indicated that electrostatic spraying of commercial antimicrobials can be considered an effective and economical approach to enhancing the microbial safety of eggs, especially for small poultry processors.

Microbiological quality assessment and validation of antimicrobials against unstressed or cold-stress adapted Salmonella and surrogate Enterococcus faecium on broiler carcasses and wings.

This study aims to evaluate the microbiological quality and efficacy of antimicrobials to inactivate unstressed or cold-stress adapted Salmonella and Enterococcus on broiler carcasses and wings processed at a small USDA-inspected slaughter facility in West Virginia. The first part of the study included 42 carcasses that were pre- and secondarily-enriched in bacterial media followed by streak-plating onto XLT-4 and HardyCHROM™-agar Salmonella and confirmation using an API20E-kit. The aerobic plate counts (APC), Escherichia coli (ECC), total coliforms (TCC), and yeast/molds were analyzed on petri-films. The second part of the study included fresh broiler carcasses and wings that were inoculated with unstressed and cold-stress-adapted (4 °C, 7-day) Salmonella Typhimurium and Tennessee, and Enterococcus faecium ATCC 8459 (5.5 to 6.0 log10CFU/mL) and later dipped into peroxyacetic acid (PAA; 1,000 ppm), lactic acid (LA; 5%), lactic and citric acid blend (LCA; 2.5%), and sodium hypochlorite (SH; 70 ppm) for 30 s without (carcasses) or with 2-min drainage (wings). The surviving bacteria were recovered onto non-selective and selective agar to analyze the total microbial population, Salmonella and Enterococcus. APC, TCC, and Yeast/Molds were 2.62, 1.08, and 2.37 log10CFU/mL on broiler carcasses, respectively. A total of 30 and 40% of the carcasses tested positive for Salmonella spp. and E. coli (0.48 to 1.70 log10CFU/mL), respectively. For carcasses, antimicrobial reductions of cold-stress-adapted cells of Salmonella and Enterococcus were greater (P < 0.05) than the unstressed cells. For wings, cold-stress-adapted Salmonella were more (P < 0.05) sensitive to antimicrobials than unstressed cells; however, unstressed and cold-stress-adapted Enterococcus behaved similarly (P > 0.05). The reduction of Salmonella and Enterococcus on carcasses and wings increased in the order of SH ≤ LCA < LA < PAA and irrespective of unstressed or cold-stress-adapted cells. Applying post-chilling antimicrobial dipping treatments could be an intervention approach to control Salmonella on locally processed broilers. In addition, Enterococcus faecium could be a Salmonella surrogate for in-plant validation studies.

A Comparison Study of Quality Attributes of Ground Beef and Veal Patties and Thermal Inactivation of Escherichia coli O157:H7 after Double Pan-Broiling Under Dynamic Conditions.

This study compared the quality variation and thermal inactivation of Escherichia coli O157:H7 in non-intact beef and veal. Coarse ground beef and veal patties (2.1 cm thick, 12.4 cm diameter, 180 g) inoculated with E. coli O157:H7, aerobically stored before double pan-broiling for 0-360 s without rest or to 55, 62.5, 71.1, and 76 °C (internal temperature) with 0.5- or 3.5-min rest. Microbial population and qualities including color, cooking losses, pH, water activity, fat, and moisture content, were tested. After cooking the beef and veal patties, the weight losses were 17.83-29%, the pH increased from 5.53-5.60 to 5.74-6.09, the moisture content decreased from 70.53-76.02% to 62.60-67.07%, and the fat content increased (p < 0.05) from 2.19-6.46% to 2.92-9.45%. Cooking beef and veal samples with increasing internal temperatures decreased a* and b* values and increased the L* value. Escherichia coli O157:H7 was more sensitive to heat in veal compared to beef with shorter D-value and "shoulder" time. Cooking to 71.1 and 76 °C reduced E. coli O157:H7 by >6 log CFU/g regardless of rest time. Cooking to 55 °C and 62.5 °C with a 3.5-min rest achieved an additional 1-3 log CFU/g reduction compared to the 0.5-min rest. Results should be useful for developing risk assessment of non-intact beef and veal products.

Impact of Built-up-Litter and Commercial Antimicrobials on Salmonella and Campylobacter Contamination of Broiler Carcasses Processed at a Pilot Mobile Poultry-Processing Unit.

The small-scale mobile poultry-processing unit (MPPU) produced raw poultry products are of particular food safety concern due to exemption of USDA poultry products inspection act. Limited studies reported the microbial quality and safety of MPPU-processed poultry carcasses. This study evaluated the Salmonella and Campylobacter prevalence in broiler ceca and on MPPU-processed carcasses and efficacy of commercial antimicrobials against Campylobacter jejuni on broilers. In study I, straight-run Hubbard × Cobb broilers (147) were reared for 38 days on clean-shavings (CS, 75) or built-up-litter (BUL, 72) and processed at an MPPU. Aerobic plate counts (APCs), coliforms, Escherichia coli, and yeast/molds (Y/M) of carcasses were analyzed on petrifilms. Ceca and carcass samples underwent microbial analyses for Salmonella and Campylobacter spp. using the modified USDA method and confirmed by API-20e test (Salmonella), latex agglutination immunoassay (Campylobacter), and Gram staining (Campylobacter). Quantitative polymerase chain reaction (CadF gene) identified the prevalence of C. jejuni and Campylobacter coli in ceca and on carcasses. In study II, fresh chilled broiler carcasses were spot inoculated with C. jejuni (4.5 log10 CFU/mL) and then undipped, or dipped into peroxyacetic acid (PAA) (1,000 ppm), lactic acid (5%), lactic and citric acid blend (2.5%), sodium hypochlorite (69 ppm), or a H2O2-PAA mix (SaniDate® 5.0, 0.25%) for 30 s. Surviving C. jejuni was recovered onto Brucella agar. APCs, coliforms, and E. coli populations were similar (P > 0.05) on CS and BUL carcasses. Carcasses of broilers raised on BUL contained a greater (P < 0.05) Y/M population (2.2 log10 CFU/mL) than those reared on CS (1.8 log10 CFU/mL). Salmonella was not detected in any ceca samples, whereas 2.8% of the carcasses from BUL were present with Salmonella. Prevalence of Campylobacter spp., C. jejuni was lower (P < 0.05), and C. coli was similar (P > 0.05) in CS-treated ceca than BUL samples. Prevalence of Campylobacter spp., C. jejuni, and C. coli was not different (P > 0.05) on CS- and BUL-treated carcasses. All antimicrobials reduced C. jejuni by 1.2-2.0 log CFU/mL on carcasses compared with controls. Hence, raising broilers on CS and applying post-chilling antimicrobial treatment can reduce Salmonella and Campylobacter on MPPU-processed broiler carcasses.

Generation of chlorine by-products in simulated wash water.

Free chlorine (FC) reacting with organic matter in wash water promotes the formation of chlorine by-products. This study aims to evaluate the dynamic impact of FC and organic load on the generation of haloacetic acids (HAAs) and trihalomethanes (THMs) in simulated wash water. Lettuce juice was sequentially added into FC solution with FC periodically replenished. Water samples were collected after each lettuce juice addition to measure water qualities and determine HAAs and THMs using US-Environmental-Protection-Agency (EPA) methods. Concentrations of 88-2103 µg/l of total HAAs and 20.79-859.47 µg/l of total THMs were detected during the study. Monobromoacetic, tribromoacetic, chlorodibromoacetic and trichloroacetic acid were the major HAAs components. Chloroform (trichloromethane) was the primary THMs present. A significant correlation of HAAs with chemical oxygen demand and THMs with FC was observed. Results indicated that optimizing wash water sanitizing systems to limit organic matters and maintain minimal effective FC concentration is critical.