Utilization of the skin attachment model to determine the antibacterial efficacy of potential carcass treatments

Evaluation of needle injection practices contributing to Campylobacter contamination in New Zealand chicken and chicken products

One hypothesis for the higher rate of campylobacteriosis in New Zealand (NZ) is that secondary poultry processing practices increase chicken contamination. Chicken marination with needle injection may introduce pathogenic bacteria from the surface deep into the interior muscle tissue. The survival of Campylobacter in/on multi-needle injected chicken products was performed at the processing plant and retail. The 'reduced salts' marinade was not effective in reducing Campylobacter contamination level as the 'high salt' marinade. At the plant, every tested single injected drumstick with 'reduced salt' marinade was contaminated with Campylobacter with up to 3.5 log per drumstick where only 30% of the injected drumsticks with the 'high salt' marinade were contaminated on the surface. At retail, chicken products injected with the 'low salt', the contamination was very low or undetectable as all the products were sold frozen, but the chicken products injected with 'high salt' marinade were sold fresh, and the contamination level varies and can marginally exceed the target Campylobacter contamination limit (3.78 log CFU/carcass) set by The NZ Authority. The multi-needle injection practice tested in this study did not indicate that the marination process could increase the contamination level on chicken or chicken products.

Effect of caprylic acid alone or in combination with peracetic acid against multidrug-resistant Salmonella Heidelberg on chicken drumsticks in a soft scalding temperature-time setup

The antimicrobial efficacy of caprylic acid (CA), a medium-chain fatty acid, against multidrug-resistant Salmonella Heidelberg (MDR SH) on chicken drumsticks in a soft-scalding temperature-time setup was investigated. Based on the standardization experiments in nutrient media and on chicken breast fillet portions, intact chicken drumsticks were spot inoculated with MDR SH and immersed in water with or without antimicrobial treatments at 54°C for 2 min. The treatments included 0.5% CA, 1% CA, 0.05% peracetic acid (PAA), 0.5% CA + 0.05% PAA, and 1.0% CA + 0.05% PAA. Additionally, the efficacy of the potential scald treatments against MDR SH survival on drumsticks for a storage period of 48 h at 4°C was determined. Furthermore, the effect of these treatments on the surface color of the drumsticks was also evaluated. Appropriate controls were included for statistical comparisons. The antimicrobial treatments resulted in a significant reduction of MDR SH on drumsticks. For the lower inoculum (∼2.5 log₁₀ CFU/g) experiments, 0.5% CA, 1% CA, 0.05% PAA, 0.5% CA + 0.05% PAA, and 1.0% CA + 0.05% PAA resulted in 0.7-, 1.0-, 2.5-, 1.4-, and 1.5- log₁₀ CFU/g reduction of MDR SH on drumsticks, respectively (P < 0.05). The same treatments resulted in 0.9-, 1.3-, 2.5-, 2.2-, and 2.6- log₁₀ CFU/g reduction of MDR SH when the drumsticks were contaminated with a higher inoculum (∼4.5 log₁₀ CFU/g) level (P < 0.05). Moreover, the antimicrobial treatments inactivated MDR SH in the treatment water to undetectable levels, whereas 2.0- to 4.0- log₁₀ CFU/mL MDR SH survived in the positive controls (P < 0.05). Also, the treatments were effective in inhibiting MDR SH on the drumsticks compared to the respective controls during a storage period of 48 h at 4°C; however, the magnitude of reduction remained the same as observed during the treatment (P < 0.05). Additionally, none of the treatments affected the color of the drumsticks (P > 0.05). Results indicate that CA could be an effective natural processing aid against MDR SH on chicken products.

Salmonella Biofilm Formation, Chronic Infection, and Immunity Within the Intestine and Hepatobiliary Tract

Within the species of Salmonella enterica, there is significant diversity represented among the numerous subspecies and serovars. Collectively, these account for microbes with variable host ranges, from common plant and animal colonizers to extremely pathogenic and human-specific serovars. Despite these differences, many Salmonella species find commonality in the ability to form biofilms and the ability to cause acute, latent, or chronic disease. The exact outcome of infection depends on many factors such as the growth state of Salmonella, the environmental conditions encountered at the time of infection, as well as the infected host and immune response elicited. Here, we review the numerous biofilm lifestyles of Salmonella (on biotic and abiotic surfaces) and how the production of extracellular polymeric substances not only enhances long-term persistence outside the host but also is an essential function in chronic human infections. Furthermore, careful consideration is made for the events during initial infection that allow for gut transcytosis which, in conjunction with host immune functions, often determine the progression of disease. Both typhoidal and non-typhoidal salmonellae can cause chronic and/or secondary infections, thus the adaptive immune responses to both types of bacteria are discussed with particular attention to the differences between Salmonella Typhi, Salmonella Typhimurium, and invasive non-typhoidal Salmonella that can result in differential immune responses. Finally, while strides have been made in our understanding of immunity to Salmonella in the lymphoid organs, fewer definitive studies exist for intestinal and hepatobiliary immunity. By examining our current knowledge and what remains to be determined, we provide insight into new directions in the field of Salmonella immunity, particularly as it relates to chronic infection.

Food Grade Pimenta Leaf Essential Oil Reduces the Attachment of Salmonella enterica Heidelberg (2011 Ground Turkey Outbreak Isolate) on to Turkey Skin

Salmonella attached to the poultry skin is a major source of carcass contamination during processing. Once attached to the poultry skin, it is difficult to detach and inactivate Salmonella by commonly used antimicrobial agents since the pathogen is entrapped deeply in the feather follicles and the crevices on the skin. Essential oils could be natural, safe, and effective alternatives to synthetic antimicrobial agents during commercial and organic processing setup. The present study evaluated the efficacy of pimenta (Pimenta officinalis Lindl.) leaf essential oil (PEO), and its nanoemulsion in reducing Salmonella Heidelberg attachment on to turkey (Meleagris gallopavo) skin during simulated scalding (65°C) and chilling (4°C) steps in poultry processing. A multidrug resistant S. Heidelberg isolate from the 2011 ground turkey outbreak in the United States was used in the study. Results showed that PEO and the nanoemulsion resulted in significant reduction of S. Heidelberg attachment on turkey skin. Turkey skin samples treated with 1.0% PEO for 5 min resulted in >2 log10 CFU/sq. inch reduction of S. Heidelberg at 65 and 4°C, respectively (n = 6; P < 0.05). Similarly, skin samples treated with 1.0% pimenta nanoemulsion (PNE) for 5 min resulted in 1.5- and 1.8- log10 CFU/sq. inch reduction of S. Heidelberg at 65 and 4°C, respectively (n = 6; P < 0.05). In addition, PEO and PNE were effective in reducing S. Heidelberg on skin during short-term storage at 4 and 10°C (temperature abuse) (n = 6; P < 0.05). No Salmonella was detected in the dipping solution containing 0.5 or 1.0% PEO or PNE, whereas a substantial population of the pathogen survived in the control dipping solution. The results were validated using scanning electron -, and confocal - microscopy techniques. PEO or PNE could be utilized as an effective antimicrobial agent to reduce S. Heidelberg attachment to turkey skin during poultry processing.

Postchill Antimicrobial Treatments To Control Salmonella, Listeria, and Campylobacter Contamination on Chicken Skin Used in Ground Chicken

Ground poultry products are frequently contaminated with foodborne pathogens. With the potential for increased regulatory scrutiny, it is important to use sufficient intervention strategies to control pathogen levels effectively. A large proportion of the bacteria introduced to ground chicken are likely to come from broiler skin, which is added to achieve target fat content and maintain product texture and taste. In this research, antimicrobials, including 50 ppm of chlorine and 1,200 ppm of peracetic acid (PAA), were applied in a postchill system to reduce the number of Salmonella Typhimurium, Listeria monocytogenes, and Campylobacter coli inoculated on chicken skin used to formulate ground chicken. Results showed that chlorine provided no significant effect in reducing the number of pathogens in ground chicken made with treated skin compared with water treatment but that it did help decrease pathogens in postchill water. PAA was found to be an effective (P ≤ 0.05) antimicrobial agent, not only in reducing the number of pathogens on ground chicken, but also in postchill water. Treating chicken skin with PAA prior to inclusion in ground chicken can be an effective intervention strategy to lessen contamination in a ground chicken meat product.

Evaluation of the effects of a mixture of organic acids and duration of storage on the survival of salmonella on turkey carcasses

Samples from turkey carcasses previously inoculated with Salmonella Enteritidis 33/66 were subjected to the effect of various mixtures of equal parts of organic acid solutions (acetic, ascorbic, citric, lactic, and tartaric acids). The first part of the study concerned analysis of the influence of the mixtures of organic acids over 15 or 30 min on Salmonella Enteritidis on turkey carcasses. Turkey breast samples were inoculated with Salmonella Enteritidis at 3.7, 2.7, 1.7, 0.7, and 0.07 log CFU. The antibacterial effectiveness of the organic acids differed depending on the initial population of Salmonella on the turkey carcasses. Salmonella was most sensitive to mixtures of equal parts of 1% ascorbic, 1% citric, and 1% tartaric acids. The second part of the study involved determining the influence the organic acid mixtures had on survival of Salmonella Enteritidis on turkey meat stored at 4°C for 2, 4, or 6 days. The level of Salmonella was determined using a most-probable-number method. Salmonella Enteritidis was inoculated into a nutrient broth, incubated at 37°C for 24 h, and then added to the diluent in which the turkey breast samples were immersed for 5 min. The initial Salmonella level of the control samples of turkey breast following immersion was determined in each analysis. After storage at 4°C, turkey samples were transferred to the organic acid solutions for 15 min. Stainless steel templates were used to swab 50 cm(2) of the turkey breast samples. During storage at 4°C, the Salmonella level in the meat samples decreased. The largest decrease occurred at 4°C after 6 days with equal parts of 1% acetic acid, 1% lactic acid, and 1% tartaric acid. Thus, treatment of raw turkey breasts with a mixture of organic acids is a promising option for reducing the risk of the presence of Salmonella.

The evaluation of combined chemical and physical treatments on the reduction of resident microorganisms and Salmonella Typhimurium attached to chicken skin

This study was conducted to evaluate the efficacy of sodium hypochlorite (NaOCl, 0-200 mg/kg), thiamine dilauryl sulfate (TDS, 1,000 mg/kg), and ultrasound (37 kHz, 380 W) on reducing Salmonella Typhimurim, mesophilic aerobic bacteria (MAB), and coliforms on chicken skin. Chemical and physical treatments were applied for 5 min either singly or jointly, and Salmonella previously inoculated on chicken skin were quantitatively assessed using brilliant green agar, and the populations of MAB and coliforms in the native flora were enumerated using plate count agar and violet red bile agar, respectively. In the evaluation of bacterial attachment/detachment, chicken skin was quantitatively assessed for loosely, intermediately, and tightly attached bacteria. The treatment effects on bacteria detachment were also visualized using field emission scanning electron microscopy. In addition, color and textural properties of the skin after treatments were evaluated using a color difference meter and texture analyzer. Antimicrobial activity of NaOCl increased as the NaOCl concentration was increased, especially for loosely attached cells. The combination of 200 mg/kg NaOCl and ultrasound (NaOCl/ultrasound) significant reduced loosely, intermediately, and tightly attached bacteria populations by 0.75 to 0.47, 0.43 to 0.41, and 0.83 to 0.54 log cfu/g for MAB, coliforms, and Salmonella Typhimurium, respectively. However, the combination of NaOCl and TDS (NaOCl/TDS) did not sufficiently reduce those cells on chicken skins, except for loosely attached MAB and coliforms. The NaOCl/ultrasound combination produced a higher reduction in numbers of inoculated and native bacteria flora than any single application, with no negative effect on skin color or texture. Generally, the loosely attached bacteria were less resistant to the chemical and physical treatments than the intermediately and tightly attached bacteria in chicken skin, presumably due to their location in deeper skin layer and crevices. Further research is needed to investigate how the intermediately and tightly attached microorganisms can be effectively eliminated from chicken skin.

Ultrastructure changes induced by dry film formation of a trisodium phosphate blend, antimicrobial solution

Trisodium phosphate (TSP) has been reported to have antimicrobial activity and is approved by the U.S. Department of Agriculture for use in food processing applications. A novel (U.S. Patent 6,184,198), antimicrobial solution containing a blend of TSP, sodium bicarbonate, and sodium carbonate (TSP blend) has demonstrated effective inhibition of microbial contamination in a broad spectrum of applications. This high-resolution cold field emission scanning electron microcopy (LVSEM) investigation details structural changes and dry film formation in various classes of microbes as a mechanism for antimicrobial activity of this solution. The results showed that this TSP blend solution completely inhibited the growth of pathogenic E. coli O157:H7, and Salmonella bacteria, the mold Cryptococcus, as well as a Norwalk virus surrogate-feline calicivirus. Results by LVSEM confirmed that the antimicrobial effect was induced when encapsulating the target microbes in a high lubricity film that is formed around these organisms as the solution dries. The thickness of the film was estimated to be approximately 60 nm.

Influence of catfish skin mucus on trisodium phosphate inactivation of attached Salmonella Typhimurium, Edwardsiella tarda, and Listeria monocytogenes

This study examined the antimicrobial effectiveness of trisodium phosphate (TSP) on Edwardsiella tarda, Listeria monocytogenes, and Salmonella Typhimurium attached to catfish skin with and without mucus. Salmonella Typhimurium and E. tarda attached more readily to catfish skin than did L monocytogenes. At high inoculum levels (10(7) CFU/ml), TSP treatments (at 2 to 6%) for 10 min reduced bacterial counts of E. tarda by >2.5 to >3.3 log10 CFU per skin sample for firmly attached cells and by 3.5 to 3.6 log10 CFU per skin sample for loosely attached cells. Counts of L. monocytogenes declined by 0.6 to >1.8 log10 CFU per skin sample for firmly attached cells and by 1.2 to 2.2 log10 CFU per skin sample for loosely attached cells. Counts of Salmonella Typhimurium were reduced by 3.6 to >3.8 log10 CFU per skin sample for firmly attached cells and by 3.5 to >3.8 log10 CFU per skin sample for loosely attached cells. Overall, counts of firmly attached bacteria on TSP-treated skins with mucus were higher than counts on skin without mucus. Firmly attached L. monocytogenes was more resistant to TSP than was firmly attached Salmonella Typhimurium or E. tarda. The presence of mucus on skins slightly decreased the antimicrobial effect of TSP Significant (P < 0.05) reduction in the numbers of all three bacteria can be achieved by treatment with 6% TSP for 10 min.

Survival and death of Salmonella typhimurium and Campylobacter jejuni in processing water and on chicken skin during poultry scalding and chilling

Salmonella Typhimurium and Campylobacter jejuni were inoculated in scalding water, in chilled water, and on chicken skins to examine the effects of scalding temperature (50, 55, and 60 degrees C) and the chlorine level in chilled water (0, 10, 30, and 50 ppm), associated with the ages of scalding water (0 and 10 h) and chilled water (0 and 8 h), on bacterial survival or death. After scalding at 50 and 60 degrees C, the reductions of C. jejuni were 1.5 and 6.2 log CFU/ml in water and <1 and >2 log CFU/cm2 on chicken skins; the reductions of Salmonella Typhimurium were <0.5 and >5.5 log CFU/ml in water and <0.5 and >2 log CFU/cm2 on skins, respectively. The age of scalding water did not significantly (P > 0.05) affect bacterial heat sensitivity. However, the increase in the age of chilled water significantly (P < 0.05) reduced the chlorine effect. In 0-h chilled water. C. jejuni and Salmonella Typhimurium were reduced by 3.3 and 0.7 log CFU/ml, respectively, after treatment with 10 ppm of chlorine and became nondetectable with 30 and 50 ppm of chlorine. In 8-h chilled water, the reduction of C. jejuni and Salmonella Typhimurium was <0.5 log CFU/ml with 10 ppm of chlorine and ranged from 4 to 5.5 log CFU/ml with 50 ppm of chlorine. Chlorination of chilled water did not effectively reduce the bacteria attached on chicken skins. The D-values of Salmonella Typhimurium and C. jejuni were calculated for the prediction of their survival or death in the poultry scalding and chilling.

Inhibition and reversal of Salmonella typhimurium attachment to poultry skin using zinc chloride

A skin attachment model was used to determine if ZnCl2 would reverse or inhibit Salmonella attachment to broiler skin. In the reversal experiments, skin samples, treated first with 1 ml of Salmonella Typhimurium suspension (10(8) CFU/ml) for 30 min, were then treated with 25 or 50 mM ZnCl2 for 5 or 15 min. Zinc chloride solutions were applied while the culture was present on the skin. In the inhibition experiments, ZnCl2 solutions were added first; treatment solutions were discarded after 5 or 15 min of application, and then the culture was added. Firmly and loosely attached Salmonella were enumerated on xylose lactose tergitol plates. A duplicate section of skin, subjected concurrently to the above treatments, was observed under a scanning electron microscope to enumerate attached bacteria directly. In the reversal experiments, 25 and 50 mM ZnCl2 reduced (P < 0.01) firmly attached cells by 77 and 89%, respectively, when compared to the control (water). Micrographs indicated that 25 and 50 mM ZnCl2 reduced (P < 0.1) Salmonella attachment by 69 and 99.9%, respectively, in the reversal experiments. In the inhibition experiments, 25 and 50 mM ZnCl2 reduced (P < 0.01) firmly attached cells by 82 and 91%, respectively. Reduction of Salmonella may be attributed, in part, to the bactericidal activity of ZnCl2 in addition to bacterial cell detachment.