Evaluation of Culture Media for Detecting Airborne Salmonella Enteritidis Collected with an Electrostatic Sampling Device from the Environment of Experimentally Infected Laying Hens

Modeling and optimization of laying hen manure drying process to reduce protein and ammonium-N losses by adding sodium bentonite and wheat straw

Laying hen manure (LHM) is a major source of pollution due to its high nitrogen (N) and moisture content (MC). Therefore, reducing the MC of LHM is necessary to retain its recyclable value and reduce environmental pollution. One effective way is by incorporating sodium bentonite (SB) and wheat straw (WS) as amendments in the LHM. This work aimed to optimize the drying conditions of LHM and investigate the effect of SB and WS utilization on the dehydration rate, reduction of crude protein (CP), and reduction of ammonium-N (N [Formula: see text] -N). The response surface methodology (RSM) was used to optimize these processes. For this purpose, two sets of experiments (drying of LHM with and without SB and Ws) were designed. The independent parameters were air temperature (70, 80, and 90 °C), air velocity (1, 1.5, and 2 m s-1), layer thickness (5, 10, and 15 mm), SB (2%, 4%, and 6%), and WS (3%, 7.5%, and 12%). The results indicated that temperature and WS had the most significant influence on all responses. To maximize the dehydration rate and minimize the reduction of CP and N [Formula: see text] -N, the optimal conditions were a temperature of 78 °C, air velocity of 1 m s-1, and layer thickness of 5 mm in the first set of experiments, and a temperature of 80 °C, air velocity of 1.5 m s-1, layer thickness of 11 mm, 6% SB, and 12% WS in the second set of experiments. Under the optimum conditions, LHM treated with 6% SB and 12% WS retained 10% more CP and 58% more N [Formula: see text] -N than untreated LHM. Therefore, according to the obtained results, SB and WS are recommended as additives to reduce the CP and N [Formula: see text] -N losses of LHM during the drying process.

The Prevalence of Salmonella and Campylobacter on Broiler Meat at Different Stages of Commercial Poultry Processing

In poultry processing, Salmonella and Campylobacter contaminations are major food safety concerns. Peracetic acid (PAA) is an antimicrobial commonly used in commercial poultry processing to reduce pathogen prevalence so as to meet the USDA-FSIS performance standards. The objective of this study was to determine the prevalence of Salmonella and Campylobacter on broiler meat in various steps of commercial poultry processing in plants that use PAA. Post-pick, pre-chill, post-chill, and drumstick chicken samples were collected from three processing plants and mechanically deboned meat (MDM) was collected from two of the three plants. Each plant was sampled thrice, and 10 samples were collected from each processing step during each visit. Among the 420 samples, 79 were contaminated with Salmonella and 155 were contaminated with Campylobacter. Salmonella and Campylobacter contamination on the post-pick samples averaged 32.2%. Significant reductions in Salmonella and Campylobacter were observed in pre-chill to post-chill samples, where the prevalence was reduced from 34% and 64.4% to nondetectable limits and 1.1%, respectively (p < 0.001). Salmonella and Campylobacter remained undetectable on the drumstick samples in all three processing plants. However, the prevalence of Salmonella and Campylobacter on MDM was similar to the post-pick prevalence, which suggests substantial cross-contamination from post-chill to MDM.

Phenotypic and genotypic characterization of locally isolated Salmonella strains used in preparation of Salmonella antigens in Egypt

Aim:

This work was conducted to study the phenotypic and genotypic characterization of locally isolated Salmonella strains (Salmonella Pullorum, Salmonella Enteritidis, and Salmonella Typhimurium) from poultry used in the preparation of Salmonella antigens in Egypt.

Materials and Methods:

The phenotypic characterization of Salmonella strains was done using standard microbiological, biochemical, and serological techniques. Molecular identification was done using different sets of primers on different genes using different polymerase chain reaction (PCR) techniques.

Results:

The phenotypic characterization of Salmonella strains was confirmed. Molecular identification revealed detection of 284 bp fragment of InvA gene in all studied Salmonella strains. Furthermore, multiplex PCR was used for more confirmation of being Salmonella spp., generally at 429 bp as well as genotyping of Salmonella Typhimurium and Salmonella Enteritidis at 559 and 312 bp, respectively, in one reaction.

Conclusion:

The locally isolated field Salmonella strains were confirmed phenotypically and genotypically to be Salmonella Enteritidis, and Salmonella Typhimurium and could be used for the preparation of Salmonella antigens.

Application of Molecular Approaches for Understanding Foodborne Salmonella Establishment in Poultry Production

Salmonellosis in the United States is one of the most costly foodborne diseases. Given that Salmonella can originate from a wide variety of environments, reduction of this organism at all stages of poultry production is critical. Salmonella species can encounter various environmental stress conditions which can dramatically influence their survival and colonization. Current knowledge of Salmonella species metabolism and physiology in relation to colonization is traditionally based on studies conducted primarily with tissue culture and animal infection models. Consequently, while there is some information about environmental signals that control Salmonella growth and colonization, much still remains unknown. Genetic tools for comprehensive functional genomic analysis of Salmonella offer new opportunities for not only achieving a better understanding of Salmonella pathogens but also designing more effective intervention strategies. Now the function(s) of each single gene in the Salmonella genome can be directly assessed and previously unknown genetic factors that are required for Salmonella growth and survival in the poultry production cycle can be elucidated. In particular, delineating the host-pathogen relationships involving Salmonella is becoming very helpful for identifying optimal targeted gene mutagenesis strategies to generate improved vaccine strains. This represents an opportunity for development of novel vaccine approaches for limiting Salmonella establishment in early phases of poultry production. In this review, an overview of Salmonella issues in poultry, a general description of functional genomic technologies, and their specific application to poultry vaccine developments are discussed.

Human pathogens and tetracycline-resistant bacteria in bioaerosols of swine confinement buildings and in nasal flora of hog producers

Swine confinement buildings in eastern Canada are enclosed and equipped with modern production systems to manage waste. Bioaerosols of these swine confinement buildings could be contaminated by human pathogens and antimicrobial resistant bacteria which could colonize exposed workers. We therefore wanted to analyze bioaerosols of swine confinement buildings and nasal flora of Canadian hog producers to evaluate possible colonization with human pathogens and tetracycline-resistant bacteria. Culturable and non-culturable human pathogens and tet genes were investigated in the bioaerosols of 18 barns. The nasal passages of 35 hog producers were sampled and total DNA was extracted from the calcium-alginate swabs to detect, by PCR, Campylobacter, C. perfringens, Enterococcus, E. coli, Y. enterocolitica, tetA/tetC, tetG and ribosomal protection protein genes. Airborne culturable C. perfringens, Enterococcus, E. coli, and Y. enterocolitica were present in the bioaerosols of 16, 17, 11 and 6 of the 18 facilities. Aerosolized total (culturable/non culturable) Campylobacter, C. perfringens, Enterococcus, E. coli and Y. enterocolitica were detected in 10, 6, 15, 18 and 2 barns, respectively. Tet genes were found in isolates of culturable human pathogens. TetA/tetC, tetG and ribosomal protection protein genes were detected in the bioaerosols of all 18 studied buildings. Campylobacter, C. perfringens, Enterococcus, E. coli, and Y. enterocolitica were found respectively in 4, 9, 17, 14 and one nasal flora of workers. One and 10 workers were positive for tetA/tetC and tetG genes, respectively. In swine confinement buildings, hog producers are exposed to aerosolized human pathogens and tetracycline-resistant bacteria that can contaminate the nasal flora.

Quantitative analysis of Salmonella Enteritidis loads in ducklings after nasal inoculation

The distribution patterns of Salmonella Enteritidis in systemic organs, which have not been described previously, should be studied to better understand its pathogenesis in vivo. We inoculated the ducklings with Salmonella Enteritidis via the nasal route and performed a real-time PCR assay for determining the concentration of Salmonella Enteritidis DNA and studied the histopathology of various tissues postinoculation. The results show that the Salmonella Enteritidis load in systemic organs has a close correlation with the progression of disease. Further, rapid dissemination and active replication of Salmonella Enteritidis in multiple systemic organs accelerated the progression of disease.

Semiquantitative assessment of the distribution of Salmonella in the environment of caged layer flocks

AIMS

To evaluate a semiquantitative technique for the enumeration of Salmonella in the environment of layer flocks and to compare findings with those of a standard qualitative technique.

METHODS AND RESULTS

Samples were taken from faeces, floor dust, dust on cages, feeders and egg belts. After mixing with buffered peptone water, serial dilutions were prepared and culture was performed using pre-enrichment, then plating on semisolid selective and solid isolation media. Comparison with a qualitative pre-enrichment technique indicated a similar sensitivity for both methods despite smaller sample sizes. The numbers of Salmonella detected for a site or sample type did not correlate closely with the prevalence of positive samples.

CONCLUSIONS

The sensitive detection and quantification of Salmonella in the flock environment is practicable with the technique described. Quantitative data in many cases do not correlate with qualitative findings.

SIGNIFICANCE AND IMPACT OF THE STUDY

The significance of certain environmental factors and interventions in the maintenance and dissemination of Salmonella in poultry houses may be over- or under-represented by prevalence data alone. The technique described allows the issue of poultry house contamination to be examined from a new perspective.

Experimental airborne transmission of Salmonella Agona and Salmonella Typhimurium in weaned pigs

This study tested the hypothesis of airborne transmission of Salmonella Agona (Trial I) and Salmonella Typhimurium (Trial II) in weaned pigs. The trials were performed using stainless-steel/glass isolation cabinets connected by air ducts to permit an unidirectional airflow from cabinet 1 (two control pigs) to cabinet 3 (two sentinel pigs), passing through cabinet 2 (two inoculated pigs). Air samples, pooled faecal samples from the floor and rectal swabs were collected daily and assessed by culture and PCR. A fumigation chamber and rubber gloves coupled to the cabinets allowed sampling without opening the system. Trials I and II lasted 15 and 19 days respectively. The recovery of S. Agona and S. Typhimurium and detection of seroconversion in sentinel pigs indicate that airborne Salmonella transmission in weaned pigs over short distances is possible. Further studies on the role of aerosols in the epidemiology of Salmonella in intensive pig production should be performed.