Molecular Epidemiology of Salmonella enterica in Poultry in South Africa Using the Farm-to-Fork Approach

A Quick Review of the Prevalence of Important Infectious Poultry Diseases all Around the World

The poultry industry is one of the fastest growing industries in the world. Poultry breeding has developed significantly to meet the food needs of the increasing population and it is expected that this growth will continue in the coming years. Prevalent poultry diseases are of great importance as they are responsible for vast economic losses and public health concerns. They also affect the national and international trade of the poultry products. This review will provide a quick and general view of different important poultry diseases for poultry breeders, scientists and decision makers. Based on this review, Campylobacteriosis and infectious bursal disease (IBD) in the Asian continent, and Campylobacteriosis, Newcastle disease (ND) and coccidiosis in the African continent were the most prevalent diseases. In Europe, Campylobacter species and in America, Escherichia coli species are widespread in poultry meat. Infectious Bronchitis (IB) in Europe and Coccidiosis in America were high-incident.

An Alternative Approach Using Nano-garlic Emulsion and its Synergy with Antibiotics for Controlling Biofilm-Producing Multidrug-Resistant Salmonella in Chicken

Surface-growing antibiotic-resistant pathogenic Salmonella is emerging as a global health challenge due to its high economic loss in the poultry industry. Their pathogenesis, increasing antimicrobial resistance, and biofilm formation make them challenging to treat with traditional therapy. The identification of antimicrobial herbal ingredients may provide valuable solutions to solve this problem. Therefore, our aim is to evaluate the potency of nano garlic as the  alternative of choice against multidrug-resistant (MDR) Salmonella isolates using disc diffusion and microdilution assays. Then, checkerboard titration in trays was applied, and FIC was measured to identify the type of interaction between the two antimicrobials. A disc diffusion assay revealed that neomycin was the drug of choice. The range of nano garlic MIC was 12.5-25 μg/ml, while the neomycin MIC range was 32-64 μg/ml. The FIC index established a synergistic association between the two tested drugs in 85% of isolates. An experimental model was used including nano garlic and neomycin alone and in combination against Salmonella infection. The combination therapy significantly improved body productivity and inhibited biofilm formation by more than 50% down regulating the CsgBAD, motB, and sipA operons, which are responsible for curli fimbriae production and biofilm formation in Salmonella serotypes.

Prevention and Control of Human Salmonella enterica Infections: An Implication in Food Safety

Salmonella is a foodborne zoonotic pathogen causing diarrhoeal disease to humans after consuming contaminated water, animal, and plant products. The bacterium is the third leading cause of human death among diarrhoeal diseases worldwide. Therefore, human salmonellosis is of public health concern demanding integrated interventions against the causative agent, Salmonella enterica. The prevention of salmonellosis in humans is intricate due to several factors, including an immune-stable individual infected with S. enterica continuing to shed live bacteria without showing any clinical signs. Similarly, the asymptomatic Salmonella animals are the source of salmonellosis in humans after consuming contaminated food products. Furthermore, the contaminated products of plant and animal origin are a menace in food industries due to Salmonella biofilms, which enhance colonization, persistence, and survival of bacteria on equipment. The contaminated food products resulting from bacteria on equipment offset the economic competition of food industries and partner institutions in international business. The most worldwide prevalent broad-range Salmonella serovars affecting humans are Salmonella Typhimurium and Salmonella Enteritidis, and poultry products, among others, are the primary source of infection. The broader range of Salmonella serovars creates concern over multiple strategies for preventing and controlling Salmonella contamination in foods to enhance food safety for humans. Among the strategies for preventing and controlling Salmonella spread in animal and plant products include biosecurity measures, isolation and quarantine, epidemiological surveillance, farming systems, herbs and spices, and vaccination. Other measures are the application of phages, probiotics, prebiotics, and nanoparticles reduced and capped with antimicrobial agents. Therefore, Salmonella-free products, such as beef, pork, poultry meat, eggs, milk, and plant foods, such as vegetables and fruits, will prevent humans from Salmonella infection. This review explains Salmonella infection in humans caused by consuming contaminated foods and the interventions against Salmonella contamination in foods to enhance food safety and quality for humans.

Salmonella Yoruba: a rare serotype revealed through genomic sequencing along the farm-to-fork continuum of an intensive poultry farm in KwaZulu-Natal, South Africa

Salmonella enterica is a zoonotic pathogen of worldwide public health importance. We characterised Salmonella isolates from poultry along the farm-to-fork continuum using whole genome sequencing (WGS) and bioinformatics analysis. Three multilocus sequence types (MLSTs), i.e., ST15 (1.9%), ST152 (5.9%) and ST1316 (92.2%) and three serotypes, i.e., S. Heidelberg (1.9%), Kentucky (5.9%) and Yoruba (92.2%) were detected. The rare serotype, S. Yoruba, was detected among the farm and abattoir isolates and contained resistance and virulence determinants. Resistome analysis revealed the presence of the aac(6')-Iaa gene associated with aminoglycoside resistance, a single point mutation in the parC gene associated with fluoroquinolone and quinolone resistance, and a single isolate contained the fosA7 gene responsible for fosfomycin resistance. No antibiotic resistance genes (ARGs) were identified for isolates phenotypically non-susceptible to azithromycin, cephalosporins, chloramphenicol and nitrofurantoin and resistance was thought to be attributable to other resistance mechanisms. The fully susceptible profiles observed for the wastewater isolates suggest that the poultry environment may receive antibiotic-resistant strains and resistance determinants from poultry with the potential of becoming a pathway of Salmonella transmission along the continuum. Six plasmids were identified and were only carried by 92.2% of the S. Yoruba isolates in varying combinations. Four plasmids were common to all S. Yoruba isolates along the continuum; isolates from the litter and faeces on the farm contained two additional plasmids. Ten Salmonella pathogenicity islands (SPIs) and 177 virulence genes were identified; some were serotype-specific. Phylogenetic analysis of S. Heidelberg and Kentucky showed that isolates were related to animal and human isolates from other countries. Phylogenetic analysis among the S. Yoruba isolates revealed four clades based on the isolate sources along the farm-to-fork continuum. Although the transmission of Salmonella strains along the farm-to-fork continuum was not evident, pathogenic, resistant Salmonella present in the poultry production chain poses a food safety risk. WGS analysis can provide important information on the spread, resistance, pathogenicity, and epidemiology of isolates and new, rare or emerging Salmonella strains to develop intervention strategies to improve food safety.

Multi-Drug Resistance to Salmonella spp. When Isolated from Raw Meat Products

Salmonella spp. is the most frequent cause of foodborne diseases, and the increasing occurrence of MDR strains is an additional and increasing problem. We collected Salmonella spp. strains isolated from meat (poultry and pork) and analysed their antibiotic susceptibility profiles and the occurrence of resistance genes. To determine the susceptibility profiles and identify MDR strains, we used two MIC methods (MICRONAUT and VITEC2 Compact) and 25 antibiotics. Phenotypic tests showed that 53.84% strains were MDR. Finally, molecular analysis strains revealed the presence of blaSHV, blaPSE-1, blaTEM, but not blaCTX-M genes. Moreover, several genes were associated with resistance to aminoglycosides, cephalosporins, fluorochinolones, sulfonamides, and tetracyclines. This suggests that further research on the prevalence of antibiotic resistance genes (ARGs) in foodborne strains is needed, especially from a One Health perspective.

In Vitro Evaluation of Antimicrobial Effect of Phytobiotics Mixture on Salmonella spp. Isolated from Chicken Broiler

Background: The identification of natural antibacterial agents from various sources that can act effectively against disease-causing foodborne bacteria is one of the major concerns throughout the world. In the present study, a unique phytobiotics mixture containing thymol, menthol, linalool, trans-anethole, methyl salicylate, 1,8-cineole, and p-cymene was evaluated for antibacterial activity against selected strains of Salmonella spp. Results: The phytobiotics mixture was effective against Salmonella enterica subsp. enterica serovars Enteritidis, Typhimurium, and Kentucky. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of this unique mixture for these three pathogens were 1:256. Among these three strains, one S. Kentucky presented the most extensive resistance profiles to 18 antibiotics belonging to 5 classes of antibiotics. One of S. Typhimurium presents extensive resistance profiles to 14 antibiotics belonging to 5 classes of antibiotics. Conclusions: The results suggest that the phytobiotics mixture used in the experiment can be used as a strong natural antibacterial agent against Gram-negative foodborne pathogens such as S. Typhimurium, S. Kentucky, and S. Enteritidis. This is a preliminary analysis of the effectiveness of a phytobiotic product in an in vitro model, which may be the starting point for further studies, including in vivo animal models.

Wild Duck (Anas platyrhynchos) as a Source of Antibiotic-Resistant Salmonella enterica subsp. diarizonae O58—The First Report in Poland

The “One Health” approach increasingly demonstrates the global spread of pathogenic microorganisms and their antimicrobial resistance in the environment, both in animals and humans. Salmonella enterica subsp. diarizonae is nowadays very often isolated from cold-blooded reptiles to a lesser extent from sheep, but unfortunately more and more often from humans. However, there are a few studies describing the isolation of Salmonella enterica subsp. diarizonae from migratory wild birds. The mallard duck (Anas platyrhynchos), a wild animal that traverses the continent of Eurasia, can be an excellent indicator of the spread of intestinal microbes as well as their resistance to antibiotics. This is the first report of the Salmonella enterica subsp. diarizonae detection in Poland in a migrating mallard duck. This research presented the identification difficulties associated with the isolation of Salmonella enterica subsp. diarizonae using three different biochemical tests and advanced serology tests. At the same time, we detected very high antimicrobial resistance in the isolated strain. By using the minimum inhibitory concentration (MIC) method, it was found that the isolated strain of S. enterica subsp. diarizonae has high antibiotic resistance against 14 of the 33 tested antimicrobials agents. The resistance genes that have been identified in S. enterica subsp. diarizonae include aadA, strA/strB, and bla_TEM.

Development of a Duplex TaqMan Real-Time Polymerase Chain Reaction for Accurate Identification and Quantification of Salmonella Enteritidis from Laboratory Samples and Contaminated Chicken Eggs

Salmonella enteritidis is a major causative agent of foodborne illnesses worldwide. As the traditional serotyping and quantification methods are labor-intensive, time-consuming, and expensive, faster and more convenient molecular diagnostic methods are needed. In this study, we developed and validated a rapid duplex TaqMan real-time polymerase chain reaction (PCR) for the accurate identification and quantification of S. enteritidis. The primers and TaqMan probes were designed based on the S. enteritidis-specific gene lygD and the Salmonella genus-specific gene invA. The melt curve and gel electrophoresis analysis showed that the designed primers had potent specificity for the amplification of lygD and invA. The duplex real-time PCR specifically identified S. enteritidis from a panel of 40 Salmonella strains that represented 29 serovars and 12 non-Salmonella organisms. The duplex real-time PCR assay detected four copies of S. enteritidis DNA per reaction. The intra- and inter- assays indicated a high degree of reproducibility. The real-time PCR could accurately detect and quantify S. enteritidis in chicken organs after Salmonella infection. Furthermore, the assay identified 100% of the S. enteritidis and Salmonella genus isolates from chicken egg samples with superior sensitivity after 6 h of pre-enrichment compared to the traditional culture method. Additionally, the most-probable-number (MPN) combined with qPCR and a shortened incubation time (MPN-qPCR-SIT) method was developed for the population determination of S. enteritidis and compared with various enumeration methods. Thus, we have established and validated a new duplex real-time PCR assay and MPN-qPCR-SIT method for the accurate detection and quantification of S. enteritidis, which could contribute to meeting the need for fast detection and identification in prevention and control measures for food safety.