This cross-sectional study determined the prevalence, characteristics, and risk factors for contamination of chicken with Salmonella at four operating broiler processing plants in Trinidad. Standard methods were used to isolate and characterize the Salmonella isolates. The overall prevalence of Salmonella at the four processing plants was 27.0% (107/396). The whole carcass enrichment (WCE) method yielded a statistically significantly (p = 0.0014) higher frequency of isolation (53.9%; 97/180) than the whole carcass rinse (35.0%; 63/180) and neck skin methods (42.2%; 38/90). S. enterica serotypes Enteritidis, Javiana, and Infantis were the predominant serotypes isolated accounting for 20.8%, 16.7% and 12.5%, respectively, of the serotyped isolates. Risk factors included the use of over 100 contract farmers (OR 4.4), pre-chiller (OR 2.3), addition of chlorine to chiller (OR 3.2), slaughtering sick broilers (OR 4.4), and flocks with >50% mortality. Multi-drug resistance was detected in 12.3% (14/114) of the isolates of Salmonella. Resistance was high to kanamycin (85.7%) and doxycycline (74.6%) but low to amoxicillin-clavulanic acid (2.4%) and sulphamethoxazole-trimethoprim (0.8%). The occurrence of resistant Salmonella in chickens processed at commercial broiler processing plants has implications for salmonellosis and therapeutic failure in consumers of improperly cooked contaminated chickens from these plants in the country.

Current diagnostic methods for detecting foodborne pathogens are time-consuming, require sophisticated equipment, and have a low specificity and sensitivity. Magnetic nanoparticles (MNPs) and plasmonic/colorimetric biosensors like gold nanoparticles (GNPs) are cost-effective, high-throughput, precise, and rapid. This study aimed to validate the use of MNPs and GNPs for the early detection of Escherichia coli O157:H7, Salmonella enterica spp., Campylobacter jejuni, and Listeria monocytogenes in bovine fecal samples. The capture efficiency (CE) of the MNPs was determined by using Salmonella Typhimurium (ATCC_13311) adjusted at an original concentration of 1.5 × 10⁸ CFU/mL. One (1) mL of this bacterial suspension was spiked into bovine fecal suspension (1 g of fecal sample in 9 mL PBS) and serially diluted ten-fold. DNA was extracted from Salmonella Typhimurium to determine the analytical specificity and sensitivity/LOD of the GNPs. The results showed that the CE of the MNPs ranged from 99% to 100% and could capture as little as 1 CFU/mL. The LOD of the GNPs biosensor was 2.9 µg/µL. The GNPs biosensor was also tested on DNA from 38 naturally obtained bovine fecal samples. Out of the 38 fecal samples tested, 81.6% (31/38) were positive for Salmonella enterica spp., 65.8% (25/38) for C. jejuni, 55.3% (21/38) for L. monocytogenes, and 50% (19/38) for E. coli O157:H7. We have demonstrated that MNP and GNP biosensors can detect pathogens or their DNA at low concentrations. Ensuring food safety throughout the supply chain is paramount, given that these pathogens may be present in cattle feces and contaminate beef during slaughter.

Salmonellosis in humans is a public health threat and cattle are important reservoirs for the pathogen. Cattle products such as ground beef have been linked to human salmonellosis outbreaks, and some disease investigations have been traced back to infected animal herds on farms and animal markets as the origin of infection. It is now common to isolate Salmonella from many cattle operations as the pathogen once introduced onto a farm can establish an undesirable endemic condition among herds. It is, therefore, essential to adopt measures to mitigate or prevent the introduction and spread of zoonotic disease agents like Salmonella in animal populations. With this background, the potential sources and risks of Salmonella infection in cattle, the control of already established infection, and other preventative measures are discussed in this article. We conclude that a holistic approach involving all stakeholders in cattle production is needed to safeguard public health, eventually forestalling human salmonellosis from cattle sources. In achieving this, it will be essential to consider the farm as a critical control point in preventing the introduction of Salmonella into the food chain.

This cross-sectional study determined the serovars, antimicrobial resistance genes, and virulence factors of Salmonella isolated from hatcheries, broiler farms, processing plants, and retail outlets in Trinidad and Tobago. Salmonella in silico serotyping detected 23 different serovars where Kentucky 20.5% (30/146), Javiana 19.2% (28/146), Infantis 13.7% (20/146), and Albany 8.9% (13/146) were the predominant serovars. There was a 76.0% (111/146) agreement between serotyping results using traditional conventional methods and whole-genome sequencing (WGS) in in silico analysis. In silico identification of antimicrobial resistance genes conferring resistance to aminoglycosides, cephalosporins, peptides, sulfonamides, and antiseptics were detected. Multidrug resistance (MDR) was detected in 6.8% (10/146) of the isolates of which 100% originated from broiler farms. Overall, virulence factors associated with secretion systems and fimbrial adherence determinants accounted for 69.3% (3091/4463), and 29.2% (1302/4463) counts, respectively. Ten of 20 isolates of serovar Infantis (50.0%) showed MDR and contained the bla_CTX-M-65 gene. This is the first molecular characterization of Salmonella isolates detected along the entire broiler production continuum in the Caribbean region using WGS. The availability of these genomes will help future source tracking during epidemiological investigations associated with Salmonella foodborne outbreaks in the region and worldwide.

Salmonella typically produces hydrogen sulfide (H₂S) gas, which appears as a black precipitate on most selective culture media and serves as a key diagnostic feature in many laboratories. However, the emergence of H₂S-negative Salmonella serovars raises concerns about their potential to evade conventional isolation protocols. This review explores the phenotypic variability in H₂S production among Salmonella and summarizes recent global reports of H₂S-negative serovars. Additionally, it discusses the limitations of current H₂S-dependent isolation methods and proposes improved strategies for effectively detecting these atypical strains. We identified several factors, including media composition and incubation duration, that can influence H₂S production in Salmonella. By analyzing various methods employed in recent years to isolate H₂S-negative strains, we advocate for the early integration of non-H₂S-dependent detection techniques to guide isolation workflows and prevent the unintentional exclusion of viable H₂S-negative serovars. Specifically, we recommend parallel plating of suspect Salmonella cultures on both H₂S-indicating media and non-H₂S-based media, such as chromogenic agars, followed by the confirmation of both black and nonblack colonies. In conclusion, this review underscores the continued occurrence of H₂S-negative Salmonella serovars and offers practical recommendations to enhance their detection, thereby supporting more comprehensive and accurate pathogen identification.

The objective of this study was to evaluate the effect of varying levels of hempseed meal supplementation on antibody and cell-mediated immune responses, as well as the expression of some of the important immunoregulatory cytokines. Treatments consisted of hempseed meal supplementation at 0 (control), 10, 20, and 30% of the total diet. Goats were randomly assigned to one of the four treatments n = 10. Cell-mediated immune response was evaluated on day 59 of the feeding period by measuring skinfold thickness at 24 h following intradermal injection of phytohemagglutinin. A significant increase in skinfold thickness was observed with increasing levels of supplementation as compared to that of the control group. Serum antibody titers to chicken ovalbumin were not significantly different between treatment groups. Cytokine concentrations of IL-6 increased linearly with increasing level of supplementation (p < 0.05), contrarily to the linear decrease that was observed for TNF-α (p < 0.05). Although IL-2 tended to increase with the 10 and 30% levels of supplementation (p < 0.07), the result was not significant, and no significant differences were obtained with respect to IL-4 concentrations. Cytokine gene expression values measured by RT-PCR, however, demonstrated some significant differences. HSM supplementation had no significant effect on the expression of IL-2 or IL-6. However, significant differences were observed with the 30% supplementation for IL-4 and TNF-α as compared to that of the control group (p < 0.05). IL-4 was down regulated for the 10 and 20% treatment groups but was upregulated for the 30% treatment group. TNF-α was downregulated in the 10% but upregulated for the 20 and 30% treatment groups. No significant differences were observed for the serum cortisol concentration or white blood cell counts. These results suggested that hempseed meal supplementation may improve cell-mediated immune response while having no effect on antibody-mediated immune response. However, more research needs to be conducted to determine the most efficacious inclusion rate.