Microbiology: Education, R&D and Market

Statement of the Problem: Salmonella infection or salmonellosis is a global public health problem and is one of the major causes of bacterial food-borne illnesses in the United States, causing an estimated 1.2 million illnesses, 23,000 hospitalizations, and 450 deaths per year. Food of animal origin, especially poultry and poultry products, are one of the major vehicles of salmonellosis. Methodology: Salmonella was recovered from chicken carcasses, confirmed and characterized using phenotypic and genotypic methods. Findings: This bacterium is widely distributed on chicken carcasses and its incidence differs among parts, with rib back and sacral back being the most contaminated. The most common serotypes isolated from chicken during our study were Salmonella typhimurium and S. Kentucky. Studies have demonstrated that processing conditions, such as the chilling process, can be a significant source of Salmonella contamination between carcasses. Recent reports on the recovery of multidrug-resistant (MDR) and genetically diverse S. typhimurium and S. Kentucky from commercially processed chicken carcasses raised serious concern about overall management practices. Studies have also revealed that chilling in chill tanks may play a significant role in promoting the selection of antimicrobial resistant pathogens during poultry processing. Whole genome sequencing of the MDR S. typhimurium and S. Kentucky strains confirmed that they shared serovar-specific conserved coding sequences, although several genomic regions with significant mismatch were detected. Phenotype microarray and intracellular killing assay results suggest that S. typhimurium is capable of utilizing certain carbon compounds at a higher rate, and can survive better and be more invasive than S. Kentucky in macrophages and chicken granulosa cells.

Conclusions and significance: To prevent Salmonella infection, it is important to assure that poultry and poultry products are not contaminated with this bacterium. Therefore, active monitoring systems and control strategies must be established from farm to fork.