Title: Application of PCR-based serogrouping of Salmonellaenterica serotypes isolated from the poultry in Egypt

Salmonella spp. remains a significant concern in poultry flocks due to its potential impact on both animal health and public health. In this study, a comprehensive approach to isolate, serotype, and identify Salmonella strains from poultry flocks was employed. A total of 350 samples were collected, including internal organs liver, lung and cecum, from poultry flocks. Salmonella isolates were isolated and characterized according to established protocols. Conventional serotyping was performed based on the Kauffman–White scheme using Salmonella antisera, and the results were classified into various serogroups. To enhance the efficiency of serotyping, a multiplex PCR assay targeting both O and H antigens was developed. DNA extraction from collected samples followed the boiling method the multiplex PCR assay used specific primers for various serogroups. Out of the 350 samples tested, approximately 14.2% were positive for Salmonella. A total of 50 Salmonella isolates were serotyped, and the strains were categorized into several serogroups including B, D1, E1, C1, and C3. The multiplex PCR assay successfully identified O and H antigens, revealing a prevalence of serogroup B (46%) and D1 (32%) strains. Interestingly, none of the Salmonella strains exhibited the Vi antigen. This investigation showcased the precision and effectiveness of the multiplex PCR technique in identifying Salmonella strains. Notably, the multiplex PCR yielded outcomes surpassing those of traditional serotyping using the Kaufmann White scheme, all within a notably reduced time frame. In conclusion, the study highlights and presents a rapid and reliable method for serotyping and identifying Salmonella strains using multiplex PCR. This approach has the potential to expedite the control and prevention of Salmonella transmission, contributing to improved poultry health and reduced public health risks associated with Salmonella infections. The rapidity and accuracy of the multiplex PCR method make it particularly suitable for international efforts to monitor and manage Salmonella outbreaks effectively