Molecular characterization of virulence genes in broiler chicken originated Salmonella Enteritidis and Salmonella Typhimurium

Abstract

Salmonella Enteritidis and Salmonella Typhimurium are the most common serovars observed in human salmonellosis while contaminated poultry products are the major source of Salmonella transmission to humans. Therefore, high pathogenicity of poultry originated S. Enteritidis and S. Typhimurium strains poses a serious risk to human health. In this study, we investigated the virulence genes of S. Enteritidis and S. Typhimurium strains isolated from litter and environmental samples of broiler chicken flocks. SipA, sipD, sopB, sopD, sopE, sopE2, sitC, sifA, ssaR, spvC, and pefA genes were investigated in a total of 137 strains consisting of 105 S. Enteritidis and 32 S. Typhimurium. Nine strains (6.6%) had all genes. No negative strain was detected for all genes. SopE was found in all strains (100.0%). SitC (89.1%), ssaR (83.9%), sipA (70.1%), sipD (73.0%), sopE2 (68.6%), spvC (68.6%), and pefA (73.0%) were also highly prevalent. Noticeable differences were observed between serovars in terms of sopE2, spvC and pefA prevalence: 77.1%, 80% and 82.9%, respectively, of S. Enteritidis strains were sopE2, spvC and pefA positive while 40.6%, 31.3% and 40.6% of S. Typhimurium strains were positive. This finding indicates that S. Enteritidis is more frequent than S. Typhimurium in poultry populations due to its higher virulence. Based on virulence gene distribution, the strains were divided into 44 different virulence genotypes, with the major genotype 4 (15.3%) carrying 8 of the 11 genes. The majority of strains (75.9%) were positive for at least 6 genes. S. Enteritidis and S. Typhimurium strains were highly virulent and pose a threat as zoonotic infection agents.

Keywords

• Broiler
• Foodborne
• S. Enteritidis
• S. Typhimurium
• Virulence genes

References

1. Almeida F, Pitondo-Silva A, Oliveira MA, et al (2013): Molecular epidemiology and virulence markers of Salmonella Infantis isolated over 25 years in Sao Paulo State, Brazil. Infect Genet Evol, 19, 145-151.
2. Chiu CH, Su LH, Chu CH, et al (2006): Detection of multidrug-resistant Salmonella enterica serovar typhimurium phage types DT102, DT104, and U302 by multiplex PCR. J Clin Microbiol, 44, 2354-2358.
3. EFSA (2021): The European Union One Health 2019 Zoonoses Report. EFSA J, 19, e06406.
4. Farahani RK, Ehsani P, Ebrahimi-Rad M, et al (2018): Molecular detection, virulence genes, biofilm formation, and antibiotic resistance of Salmonella enterica serotype Enteritidis isolated from poultry and clinical samples. Jundishapur J Microbiol, 11, 1-9.
5. Grimont PAD, Weill FX (2007): Antigenic Formulae of The Salmonella Serovars. 9th ed. Institut Pasteur, Paris.
6. Hashemi A, Baghbani-Arani F, Ahmadiyan S, et al (2017): Multiple-locus variable-number tandem-repeat analysis in Salmonella isolates as an effective molecular subtyping method. Microb Pathog, 113, 11-16.
7. Hu Q, Coburn B, Deng W, et al (2008): Salmonella enterica serovar Senftenberg human clinical isolates lacking SPI-1. J Clin Microbiol, 46, 1330-1336.
8. Karacan Sever N, Akan M (2019): Molecular analysis of virulence genes of Salmonella Infantis isolated from chickens and turkeys. Microb Pathog, 126, 199-204.

9. Krawiec M, Kuczkowski M, Kruszewicz AG, et al (2015): Prevalence and genetic characteristics of Salmonella in free-living birds in Poland. BMC Vet Res, 11, 15.
10. Mezal EH, Sabol A, Khan MA, et al (2014): Isolation and molecular characterization of Salmonella enterica serovar Enteritidis from poultry house and clinical samples during 2010. Food Microbiol, 38, 67-74.
11. Raffatellu M, Wilson RP, Chessa D, et al (2005): SipA, SopA, SopB, SopD, and SopE2 contribute to Salmonella enterica serotype typhimurium invasion of epithelial cells. Infect Immun, 73, 146-154.
12. Shah DH, Zhou X, Addwebi T, et al (2011): Cell invasion of poultry-associated Salmonella enterica serovar Enteritidis isolates is associated with pathogenicity, motility and proteins secreted by the type III secretion system. Microbiology, 157, 1428-1445.
13. Siddiky NA, Sarker MS, Khan MSR, et al (2021): Virulence and antimicrobial resistance profiles of Salmonella enterica serovars isolated from chicken at wet markets in Dhaka, Bangladesh. Microorganisms, 9, 1-16.
14. Skyberg JA, Logue CM, Nolan LK (2006): Virulence genotyping of Salmonella spp. with multiplex PCR. Avian Dis, 50, 77-81.
15. Tasmin R, Gulig PA, Parveen S (2019): Detection of virulence plasmid-encoded genes in Salmonella Typhimurium and Salmonella Kentucky isolates recovered from commercially processed chicken carcasses. J Food Prot, 82, 1364-1368.
16. Utrarachkij F, Nakajima C, Siripanichgon K, et al (2016): Genetic diversity and antimicrobial resistance pattern of Salmonella enterica serovar Enteritidis clinical isolates in Thailand. J Infect Chemother, 22, 209-215.
17. Van Asten AJAM, Van Dijk JE (2005): Distribution of ‘‘classic’’ virulence factors among Salmonella spp. FEMS Immunol Med Microbiol, 44, 251–259.
18. Wang XC, Biswas S, Paudyal N, et al (2020): Antibiotic Resistance in Salmonella Typhimurium isolates recovered from the food chain through National Antimicrobial Resistance Monitoring System between 1996 and 2016. Front Microbiol, 11, 1-12.
19. Wei XY, You L, Wang D, et al (2019): Antimicrobial resistance and molecular genotyping of Salmonella enterica serovar Enteritidis clinical isolates from Guizhou province of Southwestern China. Plos One, 14, 1-14.
20. Yue MN, Li XY, Liu D, et al (2020): Serotypes, antibiotic resistance, and virulence genes of Salmonella in children with diarrhea. J Clin Lab Anal, 34, 1-8.
21. Zhang D, Zhuang L, Wang C, et al (2018): Virulence gene distribution of Salmonella Pullorum isolates recovered from chickens in China (1953-2015). Avian Dis, 62, 431-436.
22. Zou W, Al-Khaldi SF, Branham WS, et al (2011): Microarray analysis of virulence gene profiles in Salmonella serovars from food/food animal environment. J Infect Dev Ctries, 5, 94-105.