Molecular Detection and Characterization of Salmonella Gallinarum From Poultry Farms in Brazil

Abstract

SUMMARY: Salmonella is a bacterium usually associated with mild gastroenteritis in chickens, but strains of the serotype Gallinarum can result in 2 severe systemic chicken diseases: fowl typhoid (by biovar Gallinarum) and pullorum disease (by biovar Pullorum). These diseases can be controlled by immunization with a specific vaccine (SG 9R). The aim of this study was to characterize recent Salmonella Gallinarum isolates by molecular analyses, as well as detect field and vaccine strains in clinical and environmental samples from poultry flocks. Field isolates of S. Gallinarum (n = 18) and other serotypes (n = 117) were obtained from Brazilian poultry farms between 2012 and 2015. In addition, clinical and environmental samples of poultry flocks (vaccinated or not) with fowl typhoid were obtained in a 3-year period (2013 to 2015). The results demonstrated that specific PCR targeted on speC and glgC genes and PCR-restriction fragment length polymorphisms based on fliC and sefA genes detected all the 18 isolates, 10 identified as field isolates of biovar Gallinarum and 8 as biovar Pullorum. All isolates of other serotypes presented negative results. In addition, PCR tests were performed directly from the pre-enrichment broth of the bacteriological procedures. Vaccine SG 9R and field S. Gallinarum strains were detected in samples with (n = 19) and without (n = 59) vaccination. These results demonstrate the use of PCR tests for detection of S. Gallinarum in clinical and environmental Brazilian poultry samples.

Keywords

• Salmonella
• fowl typhoid
• pullorum disease
• SG 9R