Salmonella spp. are one of the most important agents of foodborne disease in several countries, including Brazil. Poultry-derived products are the most common food products, including meat and eggs, involved in outbreaks of human salmonellosis. Salmonella has the capacity to form biofilms on both biotic and abiotic surfaces. The biofilm formation process depends on an interaction among bacterial cells, the attachment surface and environmental conditions. These structures favor bacterial survival in hostile environments, such as slaughterhouses and food processing plants. Biofilms are also a major problem for public health because breakage of these structures can cause the release of pathogenic microorganisms and, consequently, product contamination. The aim of this study was to determine the biofilm production capacity of Salmonella serotypes at four different temperatures of incubation. Salmonella strains belonging to 11 different serotypes, isolated from poultry or from food involved in salmonellosis outbreaks, were selected for this study. Biofilm formation was investigated under different temperature conditions (37°, 28°, 12° and 3°C) using a microtiter plate assay. The tested temperatures are important for the Salmonella life cycle and to the poultry-products process. A total of 92.2% of the analyzed strains were able to produce biofilm on at least one of the tested temperatures. In the testing, 71.6% of the strains produced biofilm at 37°C, 63% at 28°C, 52.3% at 12°C and 39.5% at 3°C, regardless of the serotype. The results indicate that there is a strong influence of temperature on biofilm production, especially for some serotypes, such as S. Enteritidis, S. Hadar and S. Heidelberg. The production of these structures is partially associated with serotype. There were also significant differences within strains of the same serotype, indicating that biofilm production capacity may be strain-dependent.
Salmonella spp. remain among the most important agents of foodborne diseases worldwide. The importance of Salmonella spp. in public health is linked to their wide range of antimicrobial resistance and to their pathogenicity and virulence in both human and animal hosts. The aim of this study was to determine the antimicrobial resistance patterns for Salmonella serotypes isolated from poultry sources in Brazil and to detect virulence-associated genes and verify their association with specific serotypes. A total of 163 strains of Salmonella enterica isolated from poultry sources in Southern Brazil were selected, and each belonged to one of 11 different serotypes. They were tested against ten antibiotics and examined for the presence of 26 virulence-associated genes by PCR. S. Typhimurium, S. Bredeney, S. Schwarzengrund and S. Tennessee showed the highest overall resistance rates. Approximately 18% of Salmonella strains were classified as multidrug-resistant strains. Our results indicate associations between antimicrobial resistance and specific serotypes. Most of the investigated genes presented a high frequency and a regular distribution, regardless of the serotype. Eight genes are positively or negatively associated with at least one serotype. The observed associations between antimicrobial resistance and specific serotypes are useful in developing specific control and treatment measures for each serotype. Despite the virulence genes being evenly distributed among the serotypes, some of these genes are associated with specific serotypes, and sefA, sopEand lpfA were selected as possible markers of Salmonella serotypes.
Salmonella spp. are among the most important agents of foodborne diseases all over the world. Human Salmonella outbreaks are often associated with the consumption of poultry products (meat and eggs), and one of the most prevalent serotypes associated with these products is Salmonella Enteritidis. Brazil is one of the most important poultry exporters in the world. In southern Brazil, three closely related clones of Salmonella Enteritidis have been responsible for the majority of foodborne Salmonella outbreaks over the past decade. However, until now, there has been little information regarding the clonal relationship among the Brazilian Salmonella strains of avian origin and those involved in foodborne outbreaks. Therefore, the aim of the present study was to complete the molecular characterization of Salmonella Enteritidis strains isolated from poultry and food sources involved in Salmonella outbreaks. PCR ribotyping was performed to discriminate the strains into different ribotype profiles according to the banding pattern amplification. This technique was able to differentiate the Salmonella Enteritidis strains into two banding patterns: R2 and R4. R2 accounted for 98.7% of the strains. DNA sequencing of the 600-bp fragment, present in all ribotypes, was applied to confirm this result. The sequences generated showed high levels of similarity, ranging from 99.7 to 100%, and were grouped into a single cluster. These results suggest that there is a clonal relationship among the Salmonella Enteritidis strains responsible for several salmonellosis outbreaks and the strains collected from poultry sources.
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