Biofilm Dynamics in Salmonella enterica Pathogenesis

Salmonella enterica employs biofilm formation as a central strategy for survival, persistence and virulence across diverse environments. These structured communities of bacterial cells encased in a self-produced extracellular polymeric matrix attach to both biotic surfaces, such as gallstones in the human gallbladder, and abiotic substrates encountered in food-processing settings. Within the biofilm state, Salmonella cells undergo profound physiological shifts, transitioning from metabolically active planktonic forms to a protected lifestyle characterised by altered gene expression, reduced growth rates and enhanced tolerance to antimicrobial agents and host defences. Key regulators such as the transcription factor CsgD coordinate synthesis of curli fimbriae and polysaccharide components, while stress-response sigma factors modulate adaptive pathways in response to bile, oxidative stress and nutrient limitation. Flagellar motility further contributes to initial surface colonisation, although mature biofilms can form independently of active motility. The dynamic interplay of regulatory circuits, matrix composition and environmental cues underlies Salmonella’s ability to establish chronic carriage in human hosts, undermine antibiotic therapy, and contaminate food and water supplies, thus posing a persistent public-health challenge worldwide.

Research from Nature Portfolio

One seminal study demonstrated that biofilm growth on cholesterol gallstones dramatically increases Salmonella’s resistance to ciprofloxacin, both in vitro and in a murine model of chronic carriage. Biofilm-embedded bacteria exhibited a marked reduction in antibiotic penetration and maintained viability under treatment regimes that eradicated planktonic cells. This work elucidated the role of the biofilm matrix in antibiotic tolerance and underscored the inadequacy of conventional therapies for chronic gallbladder infection, pointing to the necessity for interventions that disrupt biofilm architecture or enhance drug delivery to the biofilm niche.

Biofilm Dynamics in Salmonella enterica Pathogenesis publication trend

The graph below shows the total number of articles in biofilm dynamics in salmonella enterica pathogenesis across all publications each year (not limited to Nature Index journals).

Technical terms

Biofilm: A structured community of microbial cells embedded in a self-produced matrix and adherent to a surface.

Extracellular polymeric substances (EPS): The mixture of polysaccharides, proteins and nucleic acids that forms the protective scaffold of a biofilm.

Planktonic cells: Free-floating bacterial cells that have not adhered or formed part of a biofilm.

Curli: Proteinaceous fimbrial fibres that mediate surface attachment and intercellular adhesion in enteric biofilms.

References

1. Better together–Salmonella biofilm-associated antibiotic resistance. Gut Microbes (2023).
2. Functional role of the biofilm regulator CsgD in Salmonella enterica sv. Typhi. Frontiers in Cellular and Infection Microbiology (2024).
3. The Role of Flagellum and Flagellum-Based Motility on Salmonella Enteritidis and Escherichia coli Biofilm Formation. Microorganisms (2024).
4. Biofilm Formation Protects Salmonella from the Antibiotic Ciprofloxacin In Vitro and In Vivo in the Mouse Model of chronic Carriage. Scientific Reports (2018).