Biofilm formation by Salmonella enterica serovar Typhimurium colonizing solid tumours

Abstract

SummarySystemic administration of Salmonella enterica serovar Typhimurium to tumour bearing mice results in preferential colonization of the tumours and retardation of tumour growth. Although the bacteria are able to invade the tumour cells in vitro, in tumours they were never detected intracellularly. Ultrastructural analysis of Salmonella-colonized tumours revealed that the bacteria had formed biofilms. Interestingly, depletion of neutrophilic granulocytes drastically reduced biofilm formation. Obviously, bacteria form biofilms in response to the immune reactions of the host. Importantly, we tested Salmonella mutants that were no longer able to form biofilms by deleting central regulators of biofilm formation. Such bacteria could be observed intracellularly in immune cells of the host or in tumour cells. Thus, tumour colonizing S. typhimurium might form biofilms as protection against phagocytosis. Since other bacteria are behaving similarly, solid murine tumours might represent a unique model to study biofilm formation in vivo.

Exposure of Salmonella enterica Serovar Typhimurium to a Protective Monoclonal IgA Triggers Exopolysaccharide Production via a Diguanylate Cyclase-Dependent Pathway

“…stones (12,59), epithelial cells, and chicken intestinal tissues (63). In addition, S. Typhimurium has been shown to form biofilms as a defense against phagocytosis by host immune cells (64). Gunn and colleagues have demonstrated that S. Typhimurium is capable of producing biofilms in vitro in response to prolonged exposure to bile (e.g., 14 days), revealing that host factors can stimulate S. Typhimurium to initiate biofilm formation (30).…”

Effectors of Salmonella Pathogenicity Island 2: An Island crucial to the life of Salmonella

“…Also, recent findings suggest that extracellular survival in spleen (a systemic site) is more desirable for Salmonella than cellular invasion. 42 This leads to many queries regarding the role of SPI2 in extracellular survival of Salmonella in these sites. So it can be speculated that SPI2-mediated functions may not be limited to intracellular survival and multiplication of Salmonella anymore, throwing light on the future platforms to work on the newly implicated roles of SPI2 in Salmonella pathogenesis.…”

In vitro Biofilm Formation Ability of Clinical Isolates of Salmonella enterica Serovars Typhi and Paratyphi

“…Within a biofilm there is reduced diffusion, physiological changes due to reduced growth rates and production of enzymes which degrade antimicrobial substances 8 leading to increased resistance. Biofilms are a concern in the food industry as they can lead to illness, disease outbreaks with subsequent economic losses 12 . In the medical field, bacterial biofilms are worrying concerns because they can occur on the surfaces of medical devices and on tissue surfaces within compromised organs 13 .…”