Caracterization of a Salmonella enterica transposon mutant strain with an increased resistance to polymyxin B

MARTÍN ESPARIZ; JULIETA BARCHIESI; ELEONORA GARCÍA VÉSCOVI; FERNANDO C. SONCINI

Alghero, Sardinia, Italy.

Conferencia; ASM conferences. Salmonella: Pathogenesis, Epidemiology, and Vaccine Development.; 2003

American Society for Microbiology

Cationic antimicrobial peptides are ancient weapons widespread distributed throughout the animal and plant kingdoms.  They are a structurally diverse group of molecules, usually amphipathic, with clusters of hydrophobic and cationic amino acids, that act against bacteria, fungi and viruses, targeting the microbial cellular membrane that distinguishes broad species of microbes from multicellular plants and animals. A crucial step in their biological activity against Gram-negative bacteria relies on the interaction with the outer membrane. In this regard, it has been shown for Salmonella enterica that structural modifications of the lipopolisaccharide (LPS) greatly affect the bacterial resistance to most of these microbicidal compounds, and that these modifications are coordinately regulated by the two-component systems PhoP-PhoQ and PmrA-PmrB. Salmonella resistance to antimicrobial peptides is a necessary step in the infection process, and mutants with increased sensitivity to these compounds are impeded to prosper within the host tissues. Because the bacterial genes involved in the resistance to antimicrobial peptides are ideal targets for the action of novel antibacterial agents, the detailed knowledge of their mechanism of action will entail the development of alternative therapies.