title: Reduction of capsular polysaccharide production in Klebsiella pneumoniae by sodium salicylate.
abstract: Heavily encapsulated Klebsiella pneumoniae (serotypes 1 and 2) was cultured in the presence of sodium salicylate. The addition of salicylate (2 to 30 micrograms/ml) progressively decreased the amount of capsular polysaccharide produced by all strains without significantly inhibiting cell growth. Further addition of salicylate (50 to 200 micrograms/ml) was progressively inhibitory to cell growth and decreased the production of polysaccharide only slightly. The optimal concentration of salicylate that could reduce the polysaccharide production of heavily encapsulated, virulent strains by 50% or more was 30 micrograms/ml. Mutants of these bacteria that produced less capsule were affected by salicylate to a lesser degree. All concentrations of salicylate tested were physiologically achievable in humans and within the therapeutic range of aspirin. The addition of calcium and magnesium partially reversed the effects of salicylate on polysaccharide production. Chelating agents, particularly EGTA [ethylene-bis(oxyethylenenitrile)tetraacetic acid], reduce capsule production as salicylate did. Thus, the chelation of calcium and magnesium by salicylate could account, at least in part, for the reduction of capsule. Optical density measurements allowed for rapid monitoring of capsule production in various culture media because a large part of culture turbidity was apparently due to the capsule. Decreased production of the primary K. pneumoniae virulence factor with salicylate may have therapeutic potential.
authors.affiliation: Infectious Disease Division, Wintrop-University Hospital, Mineola, New York 11501.
authors.forename: P
authors.initials: P
authors.lastname: Domenico
authors.forename: S
authors.initials: S
authors.lastname: Schwartz
authors.forename: B A
authors.initials: BA
authors.lastname: Cunha
mesh_terms: D002118:Calcium / Q000494:pharmacology; D002614:Chelating Agents / Q000494:pharmacology; D003470:Culture Media; D004305:Dose-Response Relationship, Drug; D007711:Klebsiella pneumoniae / Q000187:drug effects* / Q000254:growth & development; D008274:Magnesium / Q000494:pharmacology; D009391:Nephelometry and Turbidimetry; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D012980:Sodium Salicylate / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D002614:Chelating Agents; D003470:Culture Media; D011135:Polysaccharides, Bacterial; D008274:Magnesium; D002118:Calcium; D012980:Sodium Salicylate