Microbial iron-chelators and their action on Klebsiella infections in the skin of guinea-pigs.

Preparations of catechols from ethyl acetate extracts of cultures of Klebsiellae in a low-iron medium contained iron-chelators whose potency was measured by the reversal of the bacteristasis of Escherichia coli and klebsiellae in unheated horse serum, and of the growth-inhibition of these two organisms by ethylene diamine di-orthohydroxyphenyl acetic acid (EDDA). As revealed by in situ tests of paper chromatograms, there was a multiplicity of biologically active chelators in the preparations. Catechols from strains both of high and low virulence for guinea-pigs enhanced the skin infectivity of most of the 10 Klebsiella strains tested. The enhancement was roughly proportional to iron-enhanceability with the 6 iron-enhanceable (E+) strains, though not as great as that by iron. But of the 4 (Eo) strains not enhanceable by iron, two were moderately enhanced by the catechols. The Streptomyces iron-chelator desferrioxamine B also enhanced infectivity, again roughly in proportion to the iron enhanceability of the strains; though one Eo strain was substantially enhanced. The synthetic iron-chelator EDDA did not enhance infection.