FIG. 1.

Differential d-gal sensitization of mice to lethality induced by clinical and laboratory bacterial isolates. Eleven gram-positive (6 S. aureus strains, 1 S. mitis strain, 1 S. pneumoniae strain, and 3 E. faecalis strains) and 10 gram-negative (3 E. coli strains, 4 K. pneumoniae strains, 1 C. diversus strain, 1 P. aeruginosa strain, and 1 P. mirabilis strain) bacterial strains were evaluated for lethal potency in d-gal-sensitized mice. Animals were injected i.p. with graded doses of each bacterial strain either with or without d-gal, and the resulting mortality was evaluated over 48 h. Each datum point represents experiments performed with at least 48 mice. The solid diagonal line is drawn at a 1:1 ratio between the LD₅₀s of untreated and d-gal-treated mice. The dashed diagonal line is drawn at a 100:1 ratio between the LD₅₀s of untreated and d-gal-treated mice. Consequently, if an isolate is aligned on the solid diagonal line, its LD₅₀ was not changed by d-gal treatment. If, however, an isolate is aligned on the dashed diagonal line, its LD₅₀ was decreased 100-fold by d-gal treatment. Symbols: ⋄, E. faecalis; •, gram-negative bacteria; ○, gram-positive bacteria other than E. faecalis.