FIG 1.

Streptococcus pneumoniae killing of cardiomyocytes at a low MOI requires contact. (A) Cell viability (left graph) and total cell count (right graph) of noninfected (white bars) or TIGR4-infected (black bars) HL-1 cells were determined by trypan blue exclusion assay. (B) HL-1 cardiomyocyte death was measured by LDH release from cells infected by live, heat-killed, or ethanol-killed TIGR4. (C) Bacterial toxicity determined by LDH release in a Transwell permeable support system (n = 3). Errors bars represent standard errors of the means. Statistical analyses were done with t test (A) and 1-way analysis of variance (ANOVA) with Holm-Sidak correction for multiple comparison (B and C). ****, P ≤ 0.0001.