FIG. 1.

(A and B) Measurement of ATP levels in cell culture medium from uninfected and E. coli IA2-infected UROtsa cells after 1 h (A) or 2 h (B). The ATP levels in medium alone and in wells with only cells or only bacteria (IA2 [10⁸ CFU/ml]) are also given. The black bars show estimated ATP levels generated by the infected cells and are calculated by subtracting the ATP levels generated by IA2 itself from the measured ATP levels in the coincubation experiments (cells plus IA2 [10⁸ CFU/ml]). Data are presented as means ± SEMs (n = 6). (C) UROtsa cells were exposed to IA2 (10⁸ CFU/ml) for 1 h, the bacteria were removed, and the medium was replaced with fresh medium. ATP levels were measured 1, 2, and 4 h after the medium was replaced with fresh medium. Uninfected cells were used as a control (Ctrl). Data are presented as means plus SEMs (error bars) (n = 4 or 5). Values that are statistically significantly different are indicated by brackets and asterisks as follows: *, P < 0.05; **, P < 0.01.