FIG 6.

Viability, wet heat sensitivity, and germination events in C. difficile spores exposed to HP. Spores of C. difficile ATCC 43601 were exposed to HPs of either 150 MPa (A) or 550 MPa (B) for various times, and phase-bright spores, spores that retained DPA, spore viability, and spore viability after exposure to 80°C in water for 30 min were measured, all as described in Materials and Methods. The various parameters measured are shown as follows: phase-bright spores, white bars (100 individual spores examined); spores retaining DPA, gray bars (100 individual spores examined); spore viability, white stippled bars (determined in triplicate); and spore viability after heat treatment, black stippled bars (determined in duplicate for panel A and in triplicate for panel B). Values for spores that retained DPA and were phase bright are expressed relative to the average values in untreated spores; values for viability with and without a heat treatment are expressed relative to the viability of spores that were HP treated for 0 min and not then heat treated. In panel B, the values for viable spores at time zero are the averages of values for spores with and without heat treatment. Average standard deviations for viability values without heat treatment were ±38% in panel A and ±43% in panel B, and those for viability values with heat treatment were ±25% in panel A and ±43% in panel B.