Table 6. Effect of residual electron microscopy fixative in tissue from guinea pigs on the growth of Bacillus anthracis Sterne in study of inactivation of bacterial Tier I Select Agents*.

Tissue type, no. samples	Fixation time, d	Incubation time for tissue in PBS/water, h	Sample inactivation†	Positive control
Spleen, 3	14	24	–/–	+/+
Spleen, 3	21	24	–/–	+/+
Liver, 3	14	24	–/–	+/+
Liver, 3	21	24	–/–	+/+

*Spleen and liver tissues fixed for 14 or 21 d and washed for 24 h permitted Sterne spores to germinate and grow in broth used for viability testing. +/− indicates presence and/or absence of growth in broth/on plates. PBS, phosphate-buffered saline.
†50% of tissue tested.