Table 3. Electron microscopy fixation of infected spleen, liver, and lung tissue from guinea pigs in study of inactivation of bacterial Tier 1 Select Agents*.
| Infectious agent, tissue type | Maximum tissue weight, g | Maximum tissue size, mm | Maximum CFU/g | Fixation time, d | Sample inactivation | Positive control |
|---|---|---|---|---|---|---|
| Bacillus anthracis Ames (inhalational and intramuscular), n = 3 | ||||||
| Spleen | 0.15 | 10 × 3 × 2 | 1.1 × 109 | 6 | –/–† | + |
| Liver | 0.18 | 9 × 5 × 2 | 9.8 × 107 | 6 | –/–† | + |
| Lung |
0.08 |
10 × 4×x 2 |
2.1 × 108; 5.5 × 104 (heated) |
6 |
–/–† |
+ |
| Burkholderia pseudomallei 1026b, n = 4 | ||||||
| Spleen | 0.09 | 8 × 4 × 2 | 7.5 × 108 | 7 | –/–‡ | + |
| Liver | 0.16 | 10 × 6 × 2 | 1.4 × 107 | 7 | –/–‡ | + |
| Lung |
0.09 |
10 × 4 × 2 |
4.0 × 107 |
7 |
–/–‡ |
+ |
| Francisella tularensis Schu S4, n = 3 | ||||||
| Spleen | 0.15 | 6 × 6 × 1 | 9.3 × 109 | 6 | –/–§ | + |
| Liver | 0.15 | 11 × 5 × 1 | 9.5 × 107 | 6 | –/–¶ | + |
| Lung |
0.08 |
7 × 6 × 1 |
4.3 × 108 |
6 |
–/–¶ |
+ |
| Yersina pestis CO92, n = 3 | ||||||
| Spleen | 0.11 | 7 × 5 × 1 | 1.4 × 1010 | 6 or 8 | –/–§ | + |
| Liver | 0.07 | 7 × 4 × 1 | 1.1 × 109 | 6 or 8 | –/–¶ | + |
| Lung | 0.07 | 7 × 6 × 1 | 7.0 × 108 | 6 or 8 | –/–¶ | + |
*<4 guinea pigs were infected with 1 Select Agent. Tissues were excised and then measured, weighed, and plated for CFU. Tissues were fixed in EM fixative for the indicated time, rinsed for 30 min in phosphate-buffered saline, and then homogenized. +/– indicates presence or absence of growth in broth/on plates. †100% of sample tested. ‡50% of sample tested. §90% of 1 sample tested, 10% of others tested. ¶10% of sample tested.