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Hamouda et al., Sporicidal Activity of BCTP Nanoemulsion Page 5 of 12 Results Invitro sporicidal activity. To assess the sporicidal activity of BCTP, spores from four species of Bacillus genus (B. cereus, B. circulans, B. megaterium, and B. subtilis) were tested. BCTP ata 1 : 100 dilution showed 97% sporicidal activity against B. cereus and B. megaterium in 4h (figure 1). B.- circulans was less sensitive to BCTP, showing only an 83% reduction in spore count, whereas B. subtilis appeared resistant to BCTP in 4 h. The other nanoemulsion, BCTP 401, was more efficient in killing the Bacillus spores. At a 1 : 1000 dilution, it showed 99% killing of B. cereus spores in 4h (compared with 50% with a 1 : 1000 dilution of BCTP). BCTP 401 at a 1: 1000 dilution resulted in 96% killing of B. subtilis spores in 4 h, in contrast to its resistance to BCTP. Bleach diluted 1 : 100 (.e., 0.0525% sodium hypochlorite) showed 98% sporicidal activity against B. cereus in 4h. There was no significant difference in sporicidal activity against B. cereus between BCTP diluted 1: 100, BCTP 401 diluted 1: 1000, and bleach diluted 1 : 100 (P=.23). Figure 1. Sporicidal activity of BCTP against 4 different Bacillus species compared with that of BCTP 401 against 2 Bacillus species. BCTP showed significant sporicidal activity after 4 h of treatment against Bacillus cereus, B. circulans, and B. megaterium spores but not against B. subtilis spores. BCTP 401 showed more effective killing against B. cereus in 4 hand also had sporicidal activity against B. subtilis that was resistant to BCTP. Bleach diluted 1 : 100 was used as positive control and was comparable to BCTP or BCTP 40] at same dilutions. Testing the stability of BCTP. Three different preparations of BCTP, stored for 2, 8, and 16 months at room temperature, were evaluated simultaneously for sporicidal activity against B. cereus spores to determine the stability of the emulsions. BCTP was diluted 1 : 10 and 1 : 100 for the experiments (figure 2), and there was no significant difference in the sporicidal activity of the preparations (P = .94 and .77). Figure 2. Comparison of sporicidal activity of 3 different preparations of BCTP aged 2, 8, and 16 months. Preparations have equivalent sporicidal activity, showing that BCTP is stable for up to 16 months. B. cereus sporicidal time course. An 8-h experiment was done to analyze the time course of the sporicidal activity of BCTP (diluted 1 : 100) and BCTP 401 (diluted 1 : 1000) against B. cereus. Incubation of a 1 : 100 dilution of BCTP with B. cereus spores resulted in a 77% reduction in the number of viable spores at 1 h and a 95% reduction after 4 h. Again, BCTP 401 diluted 1 : 1000 was more effective than BCTP diluted 1 : 100 and resulted in an “95% reduction in count in 30 min (figure 3). The improvement in killing between BCTP 401 diluted 1 : 1000 and BCTP diluted 1 : 100 was statistically significant up to the 4-h time point (P <.05). http://www .journals.uchicago.edu/JID/journal/issues/v180n6/99028 1/990281.text.html 2/18/2005