Surface bioburden expressed as mean cfu count per ampoule or vial before disinfection and after one-step TT and two-step TT disinfection
| Plastic ampoules | Glass ampoules | Injection vials | ||||||||
| Contact plate | Total immersion | Contact plate | Contact plate | Total immersion | ||||||
| Mean cfu | SD | Mean cfu | SD | Mean cfu | SD | Mean cfu | SD | Mean cfu | SD | |
| Before disinfection | 0.67 (n=30) | 1.64 | 2.45 (n=20) | 2.50 | 0.93 (n=30) | 1.82 | 0.57 (n=30) | 1.04 | 7.35 (n=20) | 17.26 |
| After one-step TT | 0.03 (n=30) | 0.18 | 0.10 (n=20) | 0.46 | 0.2 (n=30) | 0.41 | 0.13 (n=30) | 0.43 | 1.35 (n=20) | 3.67 |
| After two-step TT | 0.03 (n=30) | 0.18 | 0.00* (n=20) | 0.00 | *0.00* (n=30) | 0.00 | 0.03 (n=30) | 0.8 | 0.30 (n=20) | 0.56 |
| p1 | 0.010 | <0.001 | 0.007 | 0.022 | 0.003 | |||||
| p2 | 0.010 | <0.001 | 0.002 | 0.008 | <0.001 | |||||
| p3 | 1.000 | 0.679 | 0.218 | 0.304 | 0.423 | |||||
*For the Wald test the mean (x̅) of zero cfu was replaced by a pseudo-count of 1 (the lowest possible contamination: x̅=0.05 in 20 samples and x̅=0.03 in 30 samples).
cfu, colony-forming unit; n, number of samples examined; p1, p value; one-step TT disinfection compared with before disinfection;p2, p value; two-step TT disinfection compared with before disinfection; p3, p value; two-step TT disinfection compared with one-step TT disinfection.