Results and Discussion

Surface Samples

A review of biological swab tests for touch and building surfaces in both wings, showed a consistent reduction of colony forming units (cfu) within the treated wing throughout the test period. The range of reductions and the average for each type of surface tested are summarized in Table 1. It is apparent that surfaces that were touched more frequently had greater reduction in the bioburden. This supports earlier tests by others (Medlin, 1997) who reported that triclosan exhibits increased effectiveness when continuously challenged. This was more clearly demonstrated in the present study in a separate set of tests involving items like telephone handsets and computers. These tests were conducted over a six – month period only. Three different telephones and computers located in the control wing were selected for separate study toward the end of the main study. These were treated with a surface spray containing triclosan. The average reductions in bioburden are presented in Table 2 for the 7-day and 6- month test periods. The effect of repeated handling of these devices resulted in an increase in antimicrobial activity. This lead to a greater reduction in surface bioburden as compared to surfaces that were not touched as frequently, such as walls, floors and ceilings as reported in Table 1.

Table 1. Reduction in cfu on Surfaces in Treated Wing

Surface Treated Test Items (number of sites tested)

Range of Reductions in cfu Compared to Control Wing

Average Reduction in cfu Compared to Control Wing

Fixtures and Components (15)

25 to 91 %

55 %

Medical Instruments (10)

0 to 80 %

45 %

Furniture (5)

0 to 85 %

50 %

Wall Paint (5)

10 to 50 %

25 %

Floor tile (5)

30 to 55 %

40 %

Ceiling tile (5)

15 to 35 %

20 %

Total (45)

0 to 91 %

40 %

Table 2. Reduction in cfu on Telephone and Computer Surfaces

Surface Treated Test Items (number of sites tested)

Seven Days Post-Treatment Ave. Reduction in cfu

Six Months Post-Treatment Ave. Reduction in cfu

Telephone Handsets (3)

55 %

99 %

Computer Keyboards (3)

45 %

85 %

Computer Mice (3)

51 %

82 %