This study evaluated the influence of temperature and organic load on the effectiveness of domestic bleach (DB), Surface Decontamination Foam (SDF), and Virkon in inactivating Geobacillus stearothermophilus spores, which are a surrogate for Bacillus anthracis spores. The spores were suspended in light or heavy organic preparations and the suspension was applied to stainless steel carrier disks. The dried spore inoculum was covered with the disinfectants and the disks were then incubated at various temperatures. At −20°C, the 3 disinfectants caused less than a 2.0 log10 reduction of spores in both organic preparations during a 24-h test period. At 4°C, the DB caused a 4.4 log10 reduction of spores in light organic preparations within 2 h, which was about 3 log10 higher than what was achieved with SDF or Virkon. In heavy organic preparations, after 24 h at 4°C the SDF had reduced the spore count by 4.5 log10, which was about 2 log10 higher than for DB or Virkon. In general, the disinfectants were most effective at 23°C but a 24-h contact time was required for SDF and Virkon to reduce spore counts in both organic preparations by at least 5.5 log10. Comparable disinfecting activity with DB only occurred with the light organic load. In summary, at temperatures as low as 4°C, DB was the most effective disinfectant, inactivating spores within 2 h on surfaces with a light organic candload, whereas SDF produced the greatest reduction of spores within 24 h on surfaces with a heavy organic load.

Vancomycin-resistant enterococci (VRE) are well-known ascendant nosocomial pathogens. The recent detection of epidemiologic strain
carrying vanA gene in the community of people working with animals and in chickens has brought to the forefront the potential public health danger posed by these organism. The farm environment is a major source of VRE persistence in poultry farms. We carried out survival test to test the survival of the VRE isolates on dry condition and surface test to evaluate the inactivation of the isolates by in-use concentration of commonly used disinfectants. In the survival test, all isolates survived for at least 4 weeks in
colony counts of (1.00 × 103 – 3.86 × 103 CFU/ml) under clean condition and (1.00 × 103 – 2.02 × 104) for soiled condition.
Those that were suspended in 5% BSA solution to mimic organic matter load as obtainable on farms survived for at least 8 weeks at (1.54 × 102 – 1.34 × 103 CFU/ ml). In the surface test, inactivation of VRE isolates by in-use concentration of Lindores®, Omnicide® and Ecos Timsen® was tested using the European surface test (EST). All the tested disinfectants were active against the VRE isolates on both the standard test surface (stainless steel) and our test surface (wooden). The results shows microbiocidal effects (ME) for test disinfectants, i.e. the log10 CFU of micro-organisms compared between test biocide and control treated with distilled water, after 7 min of exposure as follows; Lindores® active on both surfaces 5.24 and 3.17, Ecos Timsen® active significantly on steel 4.90 than wood 2.98 and Omnicide® significantly less active on stainless steel
2.40 than on wood 3.50.