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The survival time of these bacteria on hard, inanimate surfaces varies depending on ambient moisture and temperature, the surface material, and other factors. With regard to Salmonella, one study found a survival time in a toilet bowl of 4 weeks after the infected patient's diarrhea had stopped despite the use of cleaning fluids and up to 50 days' survival in an experimentally-contaminated toilet bowl (in contrast, normally dry areas, such as the toilet seat, flush handle, and bathroom doorknob, did not show such lengthy persistence). E. coli has been shown in a separate study to survive over 28 days at both refrigeration and room temperatures on stainless steel, but the bacteria only survived 90-360 minutes on surfaces of copper or copper alloy. In general, without bacteridal conditions or measures, both of these hardy bacteria appear to be able to survive on hard, inanimate surfaces for weeks.
Salmonella reference: http://www.ncbi.nlm.nih.gov/pubmed/10945790
E. coli reference: http://www.ncbi.nlm.nih.gov/pubmed/16253366
Pathogenic bacteria, such as Salmonella and E.coli, can survive on kitchen surfaces for hours despite typical hygienic procedures.
Bacterial adhesion reference: http://www.formatex.org/microbio/pdf/Pages13-20.pdf
Moisture is a strong factor affecting bacterial survival on surfaces, especially for Salmonella, even on an outdoor granite outcropping.
Salmonella and moisture reference: http://aem.asm.org/cgi/reprint/30/5/764.pdf