Fingertip impression cultures of 18 subjects and tests with pure cultures of bacteria have shown that 0.5% sodium thiosulfate inhibited bacterial growth up to 100%. The average bacterial colony counts of fingertip impressions of 18 subjects on two culture media without the inactivating agent were 100.8 and 104.6 as opposed to average counts of 12.4 and 15.2, respectively, on media with 0.5% sodium thiosulfate. Serial dilutions of pure cultures of bacteria confirmed results described above and indicated that the predominant inhabitant of skin, Staphylococcus epidermidis, and pathogenic S aureus are particularly sensitive to sodium thiosulfate. It is concluded that results of bacteriologic testing of iodine scrub preparations are misleading if sodium thiosulfate is incorporated into culture media.
Gross A, Cofone L, Huff MB. Iodine Inactivating Agent in Surgical Scrub Testing. Arch Surg. 1973;106(2):175-178. doi:10.1001/archsurg.1973.01350140037012