Mutagenic activity of sterilization indicators.

Using the Ames Salmonella/microsomal assay, mutagens were detected in acetone-methylene chloride extracts of black threads on glass tube-type sterilization indicators used in hospitals and research laboratories. Extracts of samples of commercially available black thread also contained mutagenic substances. Fluids autoclaved with these sterilization indicators may alter the results in mutagenicity and other studies.