title: Inactivation of Geobacillus stearothermophilus spores by alkaline hydrolysis applied to medical waste treatment.
abstract: Although alkaline hydrolysis treatment emerges as an alternative disinfection/sterilization method for medical waste, information on its effects on the inactivation of biological indicators is scarce. The effects of alkaline treatment on the resistance of Geobacillus stearothermophilus spores were investigated and the influence of temperature (80 °C, 100 °C and 110 °C) and NaOH concentration was evaluated. In addition, spore inactivation in the presence of animal tissues and discarded medical components, used as surrogate of medical waste, was also assessed. The effectiveness of the alkaline treatment was carried out by determination of survival curves and D-values. No significant differences were seen in D-values obtained at 80 °C and 100 °C for NaOH concentrations of 0.5 M and 0.75 M. The D-values obtained at 110 °C (2.3-0.5 min) were approximately 3 times lower than those at 100 °C (8.8-1.6 min). Independent of the presence of animal tissues and discarded medical components, 6 log10 reduction times varied between 66 and 5 min at 100 °C-0.1 M NaOH and 110 °C-1 M NaOH, respectively. The alkaline treatment may be used in future as a disinfection or sterilization alternative method for contaminated waste.
authors.affiliation: LEPABE, Department of Metallurgical and Materials Engineering, Faculty of Engineering, University of Porto, Portugal. Electronic address: scpinho@fe.up.pt.
authors.forename: Sílvia C
authors.initials: SC
authors.lastname: Pinho
authors.affiliation: LEPABE, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Portugal.
authors.forename: Olga C
authors.initials: OC
authors.lastname: Nunes
authors.affiliation: Department of Microscopy, Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, Portugal.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Lobo-da-Cunha
authors.affiliation: LEPABE, Department of Metallurgical and Materials Engineering, Faculty of Engineering, University of Porto, Portugal.
authors.forename: Manuel F
authors.initials: MF
authors.lastname: Almeida
mesh_terms: D000818:Animals; D004203:Disinfection / Q000379:methods*; D001411:Geobacillus stearothermophilus / Q000737:chemistry*; D006358:Hot Temperature; D006868:Hydrolysis; D008506:Medical Waste; D017744:Medical Waste Disposal / Q000379:methods*; D013171:Spores, Bacterial / Q000737:chemistry*
chemical_list: D008506:Medical Waste; D017744:Medical Waste Disposal
keywords: D-value; Disinfection method; Medical waste; Sodium hydroxide; Sterilization method