In situ decontamination of medical wastes using oxidative agents: a 16-month study in a polyvalent intensive care unit.

Over a 16-month period from September 1997 to December 1998, a prospective study was made of an on-site treatment of medical wastes in a 10-bed intensive care unit. First, the wastes were ground and then, a high concentration of ozone in air was repeatedly injected into the ground wastes. The study analysed the practical application of the system and its microbiological efficiency. Inactivation experiments were made with reference strains of Staphylococcus aureus, Enterococcus hirae, Pseudomonas aeruginosa, Escherichia coli, Mycobacterium smegmatis, Bacillus subtilis var niger, Bacillus stearothermophilus, Candida albicans and Aspergillus niger. Two thousand eight hundred treatment cycles, i.e. 84,000 grindings and 140,000 ozone injections gave a treatment capacity of 50 kg of waste per day with a good staff acceptability. All kinds of medical devices used in an intensive care unit were treated. In untreated ground wastes, the median bacterial load was 105.86 (range 10(2.35)-10(8.05)) cfu/g. After ozone treatment, bacteria and fungi were reduced by a factor of 10(5). Aero-contamination of the ward was unchanged. Computer control allowed all events to be tracked. On-site medical waste treatment appears to be an efficient alternative to the usual centralized collection and treatment. Copyright 2002 The Hospital Infection Society.