Background: Surgical instruments and other items of medical equipment are routinely re-used by health staff throughout the world, and various methods of decontamination are used to prevent infections. The WHO recently reviewed their guidelines for heat and chemical sterilisation procedures, and showed inconsistent recommendations for the use of bleach and the time required for autoclaving. This review aimed to systematically summarise the evidence around the effectiveness of commonly used decontamination techniques, and identify the procedural specifications necessary to achieve destruction of micro organisms and to prevent infection.

Methods: A protocol was constructed, which identified decontamination procedures that have been described as able to sterilise or high-level disinfect. The outcomes chosen were the procedures' abilities to kill key indicator micro organisms and to prevent infection from decontaminated equipment. In two subsidiary reviews, the presence of micro organisms and actual infection in humans and animals was sought following different decontamination procedures. Laboratory based studies of procedural efficacy were included if they met certain predefined criteria of experimental design.. Quality was assessed by experimental quality, study design and the replication of results. The included studies were briefly summarised and procedural specifications (such as time of exposure, concentration of chemical agent) were recorded for each procedure

Results: A large number of studies were recovered that used different combinations of decontamination parameters. A single set of standard specifications effective to destroy the indicator micro organisms was built up for each procedure, stratified by the indicator micro organisms. This standard was continually adjusted with each subsequent included study, so that the majority was incorporated. Each study was presented as evidence for or against the standard and the possible reasons for heterogeneity in results were recorded. In this way, procedures that are generally effective were elucidated and the major factors influencing their efficacy became clearer. The results provide a clear evidence base for many published recommendations and reveal gaps in the data for others. Some chemical decontaminants were revealed to be more effective than supposed from published guidelines.

Conclusions: The methods used enabled the description of standard specifications, for each decontamination procedure, that incorporated the majority of included studies. Where studies disagreed with the standard reached, clear limitations of procedures became evident and allowed the description of a number of critical points for each procedure. This method is new, and effective for systematically summarising observational data in relation to the efficacy of decontamination procedures.