Identification of Factors Associated with Rust on Medical Instruments Following Steam Sterilization in Mae Sot Hospital, Tak Province: an Experimental Study

Abstract

From May 2007 to May 2008, there were intermittent reports of rust on surface of medical instruments made of stainless steel following steam sterilization in Mae Sot hospital, Tak Province. This paper reported an investigation conducted in May-June 2008 to identify possible causes or risk factors for rusting.  The methods included reviews of procedures of steam sterilization in the hospital, formation of hypotheses of possible causes or risk factors, and use of an experimental study to determine such causes or factors.  The similar 2 sets for wound dressing and 2 for perineum flushing were used in the experimental study.  The identified important factor of rusting was the chloride deposits on clothes used for instrument wrapping before steam sterilization.  Other risk factors were increased amount of total dissolved solids in water used in the sterilizer and longer duration of steam contact in the gravity displacement sterilizer than the pre-vacuum steam sterilizer.  Preventive and control measures included no bleach with high chloride concentration for washing such clothes and use of deionized water in the steam sterilization. No attacks of rust on instruments were reported during the proceeding surveillance of 2 months.