Failure of an Autoclave to Sterilize the Contents of 3.5 and 17 Gallon Sharps Containers

Background: Containers for the management of sharps have been in use since the mid 1980’s. Previous studies conducted on autoclaving these sharps containers filled with sharps/syringes seeded with bacterial spores indicated a standard gravity cycle (124^oC, 15 psig, 30 minutes) proved ineffective in killing the spores.  Vacuum assist autoclaves (131^oC, 30 psig, and 10 minute) killed all spores. Since that time, the style and sizes of containers has increased dramatically while treatment parameters have essentially remained the same.  Little information exists on the effectiveness of autoclaves to treat larger sharps containers and their contents. Objective: This study was designed to evaluate the effective treatment of an autoclave on bacterial spores present in sharps placed in large sharps containers. Methods:   Spore strips 10⁴ spores of G. stearothermophilus were inserted into the barrel of 3 cc syringes in studies of 3.5 gal sharps containers.  In addition, 3 cc syringes, loaded with 2 cc suspensions of 10⁴ spores of G. stearothermophilus were placed into the same 3.5 gal sharps containers which were three-quarters filled with unused syringes.  Self-contained biological indicators (SCBI) with 10⁴ spores of G. stearothermophilus were placed in the bottom, middle and top of 17 gal sharps containers which were three-quarters filled with empty vacutainer tubes. Results: In the 3.5 gallon containers, seven(7) out of twelve (12) spores suspensions demonstrated growth, while all spore strips demonstrated growth. The SCBI ampoules placed at the bottom, middle and top of 17-gal sharps containers three-quarters filled with empty vacutainer tubes = all showed growth Conclusions: 1. Spores of G. stearothermophilus on strips within the syringe barrels were not inactivated regardless of the location of the syringes within the containers or the location of the containers. 
2.  Spores of G. stearothermophilus in suspensions within the syringe barrels were inactivated when the containers were located at the top position.
3.  Spores of G. stearothermophilus in suspensions within the syringe barrels were not inactivated when the containers were located in the middle or bottom of the load (containers 1 and 2).
4. Spores of G. stearothermophilus in SCBI in 17 gallon sharps containers were not inactivated at any location in the container.
5. Further assessment is warranted of the range of sharps containers and different capacity autoclaves to establish appropriate time/temperature/pressure and vacuum parameters to achieve effective kill of bacterial spores.