Evaluation of steam penetration and sterilization of natural latex wraps

To evaluate the efficacy of steam and ethylene oxide (EtO) sterilization of Vetrap™ bandages.

Prospective experimental study.

Vetrap™ bandages (n = 70; 35 as supplied by the manufacturer, 35 unwound and tightly rewound).

Vetrap™ bandage rolls (n = 60) marked with a 1 cm square were inoculated with 0.1 mL Geobacillus stearothermophilus spores, packaged in a pouch together with independent sterilization indicators and assigned into 3 sub-groups for sterilizer type: dynamic air removal, gravity displacement, and bench-top pre-vacuum and further sub-divided into 2 sterilization temperatures. Vetrap™ bandages rolls (n = 10) were inoculated with 0.1 mL Bacillus atrophaeus spores in the same manner and underwent EtO sterilization. After sterilization, the 1 cm marked square was aseptically resected to the level of the cardboard tube and enriched in a flask containing 10 mL tryptic soy broth for 24 hours at 60°C for G. stearothermophilus and 37°C for B. atrophaeus. Aliquots were subsequently plated on a Petri dish of tryptic soy agar and incubated at 60°C for G. stearothermophilus and 37°C for B. atrophaeus for 24 hours. Samples were scored positive if colonies of indicator organism were present on the nutrient agar after 24 hours.

Three Vetrap™ bandages yielded post-sterilization growth of G. stearothermophilus: 2 from the dynamic air removal sterilizer at 134°C for 3.5 minutes, and 1 from the bench-top pre-vacuum sterilizer at 121°C for 15 minutes. After EtO sterilization, no positive samples were detected.

Steam sterilization may be incomplete for Vetrap™ bandages whereas EtO showed complete destruction of resistant bacterial spores.