BACTERIAL KILLING ABILITY OF 10-PERCENT ETHYLENE-OXIDE PLUS 90-PERCENT HYDROCHLOROFLUOROCARBON STERILIZING GAS

OBJECTIVES: To use a serum and salt challenge in narrow-lumen carriers to evaluate a 10% ethylene oxide plus 90% hydrochlorofluorocarbon (EO -HCFC) sterilant mixture in a retrofitted 12/88 sterilizer as an alter native to the banned chlorofluorocarbon-ethylene oxide (EO) sterilant mixture. DESIGN: An EO-HCFC sterilizing gas mixture in a retro fitted 12/88 sterilizer was compared to 100% ethylene oxide (100% EO) sterili zing gas to determine its relative ability to kill seven different bac teria (Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis , Bacillus subtilis spores, Bacillus stearothermophilus spores, Bacill us circulans spores, and mycobacterium chelonei) in the presence or ab sence of a combined 10% serum and 0.65% salt challenge using both peni cylinders (PC) and long narrow-lumen (LU) carriers. RESULTS: The EO-HC FC sterilant mixture (96% sterile carriers) was equivalent to the 100% EO sterilant (98% sterile carriers) for killing vegetative organisms, as well as spore suspensions, on the 27 PC and 27 LU carriers in the absence of serum and salt. In the presence of serum and salt, the EO-H CFC sterilant mixture was markedly better than the 100% EO sterilant a t reducing the bacterial load on the 63 PC carriers (95% vs 62% steril e PC carriers, respectively), whereas both sterilizers were equivalent for the 63 LU carriers (49% vs 40% sterile LU carriers, respectively) . Of the seven test organisms, E faecalis, B subtilis, B stearothermop hilus, and B circulans were the most difficult to kill for both PC and LU carriers when serum and salt were present. CONCLUSIONS: The data p resented in this report indicate that the EO-HCFC sterilant mixture is an effective alternative for gas sterilization. Indeed, the efficienc y of bacterial killing for the EO-HCFC sterilant mixture was similar t o that achieved by the 12/88 EO-CFC sterilant mixture.