Chlorine Dioxide Gas Decontamination of Large Animal Hospital Intensive and Neonatal Care Units

Abstract

In May of 2004, the large animal intensive care and neonatal intensive care units (ICU/NICU) of the University of Pennsylvania's New Bolton Center were temporarily closed to all admissions following an outbreak of salmonellosis that had affected its patients. Environmental testing continued to recover a multi-drug resistant organism identified as Salmonella enterica serovar Newport following repeated liquid disinfection treatments of the facility. Based upon various environmental considerations, it was decided that the most feasible and effective process for disinfecting the facility would be achieved using chlorine dioxide (ClO₂) gas. The facility was appropriately sealed, supplied with gas distribution mechanisms and demonstrated to have met the specification for humidity before introduction of ClO₂. The total exposure for this 4800 cubic meters structure was approximately 400 ppm-hr. Efficacy of the decontamination was monitored by the placement of 20 Bacillus atrophaeus spore, 40 Geobacillus stearothermophilus spore, and 40 Salmonella Newport vegetative cell strips. Microbiological testing demonstrated greater than 5.5 and 6.1 log reduction for the G. stearothermophilus and B. atrophaeus spore strips, respectively. Log reductions of the S. Newport bacterial strips were also within acceptable levels. The success of this project demonstrates the utility of ClO₂ gas as a biological decontaminant approach for mid-sized commercial and public facilities.