Evaluation of Peroxides and Chlorine Oxides as Disinfectants for Chemical Sterilization of Gnotobiotic Rodent Isolators

Abstract

Gnotobiotic animal research has expanded markedly over the past decade. Although germ-free animals were first described more than 100 y ago, little evidence-based guidance is available on best operational procedures. A key aspect of gnotobiotic technology is the sterilization of animal enclosures, most commonly flexible vinyl film isolators. The objective of this study was to determine the most effective methods for chemical sterilization of gnotobiotic isolators and associated equipment. As test microbes, we used bacteria from 4 different accidental isolator contaminations that occurred in a gnotobiotic core facility. Identification by 16S ribotyping revealed facultative anaerobic firmicutes, including several Paenibacillus and Bacillus species, and obligate aerobic actinobacteria, namely Micrococcus luteus, among the contaminants. We selected 6 products commonly used for disinfecting hospital rooms, kitchens, and veterinary facilities to represent chlorine-oxideand peroxide-based disinfectants and tested the hypothesis that these 2 classes are equally effective. However, evaluation of bactericidal and sporicidal activity in liquid cultures revealed that chlorine oxide-based disinfectants were more effective than peroxide-based disinfectants. In both groups, various products effectively sterilized gnotobiotic isolators by fogging in field tests, although bactericidal concentrations were markedly higher than those in suspension cultures, and effectiveness was contact-time-dependent. In addition, in both groups, some disinfectants were excessively corrosive to ferrous metals and acrylic. These results demonstrate that no single disinfectant has all desirable properties and that the different characteristics of disinfectants must be balanced during their selection. However, chlorine oxide-based disinfectants were generally more effective and less corrosive than peroxide-based products.

Sterility testing of germ-free mouse colonies

“…Other approaches included sterilization by ethylene oxide gas (68) or formaldehyde gas (69). Nowadays, in order to avoid toxicity and to achieve more safety and cost efficiency, chemical compounds such as chlorine-oxide products are commonly used, which have proved to be efficient against both bacteria and spores (70). Another benefit of chlorine-oxide products is their fogging capacity (70).…”

Colesevelam ameliorates non-alcoholic steatohepatitis and obesity in mice

“…Mice were randomly assigned to the different groups at the beginning of the study. Animals were maintained on a 12 h:12 h light–dark cycle in Sentry SPP systems (Allentown, NJ) under gnotobiotic conditions [ 12 ]. All manipulations were performed during the light cycle.…”

Immune Response of an Oral Enterococcus faecalis Phage Cocktail in a Mouse Model of Ethanol-Induced Liver Disease

“…Initially, germ-free C57BL/6NTac mice were obtained from Taconic Biosciences (Rensselaer, NY, USA) [ 13 ] and then bred at the University of California San Diego. Fecal transplantation was performed into germ-free mice using a cytolysin-positive stool sample from a human donor with alcohol-associated hepatitis [ 1 ].…”