3-Methyl-4-Chlorophenol for Prion Decontamination of Medical Devices

Degradation of p-chlorocresol by facultative Thauera sp. strain DO

In this work, Thauera sp. DO isolated from sludge and sediment utilized p-chlorocresol and some related compounds as the sole carbon and energy sources under both aerobic and anaerobic conditions. The pathways for p-chlorocresol in the isolate under each condition were different. Under the aerobic condition, p-chlorocresol was degraded via two separate pathways. The first was the reductive dehalogenation reaction, in which the substrate was transformed to m-cresol followed by the catechol degradation pathway, and the second aerobic pathway for p-chlorocresol was the methyl oxidation to 4-chlorobenzoate. Under the anaerobic conditions, p-chlorocresol was rapidly dechlorinated in the first step to m-cresol, followed by sevaral steps prior to the complete degradation. The determination of p-chlorocresol degradation in liquid media by whole cells showed that 100% and 85% of the substrate (0.3 mM) were transformed within 12 h under aerobic and anaerobic conditions, respectively, while nearly 100% of this compound was degraded within 6 h using the two-stage anaerobic-aerobic degradation process. These results show a novel method to increase the degradation rates of p-chlorocresol using the anaerobic process followed by the aerobic process.

Investigations of a prion infectivity assay to evaluate methods of decontamination

Prions are unique infectious agents which have been shown to be transmitted iatrogenically through contaminated surfaces. Surface contamination is a concern on reusable medical devices and various industrial surfaces, but there is currently no standard, accepted model to evaluate surface prion decontamination. In this report, a set of both in vitro and in vivo methods were investigated based on the contamination of surface through artificial exposure to infected brain. An in vitro surface contamination protocol was developed with subsequent biochemical detection of the prion protein (PrPres). In parallel, the in vivo investigations included the contamination of different types of surface materials (stainless steel or plastic wires) with different prion strains (scrapie strain adapted to hamsters 263K or bovine spongiform encephalopathy strain adapted to mouse 6PB1). The in vivo models with various prion strains and brain homogenate dilutions reproducibly transmitted the disease and a relationship was established between the infectivity titre, the transmission rate and the incubation period. Moreover, the in vivo models were studied for their ability to demonstrate the efficacy of heat and chemical-based decontamination methods, with similar results. The in vivo scrapie method described is proposed as a standard to evaluate existing and developing prion decontamination technologies.