Evaluation of endoscope sheaths as viral barriers.

OBJECTIVES: Evaluate ENT endoscope sheaths as barriers to virus passage. STUDY DESIGN: "Defective" sheaths covering an endoscope were challenged with virus to determine how many virus particles could be recovered from the endoscope. METHODS: Sheaths with small laser-drilled holes (2 to 30 microm) were challenged with high-titer virus suspensions (10(8) viruses/mL). The inside of the sheath and the endoscope were separately rinsed to recover any virus that penetrated through the hole in the sheath. In an attempt to assess the possible importance of holes in the sheaths, a sequential test was conducted with an initial virus challenge outside a defective sheath (30-micron hole in the sheath), after which the possibly contaminated endoscope was removed and inserted into a second defective sheath (with a 20-micron hole at the same location) to determine whether the contaminating virus would pass outward through the second sheath. RESULTS: Small volumes of virus-containing fluid penetrated through the hole, e.g., 500 virus particles passed through one of three 30-microm holes. A significant fraction of those virus particles was occasionally found on the endoscope after removal from the sheath. Similar results were obtained with sheaths that had small tears (34-84 microm in length, from punctures with fine wires). Although some virus penetration could occur during the initial challenge contaminating the endoscope, no virus was detected passing outward through the second sheath. CONCLUSIONS: Use of a sheath combined with intermediate level disinfection should provide a safe instrument for ENT endoscopy.

Extraction of light filth from tea: collaborative study.

The present AOAC method for determining insect and rodent filth in tea is time-consuming because it produced filter papers which are heavy in plant residue and therefore required long paper-reading times. A new method for the analysis of light filth in tea was developed to remedy existing problems and to improve recoveries. The method consists of the following steps: sample preparation, wet sieving, dilution with 40% isopropanol, flotation with mineral oil-heptane, and trapping off in a Wildman trap flask. In an interlaboratory collaborative study, analysts reported combined insect fragment recoveries of 99.2% for the proposed method and 93.0% for the AOAC method; the same analysts recorded combined rodent hair recoveries of 92.2% for the proposed method and 47.6% for the official method. Average times for reading individual subsamples were 9 min for the proposed method and 27 min for AOAC method. the proposed method has been adopted official first action.