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Biomedical subjects

D Vesley

Publications and source records attributed to D Vesley.

At least 37 records · Page 2Linked to original sources
PubMed1982

Decontaminating infectious laboratory waste by autoclaving.

The temperature profile of infectious laboratory waste being autoclaved was examined relative to the type of containers used in the process. A standardized waste load (1,750 +/- 4 g) placed in the container was evaluated by using a direct readout thermocouple. The sensor of the thermocouple was placed within an unused and outdated agar plate, centrally located about 5 cm from the bottom of the container. The gravity displacement autoclave tested reached 121 degrees C within 3 min. Waste within a steel container (plus 1 liter of water) reached 108, 120, and 122 degrees C at 12, 30, and 50 min, respectively. Without the addition of water, the corresponding temperatures were 60, 110, and 120 degrees C, respectively. With a steel container, "autoclavable" plastic bags, and no additional water, the temperatures were 36, 71, and 105 degrees C, respectively. When 1 liter of water was placed in the autoclavable bag, the temperatures were 98, 115, and 121 degrees C, respectively. Waste within a polypropylene container (dimensions similar to those of the steel container) with and without the addition of 1 liter of water, reached a maximum temperature of 108 degrees C at 50 min. With a polypropylene container, autoclavable plastic bag, and 1 liter of water, the corresponding temperature was 99 degrees C. Without the addition of water, the temperature was 92 degrees C. The importance of container, moisture, and material in autoclaving was demonstrated.

Decontamination↗
PubMed1979

Bacterial output from three respiratory therapy humidifying devices.

Three devices used to humidify the air delivered to hospitalized patients were evaluated for their relative hazard as measured by the concentration of bacterial output delivered with the gas. Two of the devices were evaporative types (commonly called "humidifiers"), moisturizing with water vapor, while the third was a nebulizer, delivering water droplets in aerosol form. Reservoirs were seeded with a tracer organism Pseudomonas cepacia (approximately 10(4)/ml) in distilled water. The output gas (approximately 30 1/min) was sampled through an Andersen six-stage bacterial sampler operated at 28.3 1/min. Excess gas was bled off through a Y-tubing. Results indicate that the nebulizer produces heavily contaminated bacterial aerosols (greater than 1000 P cepacia colonies in the 3-minute sampling period) even after a 20-minute warm-up period that raised the reservoir temperature to greater than 45 degrees C. The two evaporative type devices produced virtually no viable organisms even when sampling was initiated with the reservoir at room temperature.

Cross Infection↗
PubMed1976

Bacterial dispersion in relation to operating room clothing.

The effect of operating clothing on the dispersal of bacterial particles from the wearers was studied in a dispersal chamber. A comparison was made of six gowns as well as four types of trousers. The gowns were of three basic types, namely a conventional cotton type, disposable types made of non-woven fabric and those of the total-body exhaust system (Charnley type). The dispersal chamber could simulate conditions as expected both in down-flow unidirectional ultra-clean systems and in a conventional turbulent plenum-ventilated system. It was found that the disposable gowns would reduce the dispersal rate by about 30% in the simulated conventionally ventilated system and about 65% in the laminar flow system. The total-body exhaust system (Charnley) would reduce the count by 10-fold in the conventional ventilated system and by 66-fold in the laminar-flow system. The poor performance of the gowns in conventionally ventilated systems was caused by the dispersal of bacterial particles from underneath the gown (about 80%). This was not reduced by the disposable gown and only partially by the Charnley type. This small drop would be further decreased in a conventionally ventilated operating-room as only scrubbed staff would wear the gown. In order to overcome this poor performance in conventionally ventilated operating-rooms impervious trousers would be required. Four types were studied and it was demonstrated that those made either from Ventile or non-woven fabric would reduce the bacterial dispersion fourfold. As these tests had been carried out in an artificial environment checks were carried out in the unidirectional-flow operating-room during total-hip arthroplasty. This was done by comparing conventional cotton gowns with non-woven gowns and total-body exhaust gowns. The results showed good correlation between the operating room and the chamber with the non-woven fabric gown but the total-body exhaust system did not perform as well in the operating room (12-fold compared to 66-fold) the difference being possibly due to the contribution from the patient. However, as this comparison was that which would be most open to influence from other variables confidence could be placed on the chamber test results. Values were also obtained for the total number of bacterial particles dispersed by persons during a standard exercise wearing different clothing. This count was dependent on the clothing worn but a median count of between 1000 and 1500 bacterial particles/min. would be expected when conventional clothing was worn, with a range of between 300 and 19,000. This count could be reduced to about 100/min. if a total-body exhaust suit was worn (range 30-400).

Air Microbiology↗
PubMed1976

High-purity water supplies for biomedical research laboratories.

A quantitative bacteriological survey of high-purity water systems used in biomedical research laboratories at the National Institutes of Health revealed great variations among the systems. In general, distilled water had significantly lower contamination levels than deionized water. Interviews with investigators revealed their conceptions about the importance of bacterial contamination in high-purity water and some expectations about bacterial quality. Guidelines are suggested for the use of water from systems of varying quality.

Bacteria↗
PubMed1971

Laminar airflow protection in bone marrow transplantation.

A laminar airflow room was used to provide a low-pathogen environment for a child with lymphopenic immune deficiency transplanted with paternal bone marrow. Comparison of flora from the patient, personnel, and the environment indicated that no colonization with exogenous organisms occurred in the patient during the 45-day period of study. The number of organisms recovered from the laminar airflow room was exceedingly small. Conventional hospital isolation rooms contained more bacteria and fungi than the laminar airflow room, even when strict aseptic procedures were followed in the former. Patients with lymphopenic immune deficiency and agranulocytosis admitted to conventional isolation rooms were colonized with exogenous organisms within 1 week. Each developed infection with these strains, and one patient died. Laminar airflow isolation seems at present the best means to prevent exogenous infection during hospitalization of patients with lymphopenic and other severe immune-deficiency diseases and may be essential when bone marrow transplantation is performed to treat their immunological defect.

Air Microbiology↗
PubMedDate not supplied

Microbial bioburden in endoscope reprocessing and an in-use evaluation of the high-level disinfection capabilities of Cidex PA.

Most endoscopy clinics use 2% glutaraldehyde as a high-level disinfectant for reprocessing flexible endoscopes. However, even with contact times greater than 30 minutes, survival of organisms has been documented. We compared the high-level disinfection capabilities of glutaraldehyde (45-minute immersion) with a new peracetic acid germicide (20- to 25-minute immersion). Channels, valve housings, and outer sheaths were sampled to quantify bioburden levels after a patient procedure, after manual cleaning, and after disinfection. Total mean bioburden after clinical use was greater than 6 log10 colony-forming units (CFU). Manual cleaning reduced the bioburden by means of 4.7 log10 CFU (gastroscopes) and 6.2 log10 CFU (colonoscopes). High-level disinfection with the new product was achieved in five of six (product stressed by EPA Reuse Test) and 7 of 10 (product stressed by dilution and organic load) successfully disinfected endoscopes, whereas glutaraldehyde achieved it in 4 of 10 (product stressed by dilution and organic load). We conclude that the new peracetic acid product (20- and 25-minute contact time) is at least as effective as glutaraldehyde (45-minute contact time) for reducing the bioburden of vegetative aerobic organisms in endoscopes.

Colony Count, Microbial↗