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Biomedical subjects

M Best

Publications and source records attributed to M Best.

At least 19 recordsLinked to original sources
PubMed1995

Mycobactericidal testing of disinfectants: an update.

Tuberculosis, a major killer in developing countries, is on the rise again in industrialized nations. AIDS, increased use of immunosuppression and the emergence of multiple drug-resistant Mycobacterium tuberculosis (MDR-TB) have further enhanced its significance. TB is projected to cause 3.5 million deaths per year by 2000. Also, other types of mycobacteria are being incriminated in human infections with increasing frequency. Thus, the enhanced risk of nosocomial and iatrogenic spread of mycobacteria is forcing a review of infection control in general and claims of mycobactericidal activity of disinfectants in particular. Mycobacteria are more resistant to disinfection than enveloped viruses and other types of vegetative bacteria, but a proper comparison with non-enveloped viruses requires more data. Flaws in currently used protocols for mycobacterial activity are: (i) a lack of proper quantitation; (ii) unrealistically long contact times at higher than ambient temperatures; (iii) absence of a suitable organic load; (iv) ineffective neutralizers; (v) unsuitable surrogates for M. tuberculosis; (vi) improper recovery media; and (vii) inappropriate types of carriers. Furthermore, we have recently found a product meant for 14 day reuse to become non-mycobactericidal after only a week under actual use in an endoscopy unit. These considerations make the available data on product efficacy unreliable, especially in view of the increasing threat from MDR-TB. Recent findings suggest that the use of Mycobacterium terrae as a surrogate, better recovery media, flat surfaces as carriers, elimination of neutralizers, proper removal of cell clumps and a required > or = 4 log10 reduction in the number of colony forming units of the test bacterium after disinfectant treatment should make mycobacteridal tests more precise and reliable, thus making product registration and selection easier. There is also an urgent need to develop standardized protocols to determine the mycobactericidal activity of disinfectants under conditions of reuse.

Disease Reservoirs↗
PubMed1995

Recommended biocontainment features for research and diagnostic facilities where animal pathogens are used. First International Veterinary Biosafety Workshop.

Recommendations are presented for the minimum structural components, special utilities, installations, and other design and operational features which define a microbiologically-secure animal containment facility. These biocontainment parameters are expected to enable the safe housing and handling of livestock and poultry infected with pathogenic agents. Physical testing and certification requirements for commissioning such facilities are described. Such a facility will minimise personnel exposure to infectious agents, limit cross-contamination between experiments, minimise horizontal transmission between research animals, and reduce the likelihood of pathogenic agents being released to the outside environment.

Animals↗
PubMed1995

Catheter cleaning for re-use in intermittent catheterization: new light on an old problem.

Clean intermittent catheterization is a common method of urinary elimination for people with Spinal Cord Injuries. The methods of catheter cleaning for re-use, however, have not been validated with research studies. This study compared the effectiveness of Hydrogen Peroxide, vinegar, dishwashing detergent, and tap water alone to clean catheters contaminated with Pseudomonas aeruginosa and Escherichia coli. The effect of rinsing and drying before cleaning was also examined, as well as the effect of storage in paper or plastic bags after cleaning. Results indicated that rinsing and drying catheters immediately after use was the most effective at reducing bacteria to very near zero. Elements of a procedure are outlined, as well as plans for further development and testing of a rinse & dry procedure for catheter cleaning and re-use.

Catheters, Indwelling↗
PubMed1994

Feasibility of a combined carrier test for disinfectants: studies with a mixture of five types of microorganisms.

BACKGROUND: There is mounting concern regarding the efficacy of many germicides on the market because officially recognized germicidal tests for various classes of microorganisms vary widely and often lack reproducibility and proper quantitation. We report here a carrier method for simultaneously and quantitatively assessing the efficacy of liquid chemical germicides against a mixture of microorganisms of varying degrees of resistance. METHODS: In the test, each small glass cup (10 mm wide x 14 mm long) was contaminated with 10 microliters of a standardized mixture of Staphylococcus aureus, Mycobacterium bovis bacille Calmette-Guérin, Trichophyton mentagrophytes spores, Sabin poliovirus type 1, and Bacillus stearothermophilus spores in 5% fetal bovine serum. The inoculum was dried for 60 minutes under ambient conditions and covered with 60 microliters of the disinfectant under test or a balanced salt solution control for the desired contact time. The carrier was then placed in 2940 microliters of an eluent and the eluates assayed separately for the five microorganisms. Tap water was used to dilute the test product as needed. RESULTS: Of the 11 products tested, 2% alkaline glutaraldehyde, 0.6% sodium hypochlorite (about 5000 ppm free chlorine), and a 0.4% quarternary ammonium compound containing 23% hydrochloric acid were effective against all five challenge organisms. A hard-surface spray containing 0.1% o-phenylphenol with 79% ethanol was effective against all but bacterial spores; 70% (volume/volume) ethanol alone and povidone-iodine (1% available iodine) were effective against S. aureus, the mycobacterium, and the fungus; a 3% solution of peroxygen compounds was effective only against S. aureus and the poliovirus; 1.5% chlorhexidine gluconate, 0.06% quaternary ammonia compound, and 0.03% o-phenylphenol + 0.03% p-tertiary amylphenol could inactivate nothing but S. aureus; and 3% hydrogen peroxide was ineffective in all tests. CONCLUSIONS: This method shows promise for use with various classes of microorganisms, individually or as mixtures. Its application should enable the classification of germicides according to spectrum of activity.

Disinfectants↗
PubMed1992

Effectiveness of handwashing agents in eliminating Staphylococcus aureus from gloved hands.

The recent emphasis on gloving has resulted in accounts of healthcare workers washing gloves instead of changing them. This study evaluated the efficacy of soap and three germicidal agents in decontaminating latex and vinyl medical gloves that were experimentally contaminated with Staphylococcus aureus. Gloves were tested for perforations before and after the glove-washing procedure. Results of this study demonstrated that contamination was reduced from the glove surfaces. Although the routine washing of gloved hands cannot be recommended, it may be carried out under limited circumstances.

Disinfectants↗
PubMed1990

Efficacy of a variety of disinfectants against Listeria spp.

The efficacy of 14 disinfectants against Listeria innocua and two strains of Listeria monocytogenes in the presence of organic matter was studied. Quantitative efficacy tests were used. Many of the disinfectants tested were not as effective on Listeria spp. when the test organisms were dried onto the surface of steel disks (carrier tests) as they were when the organisms were placed in suspension (suspension test). The presence of whole serum and milk (2% fat) further reduced the disinfectant capacities of most of the formulations studied. Only three disinfectants (povidone-iodine, chlorhexidine gluconate, and glutaraldehyde) were effective in the carrier test in the presence of serum; however, all three were ineffective when challenged with milk (2% fat). Only one solution, sodium dichloroisocyanurate, was effective in the presence of milk. All but four formulations (chloramine-T, phosphoric acid, an iodophor, and formaldehyde) were effective in the suspension tests, regardless of the organic load. L. monocytogenes was observed to be slightly more resistant to disinfection than L. innocua was. There was no difference in disinfectant susceptibility between the two strains of L. monocytogenes. These findings emphasize the need for caution in selecting an appropriate disinfectant for use on contaminated surfaces, particularly in the presence of organic material.

Animals↗
PubMed1990

Efficacies of selected disinfectants against Mycobacterium tuberculosis.

The activities of 10 formulations as mycobactericidal agents in Mycobacterium tuberculosis-contaminated suspensions (suspension test) and stainless steel surfaces (carrier test) were investigated with sputum as the organic load. The quaternary ammonium compound, chlorhexidine gluconate, and an iodophor were ineffective in all tests. Ethanol (70%) was effective against M. tuberculosis only in suspension in the absence of sputum. Povidone-iodine was not as efficacious when the test organism was dried on a surface as it was in suspension, and its activity was further reduced in the presence of sputum. Sodium hypochlorite required a higher concentration of available chlorine to achieve an effective level of disinfection than did sodium dichloroisocyanurate. Phenol (5%) was effective under all test conditions, producing at least a 4-log10 reduction in CFU. The undiluted glutaraldehyde-phenate solution was effective against M. tuberculosis and a second test organism, Mycobacterium smegmatis, even in the presence of dried sputum, whereas the diluted solution (1:16) was only effective against M. smegmatis in the suspension test. A solution of 2% glutaraldehyde was effective against M. tuberculosis. This investigation presents tuberculocidal efficacy data generated by methods simulating actual practices of routine disinfection.

Bacteriological Techniques↗
PubMed1988

Comparative mycobactericidal efficacy of chemical disinfectants in suspension and carrier tests.

The efficacy of nine disinfectants on Mycobacterium smegmatis was tested in the presence of sputum, using quantitative suspension and carrier tests. Glutaraldehyde, povidone iodine, and chlorhexidine gluconate produced at least a 6-log10 reduction in CFU in all tests. Four disinfectants (sodium dichloroisocyanurate, phenol, ethanol, and sodium hypochlorite) were not as effective in the carrier tests as in the suspension tests; this difference ranged from a 1- to a 5-log10 reduction in CFU. The efficacy of ethanol and sodium hypochlorite was further reduced (3- and 1-log10 reductions in CFU, respectively) in the presence of sputum. The quaternary ammonium compound and iodophor were ineffective in all tests. The findings of this study demonstrate the need for a quantitative carrier test such as the one presented here.

Aerosols↗
PubMed1988

Self-evaluation and its relationship to clinical evaluation.

An exploratory study was undertaken in a three-year nursing diploma program to determine instructor and student perceptions of self-evaluation (SE) and its relationship to clinical evaluation. A cross-section of instructors (n = 9) participated in three rounds of a Delphi survey. From this validated data base a questionnaire was developed and distributed to a stratified sample of 145 students. Combined results were then analyzed and compared. Results indicated that both students and instructors perceive self-evaluation more positively than negatively and they see the main purpose as providing direction for learning. Contrary to the literature and perceptions of surveyed instructors, students did not perceive self-evaluation as a factor in promotion of professional growth. Although students value a participatory role in clinical evaluation, the process of self-evaluation generates anxiety and underrating of performance. The authors conclude that self-evaluation is a developmental skill requiring guidelines and practice, and offer recommendations for its use.

Alberta↗
PubMed1983

Legionellaceae in the hospital water-supply. Epidemiological link with disease and evaluation of a method for control of nosocomial legionnaires' disease and Pittsburgh pneumonia.

An epidemiological link was found between contamination of a hospital water-supply by Legionella pneumophila and by Pittsburgh pneumonia agent (PPA) and subsequent cases of nosocomial legionnaires' disease and Pittsburgh pneumonia. The extent of L pneumophila isolation from the water-supply paralleled the occurrence of disease. Whenever L pneumophila was isolated from more than 30% of ten selected water sites, nosocomial legionellosis occurred. The temperature of the hot water tanks was raised to 60-77 degrees C for 72 h, and water outlets were flushed for 30 min with hot water. A decline in numbers of L pneumophila and PPA in the water-supply was followed by a fall in the incidence of legionnaires' disease and Pittsburgh pneumonia. In addition, intermittent raising of the temperature in the hot water system decreased both the number of months in which disease occurred and the proportion of nosocomial pneumonias caused by these organisms.

Cross Infection↗
PubMed1983

Legionella pneumophila contamination of a hospital humidifier. Demonstration of aerosol transmission and subsequent subclinical infection in exposed guinea pigs.

Water from a humidifier located in the hospital was found to be contaminated with Legionella pneumophila, serogroup 1. The source of water for the humidifier was the hospital potable water system. Exposure of culture mediums to the humidifier aerosols yielded L. pneumophila, serogroup 1. Exposure of guinea pigs to humidifier aerosols produced a subclinical infection as demonstrated by seroconversion to L. pneumophila. Seroconversion rate of guinea pigs to L. pneumophila was higher when greater quantities of L. pneumophila were present in the water; a corresponding increase in recovery of the organism from culture mediums exposed to aerosols was also seen. This report shows that mechanically created aerosols of Legionella-contaminated potable water might be the vehicle of transmission of Legionnaires' disease, especially in the hospital setting.

Aerosols↗
PubMed1977

Early environmental influences on conditioned and unconditioned ingestional and locomotor behaviors.

For 34-44 days after weaning one group of rats was raised in a socially enriched environment, whereas another group was raised in isolated individual cages without handling. Following this differential rearing subjects were tested for ingestional neophobia and its attenuation, enhancement of ingestional neophobia by aversive drug administration, taste-aversion learning and extinction, open-field activity, and passive shock-avoidance learning. Although the differential rearing influenced open-field activity and shock-avoidance this manipulation did not have a significant effect on the various measures of conditioned and unconditioned ingestional behaviors. The results provide further evidence for the distinctiveness of gustatory-visceral and telereceptor-cutaneous sensory systems.

Animals↗
PubMed1975

Experimental alphachymotrypsin glaucoma.

Experimental glaucoma was produced in 50% of rabbit eyes by injecting 75 units of alphachymotrypsin into the posterior chamber. The elevation of intraocular pressure was stable, rarely exceeded 50 mm Hg, and lasted one year or longer. Progressive buphthalmos first appeared 2 to 3 weeks following injection of the enzyme. Ocular histologic changes included bullous keratopathy, iris and ciliary body atrophy, and cupping of the optic disc. The optic nerve became atrophic but no cavernous degeneration occurred. In the retina there was thinning of the nerve fiber layer and loss of ganglion cells with preservation of the other retinal elements. The mechanism leading to glaucoma following alphachymotrypsin injection is unclear. This study demonstrated formation of peripheral anterior synechiae and reduction of outflow facility within 2 weeks following injection and these factors may play a role.

Animals↗