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Biomedical subjects

J R Babb

Publications and source records attributed to J R Babb.

At least 19 recordsLinked to original sources
PubMed1995

Endoscope decontamination: automated vs. manual.

Automated endoscope washer disinfectors are widely used for the decontamination of flexible endoscopes. They are more effective than manual techniques and reduce the likelihood of skin contact with irritant disinfectants. Suitable machines are those which effectively clean, disinfect and rinse all channels and external surfaces without damaging the instrument. If glutaraldehyde is used, fumes should be removed or contained to protect endoscopy and processing staff. Machines should also be equipped with a self-disinfect facility and the rinse water should be of a suitable microbiological quality for the instruments processed, i.e. bacteria-free (sterile or filtered) water should be used for bronchoscopes and all invasive endoscopes. The choice of machine and cycle will depend on the following: whether a mobile or fixed unit is required; the type of disinfectant used; instrument throughput; and whether or not it is necessary to process more than one endoscope at a time. Purchasers are advised to request independent test reports which substantiate manufacturers' claims.

Automation↗
PubMed1995

Endoscope decontamination: where do we go from here?

Thorough cleaning and disinfection or sterilization of endoscopes and associated equipment will reduce the likelihood of misdiagnosis and post-procedural infection. It will also prevent instrument deterioration and malfunction. With a rapid escalation in demand for endoscopy, particularly that associated with minimally invasive surgery, it is important that we have the processing technology to match the diagnostic and therapeutic value of these instruments without exposing staff and patients to unnecessary risk. Wherever possible staff should purchase heat tolerant endoscopic equipment that is readily accessible for cleaning. Automated processors, e.g. washer disinfectors and ultrasonic cleaners, improve the quality of the decontamination process but machines must have a self-disinfect function to prevent instrument recontamination during processing. Sterile, or filtered bacteria-free, water is essential for bronchoscopes and invasive instruments. Glutaraldehyde is still the most widely used disinfectant, particularly for the heat sensitive flexible endoscopes, but it is irritant and sensitizing and a safer alternative is sought. Peracetic acid is more rapidly efficacious and probably less irritant and, provided it does not damage endoscopes and processing equipment, may prove a suitable alternative. Unfortunately there are no nationally agreed test methods for assessing this and other new endoscope disinfectants and therefore no register of suitable or approved products. There is also no proven safe alternative to ethylene oxide for sterilizing invasive heat labile flexible endoscopes. It is important that, if toxic disinfectants and sterilants are used, staff and patients are suitably protected from exposure. Update training is essential for all processing staff if infection risks are to be minimized and sensitization problems avoided.

Cross Infection↗
PubMed1995

Risk of airborne transmission in an operating theatre containing four ultraclean air units.

This study shows that a single, large, operating theatre (barn) containing four ultraclean operating units (cabins), was highly effective in reducing the number of airborne bacteria in the operating fields providing all occupied ultraclean cabins were functioning correctly. The air flows and bacterial counts during operations within the cabins met the current standard for ultraclean systems (HTM 2025 1994) and there was no evidence of mixing of air between cabins. It is, however, recommended that air flows are regularly checked for compliance with the standard. If failure occurs in any single ultraclean unit, surgery in that cabin should cease as contaminated air may enter from the barn and surrounding cabins. Routine microbiological sampling should not be necessary providing there is no evidence of filter leakage. An operating theatre with several ultraclean operating tables in a single room would appear to be a viable proposition for the future. Considerable savings are likely in revenue costs as much of the air is reused and support services are shared.

Air Microbiology↗
PubMed1995

Infection risk and potential contamination of urine specimens associated with sample port design of catheter leg bags.

The ease of disinfection of the sample ports of three types of urine drainage leg bags with different sampling port systems was assessed using a bladder bag model. The ports were contaminated with Escherichia coli, 'disinfected' using a standard method, then sampled at time intervals up to one week after contamination. It was discovered that leg bags which employ a needle-based sampling system (the 'sample safe port system') were easier to disinfect than those which did not, and that organisms are retained in large enough numbers to lead to misdiagnosis of a urinary tract infection or to pose a retrograde infection risk.

Catheters, Indwelling↗
PubMed1995

Evaluation of the Steris System 1 Peracetic Acid Endoscope Processor.

An automated endoscope sterilizing machine, the Steris System 1 Processor, was tested for bactericidal and sporicidal efficacy. The disinfectant, peracetic acid, was diluted to 0.2% within an enclosed system. The exposure time to the disinfectant was 12 min and the overall cycle time ranged from 25-38 min, mean 29 min. Preliminary suspension tests, with and without yeast or serum, showed a log10 reduction of > 5 with Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis in 5 min with 0.2% peracetic acid. After a routine cycle in the machine, endoscopes contaminated with the same organisms showed no growth. Two of 24 spore strips, containing 10(6) B. subtilis showed a small number of survivors (less than 10 per strip). No significant damage to the endoscope was observed although the number of cycles tested was small (i.e. 31). The advantage of the system is that staff are not directly exposed to the agent, but the costs per cycle are higher than glutaraldehyde, since peracetic acid is not renewed. Unlike other automated processors the Steris machine has no cleaning cycle.

Bacillus subtilis↗
PubMed1994

Methods of cleaning and disinfection.

Most equipment associated infection is due to inadequate cleaning and disinfection and not a failure in sterilisation practices. The method of disinfection chosen should depend on the risks associated with the procedure undertaken, the heat, pressure and chemical tolerances of the item and the time available for processing. Heat disinfection or sterilisation is preferred but if the item is heat sensitive, chemicals may have to be used. It is important that the process selected is effective against patient associated organisms and opportunistic pathogens present in the environment. The most effective stage of any decontamination procedure is thorough cleaning and this should accompany or precede all disinfection procedures. Automated processors offer the safest, most reliable option, providing they are suitably monitored and maintained and that staff wear appropriate protective clothing.

Disinfection↗
PubMed1993

A test for the assessment of 'hygienic' hand disinfection using rotavirus.

A standardized test procedure is described in which finger tips are inoculated with bovine rotavirus. The level of virus recovered after disinfection of artificially contaminated hands with various disinfectant detergents, alcoholic solutions and alcoholic formulations was determined. The method was found to be easy to perform and reproducible. The most efficient method for removal of virus from fingertips was found to be treatment with alcoholic solutions or products. Soap and water and disinfectant detergents were found to be a much less effective method of removing virus from contaminated hands.

Alcohols↗
PubMed1993

Preliminary study of test methods to assess the virucidal activity of skin disinfectants using poliovirus and bacteriophages.

Two tests for assessing the virucidal activity of antiseptics are proposed. These involve applying either poliovirus (vaccine strain Sabin 1 an) or Escherichia coli bacteriophage (MS2 or K1-5) to the fingertips. Both test viruses are considered safe although poliovirus may be unacceptably tolerant to antiseptics. The use of bacteriophages as test organisms precludes the need for sophisticated recovery systems and can be undertaken readily by any bacteriology laboratory. The virucidal activity of 70%, 80% and 90% ethanol, 7.5% povidone-iodine, and soap and water was assessed using these tests. Thorough cleansing, followed by disinfection with 90% ethanol, was the most effective treatment. Removal of viruses from the gloved hand was also assessed and this was found to be more easily achieved than cleaning and disinfecting the ungloved hand. Wearing gloves protects the hands from viral contamination but changing them after each patient or contact is expensive.

Administration, Topical↗
PubMed1991

The mechanics of endoscope disinfection.

The decontamination of flexible fibreoptic endoscopes has considerably improved in recent years. This is mainly due to the introduction of instruments with more accessible channels, the use of automated washer disinfectors and a greater awareness of the problems associated with disinfection. Unfortunately the most widely used and effective disinfectant is 2% glutaraldehyde and this is toxic, irritant and sensitizing. With the implementation of Control of Substances Hazardous to Health legislation, strict environmental controls are required to reduce skin contact and vapour inhalation. Alcohol is probably the most suitable alternative disinfectant at present but it is flammable and cannot be used in automated systems. Other agents are either insufficiently effective or corrosive. Autoclavable or heat tolerant rigid endoscopes are now available but flexible endoscopes will not tolerate heat disinfection temperatures.

Disinfection↗
PubMed1991

A test procedure for evaluating surgical hand disinfection.

A technique for assessing the immediate and prolonged efficacy of surgical scrubs and alcoholic hand rubs is described. A mean baseline count is obtained from all volunteers and logarithmic reductions in resident skin flora immediately after one or more applications, and after wearing gloves for 3 h, are measured. Loose-fitting surgical gloves are used for sampling resident flora. Preparations were applied using a standard technique for 2 min, apart from one test with 70% isopropanol (IPA) in which the application time was 30 s. Two studies are described, one of which compared four chlorhexidine scrubs, and the second 70% IPA, 7.5% povidone-iodine scrub, 2% triclosan cleanser and unmedicated bar soap. In spite of their constituent similarity, the four chlorhexidine scrubs varied considerably in efficacy and user acceptability. A 2 min application of 70% IPA was the most effective treatment, and gave log10 reductions of 1.65 for immediate and 1.58 for prolonged effect. This was marginally more effective than a 30 s application, but the difference was not significant. 'Hibiscrub' was the most effective aqueous formulation and gave reductions of 1.01 for immediate effect and 1.16 for prolonged effect. The test described could be used by reference centres and manufacturers to assess the efficacy of new and existing surgical hand disinfection formulations.

Adolescent↗
PubMed1990

Hygienic hand disinfection tests in three laboratories.

A comparative study was made in three laboratories of a test for hygienic hand disinfection. Staphylococcus aureus was applied to the fingertips of a total of 74 volunteers (49 female and 25 male) and the effect of washing with three chlorhexidine preparations and one non-medicated soap was assessed after one and five applications. Fingertip inoculation is convenient and is a realistic representation of the in-use situation. Although significant differences were obtained between log10 reductions in test organisms using the same formulation in different centres, and different periods in the same centre, the maximum differences after a single application of a preparation were small, e.g. between centres 0.39 and between periods in the same centre 0.55, and after multiple applications the maximum difference between centres was 0.42 and between periods in the same centre it was 0.51. The differences between preparations were similar in all centres. This test compares well with other similar tests and products can be placed in rank order of effectiveness. It is concluded that this test, if carried out under the controlled conditions described, is sufficiently reproducible between laboratories and repeatable within laboratories to be used as a standard test.

Chlorhexidine↗
PubMed1989

Bacteriological sampling of postmortem rooms.

Thirty hospital and coroners' postmortem rooms in the West Midlands were visited over two years. The design, environmental facilities, and hygienic practices were investigated and air exchange rates were measured. Microbiological samples were taken from the environment and from gloves, hands, and protective clothing of staff. Glove punctures were also recorded and a plastic isolator evaluated. Bacterial counts in the air were low and related more to the number of people in the room than to the air exchange rate. There was little evidence of the production of aerosol containing bacteria, although splashing occurred while intestines were being washed out. Surfaces often remained contaminated with Gram negative bacilli after cleaning but numbers were considerably reduced on drying. Decontamination of instruments was satisfactory. A wide range of disinfectants and concentrations was used, but none showed evidence of contamination. Gloves were heavily contaminated after use, and occasionally the hands of the wearer after removal of the gloves. Washing the hands effectively removed residual transient organisms, irrespective of the agent used. The incidence of glove punctures was higher among technicians (38%) than pathologists (12%). The plastic isolator reduced smells and limited environmental contamination but visibility and acceptability were poor. The results of the study suggest that there is little evidence of risk of infection to staff, providing basic hygienic precautions are taken, but consideration should be given to the prevention of glove punctures.

Air Microbiology↗
PubMed1988

Hand disinfection: a comparison of various agents in laboratory and ward studies.

The efficacy of 14 handwashing or disinfectant preparations was compared in laboratory tests on staff volunteers. The test organism, Escherichia coli, was applied to the fingertips and log reductions (LR) were measured following treatment with the test agent and control preparations (70% isopropanol and non-medicated bar soap). Alcoholic preparations, particularly n-propanol and isopropanol were the most effective showing LRs of 3.1-3.8. Chlorhexidine (LR 2.9) and povidone-iodine detergent preparations were significantly more effective than non-medicated soap (LR 2.1), but triclosan products were not. In addition the residual effect of several of these formulations was assessed after 10 applications by comparing the survival of E. coli on the fingertips over a 32-min period. This number of handwashes compares favourably with those recorded during an 8 h nursing shift. Chlorhexidine-detergent consistently showed the best residual activity. Alcoholic formulations showed little or no residual effect. The survival studies show that on the whole gram-positive organisms (Staphylococcus aureus and Candida albicans) survive better on the skin than Gram-negative bacilli (GNB). However, it would seem that GNB which are considered to be residents (Acinetobacter calcoaceticus and Enterobacter spp.) survive much better than many other GNB (Pseudomonas aeruginosa, E. coli and Proteus vulgaris). The Klebsiella species varied in survival times. Random sampling of ward staff hands showed that contamination with S. aureus and GNB was greater in dermatological and general wards than in an isolation unit, where handwashing or disinfection was carried out after every patient contact. No cross-infection occurred in the isolation ward during periods of study in which 70% alcohol, chlorhexidine-detergent and non-medicated soap were used.

Alcohols↗
PubMed1988

Methods of reprocessing complex medical equipment.

The choice as to which of the two gaseous processes is best suited to individual hospital needs is a difficult one. Very few items are unable to tolerate 73 degrees C (LTSF) and these few can withstand 37 degrees C or 55 degrees C (EO). Unfortunately, LTSF is a 'moist' process and sterilizers have a poor history of providing sterilization without modification, and consequently few are used. Ethylene oxide is more reliable, but environmental hazards are greater and running costs high. Both processes are time-consuming and the use of sporicidal disinfectants such as glutaraldehyde is often the only practical alternative. Before purchasing any gaseous sterilizer it is essential to consider throughput and the availability of alternative processes. It may prove sensible to share facilities or at least offer a regional facility. It is certainly not worthwhile purchasing expensive gas sterilizers for reprocessing inexpensive single-use items or for those that require disinfection only. Low temperature steam is safe, inexpensive and no special environmental provisions are necessary. It is, however, not a sterilization process. Disinfectants, hot water and steam will continue to be the only suitable methods for reprocessing items outside the hospital sterile supply department or disinfection unit. Concern over the decontamination of blood-stained instruments following use on patients with hepatitis B or HIV has led to an upsurge of interest in boilers and inexpensive bench top ovens and autoclaves. Such processes are likely to prove more effective than disinfectants but should heat treatment prove impractical then 2% glutaraldehyde or 70% alcohol may be used.(ABSTRACT TRUNCATED AT 250 WORDS)

Cross Infection↗