A history of lameness and low body condition score is associated with reduced digital cushion volume, measured by magnetic resonance imaging, in dairy cattle.

Claw horn lesions (CHL) are the result of a failing of the functional anatomy of the hoof in dairy cows. The digital cushion is understood to be a vital structure in the prevention of CHL. Claw horn lesions have previously been shown to lead to pathological change to the pedal bone; however, their effects on the digital cushion are unknown. The primary aim of this study was to examine associations between the history of CHL through an animal's life and the structure of the digital cushion at slaughter using magnetic resonance imaging. The retrospective cohort study resulted in the scanning of 102 pairs of hindfeet, collected from adult Holstein dairy cows culled from a research herd, using a 3-Tesla research-grade magnetic resonance imaging scanner. Volume and fat measurements were calculated for each digital cushion within each claw from a modified Dixon Quant sequence. Animal-level variables were constructed around the animals' lactating lifetime, with lameness scores and body condition score collected at least every 2 wk. The combined volume of digital cushion in the lateral claws was used as the outcome variable in multivariable linear models. The volume of the digital cushion was negatively associated with the number of lameness events or CHL recorded. Furthermore, animals with body condition score >3, culled later in lactation, or of a greater body weight were more likely to have a higher volume of digital cushion in the lateral claws. We propose that the observations made in the current study are the effects of a range of factors broadly associated with genetic, developmental, and disease-related inputs. Our understanding of how we can select for genetically more robust animals and how we can precondition the hoof before first calving needs to be improved to reduce the risk of future CHL in adult dairy cattle. Furthermore, understanding optimal treatment regimens and their effect on hoof anatomy may reduce the recurrence of CHL in the current lactation and future lactations.

Beaufort trout MicroPlex: a high-throughput multiplex platform comprising 38 informative microsatellite loci for use in resident and anadromous (sea trout) brown trout Salmo trutta genetic studies.

A flexible panel consisting of 38 informative microsatellite markers for Salmo trutta is described. These markers were selected from a pool of over 150 candidate loci that can be readily amplified in four multiplex PCR groups but other permutations are also possible. The basic properties of each markers were assessed in six population samples from both the Burrishoole catchment, in the west of Ireland, and Lough Neagh, in Northern Ireland. A method to assess the relative utility of individual markers for the detection of population genetic structuring is also described. Given its flexibility, technical reliability and high degree of informativeness, the use of this panel of markers is advocated as a standard for S. trutta genetic studies.

Colloid formation during waste form reaction: implications for nuclear waste disposal.

Insoluble plutonium- and americium-bearing colloidal particles formed during simulated weathering of a high-level nuclear waste glass. Nearly 100 percent of the total plutonium and americium in test ground water was concentrated in these submicrometer particles. These results indicate that models of actinide mobility and repository integrity, which assume complete solubility of actinides in ground water, underestimate the potential for radionuclide release into the environment. A colloid-trapping mechanism may be necessary for a waste repository to meet long-term performance specifications.

Guidance for the decontamination of intracavity medical devices: the report of a working group of the Healthcare Infection Society.

BACKGROUND: Intracavity medical devices (ICMDs) are used in a wide variety of healthcare settings. The approach to their decontamination and the resources available also differ widely. Their potential for infection transmission is considerable. AIM: To produce a comprehensive risk assessment-based approach to the decontamination of ICMDs, accompanied by an adaptable audit tool.

Comparison of the efficacy and drying times of liquid, gel and foam formats of alcohol-based hand rubs.

BACKGROUND: Hand rubs containing alcohols such as isopropanol (IPA) or ethanol (EtOH) are widely used for hygienic hand disinfection, and are presented in different formats (i.e. liquid, gel or foam). AIM: To determine if there is any difference in efficacy between these two active ingredients in the three formats. In addition, an assessment of the drying time was undertaken. Two non-commercial, 'standard' formulations were tested in each format: one containing 60% IPA, and the other containing 80% EtOH. METHODS: EN 1500 tests were performed with 20 volunteers to assess efficacy. The reference product was 2 x 3 mL of 60% IPA for 60 s, as described in EN 1500 (2013). The test products were 3 mL of liquid, gel or foam format; one full EN 1500 test was performed for each formulation (60% IPA and 80% EtOH). To assess drying time, two different volumes (1.5 and 3.0 mL) of the test formulations in liquid, gel or foam format were applied to the hands of 15 volunteers. Volunteers self-reported when their hands were dry; at the end of the test, the volunteers were asked to rate the time taken to dry on a three-point scale (too short, OK, too long). FINDINGS: This study found no difference in antibacterial efficacy attributable to formulation or format for the two 'standard' ABHR formulations, as assessed by EN 1500. When measured objectively, the EtOH-based formulations dried more rapidly than the IPA-based formulations, and for both formulations, gels took longer to dry than other formats. User perception of drying time broadly agreed with objective measurement. CONCLUSION: Given that there was no difference in efficacy and only moderate difference in drying time, it is proposed that ABHR in liquid, foam or gel format may be appropriate, provided that the specific product passes the required efficacy and safety standards.

Assessment of the efficacy of a patient hand wipe: development of a test method.

BACKGROUND: Much attention has focused on hand decontamination for healthcare workers, but little attention has been paid to patient hand hygiene. Patients confined to bed are often unable to access handwashing facilities. They could use an alcohol hand rub, but these are not advised for soiled hands or social hand hygiene. One alternative is the use of a hand wipe. However, it is important to ascertain the effectiveness of hand wipes for removal of transient micro-organisms from the hands. AIM: To develop a method to assess the antimicrobial efficacy of hand wipes compared with handwashing, and thus determine if a hand wipe can be acceptable for patient hand hygiene. METHODS: The methodology was based on European Standards EN 1499 (2013) and EN 1500 (2013) as there is no standard for hand wipes. The hands of 20 healthy volunteers were contaminated artificially by immersion in Escherichia coli, and then sampled before and after the use of a reference soft soap or hand wipes for 60 s. The counts obtained were expressed as log10, and the log10 reductions were calculated. FINDINGS: The hand wipe with no antimicrobial agent (control wipe) was inferior to the soft soap. However, the antimicrobial hand wipe was statistically non-inferior to the soft soap. A log10 reduction of 3.54 was obtained for the soft soap, 2.46 for the control hand wipe, and 3.67 for the antimicrobial hand wipe. CONCLUSION: The evidence suggests that the antimicrobial hand wipe, when applied for 60 s, is at least as good as soap and water, representing an acceptable alternative to handwashing from a bactericidal perspective.

Dose considerations for alcohol-based hand rubs.

BACKGROUND: Manufacturers' recommended dosages for alcohol-based hand rubs are typically determined by measuring product efficacy using a model protocol such as EN 1500; however, anecdotal reports and informal observation suggests that in many cases users self-titrate to much lower doses in real-world application. AIM: To examine the interdependence of alcohol-based hand-rub volume on in-vivo efficacy using the EN 1500 standard test method, on drying time on users' hands, and on their perceptions of acceptability. METHODS: Three formulations were studied using EN 1500 and a modification of this method. The modification used volumes ranging from 0.5 to 3.0 mL and 30 s application. Drying times were recorded and user acceptability was established using a three-point scale (too long, OK, or too short). Dying times were analysed in relation to hand surface area. FINDINGS: The drying time for all three products increased as a function of volume. The drying time displayed a positive association with volume and a negative association with hand surface area. The optimum volume for user acceptability was between 1.5 and 2 mL, yielding a drying time of between 20 and 30 s. CONCLUSION: Whereas EN 1500 is appropriate for establishing the efficacy of a hygienic hand-rub formulation compared to a benchmark, it does not reflect actual in-use conditions or the likely clinical effectiveness of the product. In particular, it fails to address the need to optimize the volume of application and user acceptability of the product.

Decontamination of heater-cooler units associated with contamination by atypical mycobacteria.

BACKGROUND: Non-tuberculosis mycobacteria such as Mycobacterium chimaera are found widely in hospital water systems. Invasive M. chimaera infections have recently been attributed to heater-cooler units (HCUs) of cardiopulmonary bypass equipment. AIM: To assess the extent of microbiological contamination within the HCUs and to inform decontamination strategies for reducing the microbial load. METHODS: Water samples taken from HCUs used at University Hospitals Birmingham for cardiopulmonary bypass surgery were sampled to determine the number of micro-organisms by membrane filtration. Various decontamination processes were used throughout the study, all based on the manufacturer's guidance. FINDINGS: Total viable counts >300cfu per 100mL containing a wide variety of micro-organisms were obtained from water inside the HCUs. Working with the manufacturers, we significantly reduced the microbial load of the water within the HCUs by removing the internal tubing soiled with biofilm followed by a weekly decontamination regimen with peracetic acid. CONCLUSION: A decontamination cycle including an initial replacement of internal tubing with weekly microbiological water samples is required to maintain the water quality within HCUs at an acceptable level.

Development of a sporicidal test method for Clostridium difficile.

BACKGROUND: Disinfectants with claimed activity against Clostridium difficile must be evaluated to ensure efficacy against the spores that comprise an environmental source of patient infection. Unfortunately there is, at present, no generally accepted method for evaluating these disinfectants. In the absence of such a method, laboratories have to adapt protocols that were not designed for products used in medical environments and consequently may use inappropriate test organisms, exposure times, and pass criteria. AIM: To develop and evaluate a method for testing the activity of disinfectants against C. difficile spores using exposure times and pass criteria which are relevant to clinical application. METHODS: A Joint Working Party of the Healthcare Infection Society (HIS) and the Advisory Committee on Antimicrobial Resistance and Healthcare Associated Infections (ARHAI) of the Department of Health in England was assembled. The Working Party adapted a previously described enzyme-based method for spore purification (the Clospore method) using an exposure time of 5 min and a 5 log10 kill as a pass criterion. FINDINGS: Evaluation of the method by three laboratories demonstrated that the method is simple to follow and that the results are repeatable and reproducible. CONCLUSION: The method described by the Working Party produces a clean suspension with a high titre of spores. It is recommended that, for a disinfectant used in the environment, the product should demonstrate a 5 log10 reduction in 5 min under clean or dirty conditions to fulfil the requirements of the test.

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.

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.

Heat and chemical resistance of enterococci.

Recent reports have highlighted the tolerance of vancomycin-resistant strains of enterococci to heat. This study examined the tolerance of vancomycin-resistant and sensitive strains of enterococci and an NCTC type strain to 65, 71 and 80 degrees C, and also to low concentrations of a chlorine-releasing agent, alcohol and glutaraldehyde. Variation in the tolerance to chemicals was observed but there was no correlation between vancomycin resistance and tolerance to chemical disinfectants. The NCTC type strain was killed within the time/temperature parameters set by the Department of Health for thermal washer/disinfectors, i.e. 65 degrees C for 10 min, 71 degrees C for 3 min and 80 degrees C for 1 min. However, the clinical strains showed varying resistance to heat, irrespective of their vancomycin susceptibility. One strain survived 80 degrees C for 3 min. These results showed that clinical isolates can be resistant to commonly used disinfection processes, although the practical significance of these results is debatable.

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.

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.

Comparison of automated systems for the cleaning and disinfection of flexible fibreoptic endoscopes.

A comparison of four cleaning and disinfection machines is described. These varied considerably in design and function and although no single machine possessed all the preferred characteristics, cleaning and disinfection, particularly between patients, was substantially improved. Before purchasing a machine it is recommended that the user ensures that it is convenient to operate, effective in removing soil and bacteria, and adaptable to the range of fibrescopes used within the unit. Infections are often caused by Gram-negative bacilli which are particularly difficult to remove manually from moist narrow channels of the fibrescope and perfusion of all channels including the air channel, is, therefore, recommended. Thorough cleaning and disinfection will not only reduce the likelihood of infection but will also reduce channel blockages and the general deterioration of the fibrescope.

Bacterial contamination and frequency of changing ventilator circuitry.

A questionnaire sent to 40 intensive care units showed that ventilator circuits were changed every 24 h in 62% and every 48 h in 20% of the units. A similar survey in 40 special-care baby units showed that only 9.7% changed circuits daily and the majority were changed weekly (38.7%) or between patients (38.7%). A prospective study of bacterial contamination of circuits in adult patients showed that when water humidification was used, 28/72 samples from inspiratory and 31/72 from expiratory tubing were contaminated with Gram-negative bacilli. None of 48 sets of tubing was contaminated when a heat-moisture exchanger was used and only one expiratory tube was contaminated in tubing from 45 neonates using a water humidifier. Gram-negative bacilli were isolated from the mouths of 21/36 adults and 6/12 neonates, and also from 6/17 hands of staff after changing circuits. It is suggested that circuits with water humidification may be changed every 48 h in adult patients, and between patients or weekly in neonatal units or between patients if a heat-moisture exchanger is used. Handwashing after removal of a circuit is of major importance in the prevention of spread of infection.

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.

Genome sequencing and characterization of an extensively drug-resistant sequence type 111 serotype O12 hospital outbreak strain of Pseudomonas aeruginosa.

A series of extensively drug-resistant isolates of Pseudomonas aeruginosa from two outbreaks in UK hospitals were characterized by whole genome sequencing (WGS). Although these isolates were resistant to antibiotics other than colistin, we confirmed that they are still sensitive to disinfectants. The sequencing confirmed that isolates in the larger outbreak were serotype O12, and also revealed that they belonged to sequence type ST111, which is a major epidemic strain of P. aeruginosa throughout Europe. As this is the first reported sequence of an ST111 strain, the genome was examined in depth, focusing particularly on antibiotic resistance and potential virulence genes, and on the reported regions of genome plasticity. High degrees of sequence similarity were discovered between outbreak isolates collected from recently infected patients, isolates from sinks, an isolate from the sewer, and a historical isolate, suggesting that the ST111 strain has been endemic in the hospital for many years. The ability to translate easily from outbreak investigation to detailed genome biology by use of the same data demonstrates the flexibility of WGS application in a clinical setting.