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.

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.

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.

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.

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.

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.

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.

The antibacterial activity and stability of acetic acid.

Acetic acid has been shown to have good antibacterial activity against micro-organisms such as Pseudomonas aeruginosa. This study examined the activity against a range of bacterial pathogens and also assessed any reduction in antibacterial activity due to evaporation or inactivation by organic material in dressings. Acetic acid was active at dilutions as low as 0.166% and the activity was not reduced by evaporation nor by inactivation by cotton swabs. Burn injuries are a major problem in countries with limited resources. Acetic acid is an ideal candidate for use in patients who are treated in those parts of the world.

Sporicides for Clostridium difficile: the devil is in the detail.

A taskforce has now been formed with representatives from the Department of Health's Advisory Committee on Antimicrobial Resistance and Healthcare Associated Infection (ARHAI), the Hospital Infection Society (HIS), the Department of Health (England) and the Health Protection Agency. The aims of the ARHAI/HIS Taskforce on Sporicidal Disinfectants are: to develop an accepted standard for laboratory testing of disinfectants which claim to have activity against C. difficile spores; to develop a network of laboratories with capability to perform in vitro assays of sporicidal activity of disinfectants; and to explore the creation of a national quality assessment scheme for laboratories which perform in vitro assays of sporicidal activity of disinfectants.

An evaluation of the suitability of the European suspension test to reflect in vitro activity of antiseptics against clinically significant organisms.

The effectiveness of four antiseptics representing soluble phenolics (Dettol), Quaternary Ammonium Compounds (QAC) (Dettol Hospital Concentrate: DHC), mixed QAC/chlorhexidine (Hibicet Hospital Concentrate: HHC) and povidone iodine (Betadine) was assessed using the proposed phase 2 step 1 European Suspension test. The in vitro activity of the antiseptics against two of the proposed challenge strains, i.e. Staphylococcus aureus and Pseudomonas aeruginosa, was compared with that of 14 problematic clinical isolates of bacteria from a range of genera, including some multiple antibiotic resistant strains, and a clinical isolate of Candida albicans. In addition to the 5 min contact time recommended in the European test, a 1 min time was included. All four products, at their recommended use dilutions and a contact time of 5 min, achieved a Microbicidal Effect (ME) log reduction of at least 5 against the majority of organisms. Differences in activity between products were more pronounced and therefore the tests more discriminatory, when the contact time was reduced to 1 min. The clinical strains were not overtly more resistant to antiseptics than the standard test strains, suggesting that the CEN test strains mimic the antiseptic susceptibility of clinical isolates.

Glutaraldehyde-resistant Mycobacterium chelonae from endoscope washer disinfectors.

Glutaraldehyde is used to disinfect flexible and other heat-sensitive endoscopes often with the aid of automated systems. Mycobacterium chelonae is being isolated with increasing frequency from these washer disinfectors and processed endoscopes. This has, on occasions, led to misdiagnosis and iatrogenic infections. Recent reports suggest that disinfecting machines, on a sessional or regular basis, with 2% glutaraldehyde may have selected and therefore encouraged the growth of strains of Myco. chelonae, possibly in biofilm, with decreasing susceptibility to glutaraldehyde. In view of this, the resistance of three strains of Myco. chelonae var. chelonae (the type strain NCTC 946 and two machine isolates) was tested against 2% glutaraldehyde and a wide range of alternative disinfectants. Disinfectants tested were a chlorine releasing agent, sodium dichloroisocyanurate at 1000 ppm and 10,000 ppm av Cl, 0.35% peracetic acid (NuCidex, Johnson & Johnson), 70% industrial methylated spirit (IMS), 1% peroxygen compound ('Virkon', Antec International) and 10% succine dialdehyde ('Gigasept', Sanofi Winthrop). Suspension and carrier tests were carried out in the presence and absence of an organic load. Results showed the type strain, which had not been exposed to the selective pressure of disinfectant usage, to be very sensitive to most disinfectants with the exception of 1% Virkon. The washer disinfector isolates, on the other hand, were extremely resistant to 2% glutaraldehyde and showed greater resistance to 1% Virkon and 1000 ppm NaDCC. Purchasing machines in which the entire fluid pathways, including those for delivering rinse water, are disinfected with an appropriate agent during each cycle are preferred. If this is not possible then sessional cleaning and disinfection at the start of each day and regular maintenance should prevent biofilm formation and contamination with disinfectant-resistant strains of mycobacteria. In addition to machine disinfection, the use of sterile or bacteria-free (filtered < 0.45 microm) water is essential for bronchoscopes and all invasive endoscopes. If there is doubt that the effectiveness of the machine disinfection procedure or water quality, the channels and surfaces of endoscopes may be rinsed with 70% IMS after automated processing.

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.