Waterline Disinfectants Reduce Dental Bioaerosols: A Multitracer Validation

Oral microbes are dispersed during dental treatment and reduction methods have been proposed, but dental unit waterline (DUWL) disinfectants have received little attention; specifically, the effect on viruses has not been studied. This study aims to 1) investigate the effect of DUWL disinfectants on viral dispersion in dental bioaerosols and 2) establish a dual-tracer system using live bacteriophage and fluorescein supported by optical particle measurement. Bacteriophage MS2 was used as a viral tracer and fluorescein as a fluorescent tracer. Validation experiments were conducted to exclude interference of one tracer with the other or of DUWL disinfectants on detection methods. Simulated “saliva” containing the tracers was infused into the mouth of a dental mannequin during 10-min dental procedures with an air turbine handpiece (n = 3 replicates). Aerosols and droplets were sampled in an enclosed dental operatory using air samplers and settlement onto sterile filter papers. Bacteriophage was quantified using plaque assays and reverse transcription quantitative polymerase chain reaction (RT-qPCR). Fluorescein was quantified fluorometrically. The effect of DUWL disinfectants on total aerosol concentration was assessed in separate experiments using an optical particle counter. DUWL disinfectants reduced bacteriophage viability, and interference between tracers was not observed. In simulated clinical procedures, the disinfectant ICX reduced bacteriophage detection substantially (P < 0.001; 2-way analysis of variance). MS2 RNA was detected in all experimental samples but not negative controls. Samples positive on RT-qPCR but not plaque assays may indicate that virions at distant sites are nonviable. Fluorescein tracer showed good agreement with the bacteriophage tracer. DUWL disinfectants designed for continuous presence in irrigants reduce the dispersion of viable virus in dental bioaerosols during simulated procedures. Their use may therefore be important for routine infection control and as a mitigation factor during infectious disease outbreaks. Future studies should explore this using a range of viruses and other microbes.

Local Exhaust Ventilation to Control Dental Aerosols and Droplets

Dental procedures produce aerosols that may remain suspended and travel significant distances from the source. Dental aerosols and droplets contain oral microbes, and there is potential for infectious disease transmission and major disruption to dental services during infectious disease outbreaks. One method to control hazardous aerosols often used in industry is local exhaust ventilation (LEV). The aim of this study was to investigate the effect of LEV on aerosols and droplets produced during dental procedures. Experiments were conducted on dental mannequins in an 825.4-m³ open-plan clinic and a 49.3-m³ single surgery. Ten-minute crown preparations were performed with an air-turbine handpiece in the open-plan clinic and 10-min full-mouth ultrasonic scaling in the single surgery. Fluorescein was added to instrument irrigation reservoirs as a tracer. In both settings, optical particle counters (OPCs) were used to measure aerosol particles between 0.3 and 10.0 µm, and liquid cyclone air samplers were used to capture aerosolized fluorescein tracer. In addition, in the open-plan setting, fluorescein tracer was captured by passive settling onto filter papers in the environment. Tracer was quantified fluorometrically. An LEV device with high-efficiency particulate air filtration and a flow rate of 5,000 L/min was used. LEV reduced aerosol production from the air-turbine handpiece by 90% within 0.5 m, and this was 99% for the ultrasonic scaler. OPC particle counts were substantially reduced for both procedures and air-turbine settled droplet detection reduced by 95% within 0.5 m. The effect of LEV was substantially greater than suction alone for the air-turbine and was similar to the effect of suction for the ultrasonic scaler. LEV reduces aerosol and droplet contamination from dental procedures by at least 90% in the breathing zone of the operator, and it is therefore a valuable tool to reduce the dispersion of dental aerosols.

Botulinum toxin-A for the treatment of overactive bladder: UK contributions

Background:

Botulinum toxin-A (BoNT/A) is now established second-line management for refractory overactive bladder (OAB) and recognised in many incontinence guidelines and pathways. For those with neurogenic detrusor overactivity secondary to spinal cord injury or multiple sclerosis, the toxin is currently licensed in certain parts of the world, including the UK. It is an effective treatment in those in whom antimuscarinics and conservative measures have failed who have symptoms of OAB and or detrusor overactivity (DO).

Methods:

Treatment can be given in an outpatient setting and can be administered under local anaesthesia. Its efficacy lasts for between six and 12 months.

Results:

It has an acceptable safety profile with the biggest risk being urinary tract infection and difficulty emptying the bladder, necessitating clean intermittent self-catheterisation (CISC). Medium-term follow-up suggests repeated injections are also safe and efficacious.

Conclusions:

The mechanism of action of the toxin is more complicated than originally thought, and it seems likely that it affects motor and sensory nerves of the bladder. In the last 10 years much of the progress of this treatment from early experimental trials to mainstream clinical use, and a better understanding of how it works in the bladder, are as a result of research conducted in the UK. This review summarises the significant and substantial evidence for BoNT/A to treat refractory OAB from UK centres.

Indistinguishability and identifiability of kinetic models for the MurC reaction in peptidoglycan biosynthesis

An important question in Systems Biology is the design of experiments that enable discrimination between two (or more) competing chemical pathway models or biological mechanisms. In this paper analysis is performed between two different models describing the kinetic mechanism of a three-substrate three-product reaction, namely the MurC reaction in the cytoplasmic phase of peptidoglycan biosynthesis. One model involves ordered substrate binding and ordered release of the three products; the competing model also assumes ordered substrate binding, but with fast release of the three products. The two versions are shown to be distinguishable; however, if standard quasi-steady-state assumptions are made distinguishability cannot be determined. Once model structure uniqueness is ensured the experimenter must determine if it is possible to successfully recover rate constant values given the experiment observations, a process known as structural identifiability. Structural identifiability analysis is carried out for both models to determine which of the unknown reaction parameters can be determined uniquely, or otherwise, from the ideal system outputs. This structural analysis forms an integrated step towards the modelling of the full pathway of the cytoplasmic phase of peptidoglycan biosynthesis.

The safety and efficacy of botulinum toxin-A in the management of bladder oversensitivity: a randomised double-blind placebo-controlled trial

OBJECTIVE

To assess the safety and efficacy of botulinum toxin-A (botn-A) in the management of patients with bladder oversensitivity (BO).

PATIENTS AND METHODS

Twenty-three consecutive patients with a diagnosis of BO refractory to anticholinergics were enrolled in this randomised, double blind, placebo-controlled trial. Patients were randomly allocated to receive intradetrusor injections of either botn-A (100 U Botox) or saline (placebo) via a flexible cystoscopic approach. The study was designed to have 90% power to detect a change in the maximum cystometric capacity (MCC) of 30%. It was calculated that a total cohort of 58 patients would be required. Urodynamic assessment (UDS), voiding diaries (VD) and quality of life (QoL) were assessed at baseline and at 4 and 12 weeks following intervention.

RESULTS

An interim analysis was performed and the trial halted after recruitment of 23 patients as a result of poorly perceived patient benefit. Data were analysed for 21 patients (10 botn-A; 11 placebo). In the treatment arm, there was a significant increase in MCC (mean rise 105 ml; p = 0.009). However, storage symptoms remained statistically unchanged following botn-A. Three patients in the treatment arm were required to perform clean intermittent self-catheterisation with no clinical improvement. The limitations of this trial include the small sample size and the unplanned interim analysis.

CONCLUSIONS

This is the first randomised, double blind, placebo-controlled trial examining the effects of botn-A exclusively in patients with BO. A significant increase in MCC was observed but this did not translate to clinical benefit with no change observed in the symptoms and quality of life for the majority of patients.

VenUS II: a randomised controlled trial of larval therapy in the management of leg ulcers

OBJECTIVES

To compare the clinical effectiveness and cost-effectiveness of larval therapy with a standard debridement technique (hydrogel).

DESIGN

A pragmatic, three-arm, randomised controlled trial with an economic evaluation.

SETTING

Community nursing services, community leg ulcer clinics and hospital outpatient leg ulcer clinics. A range of urban and rural settings.

PARTICIPANTS

Patients with venous or mixed venous/arterial ulcers (minimum ankle brachial pressure index of 0.6) where a minimum of 25% of ulcer area was covered by slough and/or necrotic material.

INTERVENTIONS

Loose larval therapy and bagged larval therapy compared with hydrogel.

MAIN OUTCOME MEASURES

The primary end point was complete healing of the largest eligible ulcer. The primary outcome was time to complete healing of the reference ulcer. Secondary outcomes were: time to debridement, cost of treatments, health-related quality of life (including ulcer-related pain), bacterial load, presence of methicillin-resistant Staphylococcus aureus and staff and patient attitudes to and beliefs about larval therapy.

RESULTS

Between July 2004 and May 2007 the trial recruited 267 people aged 20-94 years at trial entry. There were more female (n = 158) than male (n = 109) participants and most ulcers were classified by the nurse as having an area greater than 5 cm(2). The time to healing for the three treatment arms was compared using the log rank test. The difference in time to healing in the three treatments was not statistically significant at the 5% level. Adjustment was then made for stratification and prespecified prognostic factors (centre, baseline ulcer area, ulcer duration and type of ulcer) using a Cox proportional hazards model. No difference was found in healing rates between the loose and bagged larvae groups. Results for larvae (loose and bagged pooled) compared with hydrogel showed no evidence of a difference in time to healing. When the same analytical steps were used to investigate time to debridement, larvae-treated ulcers debrided significantly more rapidly than hydrogel-treated ulcers; however, the difference in time to debridement between loose and bagged larvae was not significant. The adjusted analysis reported the hazard of debriding at any time for those in loose and bagged larvae groups as approximately twice that of the hydrogel group. No differences in health-related quality of life or bacteriology were observed between trial arms. Larval therapy was associated with significantly more ulcer-related pain than hydrogel. Our base-case economic evaluation showed large decision uncertainty associated with the cost-effectiveness of larval therapy compared with hydrogel, suggesting that larval therapy and hydrogel therapy have similar costs and effects in the treatment of sloughy and/or necrotic leg ulcers.

CONCLUSIONS

Larval therapy significantly reduced the time to debridement of sloughy and/or necrotic, chronic venous and mixed venous/arterial leg ulcers, compared with hydrogel; however, larval therapy did not significantly increase the rate of healing of the ulcers. It was impossible to distinguish between larval therapy and hydrogel in terms of cost-effectiveness. Future research should investigate the association of debridement and healing and the value of debridement as a clinical outcome for patients and clinicians. To inform decision-makers' selection of debriding agents where debridement is the treatment goal, decision analytic modelling of all alternative debridement treatments is required.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN55114812.

Evolution of transdermal oxybutynin in the treatment of overactive bladder

Overactive bladder (OAB) syndrome affects millions of people worldwide. In addition to adversely affecting quality of life, the direct and indirect costs in managing patients with OAB incur a substantial financial burden on health services. Among the approved anticholinergics for treating OAB, oxybutynin is the most extensively studied drug in clinical trials. The principle metabolite of oxybutynin has a higher affinity for muscarinic receptors in salivary glands which lead to significantly high dry mouth rates. This prompted the development of alternative formulations of oxybutynin aiming to achieve better tolerability whilst sustaining efficacy. This editorial examines the efficacy and tolerability of transdermal oxybutynin (OXY-TD) in treating OAB. Articles were retrieved from PubMed between 2000 to the present day relating to OXY-TD. Data is presented from phase I-IV trials. The results from placebo-controlled trials indicate that OXY-TD is efficacious in treating patients with OAB associated with urge urinary or mixed incontinence. Systemic side effects most notably dry mouth, appear to be less with this formulation compared with oral anticholinergics. However, further study is required in different OAB populations. The main limitation appears to be related to application site adverse events such as pruritus and erythema. OXY-TD is likely to find its place as first-line pharmacotherapy in the clinicians' armamentarium in treating OAB.

Are doctors working the EWTD night shift pattern less tired?

The introduction of the European Working Time Directive (EWTD) has resulted in shift pattern rotas that include a week of night shifts. The EWTD was introduced to reduce the number of hours worked per week and consequently ensure that tired doctors were not treating patients. A week of night shifts allows rotas to meet the EWTD requirements while providing night-time cover with regular interspersed rest periods, which seems an advantage over the now largely redundant on-call system.

A series of systematic reviews to inform a decision analysis for sampling and treating infected diabetic foot ulcers

OBJECTIVES

To review systematically the evidence on the performance of diagnostic tests used to identify infection in diabetic foot ulcers (DFUs) and of interventions to treat infected DFUs. To use estimates derived from the systematic reviews to create a decision analytic model in order to identify the most effective method of diagnosing and treating infection and to identify areas of research that would lead to large reductions in clinical uncertainty.

DATA SOURCES

Electronic databases covering period from inception of the database to November 2002.

REVIEW METHODS

Selected studies were assessed against validated criteria and described in a narrative review. The structure of a decision analytic model was derived for two groups of patients in whom diagnostic tests were likely to be used.

RESULTS

Three studies that investigated the performance of diagnostic tests for infection on populations including people with DFUs found that there was no evidence that single items on a clinical examination checklist were reliable in identifying infection in DFUs, that wound swabs perform poorly against wound biopsies, and that semi-quantitative analysis of wound swabs may be a useful alternative to quantitative analysis. However, few people with DFUs were included, so it was not possible to tell whether diagnostic performance differs for DFUs relative to wounds of other aetiologies. Twenty-three studies investigated the effectiveness (n = 23) or cost-effectiveness (n = 2) of antimicrobial agents for DFUs. Eight studied intravenous antibiotics, five oral antibiotics, four different topical agents such as dressings, four subcutaneous granulocyte colony stimulating factor (G-CSF), one evaluated oral and topical Ayurvedic preparations and one compared topical sugar versus antibiotics versus standard care. The majority of trials were underpowered and were too dissimilar to be pooled. There was no strong evidence for recommending any particular antimicrobial agent for the prevention of amputation, resolution of infection or ulcer healing. Topical pexiganan cream may be as effective as oral antibiotic treatment with ofloxacin for the resolution of local infection. Ampicillin and sulbactam were less costly than imipenem and cilastatin, a growth factor (G-CSF) was less costly than standard care and cadexomer iodine dressings may be less costly than daily dressings. A decision analytic model was derived for two groups of people, those for whom diagnostic testing would inform treatment--people with ulcers which do not appear infected but whose ulcer is not progressing despite optimal concurrent treatment--and those in whom a first course of antibiotics (prescribed empirically) have failed. There was insufficient information from the systematic reviews or interviews with experts to populate the model with transition probabilities for the sensitivity and specificity of diagnosis of infection in DFUs. Similarly, there was insufficient information on the probabilities of healing, amputation or death in the intervention studies for the two populations of interest. Therefore, we were unable to run the model to inform the most effective diagnostic and treatment strategy.

CONCLUSIONS

The available evidence is too weak to be able to draw reliable implications for practice. This means that, in terms of diagnosis, infection in DFUs cannot be reliably identified using clinical assessment. This has implications for determining which patients need formal diagnostic testing for infection, on whether empirical treatment with antibiotics (before the results of diagnostic tests are available) leads to better outcomes, and on identifying the optimal methods of diagnostic testing. With respect to treatment, it is not known whether treatment with systemic or local antibiotics leads to better outcomes or whether any particular agent is more effective. Limited evidence suggests that both G-CSF and cadexomer iodine dressings may be less expensive than 'standard' care, that ampicillin/sulbactam may be less costly than imipenem/cilastatin, and that an unlicensed cream (pexiganan) may be as effective as oral ofloxacin. Further research is needed to ascertain the characteristics of infection in people with DFUs that influence healing and amputation outcomes, to determine whether detecting infection prior to treatment offers any benefit over empirical therapy, and to establish the most effective and cost-effective methods for detecting infection, as well as the relative effectiveness and cost-effectiveness of antimicrobial interventions for DFU infection.

Distribution of epidemic antibiotic-resistant pneumococcal clones in Scottish pneumococcal isolates analysed by multilocus sequence typing

Sequence types of pneumococci isolated in Scotland between 1996 and 2003 were compared with those of globally prevalent antibiotic-resistant clones. Multilocus sequence typing was performed on 252 invasive pneumococcal isolates referred to the Scottish Meningococcus and Pneumococcus Reference Laboratory. Isolates were not preselected for antimicrobial resistance, patient age or disease caused. Sequence types were compared with globally significant antimicrobial-resistant clones identified by the Pneumococcal Molecular Epidemiology Network (PMEN). Sequence types identical with three of the 26 PMEN clones were present in the Scottish collection; the clones were the Spain9V-3 clone (sequence type 156, seven isolates), the England14-9 clone (sequence type 9, eight isolates) and the Utah35B-24 clone (sequence type 377, one isolate). Many Scottish isolates related to PMEN clones had lower antimicrobial MICs than those described for the corresponding PMEN type strain. A number of single- (SLVs) and double-locus variants (DLVs) were present. Fifteen SLVs related to PMEN sequence types 37, 67, 90, 81, 156, 236 and 377 were detected. The collection contained 10 DLVs related to PMEN sequence types 37, 156, 173 and 338. The majority of SLVs and DLVs were penicillin- or erythromycin-sensitive variants of the resistant PMEN type strains. Capsule switching in isolates related to the PMEN clones was also detected. The highest levels of penicillin resistance were detected in sequence type 320 (serotype 19F), which is not a PMEN clone. These data suggest that PMEN clones are not widely distributed in disease-causing isolates in Scotland.

Competence-based assessment of specialist registrars: evaluation of a new assessment of out-patient consultations

OBJECTIVE

To implement and evaluate formal assessment of the performance of West Midlands rheumatology specialist registrars (SpRs) in conducting out-patient consultations.

METHODS

SpRs conducted a full out-patient clinic while being observed by one or two consultants who scored each SpR's performance on a structured pro forma. The assessment was conducted within the examining consultant's hospital trust (in which the SpR was not working). The process was evaluated by trainees and trainers by means of a questionnaire.

RESULTS

Sixteen SpRs were assessed. No trainee failed to reach the required standard. Six trainees scored 'borderline' for management planning and four had a borderline performance recorded for examination skills. Overall the process was valued by trainers and trainees, although consensus was that it would be more practicable for the trainee to be examined within the hospital in which they were working by a visiting consultant examiner. It was also felt that a broader range of scoring options would be preferable.

CONCLUSION

Formal assessment, by direct observation, of the skills of SpRs in conducting an out-patient clinic is practicable and offers information which is useful to trainer and trainee. A culture of direct observation of performance can be achieved within the context of rheumatology higher medical training.

Data reduction in headspace analysis of blood and urine samples for robust bacterial identification

This paper demonstrates the application of chemical headspace analysis to the problem of classifying the presence of bacteria in biomedical samples by using computational tools. Blood and urine samples of disparate forms were analysed using a Cyrano Sciences C320 electronic nose together with an Agilent 4440 Chemosensor. The high dimensional data sets resulting from these devices present computational problems for parameter estimation of discriminant models. A variety of data reduction and pattern recognition techniques were employed in an attempt to optimise the classification process. A 100% successful classification rate for the blood data from the Agilent 4440 was achieved by combining a Sammon mapping with a radial basis function neural network. In comparison a successful classification rate of 80% was achieved for the urine data from the C320 which were analysed using a novel nonlinear time series model.

The use of the Hospital Anxiety and Depression Scale (HADS) in patients with chronic obstructive pulmonary disease: a pilot study

AIMS

To investigate the use of the Hospital Anxiety and Depression Scale (HADS) with recuperating chronic obstructive pulmonary disease (COPD) patients. To study prevalence rates and changes in clinically relevant anxiety and depression during rehabilitation.

METHODS

Consecutive patients admitted to a non acute respiratory ward over a twelve week period were asked to complete a HADS questionnaire on three occasions. Nurses recorded basic demographic information on admission. Additional demographic, medical and psychiatric data were obtained by retrospective review of medical records.

RESULTS

Of 93 consecutive inpatients, 79 (85%) completed the admission HADS. 72 patients were eligible to complete the day three HADS and 60 the discharge HADS. Clinically relevant anxiety (HADS score of > or =8) was indicated in 39 patients (50%) and depression in 22 (28%). HADS anxiety (p=0.05) and total scores (anxiety+depression) (p=0.03) decreased between admission and discharge. A larger proportion of patients scored within the normal or mild psychopathology range by discharge. More severe COPD (FEV1% predicted) correlated with higher HADS anxiety scores (r=-0.39, p<0.001) and HADS depression scores (r=-0.34, p<0.005). Patients with a recorded history of anxiety (p<0.0001) and depression (p<0.02) had higher WADS scores. Females (n=37) when compared to males (n=42), recorded significantly higher HADS anxiety scores throughout (p<0.005).

CONCLUSIONS

Clinically relevant anxiety, indicated by higher HADS scores, was more common in patients with severe COPD, a past history of anxiety or depression and females. Anxiety and total mood improved during inpatient rehabilitation. The use of this instrument with New Zealand COPD patients may improve identification and treatment of anxious and depressed patients.

Penicillin-binding protein 2b of Streptococcus pneumoniae in piperacillin-resistant laboratory mutants

In Streptococcus pneumoniae, alterations in penicillin-binding protein 2b (PBP 2b) that reduce the affinity for penicillin binding are observed during development of beta-lactam resistance. The development of resistance was now studied in three independently obtained piperacillin-resistant laboratory mutants isolated after several selection steps on increasing concentrations of the antibiotic. The mutants differed from the clinical isolates in major aspects: first-level resistance could not be correlated with alterations in the known PBP genes, and the first PBP altered was PBP 2b. The point mutations occurring in the PBP 2b genes were characterized. Each mutant contained one single point mutation in the PBP 2b gene. In one mutant, this resulted in a mutation of Gly-617 to Ala within one of the homology boxes common to all PBPs, and in the other two cases, the same Gly-to-Asp substitution at the end of the penicillin-binding domain had occurred. The sites affected were homologous to those determined previously in the S. pneumoniae PBP 2x of mutants resistant to cefotaxime, indicating that, in both PBPs, similar sites are important for interaction with the respective beta-lactams.