Investigation and management of prosthetic joint infection in knee replacement: A BASK Surgical Practice Guideline

BACKGROUND

The burden of knee replacement prosthetic joint infection (KR PJI) is increasing. KR PJI is difficult to treat, outcomes can be poor and it is financially expensive and limited evidence is available to guide treatment decisions.

AIM

To provide guidelines for surgeons and units treating KR PJI.

METHODS

Guideline formation by consensus process undertaken by BASK's Revision Knee Working Group, supported by outputs from UK-PJI meetings.

RESULTS

Improved outcomes should be achieved through provision of care by revision centres in a network model. Treatment of KR PJI should only be undertaken at specialist units with the required infrastructure and a regular infection MDT. This document outlines practice guidelines for units providing a KR PJI service and sets out: CONCLUSIONS: KR PJI patients treated within the NHS should be provided the best care possible. This report sets out guidance and support for surgeons and units to achieve this.

Prosthetic fungal infections: poor prognosis with bacterial co-infection

AIMS

The aims of this study were to report the efficacy of revision surgery for patients with co-infective bacterial and fungal prosthetic joint infections (PJIs) presenting to a single institution, and to identify prognostic factors that would guide management.

PATIENTS AND METHODS

A total of 1189 patients with a PJI were managed in our bone infection service between 2006 and 2015; 22 (1.85%) with co-infective bacterial and fungal PJI were included in the study. There were nine women and 13 men, with a mean age at the time of diagnosis of 64.5 years (47 to 83). Their mean BMI was 30.9 kg/m² (24 to 42). We retrospectively reviewed the outcomes of these PJIs, after eight total hip arthroplasties and 14 total knee arthroplasties. The mean clinical follow-up was 4.1 years (1.4 to 8.8).

RESULTS

The median number of risk factors for PJI was 5.5 (interquartile range (IQR) 3.25 to 7.25). All seven patients who initially underwent debridement and implant retention (DAIR) had a recurrent infection that led to a staged revision. All 22 patients underwent the first of a two-stage revision. None of the nine patients with negative tissue cultures at the second stage had a recurrent infection. The rate of recurrent infection was significantly higher in the presence of multidrug-resistant bacteria (p = 0.007), a higher C-reactive protein (CRP) at the time of presentation (p = 0.032), and a higher number of co-infective bacterial organisms (p = 0.041). The overall rate of eradication of infection after two and five years was 50% (95% confidence interval (CI) 32.9 to 75.9) and 38.9% (95% CI 22.6 to 67), respectively.

CONCLUSION

The risk of failure to eradicate infection with the requirement of amputation associated with this diagnosis is much higher than in patients with PJI without bacterial and fungal co-infection, and this risk is heightened when the fungal organism is joined by polymicrobial and multidrug-resistant bacterial organisms. Cite this article: Bone Joint J 2019;101-B:582-588.

Faculty Perceptions of Engaging Students in Active Learning to Address Implicit Bias Using Videos Exemplifying the Prenatal Visit of a Lesbian Couple

Introduction: Implicit bias affects patient–nurse interactions and care management decisions. The purpose of this educational project was to explore faculty perceptions of engaging students in active learning to address implicit bias using videos vignettes. Method: Three videos were created with a corresponding instructor guide. The vignettes depicted insensitive behaviors, best practice clinical interactions, and a reflection about bias in health care. Faculty who implemented the active learning strategy were invited to complete an online, confidential survey regarding their perceptions. Results: Most faculty (83%) agreed that students benefit from discussing implicit bias using an active learning approach. All faculty ( N = 12) believed the videos and instructor guide to be effective tools in creating meaningful discussion. Discussion: Video vignettes illustrating insensitive behaviors and demonstrating best practice enable faculty to actively engage students in addressing the impact of implicit bias. Educational strategies intended to ensure equitable care are indicated to support positive patient outcomes.

Giant frequency down-conversion of the dancing acoustic bubble

We have demonstrated experimentally the existence of a giant frequency down-conversion of the translational oscillatory motion of individual submillimeter acoustic bubbles in water in the presence of a high frequency (500 kHz) ultrasonic standing wave. The frequency of the translational oscillations (~170 Hz) is more than three orders of magnitude smaller than that of the driving acoustic wave. We elucidate the mechanism of this very slow oscillation with an analytical model leading to an equation of translational motion of a bubble taking the form of Mathieu's equation. This equation illuminates the origin of the giant down conversion in frequency as arising from an unstable equilibrium. We also show that bubbles that form chains along the direction of the acoustic standing wave due to radiation interaction forces exhibit also translation oscillations that form a spectral band. This band extends approximately from 130 Hz up to nearly 370 Hz, a frequency range that is still at least three orders of magnitude lower than the frequency of the driving acoustic wave.

Revisiting the vortex-core tunnelling spectroscopy in YBa2Cu3O7-δ

The observation by scanning tunnelling spectroscopy of Abrikosov vortex cores in the high-temperature superconductor YBa2Cu3O7-δ (Y123) has revealed a robust pair of electron-hole symmetric states at finite subgap energy. Their interpretation remains an open question because theory predicts a different signature in the vortex cores, characterized by a strong zero-bias conductance peak. Here, we present scanning tunnelling spectroscopy data on very homogeneous Y123 at 0.4 K revealing that the subgap features do not belong to vortices: they are actually observed everywhere along the surface with high spatial and energy reproducibility, even in the absence of magnetic field. Detailed analysis and modelling show that these states remain unpaired in the superconducting phase and belong to an incoherent channel, which contributes to the tunnelling signal in parallel with the superconducting density of states.

Gram-negative bacteraemia; a multi-centre prospective evaluation of empiric antibiotic therapy and outcome in English acute hospitals

Increasing antibiotic resistance makes choosing antibiotics for suspected Gram-negative infection challenging. This study set out to identify key determinants of mortality among patients with Gram-negative bacteraemia, focusing particularly on the importance of appropriate empiric antibiotic treatment. We conducted a prospective observational study of 679 unselected adults with Gram-negative bacteraemia at ten acute english hospitals between October 2013 and March 2014. Appropriate empiric antibiotic treatment was defined as intravenous treatment on the day of blood culture collection with an antibiotic to which the cultured organism was sensitive in vitro. Mortality analyses were adjusted for patient demographics, co-morbidities and illness severity. The majority of bacteraemias were community-onset (70%); most were caused by Escherichia coli (65%), Klebsiella spp. (15%) or Pseudomonas spp. (7%). Main foci of infection were urinary tract (51%), abdomen/biliary tract (20%) and lower respiratory tract (14%). The main antibiotics used were co-amoxiclav (32%) and piperacillin-tazobactam (30%) with 34% receiving combination therapy (predominantly aminoglycosides). Empiric treatment was inappropriate in 34%. All-cause mortality was 8% at 7 days and 15% at 30 days. Independent predictors of mortality (p <0.05) included older age, greater burden of co-morbid disease, severity of illness at presentation and inflammatory response. Inappropriate empiric antibiotic therapy was not associated with mortality at either time-point (adjusted OR 0.82; 95% CI 0.35-1.94 and adjusted OR 0.92; 95% CI 0.50-1.66, respectively). Although our study does not exclude an impact of empiric antibiotic choice on survival in Gram-negative bacteraemia, outcome is determined primarily by patient and disease factors.

Influence of exercise training with resveratrol supplementation on skeletal muscle mitochondrial capacity

Physical inactivity reduces, and exercise training increases, mitochondrial capacity. In rodents, exercise training effects can be augmented by large doses of resveratrol supplementation but whether this can occur in humans with a smaller dose is unclear. This study sought to determine the effects of resveratrol supplementation in combination with exercise training on skeletal muscle mitochondrial capacity. Sixteen healthy young adults were randomly assigned in a double-blind fashion to consume either placebo or 500 mg of resveratrol plus 10 mg of piperine, a bioenhancer to increase bioavailibilty and bioefficacy of resveratrol. Participants ingested the pills daily for 4 weeks and completed 3 sessions per week of submaximal endurance training of the wrist flexor muscles of the nondominant arm. The contralateral arm served as an untrained control. Skeletal muscle mitochondrial capacity was measured using near-infrared spectroscopy. Changes in mitochondrial capacity from baseline to post-testing indicated significant differences between the resveratrol+piperine-trained arm and the placebo-trained arm (p = 0.02), with the resveratrol+piperine group increasing about 40% from baseline (Δk = 0.58), while the placebo group increased about 10% from baseline (Δk = 0.13). Neither the placebo group nor the resveratrol+piperine group exhibited changes in mitochondrial capacity in the untrained arm. In conclusion, low-intensity exercise training can increase forearm skeletal muscle mitochondrial capacity when combined with resveratrol and piperine supplementation.

Age-related reference intervals for bone turnover markers from an Australian reference population

BACKGROUND

This study was performed to establish age-related serum reference intervals for procollagen type I N-propeptide (P1NP) and type I collagen C-telopeptide (CTx) in the Australian population.

METHODS

Fasting sera from 1143 males (mean age 60 years; range 20-97 years) and 1246 females (mean age 53 years; range 20-93 years) who participated in the Geelong Osteoporosis Study were analysed for CTx and P1NP using the automated Roche Modular Analytics E170 analyser.

RESULTS

Optimal age-related reference intervals were based on the central 90% of the distribution. The male CTx reference interval was divided into three age groups. For men aged 25 to 40 years, the interval was 170-600 ng/L; 40 to 60 years, the interval was 130-600 ng/L; and for men aged greater 60 years the interval was 100-600 ng/L. For P1NP the male reference interval was 15-80 μg/L for men aged between 25 to 70 years. In men greater than 70 years of age values were higher possibly due to increased bone turnover. High values are frequently seen for both CTx and P1NP in males aged younger than 25 years. This is probably due to bone growth that is not completely finalised. The female CTx reference interval was divided into four age groups. For women aged less than 30 years, the interval was 150-800 ng/L; 30-39 years, the interval was 100-700 ng/L; 40-49 years, the interval was 100-600 ng/L; and for women aged 50 years or more the interval was 100-700 ng/L. The female P1NP reference interval was divided into four age groups. For women aged less than 30 years, the interval was 25-90 μg/L; 30-39 years, the interval was 15-80 μg/L; 40-49 years, the interval was 15-60 μg/L; and for women aged 50-69 years the interval was 15-75 μg/L. In women greater than 70 years of age values were higher possibly due to increased bone turnover.

CONCLUSION

Values obtained from this large study provide sound age-related reference intervals for serum P1NP and CTx values in the Australian population.

Acute mastoiditis--the role of radiology

Acute mastoiditis is a commonly occurring condition in children and adults, and one that most radiologists will come across at some point during their on-call duties. Acute mastoiditis is usually clinically apparent. However, the complications, especially the intracranial ones, can be more insidious and may have fatal consequences. Therefore, it is imperative that the radiologist is well versed in identifying these. Local spread of infection from the mastoids and middle ear cleft may occur via four routes: bone erosion, thrombophlebitis, periphlebitis, and via the anatomical pathways. The role of radiology is largely to demonstrate the complications of mastoiditis, which can be clinically occult and are often serious; this article will highlight these complications.

Na-butyrate increases the production and alpha2,6-sialylation of recombinant interferon-gamma expressed by alpha2,6- sialyltransferase engineered CHO cells

A non-human like glycosylation pattern in human recombinant glycoproteins expressed by animal cells may compromise their use as therapeutic drugs. In order to correct the CHO glycosylation machinery, a CHO cell line producing recombinant human interferon- gamma (IFN) was transformed to replace the endogenous pseudogene with a functional copy of the enzyme alpha2,6-sialyltransferase (alpha2,6-ST). Both the parental and the modified CHO cell line were propagated in serum-free batch culture with or without 1 mM sodium butyrate. Although Na-butyrate inhibited cell growth, IFN concentration was increased twofold. The IFN sialylation status was determined using linkage specific sialidases and HPLC. Under non- induced conditions, IFN expressed by alpha2,6-engineered cells contained 68% of the total sialic acids in the alpha2,6- conformation and the overall molar ratio of sialic acids to IFN was 2.3. Sodium butyrate addition increased twofold the molar ratio of total sialic acids to IFN and 82% of total sialic acids on IFN were in the alpha2,6-conformation. In contrast, no effect of the sodium butyrate was noticed on the sialylation of the IFN secreted by the alpha2,6-ST deficient parental cell line. This study deals for the first time with the effect of Na-butyrate on CHO cells engineered to produce human like sialylation.

Participants' experiences of intensifying insulin therapy during the Treating to Target in Type 2 Diabetes (4-T) trial: qualitative interview study

AIM

To explore participants' experiences of intensifying insulin therapy during the Treating to Target in Type 2 Diabetes (4-T) trial.

METHODS

In-depth interviews were conducted with 41 trial participants who had had their insulin therapy intensified during this trial. Data were analysed using an inductive, thematic approach.

RESULTS

The vast majority of participants were receptive towards intensifying treatment. Whilst some were happy simply to follow health professionals' recommendations, others saw taking two types of insulin as a more effective way of controlling their diabetes. Post-intensification, participants sought to remember to take their additional injections by developing injection-related strategies and daily routines. The need to inject insulin whilst in public often arose more frequently following intensification and was a consistent source of anxiety. Those who were worried about injecting in public sought to avoid having to do so; for example, by injecting in toilets or by advancing or delaying the timing of their injections.

CONCLUSIONS

IT was not increasing the number of daily injections per se which was problematic for the participants who had agreed to have their insulin therapies intensified, but the increased likelihood of having to inject insulin in public. Addressing concerns about injecting in public places may help promote adherence to intensified insulin regimens.

Limbic encephalitis secondary to HIV seroconversion

We present a case of acute limbic encephalitis secondary to HIV seroconversion. The patient made a gradual neurological recovery following treatment with antiretroviral therapy, steroids and intravenous immunoglobulin.

Glucose-limited chemostat culture of Chinese hamster ovary cells producing recombinant human interferon-gamma

A Chinese hamster ovary (CHO) cell line expressing recombinant human interferon-gamma (IFN-gamma) was grown under glucose limitation in a chemostate at a constant dilution rate of 0.015 h(-1) with glucose feed concentrations of 2.75 mM and 4.25 mM. The changes in cell concentration that accompanied changes in the glucose feed concentration indicated that the cells were glucose-limited. The cell yield on glucose remained constant, but there was a decline in residual glucose concentration and a reduced lactate yield from glucose in the latter stages of the culture. The consumption rates for many of the essential amino acids were increased later in the culture. The volumetric rate of interferon-gamma production was maintained throughout the course of this culture, indicating that IFN-gamma expression was stable under these conditions. However, the specific rate of IFN-gamma production was significantly lower at the higher glucose feed concentration. Under glucose limitation, the proportion of fully glycosylated IFN-gamma produced by these cells was less than that produced in the early stages of batch cultures. The proportion of fully glycosylated IFN-gamma increased during transient periods of glucose excess, suggesting that the culture environment influences the glycosylation of IFN-gamma.

Imaging the essential role of spin fluctuations in high-T(c) superconductivity

We have used scanning tunneling spectroscopy to investigate short-length electronic correlations in three-layer Bi2Sr2Ca2Cu3O(10+delta) (Bi-2223). We show that the superconducting gap and the energy Omega(dip), defined as the difference between the dip minimum and the gap, are both modulated in space following the lattice superstructure and are locally anticorrelated. Based on fits of our data to a microscopic strong-coupling model, we show that Omega(dip) is an accurate measure of the collective-mode energy in Bi-2223. We conclude that the collective mode responsible for the dip is a local excitation with a doping dependent energy and is most likely the (pi, pi) spin resonance.

Microcollimator for micrometer-wide stripe irradiation of cells using 20-30 keV X rays

Abstract Pataky, K., Villanueva, G., Liani, A., Zgheib, O., Jenkins, N., Halazonetis, D. J., Halazonetis, T. D. and Brugger, J. Microcollimator for Micrometer-Wide Stripe Irradiation of Cells Using 20-30 keV X Rays. Radiat. Res. 172, 252-259 (2009). The exposure of subnuclear compartments of cells to ionizing radiation is currently not trivial. We describe here a collimator for micrometer-wide stripe irradiation designed to work with conventional high-voltage X-ray tubes and cells cultured on standard glass cover slips. The microcollimator was fabricated by high-precision silicon micromachining and consists of X-ray absorbing chips with grooves of highly controlled depths, between 0.5-10 microm, along their surfaces. These grooves form X-ray collimating slits when the chips are stacked against each other. The use of this device for radiation biology was examined by irradiating human cells with X rays having energies between 20-30 keV. After irradiation, p53 binding protein 1 (53BP1), a nuclear protein that is recruited at sites of DNA double-strand breaks, clustered in lines corresponding to the irradiated stripes.

Autopsies in HIV: still identifying missed diagnoses

This study reviews the deaths and autopsies carried out over 23 years, 1983–2005, in a British Infection Unit in HIV patients. Of 115 HIV patients known to have died, we obtained data on 93%. Of this 80% were male, median age 38 (25–68) years; 83% were Caucasian; 12% Black African. Major risk factors were men who have sex with men, 52%; heterosexual in Africa, 17%; and injecting drug use, 8%. The commonest diagnosis pre- and post-autopsy diagnosis was pneumonia. Changes in diagnoses in the 38% who underwent autopsy were high (we requested autopsy in 50%). Primary diagnosis changed in 70%, and 36% of all opportunistic infections were missed. This included six of nine cytomegalovirus, all tuberculosis and 75% of Kaposi's sarcoma. Lymphoma was overdiagnosed. Thus, despite excellent resources, the majority of primary diagnoses were wrong, suggesting inadequacy of current diagnostics. To improve these and improve both epidemiological data and future management autopsy should be considered for all deaths.

Scanning tunneling spectroscopy in the superconducting state and vortex cores of the beta-pyrochlore KOs2O6

We performed the first scanning tunneling spectroscopy measurements on the pyrochlore superconductor KOs2O6 (T(c)=9.6 K) in both zero magnetic field and the vortex state at several temperatures above 1.95 K. This material presents atomically flat surfaces, yielding spatially homogeneous spectra which reveal fully gapped superconductivity with a gap anisotropy of 30%. Measurements performed at fields of 2 and 6 T display a hexagonal Abrikosov flux line lattice. From the shape of the vortex cores, we extract a coherence length of 31-40 A, in agreement with the value derived from the upper critical field H(c2). We observe a reduction in size of the vortex cores (and hence the coherence length) with increasing field which is consistent with the unexpectedly high and unsaturated upper critical field reported.

Pauli paramagnetic effects on vortices in superconducting TmNi2B2C

The magnetic field distribution around the vortices in TmNi2B2C in the paramagnetic phase was studied experimentally as well as theoretically. The vortex form factor, measured by small-angle neutron scattering, is found to be field independent up to 0.6Hc2 followed by a sharp decrease at higher fields. The data are fitted well by solutions to the Eilenberger equations when paramagnetic effects due to the exchange interaction with the localized 4f Tm moments are included. The induced paramagnetic moments around the vortex cores act to maintain the field contrast probed by the form factor.

Clinical and diagnostic findings of an echovirus meningitis outbreak in the north west of England

INTRODUCTION

An outbreak of echovirus meningitis occurred in the north west of England in 2001. This paper reviewed the clinical features and the role of different diagnostic methods.

METHODS

This was a prospective study of adults admitted to a regional infectious disease unit with a probable diagnosis of meningitis, March to August 2001.

RESULTS

Half the 40 cases were male; median age was 28 (range 16-51) years. Fifteen of 38 (39.5%) were smokers, and 20 of 24 (83.3%) had close contact with children. Median (range) duration of symptoms was 1.1 (0.25-7) days. Symptoms included headache (100%), photophobia (87.5%), and nausea (67.5%), and severity ranged from minimal signs to those consistent with a meningoencephalitis. The diagnosis was confirmed virologically in 29 of 40 (72%); echovirus 30 was isolated from six. Cerebrospinal fluid (CSF) enterovirus polymerase chain reaction (PCR) was positive in 26 of 32 (81%), and CSF virus culture in 3 of 16 (19%). Thirty one per cent of CSF samples had a neutrophil predominance, and 3 of 29 (10%) virologically confirmed cases had normal CSF microscopy and biochemistry.

CONCLUSION

CSF microscopy may be normal or suggest bacterial meningitis in a substantial minority of cases of echovirus meningitis. CSF PCR for enterovirus seems to be more sensitive than virus culture of CSF, although PCR does not yield information on circulating virus type. Early and accurate diagnosis could reduce both use of parenteral antibiotics and length of hospital stay with both morbidity and cost implications. Close contact with children may be a risk factor, particularly if good hygiene measures are not practised.