Ensuring accuracy in the development and application of nucleic acid amplification tests (NAATs) for infectious disease

Diagnostic tests were heralded as crucial during the Coronavirus disease (COVID-19) pandemic with most of the key methods using bioanalytical approaches that detected larger molecules (RNA, protein antigens or antibodies) rather than conventional clinical biochemical techniques. Nucleic Acid Amplification Tests (NAATs), like the Polymerase Chain Reaction (PCR), and other molecular methods, like sequencing (that often work in combination with NAATs), were essential to the diagnosis and management during COVID-19. This was exemplified both early in the pandemic but also later on, following the emergence of new genetic SARS-CoV-2 variants. The 100 day mission to respond to future pandemic threats highlights the need for effective diagnostics, therapeutics and vaccines. Of the three, diagnostics represents the first opportunity to manage infectious diseases while also being the most poorly supported in terms of the infrastructure needed to demonstrate effectiveness. Where performance targets exist, they are not well served by consensus on how to demonstrate they are being met; this includes analytical factors such as limit of detection (LOD) false positive results as well as how to approach clinical evaluation. The selection of gold standards or use of epidemiological factors such as predictive value, reference ranges or clinical thresholds are seldom correctly considered. The attention placed on molecular diagnostic tests during COVID-19 illustrates important considerations and assumptions on the use of these methods for infectious disease diagnosis and beyond. In this manuscript, we discuss state-of-the-art approaches to diagnostic evaluation and explore how they may be better tailored to diagnostic techniques like NAATs to maximise the impact of these highly versatile bioanalytical tools, both generally and during future outbreaks.

Within-host diversity improves phylogenetic and transmission reconstruction of SARS-CoV-2 outbreaks

Accurate inference of who infected whom in an infectious disease outbreak is critical for the delivery of effective infection prevention and control. The increased resolution of pathogen whole-genome sequencing has significantly improved our ability to infer transmission events. Despite this, transmission inference often remains limited by the lack of genomic variation between the source case and infected contacts. Although within-host genetic diversity is common among a wide variety of pathogens, conventional whole-genome sequencing phylogenetic approaches exclusively use consensus sequences, which consider only the most prevalent nucleotide at each position and therefore fail to capture low-frequency variation within samples. We hypothesized that including within-sample variation in a phylogenetic model would help to identify who infected whom in instances in which this was previously impossible. Using whole-genome sequences from SARS-CoV-2 multi-institutional outbreaks as an example, we show how within-sample diversity is partially maintained among repeated serial samples from the same host, it can transmitted between those cases with known epidemiological links, and how this improves phylogenetic inference and our understanding of who infected whom. Our technique is applicable to other infectious diseases and has immediate clinical utility in infection prevention and control.

Impact of Neighborhood on Cardiovascular Health: A Contemporary Narrative Review

PURPOSE OF REVIEW

This review summarizes approaches towards neighborhood characterization in relation to cardiovascular health; contemporary investigations relating neighborhood factors to cardiovascular risk and disease; and initiatives to support community-based interventions to address neighborhood-based social determinants related to cardiovascular health.

RECENT FINDINGS

Neighborhoods may be characterized by Census-derived measures, geospatial data, historical databases, and metrics that incorporate data from electronic medical records and health information exchange databases. Current research has examined neighborhood determinants spanning racial segregation, access to healthcare and food, educational opportunities, physical and built environment, and social environment, and their relations to cardiovascular health and associated outcomes. Community-based interventions have potential to alleviate health disparities but remain limited by implementation challenges. Consideration of neighborhood context is essential in the design of interventions to prevent cardiovascular disease (CVD) and promote health equity. Partnership with community stakeholders may enhance implementation of programs addressing neighborhood-based health determinants.

Evaluation of a Multilevel Laboratory Stewardship Intervention Targeted to Cardiac and Thoracic Surgical Services at an Academic Medical Center

CONTEXT.—

Unnecessary laboratory tests are ordered because of factors such as preselected orders on order sets, clinician habits, and trainee concerns. Excessive use of laboratory testing increases patient discomfort via unnecessary phlebotomy, contributes to iatrogenic anemia, increases risk of bloodstream infections, and increases the cost of care.

OBJECTIVE.—

To address these concerns, we implemented a multilevel laboratory stewardship intervention to decrease unnecessary laboratory testing, measured by laboratory tests per day attributed to service, across 2 surgical divisions with high laboratory use.

DESIGN.—

The multilevel intervention included 5 components: stakeholder engagement, provider education, computerized provider order entry modification, performance feedback, and culture change supported by leadership. The primary outcome of the study was laboratory tests ordered per patient-day. Secondary outcomes included the number of blood draws per patient-day, total lab-associated costs, length of stay, discharge to a nursing facility, 30-day readmissions, and deaths. A difference-in-differences analytic approach assessed the outcome measures in the intervention period, with other surgical services as controls.

RESULTS.—

The primary outcome of laboratory tests per patient-day showed a significant decrease across both thoracic and cardiac surgery services, with between 1.5 and 2 fewer tests ordered per patient-day for both services and an estimated 20 000 fewer tests performed during the intervention period. Blood draws per patient-day were also significantly decreased on the thoracic surgery service but not for cardiac surgery.

CONCLUSIONS.—

A multilevel laboratory stewardship intervention targeted to 2 surgical services resulted in a significant decrease in laboratory test use without negatively impacting length of stay, readmissions, or mortality.

CD163+ macrophages restrain vascular calcification, promoting the development of high-risk plaque

Vascular calcification (VC) is concomitant with atherosclerosis, yet it remains uncertain why rupture-prone high-risk plaques do not typically show extensive calcification. Intraplaque hemorrhage (IPH) deposits erythrocyte-derived cholesterol, enlarging the necrotic core and promoting high-risk plaque development. Pro-atherogenic CD163+ alternative macrophages engulf hemoglobin:haptoglobin (HH) complexes at IPH sites. However, their role in VC has never been examined to our knowledge. Here we show, in human arteries, the distribution of CD163+ macrophages correlated inversely with VC. In vitro experiments using vascular smooth muscle cells (VSMCs) cultured with HH-exposed human macrophage - M(Hb) - supernatant reduced calcification, while arteries from ApoE-/- CD163-/- mice showed greater VC. M(Hb) supernatant-exposed VSMCs showed activated NF-κB, while blocking NF-κB attenuated the anticalcific effect of M(Hb) on VSMCs. CD163+ macrophages altered VC through NF-κB-induced transcription of hyaluronan synthase (HAS), an enzyme that catalyzes the formation of the extracellular matrix glycosaminoglycan, hyaluronan, within VSMCs. M(Hb) supernatants enhanced HAS production in VSMCs, while knocking down HAS attenuated its anticalcific effect. NF-κB blockade in ApoE-/- mice reduced hyaluronan and increased VC. In human arteries, hyaluronan and HAS were increased in areas of CD163+ macrophage presence. Our findings highlight an important mechanism by which CD163+ macrophages inhibit VC through NF-κB-induced HAS augmentation and thus promote the high-risk plaque development.

Factors affecting turnaround time of SARS-CoV-2 sequencing for inpatient infection prevention and control decision making: analysis of data from the COG-UK HOCI study

BACKGROUND

Barriers to rapid return of sequencing results can affect the utility of sequence data for infection prevention and control decisions.

AIM

To undertake a mixed-methods analysis to identify challenges that sites faced in achieving a rapid turnaround time (TAT) in the COVID-19 Genomics UK Hospital-Onset COVID-19 Infection (COG-UK HOCI) study.

METHODS

For the quantitative analysis, timepoints relating to different stages of the sequencing process were extracted from both the COG-UK HOCI study dataset and surveys of study sites. Qualitative data relating to the barriers and facilitators to achieving rapid TATs were included from thematic analysis.

FINDINGS

The overall TAT, from sample collection to receipt of sequence report by infection control teams, varied between sites (median 5.1 days, range 3.0-29.0 days). Most variation was seen between reporting of a positive COVID-19 polymerase chain reaction (PCR) result to sequence report generation (median 4.0 days, range 2.3-27.0 days). On deeper analysis, most of this variability was accounted for by differences in the delay between the COVID-19 PCR result and arrival of the sample at the sequencing laboratory (median 20.8 h, range 16.0-88.7 h). Qualitative analyses suggest that closer proximity of sequencing laboratories to diagnostic laboratories, increased staff flexibility and regular transport times facilitated a shorter TAT.

CONCLUSION

Integration of pathogen sequencing into diagnostic laboratories may help to improve sequencing TAT to allow sequence data to be of tangible value to infection control practice. Adding a quality control step upstream to increase capacity further down the workflow may also optimize TAT if lower quality samples are removed at an earlier stage.

Recurrent SARS-CoV-2 mutations in immunodeficient patients

Long-term severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in immunodeficient patients are an important source of variation for the virus but are understudied. Many case studies have been published which describe one or a small number of long-term infected individuals but no study has combined these sequences into a cohesive dataset. This work aims to rectify this and study the genomics of this patient group through a combination of literature searches as well as identifying new case series directly from the COVID-19 Genomics UK (COG-UK) dataset. The spike gene receptor-binding domain and N-terminal domain (NTD) were identified as mutation hotspots. Numerous mutations associated with variants of concern were observed to emerge recurrently. Additionally a mutation in the envelope gene, T30I was determined to be the second most frequent recurrently occurring mutation arising in persistent infections. A high proportion of recurrent mutations in immunodeficient individuals are associated with ACE2 affinity, immune escape, or viral packaging optimisation. There is an apparent selective pressure for mutations that aid cell-cell transmission within the host or persistence which are often different from mutations that aid inter-host transmission, although the fact that multiple recurrent de novo mutations are considered defining for variants of concern strongly indicates that this potential source of novel variants should not be discounted.

Within-host diversity improves phylogenetic and transmission reconstruction of SARS-CoV-2 outbreaks

Accurate inference of who infected whom in an infectious disease outbreak is critical for the delivery of effective infection prevention and control. The increased resolution of pathogen whole-genome sequencing has significantly improved our ability to infer transmission events. Despite this, transmission inference often remains limited by the lack of genomic variation between the source case and infected contacts. Although within-host genetic diversity is common among a wide variety of pathogens, conventional whole-genome sequencing phylogenetic approaches to reconstruct outbreaks exclusively use consensus sequences, which consider only the most prevalent nucleotide at each position and therefore fail to capture low frequency variation within samples. We hypothesized that including within-sample variation in a phylogenetic model would help to identify who infected whom in instances in which this was previously impossible. Using whole-genome sequences from SARS-CoV-2 multi-institutional outbreaks as an example, we show how within-sample diversity is stable among repeated serial samples from the same host, is transmitted between those cases with known epidemiological links, and how this improves phylogenetic inference and our understanding of who infected whom. Our technique is applicable to other infectious diseases and has immediate clinical utility in infection prevention and control.

Generation of Novel Severe Acute Respiratory Syndrome Coronavirus 2 Variants on the B.1.1.7 Lineage in 3 Patients With Advanced Human Immunodeficiency Virus-1 Disease

The emergence of new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants is of public health concern in case of vaccine escape. Described are 3 patients with advanced human immunodeficiency virus (HIV)-1 and chronic SARS-CoV-2 infection in whom there is evidence of selection and persistence of novel mutations that are associated with increased transmissibility and immune escape.

Early imaging predictors of fetal cerebral ischemic injury in monochorionic twin pregnancy complicated by spontaneous single intrauterine death

OBJECTIVE

Monochorionic twin pregnancies are at increased risk of single intrauterine death (sIUD) and subsequent brain injury in the surviving twin owing to shared placentation. We assessed the association between middle cerebral artery peak systolic velocity (MCA-PSV) and cerebral injury on magnetic resonance imaging (MRI) and examined the association between cerebral findings on diffusion-weighted imaging (DWI) and those on T2-weighted imaging following spontaneous sIUD.

METHODS

This was a retrospective cohort study of monochorionic pregnancies complicated by spontaneous sIUD followed at a tertiary center between January 2008 and January 2020. Pregnancies with sIUD following laser treatment, those with selective feticide, double IUD occurring on the same day or sIUD before 14 weeks' gestation were excluded, as were cases in which MCA-PSV was not measured or DWI-MRI was not performed. The ability of MCA-PSV Doppler to predict subsequent cerebral injury on MRI was assessed, and DWI findings were analyzed and compared with those on susceptibility-weighted imaging (SWI) and T2-weighted MRI to determine its diagnostic accuracy.

RESULTS

We assessed 64 monochorionic pregnancies complicated by spontaneous sIUD. Of these, 47 (73.4%) pregnancies underwent fetal brain MRI and met the inclusion criteria. Sixteen (34.0%) of these fetuses demonstrated cerebral injury on MRI. The median interval between the diagnosis of sIUD and MRI examination was 5 days. Fetuses with increased MCA-PSV > 1.5 multiples of the median (MoM) following sIUD were significantly more likely to demonstrate cerebral injury on MRI than were those with normal MCA-PSV (68.8% vs 38.7%; P = 0.05). The sensitivity and specificity of MCA-PSV > 1.5 MoM for predicting cerebral injury on MRI were 68.8% (95% CI, 41.3-88.9%) and 61.3% (95% CI, 42.2-78.2%), respectively. Patterns of early cerebral injury on T2-weighted and SWI-MRI included acute or subacute tissue swelling (n = 6), parenchymal atrophy (n = 7), loss of cortical ribbon (n = 1) and hemorrhage (n = 8). Early MRI within approximately 2 weeks after the diagnosis of sIUD demonstrated abnormal DWI along with coexisting SWI and T2-weighted sequelae in 56.3% (9/16) of cases. When DWI was normal and a second MRI examination was performed later (n = 7), there were no ischemic changes evident on T2-weighted imaging.

CONCLUSIONS

Increased MCA-PSV is associated with, but predicts poorly, cerebral injury after sIUD. Early MRI with DWI within approximately 2 weeks after the diagnosis of sIUD is valuable in identifying any cerebral injury. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Perspective: Utilizing High Amylose Wheat Flour to Increase Dietary Fiber Intake of Children and Adolescents: A Health by Stealth Approach

Children and adolescents have consistently failed to meet recommended levels of dietary fiber consumption, thus making fiber a nutrient of concern. The importance of adequate dietary fiber intake to attain a healthy diet necessitates the identification of fiber-rich and readily consumed food sources by youth. Grain-based foods derived from whole grains represent a strategic initiative to increase dietary fiber consumption and is consistent with the American diet pattern. Increased intake of foods made from whole grains have been positively associated with improved health outcomes but are also less preferred among youth compared to refined grain products, which make up the majority of their carbohydrate intake. Advances in the commercialization and availability of high amylose wheat flour, a source of resistant starch fiber, provides an opportunity to remedy the suggested acceptability issues of whole grain products indicative of sensory factors, without compromising the amount of fiber ingested. Resistant starch fiber consumption has been associated with health benefits including improved blood sugar management, improved markers of digestive and gut health, increased satiety, and a reduced inflammatory response among adults. The limited studies that indicate fiber's direct benefit among youth are largely observational, thereby necessitating the need for more controlled trials for these age groups. Replacing traditional refined wheat flour with refined high amylose wheat flour has the unique ability to increase dietary fiber consumption without compromising desired sensory and finished product characteristics and thus can help increase dietary fiber consumption in children and adolescents who struggle to meet adequate intakes of fiber.

Surgical management of intrathoracic wooden skewers migrating from the stomach and duodenum in dogs: 11 cases (2014-2020)

Objectives

To describe the clinical presentation, management and outcome of cases presenting with intrathoracic wooden skewers originating from the abdominal gastrointestinal tract.

Materials and Methods

Clinical records of dogs presented and treated for an intrathoracic wooden skewer were reviewed from June to August 2020. Data included signalment, clinical presentation, duration of clinical signs, haematological and biochemical abnormalities, diagnostic imaging findings, surgical procedure, postoperative complications and outcome.

Results

Eleven dogs were included in the study. In all cases, the foreign body was identified as a wooden skewer. The most common clinical signs were anorexia/hyporexia (n=7), vomiting/regurgitation (n=7), lethargy (n=6), pyrexia (n=4) and gait abnormalities/lameness (n=3). CT correctly identified a wooden skewer in all cases when performed (n=7). A coeliotomy combined with transdiaphragmatic thoracotomy was performed in six of 11 cases (55%), a coeliotomy combined with median sternotomy in four of 11 cases (36%) and a median sternotomy alone was performed in one case. Foreign bodies penetrated from the stomach (n=10) or the duodenum (n=1). Intrathoracic trauma was most commonly identified to the lungs (n=3) and pericardium (n=3). Complications occurred in three of 11 cases (27%), two minor and one resulting in death. Ten of the 11 cases (91%) survived to discharge. Long‐term outcome was available for seven of 11 cases (66%), all of them excellent.

Clinical Significance

Despite the challenges of managing wooden skewers penetrating the thoracic cavity from the abdominal gastrointestinal tract, the majority of the patients are stable to undergo diagnostic procedures, surgical exploration and management with low morbidity and excellent short‐ and long‐term prognosis.

Activated Charcoal and Bicarbonate for Aspirin Toxicity: a Retrospective Series

INTRODUCTION

Aspirin overdose causes acid-base disturbances and organ dysfunction. Management is guided by research reported over 50 years ago when chronic aspirin toxicity was common and accounted for significant morbidity. We investigate our experience of aspirin overdose and the effectiveness of charcoal and bicarbonate administration over 20 years.

METHODS

This is a retrospective series of acute aspirin overdose from two toxicology units from January 2000 to September 2019. Acute aspirin ingestions > 3000 mg were identified in each unit's database. Excluded were cases of chronic exposure, hospital presentation > 24 hours after ingestion, and cases without a salicylate concentration. Included in our analysis was demographic data, clinical effects, investigations, complications, and treatment.

RESULTS

There were 132 presentations in 108 patients (79 females (73%)). The median age was 28 years (range: 13-93 years). The median dose ingested was 7750 mg (IQR: 6000-14,400 mg). There were 44 aspirin-only ingestions. Mild toxicity (nausea, vomiting, tinnitus or hyperventilation) occurred in 22 with a median dose of 160 mg/kg. Moderate toxicity (acid-base disturbance, confusion) occurred in 16 with a median ingested dose of 297 mg/kg. There were no cases of severe toxicity (coma or seizures) due to aspirin alone. The median peak salicylate concentration was 276 mg/L (IQR: 175-400 mg/L, range: 14-814 mg/L). There was a moderate association between dose ingested and peak concentration (Pearson r = 0.58; 95% CI 0.45-0.68). Activated charcoal was administered in 36 (27%) cases, which decreased the median peak salicylate concentration (34.2 to 24.8 mg/L/g (difference: 9.4, 95% CI: 1.0-13.1)). Bicarbonate was administered in 34 (26%) presentations, decreasing the median apparent elimination half-life from 13.4 to 9.3 h (difference: 4.2 h, 95% CI: 1.0-6.5 h).

CONCLUSIONS

Acute aspirin overdose caused only mild to moderate effects in this series. Early administration of activated charcoal decreased absorption and use of bicarbonate enhanced elimination.

The Dangers of Using Cq to Quantify Nucleic Acid in Biological Samples: A Lesson From COVID-19

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA quantities, measured by reverse transcription quantitative PCR (RT-qPCR), have been proposed to stratify clinical risk or determine analytical performance targets. We investigated reproducibility and how setting diagnostic cutoffs altered the clinical sensitivity of coronavirus disease 2019 (COVID-19) testing.

METHODS

Quantitative SARS-CoV-2 RNA distributions [quantification cycle (Cq) and copies/mL] from more than 6000 patients from 3 clinical laboratories in United Kingdom, Belgium, and the Republic of Korea were analyzed. Impact of Cq cutoffs on clinical sensitivity was assessed. The June/July 2020 INSTAND external quality assessment scheme SARS-CoV-2 materials were used to estimate laboratory reported copies/mL and to estimate the variation in copies/mL for a given Cq.

RESULTS

When the WHO-suggested Cq cutoff of 25 was applied, the clinical sensitivity dropped to about 16%. Clinical sensitivity also dropped to about 27% when a simulated limit of detection of 106 copies/mL was applied. The interlaboratory variation for a given Cq value was >1000 fold in copies/mL (99% CI).

CONCLUSION

While RT-qPCR has been instrumental in the response to COVID-19, we recommend Cq (cycle threshold or crossing point) values not be used to set clinical cutoffs or diagnostic performance targets due to poor interlaboratory reproducibility; calibrated copy-based units (used elsewhere in virology) offer more reproducible alternatives. We also report a phenomenon where diagnostic performance may change relative to the effective reproduction number. Our findings indicate that the disparities between patient populations across time are an important consideration when evaluating or deploying diagnostic tests. This is especially relevant to the emergency situation of an evolving pandemic.

Improving smoking history documentation in the electronic health record for lung cancer risk assessment and screening in primary care: A case study

Improving risk factor documentation in the electronic health record (EHR) is important in order to determine patient eligibility for lung cancer screening. System-level prioritization combined with a clinic-level initiative can improve risk factor documentation rates. Multi-faceted interventions that include training, process improvement, data management, and continuous performance feedback are effective and can be integrated into existing workflows.

Gastroesophageal intussusception secondary to induction of emesis with subsequent development of septic pericardial effusion after corrective surgery

A juvenile boxer dog was diagnosed with gastroesophageal intussusception that occurred after the induction of emesis with apomorphine. A ventral midline coeliotomy and diaphragmotomy were performed and the intussusception was manually reduced. Despite initial satisfactory recovery, the dog was diagnosed with cardiac tamponade 1 week post-operatively. Escherichia coli was cultured from pericardial and pleural effusion samples. During subtotal pericardiectomy surgery the pericardium was found to be markedly thickened with adhesions to the epicardium, thoracic wall and diaphragm. Substantial haemorrhage and refractory hypotension necessitated the administration of a blood transfusion during surgery. The dog entered cardiac arrest in the immediate post-operative period and cardiopulmonary resuscitation was unfortunately unsuccessful. Gastroesophageal intussusception should be considered a possible severe adverse effect of administering apomorhine to induce emesis in dogs. Additionally, septic pericardial and pleural effusions may occur post-reduction of gastroesophageal intussusception.

Comparison of SARS-CoV-2 N gene real-time RT-PCR targets and commercially available mastermixes

BACKGROUND

This study aimed to evaluate the impact of four different reverse transcription quantitative PCR (RT-qPCR) master mixes on the performance of SARS-CoV-2 diagnostic PCRs using three primer/probe assays targeting the N gene (A, B and C). The dynamic range and lowest detected quantity was determined using a SARS-CoV-2 partial N gene RNA transcript dilution series (100,000-1 copy/μl) and verified using 72 nose and throat swabs, 29 of which tested positive for SARS-CoV-2 RNA.

RESULTS

Assay C consistently detected the lowest quantity of partial N gene RNA transcript with all mastermixes. The Takara One Step PrimeScript™ III RT-PCR Kit mastermix enabled all primer pairs to detect the entire dynamic range evaluated, with the Qiagen Quantifast and Thermofisher TaqPath 1-Step kits also performing well. Sequences from all three primer/probe sets tested in this study (assay A, B and C) have 100 % homology to ≥97 % of the of SARS-CoV-2 sequences available up to 31st December 2020 (n = 291,483 sequences).

CONCLUSIONS

This work demonstrates that specific assays (in this case assay C) can perform well in terms of dynamic range and lowest detected quantity regardless of the mastermix used. However we also show that, by choosing the most appropriate mastermix, poorer performing primer pairs are also able to detect all of the template dilutions investigated. This work increases the potential options when choosing assays for SARS-CoV-2 diagnosis and provides solutions to enable them to work with optimal analytical sensitivity.

Genetic Variants Associated With Unexplained Sudden Cardiac Death in Adult White and African American Individuals

Importance

Unexplained sudden cardiac death (SCD) describes SCD with no cause identified. Genetic testing helps to diagnose inherited cardiac diseases in unexplained SCD; however, the associations between pathogenic or likely pathogenic (P/LP) variants of inherited cardiomyopathies (CMs) and arrhythmia syndromes and the risk of unexplained SCD in both White and African American adults living the United States has never been systematically examined.

Objective

To investigate cases of unexplained SCD to determine the frequency of P/LP genetic variants of inherited CMs and arrhythmia syndromes.

Design, Setting, and Participants

This genetic association study included 683 African American and White adults who died of unexplained SCD and were included in an autopsy registry. Overall, 413 individuals had DNA of acceptable quality for genetic sequencing. Data were collected from January 1995 to December 2015. A total of 30 CM genes and 38 arrhythmia genes were sequenced, and variants in these genes, curated as P/LP, were examined to study their frequency. Data analysis was performed from June 2018 to March 2021.

Main Outcomes and Measures

The frequency of P/LP variants for CM or arrhythmia in individuals with unexplained SCD.

Results

The median (interquartile range) age at death of the 413 included individuals was 41 (29-48) years, 259 (62.7%) were men, and 208 (50.4%) were African American adults. A total of 76 patients (18.4%) with unexplained SCD carried variants considered P/LP for CM and arrhythmia genes. In total, 52 patients (12.6%) had 49 P/LP variants for CM, 22 (5.3%) carried 23 P/LP variants for arrhythmia, and 2 (0.5%) had P/LP variants for both CM and arrhythmia. Overall, 41 P/LP variants for hypertrophic CM were found in 45 patients (10.9%), 9 P/LP variants for dilated CM were found in 11 patients (2.7%), and 10 P/LP variants for long QT syndrome were found in 11 patients (2.7%). No significant difference was found in clinical and heart characteristics between individuals with or without P/LP variants. African American and White patients were equally likely to harbor P/LP variants.

Conclusions and Relevance

In this large genetic association study of community cases of unexplained SCD, nearly 20% of patients carried P/LP variants, suggesting that genetics may contribute to a significant number of cases of unexplained SCD. Our findings regarding both the association of unexplained SCD with CM genes and race-specific genetic variants suggest new avenues of study for this poorly understood entity.

Lawsonella clevelandensis is a rare cause of infected chronic contained rupture of abdominal aortic aneurysm

Lawsonella clevelandensis is an anaerobic, partially acid-fast, Gram-positive bacillus associated with abscess formation. We present the case of a 70-year-old male with chronic contained rupture of abdominal aortic aneurysm (CCR-AAA) complicated by intra-abdominal abscess formation. An abdominal computed tomography scan revealed a rim-enhancing retroperitoneal collection tracking into the subcutaneous layer of the left flank and buttock, suggestive of CCR-AAA with infected haematoma. He underwent ultrasound-guided needle aspiration of the intra-abdominal collection. Conventional culture techniques failed to isolate L. clevelandensis, and the diagnosis was only confirmed by means of 16S rRNA PCR. The patient underwent branched endovascular repair of his aneurysm, and was commenced on treatment with co-amoxiclav, resulting in significant reduction in the size of the infected collection. This is only the second reported case of infection with L. clevelandensis in the UK, and the first reported case of this organism causing infected CCR-AAA.

Current and future challenges in quality assurance in molecular diagnostics

The development and performance of molecular genetic assays has required increasingly complex quality assurance in recent years and continues to pose new challenges. Quality management officers, as well as academic and technical personnel are confronted with new molecular genetic parameters, methods, changing regulatory environments, questions regarding appropriate validation, and quality control for these innovative assays that are increasingly applying quantification and/or multiplex formats. Yet, quality assurance and quality control guidelines are still not widely available or in some circumstances have become outdated. For these reasons, the need for solutions to provide test confidence continues to grow. In order to integrate new test procedures into existing quality assurance measures, the ISO 15189 guideline can serve as an orientation. The ISO 15189 guideline describes requirements for medical laboratories and thus includes those performing molecular diagnostics. This article gives an overview of the possibilities and challenges in quality assurance of molecular parameters and shows possible solutions.

Breakthrough percepts of famous names

Studies have shown that presenting own-name stimuli on the fringe of awareness in Rapid Serial Visual Presentation (RSVP) generates a P3 component and provides an accurate and countermeasure resistant method for detecting identity deception (Bowman et al., 2013, 2014). The current study investigates how effective this Fringe-P3 method is at detecting recognition of familiar name stimuli with lower salience (i.e., famous names) than own-name stimuli, as well as its accuracy with multi-item stimuli (i.e., first and second name pairs presented sequentially). The results demonstrated a highly significant ERP difference between famous and non-famous names at the group level and a detectable P3 for famous names for 86% of participants at the individual level. This demonstrates that the Fringe-P3 method can be used for detecting name stimuli other than own-names and for multi-item stimuli, thus further supporting the method's potential usefulness in forensic applications such as in detecting recognition of accomplices.

Breakthrough percepts of online identity: Detecting recognition of email addresses on the fringe of awareness

A key issue facing cybercrime investigations is connecting online identities to real-world identities. This paper shows that by combining the Fringe-P3 method with a concealed information test, we can detect a participant's familiarity with their own email address, thus connecting their real-world identity to their online one. Participants were shown Rapid Serial Visual Presentation (RSVP) streams of email addresses, some including their own email address (probe) or a target email address. Familiarity with the probe was accurately detected with significant results at the group level and for 7 of 11 participants at the individual level. These promising results demonstrate that the method can be successfully used to detect online identities. Factors that may affect how well an email address probe stands out in the RSVP streams are also discussed.

THU0040 PROTEINASE 3-REACTIVE B CELL RECONSTITUTION AFTER TREATMENT WITH RITUXIMAB FOR ANCA-ASSOCIATED VASCULITIS

Background:

Proteinase 3 (PR3)-reactive B cells are present in PR3-ANCA-associated vasculitis (AAV) at levels higher than healthy controls.

Objectives:

To evaluate the dynamics of the PR3-reactive B cell repopulation in patients with PR3-AAV after treatment with rituximab, and to analyze possible associations between these immunological changes and long-lasting remissions.

Methods:

We analyzed all available frozen peripheral blood mononuclear cells (n=148) from 23 randomly-selected PR3-AAV patients who participated in the RAVE trial and achieved complete remission (BVAS=0, prednisone=0) after treatment with rituximab.

We measured PR3-reactive B cells and the relative subsets by a multi-color flow cytometry panel including CD19, IgD, CD27, CD38, CD24, and a biotinylated PR3 revealed by fluorescent streptavidin. The clinical data of the trial were correlated with flow-cytometry data.

Results:

10/23 (43%) patients relapsed during the follow up, 8/10 relapses were severe. At baseline, clinical features, PR3-ANCA levels, % of total PR3-reactive B cells and PR3-reactive B cell subsets were similar between relapsers and non-relapsers. All patients were followed until the end of the trial, for a mean of 44 months (25-75%IQR 31-54), without difference in follow-up time between relapsers and non-relapsers (p=0.98).

The majority of patients had B cell repopulation at 12 (range 12-24) months after rituximab. At the time of B cell repopulation, transitional (CD19+CD24+CD38+) and naïve (CD19+CD27+IgD-) B cells were higher compared to baseline, while total plasmablasts (PB) were unchanged, and mature B cells significantly decreased in both relapsers and non relapsers. PR3-reactive B cells reappeared in all the patients, and the % of PR3-reactive of B cells were higher at the B cell repopulation visit compared to baseline (5.82% vs 4.25%, p<0.05), while total B cells were lower (66/μL vs 151/μL, p<0.01), regardless of future relapse.

Within PR3-reactive B cells, only the % of PB (CD19+CD27+CD38+PR3+) were higher in relapsers vs. non-relapsers (median [25-75%IQR]; 1.95% [1.315-3.845] vs 0.84% [0.05-1.66], p=0.022) and severe relapsers vs non-severe relapsers (2.165% [1.66-4.315] vs 0.84% [0.1-1.74], p=0.015). Time-to-relapse and time-to severe-relapse were significantly shorter in patients with circulating PR3-PB higher than the median value of the cohort (1.6%) during B cell reconstitution (Figure 1A-B).

Conclusion:

In PR3-AAV, during B cell reconstitution after rituximab, the total fraction of PR3-B cells increases, due to the expansion of the transitional and naïve B cell compartments. Circulating PR3-PB within PR3-B cells are enriched in the peripheral blood of relapsing and severely relapsing patients compared to non-relapsing patients. Higher levels of PR3-PB after rituximab during B cell reappearance significantly increased the risk of subsequent relapse and severe relapse.

References:

[1]Cornec D, Berti A, Hummel A, et al. J Autoimmun. 2017

Disclosure of Interests:

Alvise Berti: None declared, Sophie Hillion: None declared, Amber Hummel: None declared, Eva Carmona: None declared, Tobias Peikert: None declared, Carol Langford: None declared, Peter A. Merkel: None declared, Paul Monach: None declared, Philip Seo: None declared, Robert Spiera Grant/research support from: Roche-Genetech, GSK, Boehringer Ingelheim, Chemocentryx, Corbus, Forbius, Sanofi, Inflarx, Consultant of: Roche-Genetech, GSK, CSL Behring, Sanofi, Janssen, Chemocentryx, Forbius, Mistubishi Tanabe, E. William St. Clair: None declared, Fernando Fervenza: None declared, Kristina Harris: None declared, John H. Stone Grant/research support from: Roche, Consultant of: Roche, Jacques-Olivier Pers: None declared, Ulrich Specks: None declared, Divi Cornec: None declared

Diaphragmotomy to aid exposure during hepatobiliary surgery: a multi-centre retrospective review of 31 dogs

OBJECTIVES

To report surgical technique, intra- and post-operative complications, and short- and long-term outcome following canine hepatobiliary surgery in which exposure of intra-abdominal hepatobiliary lesions was aided by diaphragmotomy.

MATERIALS AND METHODS

Clinical records from four multi-disciplinary UK-based small animal referral hospitals were retrospectively reviewed for dogs in which diaphragmotomy was performed between January 2014 and May 2019. Signalment, diagnosis, surgery performed, diaphragmotomy technique, management of diaphragmotomy and pneumothorax, intra- and post-operative complications, short-term outcome and long-term outcome were recorded.

RESULTS

Thirty-one cases were identified. The most common hepatobiliary surgeries performed alongside diaphragmotomy were single hepatic lobectomy (14/31) and cholecystectomy (11/31). The most common diagnoses were hepatocellular carcinoma (10/31), gall bladder mucocoele (7/31) and hepatic nodular hyperplasia (4/31). Peri-operative mortality rate was 9.7% (3/31 cases) though none of these deaths were considered attributable to diaphragmotomy. Post-operative complications were encountered in 67.9% (19/28) cases that survived the peri-operative period, of which 25.0% (7/28) suffered complications that were considered attributable or likely attributable to diaphragmotomy. These seven complications resolved following non-surgical intervention. Follow-up was available for 26 of 28 patients that survived to discharge at a median of 4-months (range 10 days to 24 months) following surgery and revealed no evidence of complications related to diaphragmotomy.

CLINICAL SIGNIFICANCE

Diaphragmotomy appears safe and increases abdominal exposure of hepatobiliary lesions. The benefit of improved exposure must be carefully weighed up against the risks inherent in inducing pneumothorax.

Norovirus Transmission Dynamics in a Pediatric Hospital Using Full Genome Sequences

Background

Norovirus is a leading cause of worldwide and nosocomial gastroenteritis. The study aim was to assess the utility of molecular epidemiology using full genome sequences compared to routine infection prevention and control (IPC) investigations.

Methods

Norovirus genomes were generated from new episodes of norovirus at a pediatric tertiary referral hospital over a 19-month period (n = 182). Phylogeny identified clusters of related sequences that were verified using epidemiological and clinical data.

Results

Twenty-four clusters of related norovirus sequences (“sequence clusters”) were observed, including 8 previously identified by IPC investigations (“IPC outbreaks”). Seventeen sequence clusters (involving 77/182 patients) were corroborated by epidemiological data (“epidemiologically supported clusters”), suggesting transmission between patients. Linked infections were identified among 44 patients who were missed by IPC investigations. Thirty-three percent of norovirus sequences were linked, suggesting nosocomial transmission; 24% of patients had nosocomial infections from an unknown source; and 43% were norovirus positive on admission.

Conclusions

We show there are frequent introductions of multiple norovirus strains with extensive onward nosocomial transmission of norovirus in a pediatric hospital with a high proportion of immunosuppressed patients nursed in isolation. Phylogenetic analysis using full genome sequences is more sensitive than classic IPC investigations for identifying linked cases and should be considered when investigating norovirus nosocomial transmission. Sampling of staff, visitors, and the environment may be required for complete understanding of infection sources and transmission routes in patients with nosocomial infections not linked to other patients and among patients with phylogenetically linked cases but no evidence of direct contact.

PCR for the detection of pathogens in neonatal early onset sepsis

Background

A large proportion of neonates are treated for presumed bacterial sepsis with broad spectrum antibiotics even though their blood cultures subsequently show no growth. This study aimed to investigate PCR-based methods to identify pathogens not detected by conventional culture.

Methods

Whole blood samples of 208 neonates with suspected early onset sepsis were tested using a panel of multiplexed bacterial PCRs targeting Streptococcus pneumoniae, Streptococcus agalactiae (GBS), Staphylococcus aureus, Streptococcus pyogenes (GAS), Enterobacteriaceae, Enterococcus faecalis, Enterococcus faecium, Ureaplasma parvum, Ureaplasma urealyticum, Mycoplasma hominis and Mycoplasma genitalium, a 16S rRNA gene broad-range PCR and a multiplexed PCR for Candida spp.

Results

Two-hundred and eight samples were processed. In five of those samples, organisms were detected by conventional culture; all of those were also identified by PCR. PCR detected bacteria in 91 (45%) of the 203 samples that did not show bacterial growth in culture. S. aureus, Enterobacteriaceae and S. pneumoniae were the most frequently detected pathogens. A higher bacterial load detected by PCR was correlated positively with the number of clinical signs at presentation.

Conclusion

Real-time PCR has the potential to be a valuable additional tool for the diagnosis of neonatal sepsis.

Colonic Basidiobolomycosis-An Unusual Presentation of Eosinophilic Intestinal Inflammation

Basidiobolomycosis is a rare fungal disease caused by Basidiobolus ranarum. Involvement of the gastrointestinal tract is unusual and poses both a diagnostic and therapeutic challenge, as clinical signs are non-specific and predisposing risk factors are lacking. It can mimick inflammatory bowel disease, primary immunodeficiency, or a malignancy and should be considered in patients who do not respond to standard therapy. We present the case of a 22 months old boy with confirmed colonic Basidiobolomycosis, who presented with severe eosinophilic inflammation of the gastrointestinal tract. Panfungal PCR performed on DNA extracted directly from a tissue sample confirmed the presence of Basidiobolus. He made a full recovery with a combination of surgery and prolonged targeted antifungal medication.

Microbial Translocation Does Not Drive Immune Activation in Ugandan Children Infected With HIV

Objective

Immune activation is associated with morbidity and mortality during human immunodeficiency virus (HIV) infection, despite receipt of antiretroviral therapy (ART). We investigated whether microbial translocation drives immune activation in HIV-infected Ugandan children.

Methods

Nineteen markers of immune activation and inflammation were measured over 96 weeks in HIV-infected Ugandan children in the CHAPAS-3 Trial and HIV-uninfected age-matched controls. Microbial translocation was assessed using molecular techniques, including next-generation sequencing.

Results

Of 249 children included, 142 were infected with HIV; of these, 120 were ART naive, with a median age of 2.8 years (interquartile range [IQR], 1.7–4.0 years) and a median baseline CD4⁺ T-cell percentage of 20% (IQR, 14%–24%), and 22 were ART experienced, with a median age of 6.5 years (IQR, 5.9–9.2 years) and a median baseline CD4⁺ T-cell percentage of 35% (IQR, 31%–39%). The control group comprised 107 children without HIV infection. The median increase in the CD4⁺ T-cell percentage was 17 percentage points (IQR, 12–22 percentage points) at week 96 among ART-naive children, and the viral load was <100 copies/mL in 76% of ART-naive children and 91% of ART-experienced children. Immune activation decreased with ART use. Children could be divided on the basis of immune activation markers into the following 3 clusters: in cluster 1, the majority of children were HIV uninfected; cluster 2 comprised a mix of HIV-uninfected children and HIV-infected ART-naive or ART-experienced children; and in cluster 3, the majority were ART naive. Immune activation was low in cluster 1, decreased in cluster 3, and persisted in cluster 2. Blood microbial DNA levels were negative or very low across groups, with no difference between clusters except for Enterobacteriaceae organisms (the level was higher in cluster 1; P < .0001).

Conclusion

Immune activation decreased with ART use, with marker clustering indicating different activation patterns according to HIV and ART status. Levels of bacterial DNA in blood were low regardless of HIV status, ART status, and immune activation status. Microbial translocation did not drive immune activation in this setting.

Clinical Trials Registration

ISRCTN69078957.

P5568Disease stages of structural and functional cardiac changes associate with outcomes in patients with mitral regurgitation receiving mitral valve intervention

Background/Introduction

Severe mitral regurgitation (MR) produces volume overload resulting in progressive cardiac dysfunction that can extend beyond the left-sided chambers. It is unknown whether a specific MR staging system, that would quantify the extent of structural and functional cardiac changes, would be associated with outcomes in severe MR patients receiving mitral valve (MV) intervention.

Purpose

To examine the clinical utility of a novel MR staging system, based on the extent of cardiac damage, for prediction of clinical outcomes for patients with severe MR who underwent surgical or transcatheter therapy.

Methods

Patients were categorized into five stages using pre-procedural echocardiography; Stage 0: no other cardiac damage detected; Stage 1: Left atrium (LA) abnormality, as defined by the presence of atrial fibrillation or LA chamber enlargement; Stage 2: LV dysfunction, as defined by LV ejection fraction <60%; Stage 3: Pulmonary artery vasculature or tricuspid valve abnormality, as defined by the presence of systolic pulmonary arterial pressure ≥60 mmHg) or ≥grade 2 tricuspid regurgitation; and Stage 4: Right ventricular (RV) disease as defined by the presence of >mild RV dysfunction. The primary outcomes were all-cause mortality, and the combined endpoint of death or heart failure rehospitalization at one-year follow-up.

Results

A total of 696 patients with MR (age 70±14 years; 60% men) who underwent MV surgery (69%) or transcatheter MV repair with MitraClip device (31%) were examined. Prevalences of stage 0, 1, 2, 3, and 4 were 6.6%, 34.6%, 20.0%, 26.6%, and 12.2%, respectively. The median follow-up time was 15 months (IQR, 6.4, 24.4 months). At one-year, there was graded increase in all-cause death and in the combined endpoint of death or heart failure rehospitalization with each MR stage (Figure). In multivariate models, these associations remained independently associated with both one-year endpoints for patients receiving either surgical or transcatheter interventions.

Figure 1

Conclusion

This novel MR staging system is practical and may improve clinical risk stratification of patients with severe MR being considered for MV interventions.

The Effect of Glutamine Supplementation on Microbial Invasion in Surgical Infants Requiring Parenteral Nutrition: Results of a Randomized Controlled Trial

BACKGROUND

To determine whether parenteral plus enteral glutamine supplementation influences microbial invasion in surgical infants who require parenteral nutrition (PN).

METHODS

An prospective double-blind randomized controlled trial studying surgical infants receiving PN for at least 5 days for congenital or acquired intestinal anomalies (2009-2012) was used. Infants were randomized to receive either glutamine supplementation (parenteral plus enteral; total 400 mg/kg/d) or isonitrogenous control. The primary end point was microbial invasion evaluated after 5 days of supplementation and defined as: (i) positive conventional blood culture, (ii) evidence of microbial DNA in blood (polymerase chain reaction), (iii) plasma endotoxin level ≥50 pg/mL, or (iv) plasma level of lipopolysaccharide binding protein ≥50 ng/mL. Data are given as median (range) and compared by logistic regression.

RESULTS

Sixty infants were randomized and reached the primary end point. Twenty-five patients had intestinal obstruction, 19 had abdominal wall defects, and 13 had necrotizing enterocolitis. Thirty-six infants showed evidence of microbial invasion during the study, and 17 of these were not detected by conventional blood culture. There was no significant difference between the 2 groups in the primary outcome; evidence of microbial invasion after 5 days was found in 9/31 (control group) and 8/29 (glutamine group) (odds ratio 0.83 [0.24-2.86; P = 0.77]).

CONCLUSION

More than half of surgical infants requiring PN showed evidence of microbial invasion. Approximately half of this was not detectable by conventional blood cultures. Parenteral plus enteral glutamine supplementation had no effect on incidence of microbial invasion.

Abstract CT065: A Phase I clinical trial: Use of 4-demethyl-4-cholesteryl- oxycarbonyl-penclomedine (DM-CHOC-PEN) plus radiation as treatments for cancers involving the CNS

Purpose: 4-Demethyl-4-cholesteryloxycarbonylpenclomedine (DM-CHOC-PEN) is a poly-chlorinated pyridine cholesteryl carbonate with a MOA via bis-alkylation of DNA @ N7-guanine and N4-cytosine that has completed Phase II studies [AACR, #CT129, 2017] in subjects with cancers involving the CNS. Four (4) subjects in the Phase I/II trials required surgery for persistent CNS lesions following DM-CHOC-PEN therapy with 39-98.8 mg/m2 of drug. DM-CHOC-PEN was identified in samples from all 4-subjects - 90-212 ng/g tumor. Thus, the drug penetrates the CNS and tumors and is available to act as a radiosensitizer; the latter has been supported with in vitro studies [AACR, #4746, 2017]. The current presentation reviews Phase I clinical data that supports the safety, dose-tolerance and use for DM-CHOC-PEN plus radiation in subjects with cancers involving the CNS - IND 68,876.

Patients & Methods: DM-CHOC-PEN was administered as a 3-hr IV infusion once to subjects with advanced cancer involving the CNS. A single dose (39 mg/m2 to 98.7 mg/m2 in escalating Phase I scheme) was administered once 3-weeks prior to receiving stereotaxic radio-surgery (SRS), gamma knife or whole brain irradiation (WBRT) therapy. Radiation was administered in doses of 15-30 Gy depending on the size and number of lesions.

Results: Thirteen (13) subjects with cancer involving the CNS have been treated to date with DM-CHOC-PEN (6-NSCLC, 1-breast, 1-melanoma, 2-GBM & 3-sarcomas). Subjects received 39, 50, 70, 86.8 or 98.7 mg/m2 and 15-30 Gy of radiation. The drug/radiation combination was well tolerated. One (1) subject with NSCLC did develop vasogenic edema and tumor necrosis which resolved and the subject is in complete remission 42+ mos. A second subject with a recurrent GBM with confusion progressed - Gr-3. Ten (10) of the thirteen (13) subjects have had objective results (OS 8-54+ mos.) Bioavailability for DM-CHOC-PEN revealed a rebound phenomenon @ ~ 50 hours post-infusion with a T-release of 26.7 h. The same phenomenon was observed with RBCs (estimation using Monolix 3.2). DM-CHOC-PEN was detected bound to RBCs for 3-days (after 70 mg/m2) and was also detected in the urine (Cmax=17.5 µg/mL) until day 15. The AUC was linear for all doses. Pre-clinical radiosensitization in vitro studies [AACR #1917, 2017] support the present trial study result. Photon induced charge transfer reactions with DM-CHOC-PEN will be discussed as a MOA.

Conclusion: Data is presented that documents effectiveness and safety of DM-CHOC-PEN plus radiation as therapy for subjects with cancers involving the CNS. Observations during Phase I/II clinical trials with DM-CHOC-PEN alone supported the drug’s persistent presence in human tumors after systemic administration and possible positive effects on response to subsequent radiation. Complete data on subject responses and observed toxicities will be presented. Supported by - NCI/SBIR grants - R43 CA213545-02 and NIH NIGMS 1 U54 GM104940 - the latter funds the Louisiana Clinical and Translational Science Center.

Citation Format: RS Weiner, T Mahmood, Lee Roy Morgan, K. Harris, A. Baghian, SJ DiBiase, P. Friedlander, ML Ware, R. Kawauchi, J. Herman, M. Bhandari. A Phase I clinical trial: Use of 4-demethyl-4-cholesteryl- oxycarbonyl-penclomedine (DM-CHOC-PEN) plus radiation as treatments for cancers involving the CNS [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT065.

Engineered bacteriophages for treatment of a patient with a disseminated drug-resistant Mycobacterium abscessus

A 15-year-old patient with cystic fibrosis with a disseminated Mycobacterium abscessus infection was treated with a three-phage cocktail following bilateral lung transplantation. Effective lytic phage derivatives that efficiently kill the infectious M. abscessus strain were developed by genome engineering and forward genetics. Intravenous phage treatment was well tolerated and associated with objective clinical improvement, including sternal wound closure, improved liver function, and substantial resolution of infected skin nodules.

The role of real-time PCR testing in the investigation of paediatric patients with community-onset osteomyelitis and septic arthritis

BACKGROUND

Culture yield in osteomyelitis and septic arthritis is low, emphasising the role for molecular techniques.

AIMS

The purpose of this study was to review the laboratory investigation of childhood osteomyelitis and septic arthritis.

METHODS

A retrospective review was undertaken in an acute tertiary referral paediatric hospital from January 2010 to December 2016. Cases were only included if they had a positive culture or bacterial PCR result from a bone/joint specimen or blood culture, or had radiographic evidence of osteomyelitis.

RESULTS

Seventy-eight patients met the case definition; 52 (66%) were male. The median age was 4.8 years. Blood cultures were positive in 16 of 56 cases (29%), with 11 deemed clinically significant (Staphylococcus aureus = 8, group A Streptococcus = 3). Thirty-seven of 78 (47%) bone/joint samples were positive by culture with S. aureus (n = 16), coagulase-negative Staphylococcus (n = 9) and group A Streptococcus (n = 4), being the most common organisms. Sixteen culture-negative samples were sent for bacterial PCR, and four were positive (Kingella kingae = 2, Streptococcus pneumoniae = 1, group A Streptococcus = 1).

CONCLUSIONS

Sequential culture and PCR testing can improve the detection rate of causative organisms in paediatric bone and joint infections, particularly for fastidious microorganisms such as K. kingae. PCR testing can be reserved for cases where culture is negative after 48 h. These results have been used to develop a standardised diagnostic test panel for bone and joint infections at our institution.

Regulation of SH3PX1 by dNedd4-long at the Drosophila neuromuscular junction

Drosophila Nedd4 (dNedd4) is a HECT E3 ubiquitin ligase present in two major isoforms: short (dNedd4S) and long (dNedd4Lo), with the latter containing two unique regions (N terminus and Middle). Although dNedd4S promotes neuromuscular synaptogenesis (NMS), dNedd4Lo inhibits it and impairs larval locomotion. To explain how dNedd4Lo inhibits NMS, MS analysis was performed to find its binding partners and identified SH3PX1, which binds dNedd4Lo unique Middle region. SH3PX1 contains SH3, PX, and BAR domains and is present at neuromuscular junctions, where it regulates active zone ultrastructure and presynaptic neurotransmitter release. Here, we demonstrate direct binding of SH3PX1 to the dNedd4Lo Middle region (which contains a Pro-rich sequence) in vitro and in cells, via the SH3PX1-SH3 domain. In Drosophila S2 cells, dNedd4Lo overexpression reduces SH3PX1 levels at the cell periphery. In vivo overexpression of dNedd4Lo post-synaptically, but not pre-synaptically, reduces SH3PX1 levels at the subsynaptic reticulum and impairs neurotransmitter release. Unexpectedly, larvae that overexpress dNedd4Lo post-synaptically and are heterozygous for a null mutation in SH3PX1 display increased neurotransmission compared with dNedd4Lo or SH3PX1 mutant larvae alone, suggesting a compensatory effect from the remaining SH3PX1 allele. These results suggest a post-synaptic-specific regulation of SH3PX1 by dNedd4Lo.