StaphAIR: A Label-Free Antigen Microarray Approach to Detecting Anti-Staphylococcus aureus Antibody Responses in Orthopedic Infections.

Arrayed imaging reflectometry (AIR) is an optical biosensor platform for simple, multiplex measurement of antigen-specific antibody responses in patient blood samples. Here, we report the development of StaphAIR, an 8-plex Staphylococcus aureus antigen array on the AIR platform for profiling antigen-specific anti-S. aureus humoral immune responses. Initial validation experiments with mouse and humanized monoclonal antibodies against the S. aureus autolysin glucosaminidase (Gmd) domain, and subsequent testing with dilution series of pooled positive human serum confirmed analytically robust behavior of the array, with all antigens displaying Langmuir-type dose-response curves. Testing a cohort of 82 patients with S. aureus musculoskeletal infections (MSKI) and 30 healthy individuals enabled discrimination of individual patient responses to different S. aureus antigens, with statistical significance between osteomyelitis patients and controls obtained overall for four individual antigens (IsdA, IsdB, Gmd, and SCIN). Multivariate analyses of the antibody titers obtained from StaphAIR revealed its utility as a potential diagnostic tool for detecting S. aureus MSKI (area under the receiver operating characteristic curve (AUC) > 0.85). We conclude that StaphAIR has utility as a high-throughput immunoassay for studying and diagnosing osteomyelitis in patients.

Association of Cardiac Resynchronization Therapy With Change in Left Ventricular Ejection Fraction in Patients With Chemotherapy-Induced Cardiomyopathy.

Importance: The incidence of chemotherapy-induced cardiomyopathy is increasing and is associated with poor clinical outcomes. Objective: To assess the association of cardiac resynchronization therapy (CRT) with improvement in cardiac function, as well as clinical improvement in patients with chemotherapy-induced cardiomyopathy. Design, Setting, and Participants: The Multicenter Automatic Defibrillator Implantation Trial-Chemotherapy-Induced Cardiomyopathy was an uncontrolled, prospective, cohort study conducted between November 21, 2014, and June 21, 2018, at 12 tertiary centers with cardio-oncology programs in the United States. Thirty patients were implanted with CRT owing to reduced left ventricular ejection fraction (LVEF≤35%), New York Heart Association class II-IV heart failure symptoms, and wide QRS complex, with established chemotherapy-induced cardiomyopathy and were followed up for 6 months after CRT implantation. The date of final follow-up was February 6, 2019. Exposures: CRT implantation according to standard of care. Main Outcomes and Measures: The primary end point was change in LVEF from baseline to 6 months after initiating CRT. Secondary outcomes included all-cause mortality and change in left ventricular end-systolic volume and end-diastolic volume. Results: Among 30 patients who were enrolled (mean [SD] age, 64 [11] years; 26 women [87%]; 73% had a history of breast cancer; 20% had a history of lymphoma or leukemia), primary end point data were available for 26 patients and secondary end point data were available for 23 patients. Patients had nonischemic cardiomyopathy with left bundle branch block, median LVEF of 29%, and a mean QRS duration of 152 ms. Patients with CRT experienced a statistically significant improvement in mean LVEF at 6 months from 28% to 39% (difference, 10.6% [95% CI, 8.0%-13.3%]; P < .001). This was accompanied by a reduction in LV end-systolic volume from 122.7 to 89.0 mL (difference, 37.0 mL [95% CI, 28.2-45.8]) and reduction in LV end-diastolic volume from 171.0 to 143.2 mL (difference, 31.9 mL [95% CI, 22.1-41.6]) (both P < .001). Adverse events included a procedure-related pneumothorax (1 patient), a device pocket infection (1 patient), and heart failure requiring hospitalization during follow-up (1 patient). Conclusions and Relevance: In this preliminary study of patients with chemotherapy-induced cardiomyopathy, CRT was associated with improvement in LVEF after 6 months. The findings are limited by the small sample size, short follow-up, and absence of a control group. Trial Registration: ClinicalTrials.gov Identifier: NCT02164721.

Tracking Anti-Staphylococcus aureus Antibodies Produced In Vivo and Ex Vivo during Foot Salvage Therapy for Diabetic Foot Infections Reveals Prognostic Insights and Evidence of Diversified Humoral Immunity.

Management of foot salvage therapy (FST) for diabetic foot infections (DFI) is challenging due to the absence of reliable diagnostics to identify the etiologic agent and prognostics to justify aggressive treatments. As Staphylococcus aureus is the most common pathogen associated with DFI, we aimed to develop a multiplex immunoassay of IgG in serum and medium enriched for newly synthesized anti-S. aureus antibodies (MENSA) generated from cultured peripheral blood mononuclear cells of DFI patients undergoing FST. Wound samples were collected from 26 DFI patients to identify the infecting bacterial species via 16S rRNA sequencing. Blood was obtained over 12 weeks of FST to assess anti-S. aureus IgG levels in sera and MENSA. The results showed that 17 out of 26 infections were polymicrobial and 12 were positive for S. aureus While antibody titers in serum and MENSA displayed similar diagnostic potentials to detect S. aureus infection, MENSA showed a 2-fold-greater signal-to-background ratio. Multivariate analyses revealed increases in predictive power of diagnosing S. aureus infections (area under the receiver operating characteristic curve [AUC] > 0.85) only when combining titers against different classes of antigens, suggesting cross-functional antigenic diversity. Anti-S. aureus IgG levels in MENSA decreased with successful FST and rose with reinfection. In contrast, IgG levels in serum remained unchanged throughout the 12-week FST. Collectively, these results demonstrate the applicability of serum and MENSA for diagnosis of S. aureus DFI with increased power by combining functionally distinct titers. We also found that tracking MENSA has prognostic potential to guide clinical decisions during FST.

Patient and Physician Perceptions of Virtual Visits for Parkinson's Disease: A Qualitative Study.

Background and Introduction: Delivering care through telemedicine directly into the patient's home is increasingly feasible, valuable, and beneficial. However, qualitative data on how patients' and physicians' perceive these virtual house calls are lacking. We conducted a qualitative analysis of perceptions of these visits for Parkinson's disease to (1) determine how patients and physicians perceive virtual visits and (2) identify components contributing to positive and negative perceptions. MATERIALS AND METHODS: Qualitative survey data were collected from patients and physicians during a 12-month randomized controlled trial of virtual house calls for Parkinson's disease. Data from 149 cases were analyzed using case-based qualitative content analysis and quantitative sentiment analysis techniques. RESULTS: Positive and negative perceptions of virtual visits were driven by three themes: (1) personal benefits of the virtual visit, (2) perceived quality of care, and (3) perceived quality of interpersonal engagement. In general, participants who identified greater personal benefit, high quality of care, and good interpersonal engagement perceived visits positively. Technical problems with the software were commonly mentioned. The sentiment analysis for patients was strongly favorable (+2.5) and moderately favorable for physicians (+0.8). Physician scores were lowest (-0.3) for the ability to perform a detailed motor examination remotely. DISCUSSION: Patients and providers generally view telemedicine favorably, but individual experiences are dependent on technical issues. CONCLUSIONS: Satisfaction with and effectiveness of remote care will likely increase as common technical problems are resolved.

Telemedicine for Parkinson's Disease: Limited Engagement Between Local Clinicians and Remote Specialists.

INTRODUCTION: The integration of remote specialists into local care teams has not been widely evaluated. METHODS: Therefore, we surveyed clinicians whose patients with Parkinson's disease had participated in a national randomized controlled trial of video visits to determine (1) whether clinicians received recommendations from remote specialists; (2) whether those recommendations were implemented; (3) what barriers to specialty care local clinicians perceived; and (4) whether they would recommend video visits. RESULTS: Of 183 clinicians surveyed, 89 (49%) responded. Less than half received the recommendations of remote specialists, but they implemented most of the recommendations they received and found them to be beneficial. CONCLUSION: The greatest perceived barrier among respondents was distance from patient to specialist, and 40% of local clinicians would recommend video visits. As telemedicine grows, improved communication between remote specialists and local clinicians is likely needed.

National Randomized Controlled Trial of Virtual House Calls for People with Parkinson's Disease: Interest and Barriers.

BACKGROUND: Delivering specialty care remotely directly into people's homes can enhance access for and improve the healthcare of individuals with chronic conditions. However, evidence supporting this approach is limited. MATERIALS AND METHODS: Connect.Parkinson is a randomized comparative effectiveness study that compares usual care of individuals with Parkinson's disease in the community with usual care augmented by virtual house calls with a Parkinson's disease specialist from 1 of 18 centers nationally. Individuals in the intervention arm receive four virtual visits from a Parkinson's disease specialist over 1 year via secure, Web-based videoconferencing directly into their homes. All study activities, including recruitment, enrollment, and assessments, are conducted remotely. Here we report on interest, feasibility, and barriers to enrollment in this ongoing study. RESULTS: During recruitment, 11,734 individuals visited the study's Web site, and 927 unique individuals submitted electronic interest forms. Two hundred ten individuals from 18 states enrolled in the study from March 2014 to June 2015, and 195 were randomized. Most participants were white (96%) and college educated (73%). Of the randomized participants, 73% had seen a Parkinson's disease specialist within the previous year. CONCLUSIONS: Among individuals with Parkinson's disease, national interest in receiving remote specialty care directly into the home is high. Remote enrollment in this care model is feasible but is likely affected by differential access to the Internet.

Reduction in inappropriate therapy and mortality through ICD programming.

BACKGROUND: The implantable cardioverter-defibrillator (ICD) is highly effective in reducing mortality among patients at risk for fatal arrhythmias, but inappropriate ICD activations are frequent, with potential adverse effects. METHODS: We randomly assigned 1500 patients with a primary-prevention indication to receive an ICD with one of three programming configurations. The primary objective was to determine whether programmed high-rate therapy (with a 2.5-second delay before the initiation of therapy at a heart rate of ≥200 beats per minute) or delayed therapy (with a 60-second delay at 170 to 199 beats per minute, a 12-second delay at 200 to 249 beats per minute, and a 2.5-second delay at ≥250 beats per minute) was associated with a decrease in the number of patients with a first occurrence of inappropriate antitachycardia pacing or shocks, as compared with conventional programming (with a 2.5-second delay at 170 to 199 beats per minute and a 1.0-second delay at ≥200 beats per minute). RESULTS: During an average follow-up of 1.4 years, high-rate therapy and delayed ICD therapy, as compared with conventional device programming, were associated with reductions in a first occurrence of inappropriate therapy (hazard ratio with high-rate therapy vs. conventional therapy, 0.21; 95% confidence interval [CI], 0.13 to 0.34; P<0.001; hazard ratio with delayed therapy vs. conventional therapy, 0.24; 95% CI, 0.15 to 0.40; P<0.001) and reductions in all-cause mortality (hazard ratio with high-rate therapy vs. conventional therapy, 0.45; 95% CI, 0.24 to 0.85; P=0.01; hazard ratio with delayed therapy vs. conventional therapy, 0.56; 95% CI, 0.30 to 1.02; P=0.06). There were no significant differences in procedure-related adverse events among the three treatment groups. CONCLUSIONS: Programming of ICD therapies for tachyarrhythmias of 200 beats per minute or higher or with a prolonged delay in therapy at 170 beats per minute or higher, as compared with conventional programming, was associated with reductions in inappropriate therapy and all-cause mortality during long-term follow-up. (Funded by Boston Scientific; MADIT-RIT ClinicalTrials.gov number, NCT00947310.).

Standardized assessment of seizures in patients with juvenile neuronal ceroid lipofuscinosis.

AIM: To evaluate seizure phenomenology, treatment, and course in individuals with juvenile neuronal ceroid lipofuscinosis (JNCL). METHOD: Data from an ongoing natural history study of JNCL were analyzed using cross-sectional and longitudinal methods. Seizures were evaluated with the Unified Batten Disease Rating Scale, a disease-specific quantitative assessment tool. RESULTS: Eighty-six children (44 males, 42 females) with JNCL were assessed at an average of three annual visits (range 1-11). Eighty-six percent (n=74) experienced at least one seizure, most commonly generalized tonic-clonic, with mean age at onset of 9 years 7 months (SD 2y 10mo). Seizures were infrequent, typically occurring less often than once every 3 months, and were managed with one to two medications for most participants. Valproate (49%, n=36) and levetiracetam (41%, n=30) were the most commonly used seizure medications. Myoclonic seizures occurred infrequently (16%, n=14). Seizure severity did not vary by sex or genotype. Seizures showed mild worsening with increasing age. INTERPRETATION: The neuronal ceroid lipofuscinoses (NCLs) represent a group of disorders unified by neurodegeneration and symptoms of blindness, seizures, motor impairment, and dementia. While NCLs are considered in the differential diagnosis of progressive myoclonus epilepsy, we show that myoclonic seizures are infrequent in JNCL. This highlights the NCLs as consisting of genetically distinct disorders with differing natural history.

A Diagnostic Serum Antibody Test for Patients With Staphylococcus aureus Osteomyelitis.

BACKGROUND: Because immunity against Staphylococcus aureus has not been fully elucidated, there is no diagnostic test to gauge how robust a patient's host response is likely to be. Therefore, we aimed to develop a test for specific antibodies in serum with diagnostic and prognostic potential. QUESTIONS/PURPOSES: We describe the development and validation of a multiplex immunoassay for characterizing a patient's immune response against 14 known S aureus antigens, which we then used to answer four questions: (1) Do certain antigens predominate in the immune response against S aureus? (2) Is there a predominant pattern of antigens recognized by patients and mice with infections? (3) Is the immunoglobulin G (IgG) response to any single antigen a useful predictor of ongoing S aureus infection? (4) Does measurement of the combined response against all 14 antigens provide a better predictor of ongoing infection? METHODS: A case-control study was performed. Sera were collected from 35 consecutive patients with S aureus culture-confirmed (methicillin-sensitive S aureus or methicillin-resistant S aureus) musculoskeletal infections (deep implant-associated, osteomyelitis, and cases of established septic arthritis). Patients were excluded only if they did not give informed consent for participation. Twenty-four patients had implant infections after total joint replacements, five had fracture implant infections, four had native knee infections, and two had chronic osteomyelitis without an implant. Control patients were chosen from a group of healthy, medically optimized patients scheduled to undergo elective arthroplasty. Control patients were matched for age (± 3 years), BMI (± 3 kg/m(2)), and sex as closely as possible to patients with infections. Sera from patients with S aureus infections and murine S aureus tibial implant infections were used to evaluate a multiplex immunoassay for immunoglobulin titers against 14 recombinant S aureus antigens. All patients were treated with organism-targeted antibiotic therapy and appropriate, timely surgery. Treatment response was monitored with clinical examination, erythrocyte sedimentation rate, C-reactive protein, and resampling of the infection site for the pathogen as needed. Elevated inflammatory markers or persistent positive culture results were considered evidence of ongoing infection. Treatment provided was considered standard-of-care therapy in our medical center and all patients were treated jointly with a board-certified infectious disease specialist. RESULTS: Four antigens elicited more than 65% of the measurable IgG, the most dominant being against iron-regulated surface determinant protein B (IsdB). Patients with infections had different patterns of elevated IgG titers, so that no single titer was elevated in more than 50% of patients with infections (area under the curve [AUC] ≤ 0.80). Multivariate analysis of IgG titers yielded greater predictive power of S aureus infection (AUC = 0.896). Patients with infections who had high titers against IsdB (median of survivors, 7.28 [25%-75% range, 2.22-21.26] vs median of patients with infection-related death, 40.41 [25%-75% range, 23.57-51.37], difference of medians, 33.13; p = 0.043) and iron-regulated surface determinant protein A (IsdA) median of survivors, 2.21 [25%-75% range, 0.79-9.11] vs median of patients with infection-related death, 12.24 [25%-75% range, 8.85-15.95], difference of medians, 10.03; p = 0.043) were more likely to die from infections than those who did not have high titers of IsdB. CONCLUSIONS: Measurement of the host antibody response is a predictor of ongoing infection that may prove to have prognostic value. Future studies will seek to enlarge the patient population with infections to allow us to reduce the number of antigens required to achieve a stronger predictive power. CLINICAL RELEVANCE: Measurement of the immune response against S aureus with this diagnostic tool may help guide future studies on prophylaxis and therapy in an era of personalized medicine and pathogen-specific therapies.

What Huntington's Disease Patients Say About Their Illness: An Online Direct-to-Participant Pilot Study.

Background: Direct-to-participant online reporting facilitates the conduct of clinical research by increasing access and clinically meaningful patient engagement. Objective: We assessed feasibility of online data collection from adults with diagnosed Huntington's disease (HD) who directly reported their problems and impact in their own words. Methods: Data were collected online from consenting United States residents who self-identified as 1) having been diagnosed with Huntington's disease, 2) able to ambulate independently, and 3) self-sufficient for most daily needs. Data for this pilot study were collected using the Huntington Study Group myHDstory online research platform. The Huntington Disease Patient Report of Problems (HD-PROP), an open-ended questionnaire, was used to capture verbatim bothersome problems and functional impact. Natural language processing, human-in-the-loop curation of verbatim reports involving clinical and experience experts, and machine learning classified verbatim-reports into clinically meaningful symptoms. Results: All 8 questionnaires in the online pilot study were completed by 345 participants who were 60.9% men, 34.5±9.9 (mean±SD) years old, and 9.5±8.4 years since HD diagnosis. Racial self-identification was 46.4% Caucasian, 28.7% African American, 15.4% American Indian/Alaska Native, and 9.5% other. Accuracy of verbatim classification was 99%. Non-motor problems were the most frequently reported symptoms; depression and cognitive impairment were the most common. Conclusions: Online research participation was feasible for a diverse cohort of adults who self-reported an HD diagnosis and predominantly non-motor symptoms related to mood and cognition. Online research tools can help inform what bothers HD patients, identify clinically meaningful outcomes, and facilitate participation by diverse and under-represented populations.

Quantifying massive allograft healing of the canine femur in vivo and ex vivo: a pilot study.

BACKGROUND: Allograft integration in segmental osseous defects is unpredictable. Imaging techniques have not been applied to investigate angiogenesis and bone formation during allograft healing in a large-animal model. QUESTIONS/PURPOSES: We used dynamic contrast-enhanced (DCE)-MRI and cone beam (CB)-CT to quantify vascularity and bone volume in a canine femoral allograft model and determined their relationship with biomechanical testing and histomorphometry. METHODS: Femoral ostectomy was performed in three dogs and reconstructed with a 5-cm allograft and compression plate. At 0.5, 3, and 6 months, we performed DCE-MRI to quantify vascular permeability (Ktrans) and perfused fraction and CB-CT to quantify bone volume. We also performed posteuthanasia torsional testing and dynamic histomorphometry of the grafted and nonoperated femurs. RESULTS: DCE-MRI confirmed the avascular nature of allograft healing (perfused fraction, 2.08%-3.25%). CB-CT demonstrated new bone formation at 3 months (26.2, 3.7, and 2.2 cm(3)) at the graft-host junctions, which remodeled down at 6 months (14.0, 2.2, and 2.0 cm(3)). The increased bone volume in one subject was confirmed with elevated Ktrans (0.22) at 3 months. CB-CT-identified remodeled bone at 6 months was corroborated by histomorphometry. Allografted femurs recovered only 40% of their strength at 6 months. CONCLUSIONS: CB-CT and DCE-MRI can discriminate differences in angiogenesis and bone formation in the canine allograft model, which has potential to detect a small (32%) drug or device effect on biomechanical healing with only five animals per group.

Low albumin level is more strongly associated with adverse outcomes and Staphylococcus aureus infection than hemoglobin A1C or smoking tobacco.

Postsurgical deep musculoskeletal infections are a major clinical problem in Orthopaedic Surgery. A serum-based nomogram, which can objectively risk-stratify patients, and aid surgeons in delineating infection risk associated with orthopedic surgical interventions, would be immensely helpful. Here, we constructed a multi-parametric nomogram based on serum anti-Staphylococcus aureus antibody responses, patient characteristics including demographics and standard clinical tests. This nomogram was formally tested in a prospective cohort study comparing 303 hospitalized patients with culture-confirmed S. aureus infection compared with a cohort of 223 healthy screened preoperative patients. Serum anti-S. aureus antibody responses, standard of care clinical tests, and patient demographic data were utilized to perform multivariate logistic regression analysis to quantify the presence of infection and adverse outcome using odds ratios (OR) and to assess predictive ability via area under the ROC curve (AUC). At enrollment, high anti-S. aureus IgG titers were predictive of infection. Remarkably, low serum albumin was found to be significantly associated with infection (OR = 479.963, 95% CI 61.59 - 3740.33, p < 0.0001) and this finding was surprisingly higher than BMI or HbA1c-associations. Combining all risk factors in the nomogram yielded a diagnostic AUC of 0.949 for predicting S. aureus infection. Our results indicate that a serum-based multi-parametric nomogram can be useful in diagnosing S. aureus infections, and importantly, malnourishment is significantly associated with these infections.

Reduction in Ventricular Tachyarrhythmia Burden in Patients Enrolled in the RAID Trial.

BACKGROUND: The RAID (Ranolazine Implantable Cardioverter-Defibrillator) randomized placebo-controlled trial showed that ranolazine treatment was associated with reduction in recurrent ventricular tachycardia (VT) requiring appropriate implantable cardioverter-defibrillator (ICD) therapy. OBJECTIVES: This study aimed to identify groups of patients in whom ranolazine treatment would result in the highest reduction of ventricular tachyarrhythmia (VTA) burden. METHODS: Andersen-Gill analyses were performed to identify variables associated with risk for VTA burden among 1,012 patients enrolled in RAID. The primary endpoint was VTA burden defined as VTA episodes requiring appropriate treatment. RESULTS: Multivariate analysis identified 7 factors associated with increased VTA burden: history of VTA, age ≥65 years, New York Heart Association functional class ≥III, QRS complex (≥130 ms), low ejection fraction (<30%), atrial fibrillation (AF), and concomitant antiarrhythmic drug (AAD) therapy. The effect of ranolazine on VTA burden was seen among patients without concomitant AAD therapy (HR [HR]: 0.68; 95% CI: 0.55-0.84; P < 0.001), whereas no effect was seen among those who are concomitantly treated with other AADs (HR: 1.33; 95% CI: 0.90-1.96; P = 0.16); P = 0.003 for interaction. In patients with cardiac resynchronization therapy (CRT) ICDs, ranolazine treatment was associated with a 36% risk reduction for VTA recurrence (HR: 0.64; 95% CI: 0.47-0.86; P < 0.001), whereas among patients with ICDs without CRT no significant effect was noted (HR: 0.94; 95% CI: 0.74-1.18; P = 0.57); P = 0.047 for interaction. CONCLUSIONS: In patients with high risk for VTA, ranolazine is effective in reducing VTA burden, with significantly greater effect in CRT-treated patients, those without AF, and those not treated with concomitant AADs. In patients already on AADs or those with AF, the addition of ranolazine did not affect VTA burden. (Ranolazine Implantable Cardioverter-Defibrillator Trial [RAID]; NCT01215253).

Serum antibodies against Staphylococcus aureus can prognose treatment success in patients with bone infections.

Prognosing life-threatening orthopedic infections caused by Staphylococcus aureus remains a major clinical challenge. To address this, we developed a multiplex assay to assess the humoral immune proteome against S. aureus in patients with musculoskeletal infections. We found initial evidence that antibodies against some antigens (autolysins: Amd, Gmd; secreted immunotoxins: CHIPS, SCIN, Hla) were associated with protection, whereas antibodies against the iron-regulated surface determinant (Isd) proteins (IsdA, IsdB, IsdH) were aligned with adverse outcomes. To formally test this, we analyzed antibody levels and 1-year clinical outcomes of 194 patients with confirmed S. aureus bone infections (AO Trauma Clinical Priority Program [CPP] Bone Infection Registry). A staggering 20.6% of the enrolled patients experienced adverse clinical outcomes (arthrodesis, reinfection, amputation, and septic death) after 1-year. At enrollment, anti-S. aureus immunoglobulin G (IgG) levels in patients with adverse outcomes were 1.35-fold lower than those in patients whose infections were successfully controlled (p < 0.0001). Overall, there was a 51%-69% reduction in adverse outcome risk for every 10-fold increase in initial IgG concentration against Gmd, Amd, IsdH, CHIPS, SCIN, and Hla (p < 0.05). Notably, anti-IsdB antibodies remained elevated in patients with adverse outcomes; for every 10-fold change in the ratio of circulating anti-Isd to anti-Atl IgG at enrollment, there was a trending 2.6-fold increased risk (odds ratio = 2.555) of an adverse event (p = 0.105). Moreover, antibody increases over time correlated with adverse outcomes and decreases with positive outcomes. These studies demonstrate the potential of the humoral immune response against S. aureus as a prognostic indicator for assessing treatment success and identifying patients requiring additional interventions.

Species-Specific Immunoassay Aids Identification of Pathogen and Tracks Infectivity in Foot Infection.

BACKGROUND: Conventional bacterial cultures frequently fail to identify the dominant pathogen in polymicrobial foot infections, in which Staphylococcus aureus is the most common infecting pathogen. Previous work has shown that species-specific immunoassays may be able to identify the main pathogen in musculoskeletal infections. We sought to investigate the clinical applicability of a S. aureus immunoassay to accurately identify the infecting pathogen and monitor its infectivity longitudinally in foot infection. We hypothesized that this species-specific immunoassay could aid in the diagnosis of S. aureus and track the therapeutic response in foot infections. METHODS: From July 2015 to July 2019, 83 infected foot ulcer patients undergoing surgical intervention (debridement or amputation) were recruited and blood was drawn at 0, 4, 8, and 12 weeks. Whole blood was analyzed for S. aureus-specific serum antibodies (mix of historic and new antibodies) and plasmablasts were isolated and cultured to quantify titers of newly synthesized antibodies (NSAs). Anti-S. aureus antibody titers were compared with culture results to assess their concordance in identifying S. aureus as the pathogen. The NSA titer changes at follow-ups were compared with wound healing status to evaluate concordance between evolving host immune response and clinically resolving or relapsing infection. RESULTS: Analysis of serum for anti-S. aureus antibodies showed significantly increased titers of 3 different anti-S. aureus antibodies, IsdH (P = .037), ClfB (P = .025), and SCIN (P = .005), in S. aureus culture-positive patients compared with culture-negative patients. Comparative analysis of combining antigens for S. aureus infection diagnosis increased the concordance further. During follow-up, changes of NSA titers against a single or combination of S. aureus antigens significantly correlated with clinically resolving or recurring infection represented by wound healing status. CONCLUSION: In the management of foot infection, the use of S. aureus-specific immunoassay may aid in diagnosis of the dominant pathogen and monitoring of the host immune response against a specific pathogen in response to treatment. Importantly, this immunoassay could detect recurrent foot infection, which may guide a surgeon's decision to intervene. LEVEL OF EVIDENCE: Level II, prospective comparative study.

Increased myocellular lipid and IGFBP-3 expression in a pre-clinical model of pancreatic cancer-related skeletal muscle wasting.

BACKGROUND: Skeletal muscle wasting (SMW) in cancer patients is associated with increased morbidity, mortality, treatment intolerance and discontinuation, and poor quality of life. This is particularly true for patients with pancreatic ductal adenocarcinoma (PDAC), as over 85% experience SMW, which is responsible for ~30% of patient deaths. While the established paradigm to explain SMW posits that muscle catabolism from systemic inflammation and nutritional deficiencies, the cause of death, and the cellular and molecular mechanisms responsible remain to be elucidated. To address this, we investigated the relationship between tumour burden and survival in the KCKO murine PDAC model. METHODS: Female C57BL/6J mice 6-8 weeks of age underwent orthotopic injection with KCKO-luc tumour cells. Solid tumour was verified on Day 5, post-tumour inoculation. In vivo, longitudinal lean mass and tumour burden were assessed via dual-energy X-ray absorptiometry and IVIS imaging, respectively, and total body weight was assessed, weekly. Animals were sacrificed at a designated end point of 'failure to thrive'. After sacrifice, lower limb hind muscles were harvested for histology and RNA extraction. RESULTS: We found a strong correlation between primary tumour size and survival (r2  = 0.83, P < 0.0001). A significant decrease in lower limb lean mass was first detected at Day 38 post-implantation vs. no tumour controls (NTCs) (P < 0.0001). SMW was confirmed by histology, which demonstrated a 38%, 32.7%, and 39.9% decrease in fibre size of extensor digitorum longus, soleus, and tibialis anterior muscles, respectively, in PDAC mice vs. NTC (P < 0.002). Histology also revealed a 67.6% increase in haematopoietic cells within the muscle of PDAC mice when compared with NTC. Bulk RNAseq on muscles from PDAC mice vs. NTC revealed significant increases in c/ebpß/Δ, il-1, il-6, and tnf gene expression. Pathway analyses to identify potential upstream factors revealed increased adipogenic gene expression, including a four-fold increase in igfbp-3. Histomorphometry of Oil Red-O staining for fat content in tibialis anterior muscles demonstrated a 95.5% increase in positively stained fibres from PDAC mice vs. NTC. CONCLUSIONS: Together, these findings support a novel model of PDAC-associated SMW and mortality in which systemic inflammation leads to inflammatory cell infiltration into skeletal muscle with up-regulated myocellular lipids.

Clinical utilization of species-specific immunoassays for identification of Staphylococcus aureus and Streptococcus agalactiae in orthopedic infections.

Staphylococcus aureus and Streptococcus agalactiae (Group B streptococcus, GBS) are common causes of deep musculoskeletal infections (MSKI) and result in significant patient morbidity and cost to the healthcare system. One of the major challenges with MSKI is the lack of faithful diagnostics to correctly identify the primary pathogen, as standard culture-based assays are prone to false positives in the case of polymicrobial infections, and false negatives due to limitations in sample acquisition and antibiotic use before presentation. To improve upon our current diagnostic methods for MSKI, we developed a multiplex immunoassay for antigen-specific IgGs in serum (Luminex), and medium enriched for newly synthesized antibodies (MENSA) for anti-S. aureus and GBS generated from cultured peripheral blood mononuclear cells (PBMCs) of orthopedic infection patients undergoing surgical treatment. Samples were obtained from 110 MSKI patients: 80 diabetic foot ulcer, 21 periprosthetic joint infection, 5 septic arthritis, 2 spine, 1 hand, and 1 fracture-related infection (FRI). Anti-S. aureus and anti-GBS antibody titers were compared to culture results to assess their concordance in identifying the pathogens. Immunoassay, particularly MENSA, showed high diagnostic potential for monomicrobial S. aureus and GBS orthopedic infections (AUC > 0.95). MENSA also demonstrated diagnostic potential for GBS polymicrobial orthopedic infection and for GBS DFU (AUC > 0.83 for both). Serum showed high diagnostic potential for S. aureus PJI (AUC > 0.95). Taken together, these findings support the development of species-specific immunoassays for the identification of causal pathogens in active MSKI, especially in conjunction with standard culture.

Mexiletine in Myotonic Dystrophy Type 1: A Randomized, Double-Blind, Placebo-Controlled Trial.

OBJECTIVE: To assess mexiletine's long-term safety and effect on 6-minute walk distance in a well-defined cohort of patients with myotonic dystrophy type 1 (DM1). METHODS: We performed a randomized, double-blind, placebo-controlled trial of mexiletine (150 mg 3 times daily) to evaluate its efficacy and safety in a homogenous cohort of adult ambulatory patients with DM1. The primary outcome was change in 6-minute walk distance at 6 months. Secondary outcomes included changes in hand grip myotonia, strength, swallowing, forced vital capacity, lean muscle mass, Myotonic Dystrophy Health Index scores, and 24-hour Holter and ECG results at 3 and 6 months. RESULTS: Forty-two participants were randomized and 40 completed the 6-month follow-up (n = 20 in both groups). No significant effects of mexiletine were observed on 6-minute walk distance, but hand grip myotonia was improved with mexiletine treatment. There were no differences between the mexiletine and placebo groups with respect to the frequency or type of adverse events. Changes in PR, QRS, and QTc intervals were similar in mexiletine- and placebo-treated participants. CONCLUSIONS: There was no benefit of mexiletine on 6-minute walk distance at 6 months. Although mexiletine had a sustained positive effect on objectively measured hand grip myotonia, this was not seen in measures reflecting participants' perceptions of their myotonia. No effects of mexiletine on cardiac conduction measures were seen over the 6-month follow-up period. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that for ambulatory patients with DM1, mexiletine does not significantly change 6-minute walk distance at 6 months.

Pivotal studies of orphan drugs approved for neurological diseases.

OBJECTIVE: To identify design elements of clinical trials leading to US Food and Drug Administration approval of drugs for neurological diseases with and without orphan indications. METHODS: We used publicly available information to identify approvals for drugs for neurological diseases with an orphan indication (n = 19) and compared them with recent approvals for drugs for neurological diseases without an orphan indication (n = 20). We identified "pivotal trials" from drug labels and drug approval packages, and assessed them on four elements of clinical trial design: control, blinding, randomization, and size. RESULTS: All drugs for neurological diseases (100%) approved without an orphan indication included at least two randomized, double-blind, placebo-controlled trials. In comparison, 32% of drugs with an orphan indication had at least two such trials (p < 0.001) and 74% had at least one (p = 0.02). Thirty-three pivotal trials were conducted for the 19 drugs approved with an orphan indication. Of the 33 trials, 11 (33%) did not use a placebo control, 9 (27%) were not double blind, and 4 (12%) were not randomized. Drugs approved without an orphan indication had more pivotal trials per drug (3.8 vs 1.7 trials; p < 0.001) and a larger mean trial size (506 vs 164 trial participants; p < 0.001). INTERPRETATION: The US Food and Drug Administration has approved orphan drugs for neurological diseases without randomized, doubled-blind, placebo-controlled pivotal trials. As orphan drug development grows, demand will likely increase for alternative designs for conducting adequate and well-controlled studies to demonstrate drug efficacy.

A U.S. survey of patients with Parkinson's disease: satisfaction with medical care and support groups.

Relatively little is known about patient satisfaction with Parkinson's disease (PD) care and the use of support groups in the United States. We surveyed members of the Muhammad Ali Parkinson's Disease Registry to assess satisfaction with medical care and to evaluate support group use. Satisfaction was measured on a 5-point Likert scale, with high satisfaction defined as a four or five. We used multiple logistic regression to identify factors associated with high satisfaction and support group use. The response rate was 38% (726 of 1923). Most (57%) expressed high satisfaction with PD care. Individuals were most satisfied with the time their provider spent with them (61%) and PD education (56%) but least satisfied with prognostic information (35%) and information about non-drug interventions (28%). Patients seeing a PD specialist were three times more satisfied with their care than those seeing a general neurologist (OR = 3.00, 95% CI: 1.92-4.71; P < 0.0001). Support group use is common, and 61% of survey respondents had attended one at any point. Caucasian race (OR = 2.85, 95% CI: 1.45-5.61), PD duration (OR = 1.05 per year, CI: 1.01-1.10), and PD specialist care (OR = 1.80, CI: 1.16-2.77) were associated with greater support group attendance. Overall, 49% reported high satisfaction with their support group. The greatest concerns were specific needs not being addressed (15%) and insufficient expertise within the group (14%). Most individuals with Parkinson's disease expressed high levels of satisfaction, especially with specialist care. Specialty care and improved education, in the clinic or through support groups, may enhance satisfaction and health care quality.