Social determinants of health in adults with whiplash associated disorders.

OBJECTIVES: Although it is well-known that chronic diseases need to be managed within the complex biopsychosocial framework, little is known about the role of sociodemographic features in adults with whiplash-associated disorders (WAD) and their association with health outcomes. The aim of this study was to investigate the association between various sociodemographic features (age, sex, ethnicity, education, working, marriage, caring for dependents, and use of alcohol and drugs) and health outcomes (pain, disability, and physical/mental health-related quality of life) in WAD, both through their individual relationships and also via cluster analysis. METHODS: Independent t-tests and Kruskal-Wallis tests (with Mann-Whitney tests where appropriate) were used to compare data for each health outcome. Variables demonstrating a significant relationship with health outcomes were then entered into two-step cluster analysis. RESULTS: N = 281 participated in study (184 females, mean (±SD) age 40.9 (±10.7) years). Individually, level of education (p = 0.044), consumption of non-prescribed controlled or illegal drugs (p = 0.015), and use of alcohol (p = 0.008) influenced level of disability. Age (p = 0.014), marriage status (p = 0.008), and caring for dependents (p = 0.036) influenced mental health quality of life. Collectively, two primary clusters emerged, with one cluster defined by marriage, care of dependents, working status, and age >40 years associated with improved mental health outcomes (F 1,265 = 10.1, p = 0.002). DISCUSSION: Consistent with the biopsychosocial framework of health, this study demonstrated that various sociodemographic features are associated with health outcomes in WAD, both individually and collectively. Recognizing factors that are associated with poor health outcomes may facilitate positive outcomes and allow resource utilization to be tailored appropriately.

Derivation of a clinical decision rule for a bone marrow aspirate concentrate injection in knee osteoarthritis.

Aim: To develop a simple clinical decision rule (CDR) to identify people with knee osteoarthritis who are likely or unlikely to benefit from bone marrow aspirate concentrate (BMAC) injection. Materials & methods: A total of 92 people with clinical and radiographic evidence of refractory knee osteoarthritis received a single intra-articular (IA) BMAC injection. Multiple logistic regression analysis was used to determine which combination of risk factors predicted BMAC responsiveness. A responder was defined as a person whose knee pain improved more than 15% from baseline 6 months post procedure. Results: The CDR demonstrated that those with lower pain levels, or high pain levels with previous surgery, could be predicted to benefit from a single IA BMAC injection. Conclusion: A simple CDR containing three variables predicted responsiveness to a single IA knee BMAC injection with high accuracy. Further validation of the CDR is required prior to routine use in clinical practice.

People with knee osteoarthritis who do not improve with exercise and medicine lack effective long-term treatment options apart from total knee replacement. Although total knee replacement provides effective outcomes in most people, not all people are candidates and not all people respond. Thus, other safe and effective treatment options are required. Bone marrow aspirate concentrate (BMAC) is a regenerative medicine treatment that has demonstrated success in people with chronic knee osteoarthritis. However, it is unclear which people do or do not respond to BMAC. This study investigated factors that predicted a successful response to a single injection of BMAC 6 months post injection. Those with lower initial pain levels (<7/10), or high pain levels with previous surgery, could be predicted to benefit from a single BMAC injection.

Associations Between Resting Heart Rate, Resting Blood Pressure, Psychological Variables and Pain Processing in Chronic Whiplash-Associated Disorder: A Cross-Sectional Study.

OBJECTIVE: Autonomic nervous system dysfunction has been implicated in chronic whiplash-associated disorder (WAD). However, the relationship between autonomic variables (e.g., resting heart rate and blood pressure) and clinical factors in chronic WAD is not well understood. This study sought to examine the associations between resting heart rate, resting blood pressure, pain processing and psychological variables in chronic WAD and in pain-free controls. DESIGN: Secondary analysis of a cross-sectional study. SETTING: University clinical research laboratory. SUBJECTS: Thirty-six people with chronic WAD Grade II (mean [SD] age 40.1 [14.6] years, 28 females) and 25 pain-free controls (35.6 [13.0] years, 17 females). METHODS: Participants had resting heart rate, systolic and diastolic blood pressure measured. Pain processing measures comprised: (i) pain pressure threshold at the cervical spine, hand and leg, (ii) temporal summation at the cervical spine and hand, and (iii) conditioned pain modulation. Psychological outcomes included measures of kinesiophobia, pain catastrophizing and post-traumatic stress symptoms. Correlations between autonomic variables, pain processing and psychological variables were determined (P < .05, 5% FDR). RESULTS: No significant correlations between autonomic and pain processing variables, or autonomic and psychological variables were found in the chronic WAD group. In the control group, diastolic blood pressure was positively correlated with cervical spine pressure pain threshold (r = 0.53, P = .007). CONCLUSIONS: An association between blood pressure and pain sensitivity was observed in the control group but not the chronic WAD group. Such an association appears to be disrupted in chronic WAD, which may infer involvement of autonomic pathways in the pathophysiology of this condition.

Evaluating Cefoperazone-Induced Gut Metabolic Functional Changes in MR1-Deficient Mice.

Mucosal-associated invariant T cells are activated following the recognition of bacterial antigens presented by the major histocompatibility complex class I-related molecule (MR1). Previous metagenomics data showed that MR1-/- knock-out (KO) mice had distinct microbiota and displayed a resistance to Clostridioides difficile (CDI) colonization vs. wild-type (WT) mice. In the present study, LC/MS-based untargeted metabolomics are applied to evaluate the changes in metabolic activities, in accordance with the changes in gut microbiota caused by cefoperazone (Cef) treatment. Adult C57Bl/6J WT and MR1-/- KO mice were given sterile drinking water or spiked with 0.5 mg/mL Cef ad libitum for five days. Fecal pellets were collected daily, and both small intestinal and cecal contents were harvested at sacrifice. The PLS-DA score plots of the metabolomic data indicate that the microbiota is relatively less disturbed by Cef treatment in KO mice, which is consistent with the metagenomics data. The most noticeable differences in the metabolome of KO and WT mice were the increases in carbohydrates in the WT mice, but not in the KO mice. Metabolic functional biomarkers were identified through the correlation analysis of gamma-aminobutyric acid (GABA) and riboflavin. These detected metabolic functional biomarkers could provide information complementary to metagenomics data.

Bile Acid Profile and its Changes in Response to Cefoperazone Treatment in MR1 Deficient Mice.

Mucosal associated invariant T-cells (MAIT cells) are activated following recognition of bacterial antigens (riboflavin intermediates) presented on major histocompatibility complex class I-related molecule (MR1). Our previous study showed that MR1-/- knock-out (KO) mice (lacking MAIT cells) harbor a unique microbiota that is resistant to antibiotic disruption and Clostridioides difficile colonization. While we have characterized the microbiota of this mouse strain, changes in global metabolic activity in these KO mice have not been assessed. Here, LC/MS-based untargeted metabolomics was applied to investigate the differences in the metabolome, specifically in the bile acid (BA) profile of wild-type (WT) and MR1-/- KO mice, as well as how antibiotics change these profiles. BA changes were evaluated in the intestinal content, cecum content, and stool samples from MR1-/- mice and WT mice treated with cefoperazone (Cef). Fecal pellets were collected daily and both intestinal and cecal contents were harvested at predetermined endpoints on day 0 (D0), day 1 (D1), day 3 (D3), and day 5 (D5). KO mice exhibited no changes in 6-hydroxymethyl-8-D-ribityllumazine (rRL-6-CH2OH; an MR1-restricted riboflavin derivative) in the stool samples at either time point vs. D0, while WT mice showed significant decreases in rRL-6-CH2OH in the stool samples on all treatment days vs. D0. Metabolomics analysis from cecal and stool samples showed that KO mice had more total BA intensity (KO/WT = ~1.7 and ~3.3 fold higher) than that from WT mice prior to Cef treatment, while the fold change difference (KO/WT = ~4.5 and ~4.4 fold) increased after five days of Cef treatment. Both KO and WT mice showed decreases in total BA intensity in response to Cef treatment, however, less dramatic decreases were present in KO vs. WT mice. Increases in taurocholic acid (TCA) intensity and decreases in deoxycholic acid (DCA) intensity in the stool samples from WT mice were associated with the depletion of certain gut bacteria, which was consistent with the previously reported microbiome data. Furthermore, the non-detected TCA and relatively higher DCA intensity in the KO mice might be related to Clostridioides difficile infection resistance, although this needs further investigation.

Phase I/II parallel double-blind randomized controlled clinical trial of perispinal etanercept for chronic stroke: improved mobility and pain alleviation.

Background: Previous open-label studies showed that chronic post-stroke pain could be abated by treatment with perispinal etanercept, although these benefits were questioned. A randomized double-blind placebo controlled clinical trial was conducted to test perispinal etanercept for chronic post-stroke pain.Research design and methods: Participants received two treatments, either perispinal etanercept (active) or saline (control). Primary outcomes were the differences in daily pain levels between groups analyzed by SPSS.Results: On the 0-100 points visual analog scale, perispinal etanercept reduced mean levels for worst and average daily pain from baseline after two treatments by 19.5 - 24 points (p < 0.05), and pain alleviation was maintained in the etanercept group, with no significant change in the control group. Thirty percent of etanercept participants had near complete pain abatement after first treatment. Goniometry of the paretic arm showed improved mean shoulder rotation by 55 degrees in active forward flexion for the etanercept group (p = 0.003) only.Conclusions: Perispinal etanercept can provide significant and ongoing benefits for the chronic post-stroke management of pain and greater shoulder flexion by the paretic arm. Effects are rapid and highly significant, supporting direct action on brain function.Trial registration: ACTRN12615001377527 and Universal Trial Number U1111-1174-3242.

Microbiota of MR1 deficient mice confer resistance against Clostridium difficile infection.

Clostridium difficile (Cd) infection (CDI) typically occurs after antibiotic usage perturbs the gut microbiota. Mucosa-associated invariant T cells (MAIT) are found in the gut and their development is dependent on Major histocompatibility complex-related protein 1 (MR1) and the host microbiome. Here we were interested in determining whether the absence of MR1 impacts resistance to CDI. To this end, wild-type (WT) and MR1-/- mice were treated with antibiotics and then infected with Cd spores. Surprisingly, MR1-/- mice exhibited resistance to Cd colonization. 16S rRNA gene sequencing of feces revealed inherent differences in microbial composition. This colonization resistance was transferred from MR1-/- to WT mice via fecal microbiota transplantation, suggesting that MR1-dependent factors influence the microbiota, leading to CDI susceptibility.

Psychological Manifestations and Chronic Pain in Whiplash-Associated Disorder Mechanisms: The Whole Pie, Please.

In the last decade, as the biopsychosocial model of patient health care has expanded, there has been an increased focus on the influence of psychological manifestations on patient symptoms and health-related outcomes. This Viewpoint explores the scientific underpinnings of psychological manifestations in chronic whiplash-associated disorders (WADs)-where opinions vary widely concerning the reason for persistent symptoms and nonrecovery. It also provides an epidemiological and scientific foundation for the management of chronic WAD, incorporating the spectrum of the biopsychosocial model. J Orthop Sports Phys Ther 2019;49(3):118-121. doi:10.2519/jospt.2019.0603.

Cervical spine findings on MRI in people with neck pain compared with pain-free controls: A systematic review and meta-analysis.

BACKGROUND: There is uncertainty regarding the clinical significance of findings on MRI in patients with whiplash associated disorder (WAD) or nonspecific neck pain (NSNP). PURPOSE: To compare the presence of cervical spine MRI findings in people with WAD or NSNP with pain-free controls. STUDY TYPE: Systematic review and meta-analysis. POPULATION: Adults with WAD (n = 994), NSNP (n = 715), or pain-free controls (n = 2323). FIELD STRENGTH: 0.5T, 1.5T, and 3.0T. ASSESSMENT: Medline, EMBASE, CINAHL, Web of Science, SCOPUS, and Cochrane CENTRAL databases were searched. Two independent reviewers identified studies for inclusion and extracted data. Risk of bias was assessed using the Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Overall quality of the evidence from meta-analysis was assessed using the Grades of Recommendation, Assessment, Development, and Evaluation approach. STATISTICAL TESTS: Meta-analysis was performed using a random-effects model to calculate odds ratios or standard mean differences (SMDs) for binary and continuous data. RESULTS: In total, 31 studies were included (eight comparing acute WAD to controls, 14 comparing chronic WAD to controls, 12 comparing chronic NSNP to controls) comprising 4032 participants. Rectus capitis posterior major cross-sectional area was smaller in people with chronic NSNP than controls (two studies: SMD -1.18 [95% confidence interval [CI] -1.65, -0.71]). The remaining meta-analysis comparisons showed no group differences in MRI findings. The quality of evidence was mostly low due to small sample sizes and high heterogeneity. DATA CONCLUSION: Given the typically low-quality evidence, definitive conclusions cannot be drawn on the presence of MRI findings in individuals with WAD or NSNP compared with pain-free controls. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018.

Variations of the lung microbiome and immune response in mechanically ventilated surgical patients.

Mechanically ventilated surgical patients have a variety of bacterial flora that are often undetectable by traditional culture methods. The source of infection in many of these patients remains unclear. To address this clinical problem, the microbiome profile and host inflammatory response in bronchoalveolar lavage samples from the surgical intensive care unit were examined relative to clinical pathology diagnoses. The hypothesis was tested that clinical diagnosis of respiratory tract flora were similar to culture positive lavage samples in both microbiome and inflammatory profile. Bronchoalveolar lavage samples were collected in the surgical intensive care unit as standard of care for intubated individuals with a clinical pulmonary infection score of >6 or who were expected to be intubated for >48 hours. Cytokine analysis was conducted with the Bioplex Pro Human Th17 cytokine panel. The microbiome of the samples was sequenced for the 16S rRNA region using the Ion Torrent. Microbiome diversity analysis showed the culture-positive samples had the lowest levels of diversity and culture negative with the highest based upon the Shannon-Wiener index (culture positive: 0.77 ± 0.36, respiratory tract flora: 2.06 ± 0.73, culture negative: 3.97 ± 0.65). Culture-negative samples were not dominated by a single bacterial genera. Lavages classified as respiratory tract flora were more similar to the culture-positive in the microbiome profile. A comparison of cytokine expression between groups showed increased levels of cytokines (IFN-g, IL-17F, IL-1B, IL-31, TNF-a) in culture-positive and respiratory tract flora groups. Culture-positive samples exhibited a more robust immune response and reduced diversity of bacterial genera. Lower cytokine levels in culture-negative samples, despite a greater number of bacterial species, suggest a resident nonpathogenic bacterial community may be indicative of a normal pulmonary environment. Respiratory tract flora samples were most similar to the culture-positive samples and may warrant classification as culture-positive when considering clinical treatment.

Germinant Synergy Facilitates Clostridium difficile Spore Germination under Physiological Conditions.

Clostridium difficile is a Gram-positive obligate anaerobe that forms spores in order to survive for long periods in the unfavorable environment outside a host. C. difficile is the leading cause of nosocomial infectious diarrhea worldwide. C. difficile infection (CDI) arises after a patient treated with broad-spectrum antibiotics ingests infectious spores. The first step in C. difficile pathogenesis is the metabolic reactivation of dormant spores within the gastrointestinal (GI) tract through a process known as germination. In this work, we aim to elucidate the specific conditions and the location within the GI tract that facilitate this process. Our data suggest that C. difficile germination occurs through a two-step biochemical process that is regulated by pH and bile salts, amino acids, and calcium present within the GI tract. Maximal germination occurs at a pH ranging from 6.5 to 8.5 in the terminal small intestine prior to bile salt and calcium reabsorption by the host. Germination can be initiated by lower concentrations of germinants when spores are incubated with a combination of bile salts, calcium, and amino acids, and this synergy is dependent on the availability of calcium. The synergy described here allows germination to proceed in the presence of inhibitory bile salts and at physiological concentrations of germinants, effectively decreasing the concentrations of nutrients required to initiate an essential step of pathogenesis.IMPORTANCEClostridium difficile is an anaerobic spore-forming human pathogen that is the leading cause of nosocomial infectious diarrhea worldwide. Germination of infectious spores is the first step in the development of a C. difficile infection (CDI) after ingestion and passage through the stomach. This study investigates the specific conditions that facilitate C. difficile spore germination, including the following: location within the gastrointestinal (GI) tract, pH, temperature, and germinant concentration. The germinants that have been identified in culture include combinations of bile salts and amino acids or bile salts and calcium, but in vitro, these function at concentrations that far exceed normal physiological ranges normally found in the mammalian GI tract. In this work, we describe and quantify a previously unreported synergy observed when bile salts, calcium, and amino acids are added together. These germinant cocktails improve germination efficiency by decreasing the required concentrations of germinants to physiologically relevant levels. Combinations of multiple germinant types are also able to overcome the effects of inhibitory bile salts. In addition, we propose that the acidic conditions within the GI tract regulate C. difficile spore germination and could provide a biological explanation for why patients taking proton pump inhibitors are associated with increased risk of developing a CDI.

Cysteine Desulfurase IscS2 Plays a Role in Oxygen Resistance in Clostridium difficile.

Clostridium difficile is an anaerobic, spore-forming bacterium capable of colonizing the gastrointestinal tract of humans following disruption of the normal microbiota, typically from antibiotic therapy for an unrelated infection. With approximately 500,000 confirmed infections leading to 29,000 deaths per year in the United States, C. difficile infection (CDI) is an urgent public health threat. We previously determined that C. difficile survives in up to 3% oxygen. Low levels of oxygen are present in the intestinal tract, with the higher concentrations being associated with the epithelial cell surface. Additionally, antibiotic treatment, the greatest risk factor for CDI, increases the intestinal oxygen concentration. Therefore, we hypothesized that the C. difficile genome encodes mechanisms for survival during oxidative stress. Previous data have shown that cysteine desulfurases involved in iron-sulfur cluster assembly are involved in protecting bacteria from oxidative stress. In this study, deletion of a putative cysteine desulfurase (Cd630_12790/IscS2) involved in the iron-sulfur cluster (Isc) system caused a severe growth defect in the presence of 2% oxygen. Additionally, this mutant delayed colonization in a conventional mouse model of CDI and failed to colonize in a germfree model, which has higher intestinal oxygen levels. These data imply an undefined role for this cysteine desulfurase in protecting C. difficile from low levels of oxygen in the gut.

Do pain-associated contexts increase pain sensitivity? An investigation using virtual reality.

Background and aims Pain is not a linear result of nociception, but is dependent on multisensory inputs, psychological factors, and prior experience. Since nociceptive models appear insufficient to explain chronic pain, understanding non-nociceptive contributors is imperative. Several recent models propose that cues associatively linked to painful events might acquire the capacity to augment, or even cause, pain. This experiment aimed to determine whether contexts associated with pain, could modulate mechanical pain thresholds and pain intensity. Methods Forty-eight healthy participants underwent a contextual conditioning procedure, where three neutral virtual reality contexts were paired with either unpredictable noxious stimulation, unpredictable vibrotactile stimulation, or no stimulation. Following the conditioning procedure, mechanical pain thresholds and pain evoked by a test stimulus were examined in each context. In the test phase, the effect of expectancy was equalised across conditions by informing participants when thresholds and painful stimuli would be presented. Results Contrary to our hypothesis, scenes that were associated with noxious stimulation did not increase mechanical sensitivity (p=0.08), or increase pain intensity (p=0.46). However, an interaction with sex highlighted the possibility that pain-associated contexts may alter pain sensitivity in females but not males (p=0.03). Conclusions Overall, our data does not support the idea that pain-associated contexts can alter pain sensitivity in healthy asymptomatic individuals. That an effect was shown in females highlights the possibility that some subgroups may be susceptible to such an effect, although the magnitude of the effect may lack real-world significance. If pain-associated cues prove to have a relevant pain augmenting effect, in some subgroups, procedures aimed at extinguishing pain-related associations may have therapeutic potential.

The influence of isometric exercise on endogenous pain modulation: comparing exercise-induced hypoalgesia and offset analgesia in young, active adults.

Background and aims Impairment of endogenous analgesia has been associated with the development, maintenance and persistence of pain. Endogenous analgesia can be evaluated using exercise-induced hypoalgesia (EIH) and offset analgesia (OffA) paradigms, which measure temporal filtering of sensory information. It is not clear if these paradigms are underpinned by common mechanisms, as EIH and OffA have not previously been directly compared. A further understanding of the processes responsible for these clinically relevant phenomena may have future diagnostic and therapeutic utility in management of individuals with persistent pain conditions. The primary aim of this study was to investigate if there is a correlation between the magnitudes of EIH and OffA. The secondary aim of the study was to examine whether exercise influences OffA. Methods Thirty-six healthy, pain-free participants were recruited. EIH was evaluated using pressure pain thresholds (PPT) and pain ratings to suprathreshold pressure stimuli over tibialis anterior and the cervical spine. OffA evaluation utilised a three-step protocol, whereby individualised heat pain thermal stimuli [Numerical Rating Scale (NRS)=50/100] were applied (T1), before increasing 1 °C (T2), followed by 1 °C reduction (T3). The magnitude of OffA was calculated as the percentage reduction in the NRS from T2 to T3. PPT/suprathreshold pain ratings and OffA measures were recorded, before and after 5 min of isometric quadriceps exercise performed at 20-25% maximum voluntary contraction (MVC); and following a 15 min rest period. Data were analysed using repeated measures (RM) ANCOVA and correlational analyses. Results There was no correlation between EIH measures (PPTs or pain ratings to suprathreshold pressure stimuli over tibialis anterior or the cervical spine) and OffA (p>0.11 for all). OffA was induced and not modulated by exercise (p=0.28). Conclusions Five minutes of 20-25% MVC lower limb isometric exercise provided non-pharmacological pain modulation in young, active adults. Magnitude of EIH was not correlated with that of OffA, and exercise did not influence magnitude of OffA. Implications These results suggest that in young, pain-free individuals, separate testing of these two paradigms is required to comprehensively evaluate efficacy of endogenous analgesia. If these results are replicated in patient populations, alternative or complementary methods to exercise interventions may be required to modulate impaired OffA.

Tactile acuity is reduced in people with chronic neck pain.

BACKGROUND: Tactile acuity deficits have been demonstrated in a range of persistent pain conditions and may reflect underlying cortical re-organisation. OBJECTIVE: This study aimed to determine whether tactile acuity is impaired in people with chronic neck pain relative to controls, and whether deficits relate to pain location, duration and intensity. METHODS: In this cross-sectional study, 20 people with chronic neck pain (5 idiopathic neck pain; 15 whiplash-associated disorder) and 20 pain-free controls underwent two-point discrimination (TPD) testing at the neck, back and arm, and point-to-point (PTP) and graphesthesia tests of tactile acuity at the neck and arm. RESULTS: Linear mixed effects models demonstrated a significant group*body region interaction for TPD, Graphesthesia and PTP tests (Ps < 0.001), with post hoc tests showing impaired TPD in people with neck pain relative to controls at the neck, low back, and arm (P ≤ 0.001). Graphesthesia and PTP was also impaired at the neck (P < 0.001) but not the arm (P ≥ 0.48). TPD correlated with intensity and duration of pain (Pearson's r = 0.48, P < 0.05; Pearson's r = 0.77, P < 0.01). There was no sig difference between the two neck pain groups for any tactile acuity measure (TPD: P = 0.054; Graphesthesia; P = 0.67; Point to Point: P = 0.77), however, low power limited confidence in this comparison. CONCLUSION: People with chronic neck pain demonstrated tactile acuity deficits in painful and non-painful regions when measured using the TPD test, with the magnitude of deficits appearing greatest at the neck. The study also revealed a positive relationship between TPD and pain intensity/duration, further supporting the main study finding.

Intestinal calcium and bile salts facilitate germination of Clostridium difficile spores.

Clostridium difficile (C. difficile) is an anaerobic gram-positive pathogen that is the leading cause of nosocomial bacterial infection globally. C. difficile infection (CDI) typically occurs after ingestion of infectious spores by a patient that has been treated with broad-spectrum antibiotics. While CDI is a toxin-mediated disease, transmission and pathogenesis are dependent on the ability to produce viable spores. These spores must become metabolically active (germinate) in order to cause disease. C. difficile spore germination occurs when spores encounter bile salts and other co-germinants within the small intestine, however, the germination signaling cascade is unclear. Here we describe a signaling role for Ca2+ during C. difficile spore germination and provide direct evidence that intestinal Ca2+ coordinates with bile salts to stimulate germination. Endogenous Ca2+ (released from within the spore) and a putative AAA+ ATPase, encoded by Cd630_32980, are both essential for taurocholate-glycine induced germination in the absence of exogenous Ca2+. However, environmental Ca2+ replaces glycine as a co-germinant and circumvents the need for endogenous Ca2+ fluxes. Cd630_32980 is dispensable for colonization in a murine model of C. difficile infection and ex vivo germination in mouse ileal contents. Calcium-depletion of the ileal contents prevented mutant spore germination and reduced WT spore germination by 90%, indicating that Ca2+ present within the gastrointestinal tract plays a critical role in C. difficile germination, colonization, and pathogenesis. These data provide a biological mechanism that may explain why individuals with inefficient intestinal calcium absorption (e.g., vitamin D deficiency, proton pump inhibitor use) are more prone to CDI and suggest that modulating free intestinal calcium is a potential strategy to curb the incidence of CDI.

Validation of droplet digital PCR for the detection and absolute quantification of Borrelia DNA in Ixodes scapularis ticks.

We evaluated the QX200 Droplet Digital PCR (ddPCR™, Bio-Rad) system and protocols for the detection of the tick-borne pathogens Borrelia burgdorferi and Borrelia miyamotoi in Ixodes scapularis nymphs and adults collected from North Truro, Massachusetts. Preliminary screening by nested PCR determined positive infection levels of 60% for B. burgdorferi in these ticks. To investigate the utility of ddPCR as a screening tool and to calculate the absolute number of bacterial genome copies in an infected tick, we adapted previously reported TaqMan®-based qPCR assays for ddPCR. ddPCR proved to be a reliable means for detection and absolute quantification of control bacterial DNA with precision as low as ten spirochetes in an individual sample. Application of this method revealed the average carriage level of B. burgdorferi in infected I. scapularis nymphs to be 2291 spirochetes per nymph (range: 230-5268 spirochetes) and 51 179 spirochetes on average in infected adults (range: 5647-115 797). No ticks naturally infected with B. miyamotoi were detected. The ddPCR protocols were at least as sensitive to conventional qPCR assays but required fewer overall reactions and are potentially less subject to inhibition. Moreover, the approach can provide insight on carriage levels of parasites within vectors.

Common Lung Microbiome Identified among Mechanically Ventilated Surgical Patients.

The examination of the pulmonary microbiome in patients with non-chronic disease states has not been extensively examined. Traditional culture based screening methods are often unable to identify bacteria from bronchoalveolar lavage samples. The advancement of next-generation sequencing technologies allows for a culture-independent molecular based analysis to determine the microbial composition in the lung of this patient population. For this study, the Ion Torrent PGM system was used to assess the microbial complexity of culture negative bronchoalveolar lavage samples. A group of samples were identified that all displayed high diversity and similar relative abundance of bacteria. This group consisted of Hydrogenophaga, unclassified Bacteroidetes, Pedobacter, Thauera, and Acinetobacter. These bacteria may be representative of a common non-pathogenic pulmonary microbiome associated within this population of patients.

Low Pain Catastrophization and Disability Predict Successful Outcome to Radiofrequency Neurotomy in Individuals with Chronic Whiplash.

OBJECTIVES: Physical and psychological symptoms of individuals with chronic whiplash-associated disorders (WAD) are modulated by successful treatment with cervical radiofrequency neurotomy (cRFN). However, not all individuals respond to cRFN, and it is unknown which clinical features predict successful response to cRFN. METHODS: This prospective cohort study investigated 53 individuals with chronic WAD (36 female, 17 male; mean age = 44.7 ± 10.9 (SD) years) who underwent cRFN. Predictor variables measured at baseline (prior to RFN) included self-reported pain (VAS), disability (NDI), post-traumatic stress symptoms (PDS), pain catastrophizing (PCS), and measures of sensory hypersensitivity (pressure and cold pain thresholds). The outcome measure was perceived Global Rating of Change (where scores ≥ 4 were classified as a successful response) 3 months post-cRFN. RESULTS: Univariate logistic regression demonstrated that lower levels of disability and pain catastrophizing were associated with successful response of cRFN (both P < 0.05). Multivariable logistic regression demonstrated that low levels of pain catastrophizing and disability remained significant predictors of a successful response to cRFN (both P < 0.05). CONCLUSIONS: Low levels of pain catastrophizing and disability independently predicted a successful response to cRFN in patients with chronic WAD.

Cervical radiofrequency neurotomy reduces psychological features in individuals with chronic whiplash symptoms.

BACKGROUND: Individuals with chronic whiplash associated disorder (WAD) demonstrate various psychological features. It has previously been demonstrated that cervical radiofrequency neurotomy (cRFN) resolves psychological distress and anxiety. It is unknown if cRFN also improves or reduces a broader spectrum of psychological substrates now commonly identified in chronic whiplash, such as post-traumatic stress disorder (PTSD) and pain catastrophizing. OBJECTIVES: To determine if reducing pain in the cervical spine (following cRFN) significantly reduces psychological features (distress, pain catastrophizing and post-traumatic stress symptoms) in individuals with chronic WAD. SETTING:   Tertiary spinal intervention centre in Calgary, Alberta, Canada. STUDY DESIGN: Prospective observational study of consecutive patients. PATIENTS: Fifty-three individuals with chronic whiplash associated disorder symptoms (Grade 2). INTERVENTION: Cervical RFN following successful response to cervical facet joint blockade. Measures were made at 4 time points: 2 prior to RFN, and 1-month and 3-months post-RFN. Psychological measures included the General Health Questionnaire (GHQ-28); Pain Catastrophizing Scale (PCS) and the Post Traumatic Stress Diagnostic Scale (PDS). Self-reported pain (VAS) and disability (NDI) measures were also collected. RESULTS: Pain, disability, psychological distress and pain catastrophization significantly decreased at both 1-month and 3 months following cervical RFN. There was no significant change in post-traumatic stress symptom severity (P = 0.39). Reducing pain via cRFN was associated with significant improvement in psychological distress and pain catastrophizing, but not posttraumatic stress symptoms. LIMITATIONS: Individual administering questionnaires was not blinded to aim(s) of the study. Other psychological features possibly present in WAD were not measured. CONCLUSION: Effective pain relief would seem a crucial element in the management of psychological features associated with chronic WAD. IRB Approval: University of Calgary Conjoint Health Research Ethics Board ID#: E-22082.