False-positive rifampicin resistance on Xpert® MTB/RIF: case report and clinical implications

The World Health Organization had endorsed Xpert® MTB/RIF (Xpert) as the initial diagnostic for multidrug-resistant tuberculosis (TB) or TB suspects co-infected with the human immunodeficiency virus. We investigated an unexpected case of rifampicin (RMP) resistance on Xpert using repeat Xpert, smear microscopy, MTBDRplus assay, culture, drug susceptibility testing, spoligotyping and rpoB gene sequencing. A false-positive result was most likely, given the wild type rpoB gene sequence and exclusion of both mixed infection and mixture of drug-susceptible and drug-resistant populations. When decentralising Xpert, test performance characteristics need to be understood by health care workers and methods of confirmation of RMP resistance need to be accessible.

X-ray phase contrast for CO2 microangiography

We demonstrate a laboratory method for imaging small blood vessels using x-ray propagation-based phase-contrast imaging and carbon dioxide (CO(2)) gas as a contrast agent. The limited radiation dose in combination with CO(2) being clinically acceptable makes the method promising for small-diameter vascular visualization. We investigate the possibilities and limitations of the method for small-animal angiography and compare it with conventional absorption-based x-ray angiography. Photon noise in absorption-contrast imaging prevents visualization of blood vessels narrower than 50 µm at the highest radiation doses compatible with living animals, whereas our simulations and experiments indicate the possibility of visualizing 20 µm vessels at radiation doses as low as 100 mGy. Experimental computed tomography of excised rat kidney shows blood vessels of diameters down to 60 µm with improved image quality compared to absorption-based methods. With our present prototype x-ray source, the acquisition time for a tomographic dataset is approximately 1 h, which is long compared to the 1-20 min common for absorption-contrast micro-CT systems. Further development of the liquid-metal-jet microfocus x-ray sources used here and high-resolution x-ray detectors shows promise to reduce exposure times and make this high-resolution method practical for imaging of living animals.

Antimicrobial resistance in Campylobacter spp. isolated from Ontario sheep flocks and associations between antimicrobial use and antimicrobial resistance

The objectives of this study were to determine the prevalence of antimicrobial resistance (AMR) in faecal Campylobacter spp. from lambs and adult sheep and associations between antimicrobial use (AMU) and AMR. A total of 275 faecal samples collected during initial and final visits from 51 sheep flocks, including one feedlot, across southern Ontario were tested for the presence of Campylobacter spp. Campylobacter jejuni was detected in 52% (143/275) of the faecal samples, Campylobacter coli in 7% (19/275), Campylobacter lari in 1% (2/275) and 2% (4/275) were non-speciated Campylobacter. Broth microdilution was used to test antimicrobial susceptibility of 162 isolates to nine antimicrobials. Campylobacter jejuni isolates (n = 142) were resistant to tetracycline (39%), ciprofloxacin (4%), nalidixic acid (4%) and telithromycin (1%). C. coli isolates (n = 19) were resistant to tetracycline (74%), and azithromycin, clindamycin, erythromycin, and telithromycin (5%). The C. lari isolate displayed resistance to nalidixic acid. No statistically significant associations were found between AMU and AMR during multivariate modelling in this study.

Soil warming alters nitrogen cycling in a New England forest: implications for ecosystem function and structure

Global climate change is expected to affect terrestrial ecosystems in a variety of ways. Some of the more well-studied effects include the biogeochemical feedbacks to the climate system that can either increase or decrease the atmospheric load of greenhouse gases such as carbon dioxide and nitrous oxide. Less well-studied are the effects of climate change on the linkages between soil and plant processes. Here, we report the effects of soil warming on these linkages observed in a large field manipulation of a deciduous forest in southern New England, USA, where soil was continuously warmed 5°C above ambient for 7 years. Over this period, we have observed significant changes to the nitrogen cycle that have the potential to affect tree species composition in the long term. Since the start of the experiment, we have documented a 45% average annual increase in net nitrogen mineralization and a three-fold increase in nitrification such that in years 5 through 7, 25% of the nitrogen mineralized is then nitrified. The warming-induced increase of available nitrogen resulted in increases in the foliar nitrogen content and the relative growth rate of trees in the warmed area. Acer rubrum (red maple) trees have responded the most after 7 years of warming, with the greatest increases in both foliar nitrogen content and relative growth rates. Our study suggests that considering species-specific responses to increases in nitrogen availability and changes in nitrogen form is important in predicting future forest composition and feedbacks to the climate system.

An investigation of the subtype diversity of clinical isolates of Irish Clostridium difficile ribotypes 027 and 078 by repetitive-extragenic palindromic PCR

A repetitive-extragenic palindromic PCR (rep-PCR) subtyping method (DiversiLab) in conjunction with ribotyping, toxinotyping and antimicrobial-susceptibility testing was used to detect subtypes within Clostridium difficile ribotypes 027 and 078. Clinical isolates of ribotypes 027 (toxinotype III) (n = 30) and 078 (toxinotype V) (n = 23) were provided by health-care facilities across the Republic of Ireland over 2 months in 2006 and 1 month in 2009. Ribotype 027 isolates were significantly more related to each other (9 different subtype profiles) when compared to ribotype 078 isolates (14 different profiles) (P = 0.001; cut-off >90 % similarity). Almost half of ribotype 078 isolates (45.5 %) showed no relationship to each other. The clonality of ribotype 027 isolates suggests effective adaptation to the human niche, whereas the considerable genetic diversity within ribotype 078 isolates suggests that they may have originated from a variety of sources. Subtyping correlated well with antimicrobial susceptibility, in particular clindamycin susceptibility for ribotype 027, but diverse antimicrobial-susceptibility profiles were seen in ribotype 078 isolates, even within a single health-care facility. Between 2006 and 2009, a change in the predominant subtype of ribotype 027 was seen, with the recent clone representing half of all ribotype 027 isolates studied. This strain exhibited 89 % similarity to a rep-PCR profile of the North American NAP-1 strain.

Introduction of an e-portfolio in clinical dentistry: staff and student views

INTRODUCTION

An electronic portfolio was introduced for undergraduate students in the School of Dental Sciences at Newcastle University. Its introduction was evaluated in terms of both staff and student response.

METHODS

A quantitative-qualitative methodology was adopted. Student views were examined quantitatively using a Likert scale based questionnaire both pre- and post-introduction of the eportfolio. Staff views were examined qualitatively by the use of focus groups.

RESULTS AND DISCUSSION

Findings included that the system was easy to use and it provided a large quantity of high quality data. The aim of the system to improve reflection and feedback was not perceived as a benefit by staff or students. The need for training was highlighted and a major disadvantage of the system was its time consuming nature. The evaluation has lead to further development of the system and continued evaluation will be important.

Sensation seeking and collegiate vulnerability to internet dependence

Past research on Internet dependence has suggested that those who are Internet dependent spend more time on-line, use chat rooms more frequently, play MUDs more often, and web surf more than nondependent Internet users, but few studies have examined how personality characteristics interact with Internet dependence. This study investigates how Internet usage, preferences, attitudes toward the Internet, and Internet behaviors are correlated with sensation seeking. It was predicted that participants who were higher in Internet usage and Internet behaviors would be higher in sensation seeking. Results indicated that Internet dependents tended to spend more time online, use E-mail, surf the web, use chat rooms, use MUDs, and visit cybersex sites more often than nondependent Internet users. However, dependents scored significantly lower on sensation seeking, thrill and adventure seeking, and excitement seeking than nondependent Internet users. It was concluded that dependents interact with the internet using a motivation scheme dissimilar to the physical thrill and excitement that typically characterize sensation seeking archetypes.

Functional differences between D(1) and D(5) revealed by high resolution imaging on live neurons

The interaction between the dopaminergic and glutamatergic systems governs normal behavior and is perturbed in many psychiatric disorders including schizophrenia. Hypofunction of the D1 family of receptors, to which the D(1) and D(5) subtypes belong, is a typical feature of schizophrenia. Here we have used confocal live cell imaging of neurons to examine the distinct roles of the D(1) and D(5) receptors in the intra-neuronal interaction with the glutamatergic system. Using fluorescently tagged D(1) or D(5) expressed in cultured striatal neurons, we show that both receptor subtypes are primarily transported via lateral diffusion in the dendritic tree. D(1) is to a much larger extent than D(5) expressed in spines. D(1) is primarily expressed in the head whereas D(5) is largely localized to the neck of the spine. Activation of N-methyl-D-aspartic acid (NMDA) receptors slowed the diffusion rate and increased the number of D(1) positive spines, while no effect on D(5) diffusion or spine localization could be observed. The observed differences between D(1) and D(5) can be attributed to structural differences in the C-terminus and its capacity to interact with NMDA receptors and PSD-95. Identification of a unique role of D(1) for the intra-neuronal interaction between the dopaminergic and glutamatergic systems will have implications for the development of more specific treatments in many neuropsychiatric disorders.

Detection of undiagnosed and poorly controlled asthma in a hospital-based outpatient pediatric primary care clinic using a health risk assessment system

OBJECTIVE

To determine the rate of undiagnosed and poorly controlled asthma detected by a computerized health risk assessment (HRA) survey system in an urban pediatric hospital-based outpatient teaching clinic.

METHODS

A software-based HRA system uses survey answer patterns to identify children with (1) probable, (2) uncontrolled, and (3) moderate to severe asthma. Parents of patients > or = 2 years of age were asked by clinic staff to complete the touch screen computer survey before seeing their physician from August 2005 through July 2006.

RESULTS

The HRA survey predicted 26% (282/1,098) to have probable asthma. Of these, 51% (144/282) were controlled and the parents reported a previous diagnosis of asthma; 14% (40/282) were controlled and the parents did not report a previous diagnosis of asthma; 25% (71/282) were uncontrolled and the parents reported a previous diagnosis of asthma; and 10% (27/282) were uncontrolled and no previous diagnosis of asthma was reported by the parents. Among active cases completing the baseline version survey (N = 217), 68% reported emergency department (ED) visits / hospitalizations in the last 2 years (44% > or =2), while 59% reported missed school days during the previous year (23% > or =5 days). Impairment, as defined by the 2007 National Heart, Lung, and Blood Institute/National Asthma Education and Prevention Program (NHLBI/NAEPP) asthma guidelines, tended to be higher in patients without a previous diagnosis of asthma, per parental report, but this trend only achieved significance in two measures: daytime symptoms > or =2 days per week in the last 4 weeks (p = 0.028) and more than 5 missed school days in the past year (p = 0.001).

CONCLUSION

A previously validated HRA system can consistently identify a high rate of undiagnosed and poorly controlled asthma in an urban pediatric hospital-based teaching clinic. The utility of such a system would be to reduce missed opportunities for delivery of care and morbidity for the patients who currently have undiagnosed and/or uncontrolled asthma in the pediatric primary care outpatient setting.