Meticillin-susceptible Staphylococcus aureus transmission among healthcare workers, patients and the environment in a large acute hospital under non-outbreak conditions investigated using whole-genome sequencing.

BACKGROUND: The role of meticillin-susceptible Staphylococcus aureus (MSSA) colonization of healthcare workers (HCWs), patients and the hospital environment in MSSA transmission events (TEs) is poorly understood. AIMS: The role of meticillin-resistant Staphylococcus aureus (MRSA) was investigated recently under non-outbreak conditions in a large hospital with a history of endemic MRSA over 2 years using whole-genome sequencing (WGS). Numerous potential MRSA TEs were identified. The present study investigated MSSA TEs from the same sources during the same 2-year hospital study. METHODS: HCW (N=326) and patient (N=388) volunteers on nine wards were tested for nasal and oral MSSA colonization over 2 years. Near-patient environment (N=1164), high-frequency touch sites (N=810) and air (N=445) samples were screened for MSSA. Representative MSSA and clinical isolates were sequenced and analysed by core genome multi-locus sequence typing. Closely related isolates (≤24 allelic differences) were segregated into related isolate groups (RIGs). Potential TEs involving MSSA in RIGs from HCWs, patients and patient infections were identified in combination with epidemiological data. FINDINGS: In total, 635 MSSA were recovered: clinical isolates (N=82), HCWs (N=170), patients (N=120), and environmental isolates (N=263). Twenty-four clonal complexes (CCs) were identified among 406/635 MSSA sequenced, of which 183/406 segregated into 59 RIGs. Numerous potential HCW-to-patient, HCW-to-HCW and patient-to-patient TEs were identified, predominantly among CC5-MSSA, CC30-MSSA and CC45-MSSA. HCW, patient, clinical and environmental isolates were identified in 33, 24, six and 32 RIGs, respectively, with 19/32 of these containing MSSA related to HCW and/or patient isolates. CONCLUSIONS: WGS detected numerous potential hospital MSSA TEs involving HCWs, patients and environmental contamination under non-outbreak conditions.

Meticillin-resistant Staphylococcus aureus transmission among healthcare workers, patients and the environment in a large acute hospital under non-outbreak conditions investigated using whole-genome sequencing.

BACKGROUND: The role of meticillin-resistant Staphylococcus aureus (MRSA) colonization of healthcare workers (HCWs), patients and the hospital environment in MRSA transmission in non-outbreak settings is poorly understood. AIMS: To investigate transmission events (TEs) involving HCWs, patients and the environment under non-outbreak conditions in a hospital with a history of endemic MRSA using whole-genome sequencing (WGS). METHODS: HCW (N = 326) and patient (N = 388) volunteers on nine wards were tested for nasal and oral MRSA colonization over two years. Near-patient environment (N = 1164), high-frequency touch sites (N = 810) and air (N = 445) samples were screened for MRSA. Representative MRSA and clinical isolates were analysed by WGS and core-genome multi-locus sequence typing (cgMLST). Closely related isolates (≤24 allelic differences) were segregated into related isolated groups (RIGs). FINDINGS: In total, 155 MRSA were recovered: clinical isolates (N = 41), HCWs (N = 22), patients (N = 37), environmental isolates (N = 55). Nine clonal complexes (CCs) were identified among 110/155 MRSA sequenced with 77/110 assigned to CC22. Seventy-nine MRSA segregated into 17 RIGs. Numerous potential TEs were associated with CC22-MRSA (RIGs 1-15), CC45-MRSA (RIG-16) and CC8-MRSA (RIG-17). RIG-1, (the largest RIG) contained 24 ST22-MRSA-IVh from six HCWs, six patients, four clinical and eight environmental samples recovered over 17 months involving 7/9 wards. TEs involving HCW-to-patient, HCW-to-HCW, patient-to-patient and environmental contamination by HCW/patient isolates were evident. HCW, patient, clinical and environmental isolates were identified in four, nine, seven and 13 RIGs, respectively, with 12/13 of these containing isolates closely related to HCW and/or patient isolates. CONCLUSIONS: WGS detected numerous potential hospital MRSA TEs involving HCWs, patients and the environment under non-outbreak conditions.

The novel collagen matrikine, endotrophin, is associated with mortality and cardiovascular events in patients with atherosclerosis.

BACKGROUND: Rupture of atherosclerotic plaques is the major cause of acute cardiovascular events. The biomarker PRO-C6 measuring Endotrophin, a matrikine of collagen type VI, may provide valuable information detecting subjects in need of intensified strategies for secondary prevention. OBJECTIVE: In this study, we evaluate endotrophin in human atherosclerotic plaques and circulating levels of PRO-C6 in patients with atherosclerosis, to determine the predictive potential of the biomarker. METHODS: Sections from the stenotic human carotid plaques were stained with the PRO-C6 antibody. PRO-C6 was measured in serum of patients enrolled in the Carotid Plaque Imagining Project (CPIP) (discovery cohort, n = 577) and the innovative medicines initiative surrogate markers for micro- and macrovascular hard end-points for innovative diabetes tools (IMI-SUMMIT, validation cohort, n = 1,378). Median follow-up was 43 months. Kaplan-Meier curves and log-rank tests were performed in the discovery cohort. Cox proportional hazard regression analysis (HR with 95% CI) was used in the discovery cohort and binary logistic regression (OR with 95% CI) in the validation cohort. RESULTS: PRO-C6 was localized in the core and shoulder of the atherosclerotic plaque. In the discovery cohort, PRO-C6 independently predicted future cardiovascular events (HR 1.089 [95% CI 1.019 -1.164], p = 0.01), cardiovascular death (HR 1.118 [95% CI 1.008 -1.241], p = 0.04) and all-cause death (HR 1.087 [95% CI 1.008 -1.172], p = 0.03). In the validation cohort, PRO-C6 predicted future cardiovascular events (OR 1.063 [95% CI 1.011 -1.117], p = 0.017). CONCLUSION: PRO-C6 is present in the atherosclerotic plaque and associated with future cardiovascular events, cardiovascular death and all-cause mortality in two large prospective cohorts.

Ediacaran metazoan reveals lophotrochozoan affinity and deepens root of Cambrian Explosion.

Through exceptional preservation, we establish a phylogenetic connection between Ediacaran and Cambrian metazoans. We describe the first three-dimensional, pyritized soft tissue in Namacalathus from the Ediacaran Nama Group, Namibia, which follows the underlying form of a stalked, cup-shaped, calcitic skeleton, with six radially arranged lobes projecting into an apical opening and lateral lumens. A thick body wall and probable J-shaped gut are present within the cup, and the middle layer of the often-spinose skeleton and skeletal pores are selectively pyritized, supporting an organic-rich composition and tripartite construction with possible sensory punctae. These features suggest a total group lophotrochozoan affinity. These morphological data support molecular phylogenies and demonstrates that the origin of modern lophotrochozoan phyla, and their ability to biomineralize, had deep roots in the Ediacaran.

Dichotomy between Regulation of Coral Bacterial Communities and Calcification Physiology under Ocean Acidification Conditions.

Ocean acidification (OA) threatens the growth and function of coral reef ecosystems. A key component to coral health is the microbiome, but little is known about the impact of OA on coral microbiomes. A submarine CO2 vent at Maug Island in the Northern Mariana Islands provides a natural pH gradient to investigate coral responses to long-term OA conditions. Three coral species (Pocillopora eydouxi, Porites lobata, and Porites rus) were sampled from three sites where the mean seawater pH is 8.04, 7.98, and 7.94. We characterized coral bacterial communities (using 16S rRNA gene sequencing) and determined pH of the extracellular calcifying fluid (ECF) (using skeletal boron isotopes) across the seawater pH gradient. Bacterial communities of both Porites species stabilized (decreases in community dispersion) with decreased seawater pH, coupled with large increases in the abundance of Endozoicomonas, an endosymbiont. P. lobata experienced a significant decrease in ECF pH near the vent, whereas P. rus experienced a trending decrease in ECF pH near the vent. In contrast, Pocillopora exhibited bacterial community destabilization (increases in community dispersion), with significant decreases in Endozoicomonas abundance, while its ECF pH remained unchanged across the pH gradient. Our study shows that OA has multiple consequences on Endozoicomonas abundance and suggests that Endozoicomonas abundance may be an indicator of coral response to OA. We reveal an interesting dichotomy between two facets of coral physiology (regulation of bacterial communities and regulation of calcification), highlighting the importance of multidisciplinary approaches to understanding coral health and function in a changing ocean.IMPORTANCE Ocean acidification (OA) is a consequence of anthropogenic CO2 emissions that is negatively impacting marine ecosystems such as coral reefs. OA affects many aspects of coral physiology, including growth (i.e., calcification) and disrupting associated bacterial communities. Coral-associated bacteria are important for host health, but it remains unclear how coral-associated bacterial communities will respond to future OA conditions. We document changes in coral-associated bacterial communities and changes to calcification physiology with long-term exposure to decreases in seawater pH that are environmentally relevant under midrange IPCC emission scenarios (0.1 pH units). We also find species-specific responses that may reflect different responses to long-term OA. In Pocillopora, calcification physiology was highly regulated despite changing seawater conditions. In Porites spp., changes in bacterial communities do not reflect a breakdown of coral-bacterial symbiosis. Insights into calcification and host-microbe interactions are critical to predicting the health and function of different coral taxa to future OA conditions.

Multiple distinct outbreaks of Panton-Valentine leucocidin-positive community-associated meticillin-resistant Staphylococcus aureus in Ireland investigated by whole-genome sequencing.

BACKGROUND: Panton-Valentine leucocidin (PVL)-positive community-associated meticillin-resistant Staphylococcus aureus (CA-MRSA) is increasingly associated with infection outbreaks. AIM: To investigate multiple suspected PVL-positive CA-MRSA outbreaks using whole-genome sequencing (WGS). METHODS: Forty-six suspected outbreak-associated isolates from 36 individuals at three separate Irish hospitals (H1-H3) and from separate incidents involving separate families associated with H2 were investigated by whole-genome multi-locus sequence typing (wgMLST). FINDINGS: Two clusters (CH1 and CH2) consisting of 8/10 and 6/6 PVL-positive t008 ST8-MRSA-IVa isolates from H1 and H2, respectively, were identified. Within each cluster, neighbouring isolates were separated by ≤5 allelic differences; however, ≥73 allelic differences were identified between the clusters, indicating two independent outbreaks. Isolates from the H3 maternity unit formed two clusters (CH3-SCI and CH3-SCII) composed of four PVL-negative t4667 ST5-MRSA-V and 14 PVL-positive t002 ST5-MRSA-IVc isolates, respectively. Within clusters, neighbouring isolates were separated by ≤24 allelic differences, whereas both clusters were separated by 1822 allelic differences, indicating two distinct H3 outbreaks. Eight PVL-positive t127 ST1-MRSA-V+fus and three PVL-negative t267 ST97-MRSA-V+fus isolates from two distinct H2-associated families FC1 (N = 4) and FC2 (N = 7) formed three separate clusters (FC1 (t127), FC2 (t127) and FC2 (t267)). Neighbouring isolates within clusters were closely related and exhibited ≤7 allelic differences. Intrafamilial transmission was apparent, but the detection of ≥48 allelic differences between clusters indicated no interfamilial transmission. CONCLUSION: The frequent importation of PVL-positive CA-MRSA into healthcare settings, transmission and association with outbreaks is a serious ongoing concern. WGS is a highly discriminatory, informative method for deciphering such outbreaks conclusively.

The oral cavity revealed as a significant reservoir of Staphylococcus aureus in an acute hospital by extensive patient, healthcare worker and environmental sampling.

BACKGROUND: Methicillin-susceptible Staphylococcus aureus (MSSA) bloodstream infection rates have risen steadily in recent years, with a marked decline in the corresponding rates due to methicillin-resistant S. aureus (MRSA). Screening for MSSA carriage is not routinely undertaken and MRSA screening is not universal, so the extent of S. aureus colonisation pressure in nosocomial settings is unknown. METHODS: We conducted a prospective, observational study of patients and healthcare workers (HCWs) across nine inpatient wards in a tertiary referral hospital over a two-year period. Participants were screened for MSSA and MRSA using nasal swabs and oral rinses. Environmental surfaces and air were also tested for S. aureus using contact plates and active air sampling. FINDINGS: We enrolled 388 patients and 326 HCWs; and took 758 contact plate samples from surfaces and 428 air samples. MSSA was recovered from 24% of patients, 31.3% of HCWs, 16% of air samples and 7.9% of surface samples. MRSA was recovered from 6.4% of patients, 3.7% of HCWs, 2.5% of air samples and 2.2% of surface samples. Inclusion of the oral cavity in addition to the anterior nares in the sampling regimen identified 30 patients and 36 HCWs who exhibited exclusive oral colonisation. CONCLUSIONS: The oral cavity comprises a significant nosocomial reservoir for S. aureus that is currently under-appreciated. Oral screening should be considered both in terms of the colonisation pressure in a healthcare facility, and on an individual patient level, especially in patients where decolonisation attempts have repeatedly failed and those undergoing high risk procedures.

Renal nitrate clearance in chronic kidney disease.

BACKGROUND: Nitric oxide (NO) is rapidly oxidised in humans to nitrite and nitrate, with nitrate being present in much greater abundance. These oxidation products can be recycled back into nitric oxide via a complex entero-salivary pathway, thus preserving NO activity. Approximately 65% of circulating nitrate is excreted in the urine in 48 h, with the excretory pathway of the remainder unknown. The effect of declining renal function on nitrate clearance is unknown METHODS: Forty five subjects, 21 M, 24F, median age 69 (range 27-75 years) with renal function assessed by CKD-EPI eGFR between 9 and 89 ml/min/1.73 m2 completed the study. Following a 24 h low nitrate diet a microplate spectrophotometric method was employed to measure plasma nitrate concentration and 24 h urinary nitrate excretion were measured to determine renal nitrate clearance. RESULTS: There was a strong positive correlation between urinary nitrate clearance and eGFR, (Spearman R = 0.7665, p < 0.0001) with a moderate negative correlation between plasma nitrate concentration and CKD-EPI eGFR, (Spearman's R = -0.37, p = 0.012). There was a trend between fractional excretion of nitrate and CKD-EPI eGFR (ml/min/1.73 m2) Spearman's R 0.27, p = 0.07 though this did not reach statistical significance. Plasma nitrate concentration and serum creatinine concentration were positively correlated, Spearman's R = 0.39, p = 0.008. CONCLUSIONS: We have observed a strong positive association between renal nitrate clearance and renal function such that plasma nitrate rises as renal function falls. Fractional excretion of nitrate appears to decline as renal function falls. As such, urinary nitrate excretion is unlikely to be a reliable marker of endogenous NO synthesis in settings where renal function is altered.

Regional nutrient decrease drove redox stabilisation and metazoan diversification in the late Ediacaran Nama Group, Namibia.

The late Ediacaran witnessed an increase in metazoan diversity and ecological complexity, marking the inception of the Cambrian Explosion. To constrain the drivers of this diversification, we combine redox and nutrient data for two shelf transects, with an inventory of biotic diversity and distribution from the Nama Group, Namibia (~550 to ~538 Million years ago; Ma). Unstable marine redox conditions characterised all water depths in inner to outer ramp settings from ~550 to 547 Ma, when the first skeletal metazoans appeared. However, a marked deepening of the redoxcline and a reduced frequency of anoxic incursions onto the inner to mid-ramp is recorded from ~547 Ma onwards, with full ventilation of the outer ramp by ~542 Ma. Phosphorus speciation data show that, whilst anoxic ferruginous conditions were initially conducive to the drawdown of bioavailable phosphorus, they also permitted a limited degree of phosphorus recycling back to the water column. A long-term decrease in nutrient delivery from continental weathering, coupled with a possible decrease in upwelling, led to the gradual ventilation of the Nama Group basins. This, in turn, further decreased anoxic recycling of bioavailable phosphorus to the water column, promoting the development of stable oxic conditions and the radiation of new mobile taxa.

The impact of cardiovascular co-morbidities and duration of diabetes on the association between microvascular function and glycaemic control.

BACKGROUND: Good glycaemic control in type 2 diabetes (T2DM) protects the microcirculation. Current guidelines suggest glycaemic targets be relaxed in advanced diabetes. We explored whether disease duration or pre-existing macrovascular complications attenuated the association between hyperglycaemia and microvascular function. METHODS: 743 participants with T2DM (n = 222), cardiovascular disease (CVD = 183), both (n = 177) or neither (controls = 161) from two centres in the UK, underwent standard clinical measures and endothelial dependent (ACh) and independent (SNP) microvascular function assessment using laser Doppler imaging. RESULTS: People with T2DM and CVD had attenuated ACh and SNP responses compared to controls. This was additive in those with both (ANOVA p < 0.001). In regression models, cardiovascular risk factors accounted for attenuated ACh and SNP responses in CVD, whereas HbA1c accounted for the effects of T2DM. HbA1c was associated with ACh and SNP response after adjustment for cardiovascular risk factors (adjusted standardised beta (ß) -0.096, p = <0.008 and -0.135, p < 0.001, respectively). Pre-existing CVD did not modify this association (ß -0.099; p = 0.006 and -0.138; p < 0.001, respectively). Duration of diabetes accounted for the association between HbA1c and ACh (ß -0.043; p = 0.3), but not between HbA1c and SNP (ß -0.105; p = 0.02). CONCLUSIONS: In those with T2DM and CVD, good glycaemic control is still associated with better microvascular function, whereas in those with prolonged disease this association is lost. This suggests duration of diabetes may be a better surrogate for "advanced disease" than concomitant CVD, although this requires prospective validation.

Kinetic energy offsets for multicharged ions from an electron beam ion source.

Using a retarding field analyzer, we have measured offsets between the nominal and measured kinetic energy of multicharged ions extracted from an electron beam ion source (EBIS). By varying source parameters, a shift in ion kinetic energy was attributed to the trapping potential produced by the space charge of the electron beam within the EBIS. The space charge of the electron beam depends on its charge density, which in turn depends on the amount of negative charge (electron beam current) and its velocity (electron beam energy). The electron beam current and electron beam energy were both varied to obtain electron beams of varying space charge and these were related to the observed kinetic energy offsets for Ar4+ and Ar8+ ion beams. Knowledge of these offsets is important for studies that seek to utilize slow, i.e., low kinetic energy, multicharged ions to exploit their high potential energies for processes such as surface modification. In addition, we show that these offsets can be utilized to estimate the effective radius of the electron beam inside the trap.

Adipose tissue is influenced by hypoxia of obstructive sleep apnea syndrome independent of obesity.

AIMS: Obstructive sleep apnea syndrome (OSAS) is associated with increased cardiovascular risk and diabetes independent of obesity. We investigated whether adipose tissue dysfunction is exacerbated due to increased tissue hypoxia. METHODS: Adipose tissue (AT) oxygenation was measured with a Clarke-type electrode (pATO2) in 16 men with OSAS before and after 4 months of continuous positive airway pressure therapy (CPAP) and in BMI-matched controls. Oxygenation was simultaneously monitored in arterial blood by pulse oximetry (SaO2); mixed blood in AT microcirculation by reflectance spectroscopy (SATO2) along with blood flow. Markers of hypoxia, adipo- and angiogenesis, inflammation and fibrosis were analysed in AT and serum. RESULTS: OSAS subjects were more insulin resistant. Despite lower arterial SaO2 (95.4±1.3% vs. 97.1±1.6%, P=0.013) in subjects with OSAS, there was no difference in the oxygen content of AT microcirculation (61.6±18.4 vs. 72.2±7.0%, P=0.07) or pATO2 (49.2±7.5 vs. 50.4±14.7mmHg, P=0.83) between groups. Resting AT blood flow was higher in OSAS compared to controls (108.5±22.7 vs. 78.9±24.9au, P<0.005) and strongly associated with inflammation markers IL-6 and MCP-1. AT of OSAS subjects showed increased inflammation (TNFA P=0.049) and fibrosis (COL3A1 P=0.02), a trend of higher HIF1A expression (P=0.06) and reduced adipogenesis (PPARG P=0.006). After CPAP, only expression of the lipid deposition marker LPL increased (30%, P=0.047). CONCLUSIONS: Adipose tissue of awake OSAS subjects appears no more hypoxic than adipose tissue of BMI-matched controls despite daytime hypoxaemia. Increased adipose tissue blood flow may be explained by an increased inflammatory response. We observe features of adipose dysfunction in subjects with OSAS, which attribute to increased cardiometabolic risk associated with this condition.

Rapid infrared mapping for highly accurate automated histology in Barrett's oesophagus.

Barrett's oesophagus (BE) is a premalignant condition that can progress to oesophageal adenocarcinoma. Endoscopic surveillance aims to identify potential progression at an early, treatable stage, but generates large numbers of tissue biopsies. Fourier transform infrared (FTIR) mapping was used to develop an automated histology tool for detection of BE and Barrett's neoplasia in tissue biopsies. 22 oesophageal tissue samples were collected from 19 patients. Contiguous frozen tissue sections were taken for pathology review and FTIR imaging. 45 mid-IR images were measured on an Agilent 620 FTIR microscope with an Agilent 670 spectrometer. Each image covering a 140 µm × 140 µm region was measured in 5 minutes, using a 1.1 µm2 pixel size and 64 scans per pixel. Principal component fed linear discriminant analysis was used to build classification models based on spectral differences, which were then tested using leave-one-sample-out cross validation. Key biochemical differences were identified by their spectral signatures: high glycogen content was seen in normal squamous (NSQ) tissue, high glycoprotein content was observed in glandular BE tissue, and high DNA content in dysplasia/adenocarcinoma samples. Classification of normal squamous samples versus 'abnormal' samples (any stage of Barrett's) was performed with 100% sensitivity and specificity. Neoplastic Barrett's (dysplasia or adenocarcinoma) was identified with 95.6% sensitivity and 86.4% specificity. Highly accurate pathology classification can be achieved with FTIR measurement of frozen tissue sections in a clinically applicable timeframe.

Reduced pro-inflammatory responses to Staphylococcus aureus bloodstream infection and low prevalence of enterotoxin genes in isolates from patients on haemodialysis.

Patients with end-stage renal failure undergo regular haemodialysis (HD) and often develop episodes of Staphylococcus aureus bloodstream infection (BSI), which can re-occur. However, clinically, patients on HD, with S. aureus BSI, respond well to treatment, rarely developing overt signs of sepsis. We investigated the contributions of bacterial virulence and cytokine responses to the clinical course of S. aureus BSI in HD and non-HD patients. Seventy patients were recruited, including 27 (38.6 %) patients on HD. Isolates were spa-typed and virulence and antimicrobial resistance gene carriage was investigated using DNA microarray analysis. Four inflammatory cytokines, IL-6, RANTES, GROγ and leptin, were measured in patient plasma on the day of diagnosis and after 7 days. There was no significant difference in the prevalence of genotypes or antimicrobial resistance genes in S. aureus isolates from HD compared to non-HD patients. The enterotoxin gene cluster (containing staphylococcal enterotoxins seg, sei, sem, sen, seo and seu) was significantly less prevalent among BSI isolates from HD patients compared to non-HD patients. Comparing inflammatory cytokine response to S. aureus BSI in HD patients to non-HD patients, IL-6 and GROγ were significantly lower (p = 0.021 and p = 0.001, respectively) in HD patients compared to other patients on the day of diagnosis and RANTES levels were significantly lower (p = 0.025) in HD patients on day 7 following diagnosis. Lowered cytokine responses in HD patients and a reduced potential for super-antigen production by infecting isolates may partly explain the favourable clinical responses to episodes of S. aureus BSI in HD patients that we noted clinically.

Microstructure and mechanics of human resistance arteries.

Vascular diseases such as diabetes and hypertension cause changes to the vasculature that can lead to vessel stiffening and the loss of vasoactivity. The microstructural bases of these changes are not presently fully understood. We present a new methodology for stain-free visualization, at a microscopic scale, of the morphology of the main passive components of the walls of unfixed resistance arteries and their response to changes in transmural pressure. Human resistance arteries were dissected from subcutaneous fat biopsies, mounted on a perfusion myograph, and imaged at varying transmural pressures using a multimodal nonlinear microscope. High-resolution three-dimensional images of elastic fibers, collagen, and cell nuclei were constructed. The honeycomb structure of the elastic fibers comprising the internal elastic layer became visible at a transmural pressure of 30 mmHg. The adventitia, comprising wavy collagen fibers punctuated by straight elastic fibers, thinned under pressure as the collagen network straightened and pulled taut. Quantitative measurements of fiber orientation were made as a function of pressure. A multilayer analytical model was used to calculate the stiffness and stress in each layer. The adventitia was calculated to be up to 10 times as stiff as the media and experienced up to 8 times the stress, depending on lumen diameter. This work reveals that pressure-induced reorganization of fibrous proteins gives rise to very high local strain fields and highlights the unique mechanical roles of both fibrous networks. It thereby provides a basis for understanding the micromechanical significance of structural changes that occur with age and disease.

Evaluation of commercial chromogenic media for the detection of meticillin-resistant Staphylococcus aureus.

BACKGROUND: Selective chromogenic media allowing one-step meticillin-resistant Staphylococcus aureus (MRSA) isolation and identification are widely used. However, the changing epidemiology of MRSA means that the suitability of these chromogenic media requires investigation. AIM: To evaluate the following chromogenic media - Colorex MRSA, MRSA Select II, ChromID MRSA, and MRSA Brilliance 2 - for the detection of divergent strain types. METHODS: We used a diverse collection of S. aureus, including strains harbouring the mecC gene, strains expressing varying levels of meticillin resistance, and isolates recovered from patient samples. FINDINGS: MRSA Select II, Colorex MRSA, and ChromID each grew at a density of 1.5 × 10(1)cfu/mL for each SCCmec type investigated. Brilliance 2 demonstrated growth at 1.5 × 10(1)cfu/mL for mecC MRSA but at a higher density (1.5 × 10(4)cfu/mL) for the three mecA MRSA strains. All four media demonstrated excellent sensitivity for MRSA detection (≥99%), but reduced levels of specificity (85-73%) when challenged with a range of meticillin-susceptible S. aureus (MSSA) isolates. High levels of false positives (∼50%) were also obtained with all chromogenic media when tested with mec-negative borderline oxacillin-resistant S. aureus (BORSA) isolates. CONCLUSION: Although false positives may be obtained with some strains of MSSA and BORSA, the high sensitivity of these media and their ability to recover almost all MRSA tested (including oxacillin-susceptible and mecC-positive strains) confirm the value of chromogenic agar in MRSA detection.

Diagnostic accuracy of high-definition CT coronary angiography in high-risk patients.

AIM: To assess the diagnostic accuracy of computed tomography coronary angiography (CTCA) using a combination of high-definition CT (HD-CTCA) and high level of reader experience, with invasive coronary angiography (ICA) as the reference standard, in high-risk patients for the investigation of coronary artery disease (CAD). MATERIALS AND METHODS: Three hundred high-risk patients underwent HD-CTCA and ICA. Independent experts evaluated the images for the presence of significant CAD, defined primarily as the presence of moderate (≥ 50%) stenosis and secondarily as the presence of severe (≥ 70%) stenosis in at least one coronary segment, in a blinded fashion. HD-CTCA was compared to ICA as the reference standard. RESULTS: No patients were excluded. Two hundred and six patients (69%) had moderate and 178 (59%) had severe stenosis in at least one vessel at ICA. The sensitivity, specificity, positive predictive value, and negative predictive value were 97.1%, 97.9%, 99% and 93.9% for moderate stenosis, and 98.9%, 93.4%, 95.7% and 98.3%, for severe stenosis, on a per-patient basis. CONCLUSION: The combination of HD-CTCA and experienced readers applied to a high-risk population, results in high diagnostic accuracy comparable to ICA. Modern generation CT systems in experienced hands might be considered for an expanded role.

Ageing modifies the effects of beetroot juice supplementation on 24-hour blood pressure variability: An individual participant meta-analysis.

OBJECTIVES: Abnormal circadian oscillations of blood pressure (BP) and nocturnal-diurnal BP differences (i.e., dipping) increase cardiovascular risk. Whether inorganic nitrate supplementation influences 24-hr BP variability is currently unknown. We studied the effects of high-nitrate beetroot juice supplementation on BP variability measured by 24-hr ambulatory BP monitoring (24-hr ABPM) in older subjects. METHODS: Data from four independent randomised clinical trials were collated. Eighty-five older participants (age range: 55-76 years) were included in the final database. Two trials had an open-label, parallel design and two trials had a cross-over, double-blind design. Participants were randomised to either beetroot juice or placebo. Changes in 24-hr ABPM (daily, diurnal, nocturnal), variability (weighted-SDs), night-dipping, morning surge for systolic and diastolic BP were measured. Meta-analysis was conducted to obtain pooled estimates of the effect size for each BP outcome. Sub-group analyses were conducted to evaluate the influence of age, BMI, gender, BP status and changes in nitrite concentrations on the effect size. RESULTS: The pooled effect of beetroot juice on all BP outcomes was not significant. Beetroot juice ingestion determined a significant decrease in nocturnal systolic BP variability in subjects aged less than 65 y (2.8 mmHg, -4.5 -1.0, p = 0.002) compared to the older group (≥ 65 y; 1.0 mmHg, -2.2 4.2, p = 0.54). A greater change in NO2(-) concentrations after beetroot supplementation was associated with significant differences for nocturnal mean (-3.4 mmHg, -0.6 -2.4, p = 0.02) and variability (-0.8 mmHg, -1.5 -0.06, p = 0.03) of systolic BP. CONCLUSIONS: The vascular responsiveness to inorganic nitrate may be modified by mechanisms of vascular ageing influencing the reducing capacity to convert inorganic nitrate into nitrite and tissue-specific responses to dietary nitrate supplementation.

Measures of atherosclerotic burden are associated with clinically manifest cardiovascular disease in type 2 diabetes: a European cross-sectional study.

BACKGROUND: There is a need to develop and validate surrogate markers of cardiovascular disease (CVD) in subjects with diabetes. The macrovascular changes associated with diabetes include aggravated atherosclerosis, increased arterial stiffness and endothelial dysfunction. The aim of this study was to determine which of these factors is most strongly associated with clinically manifest cardiovascular events. METHODS: Vascular changes were measured in a cohort of 458 subjects with type 2 diabetes (T2D) and CVD (myocardial infarction, stroke or lower extremity arterial disease), 527 subjects with T2D but without clinically manifest CVD and 515 subjects without T2D and with or without CVD. RESULTS: Carotid intima-media thickness (IMT) and ankle-brachial pressure index were independently associated with the presence of CVD in subjects with T2D, whereas pulse wave velocity and endothelial function provided limited independent additive information. Measurement of IMT in the carotid bulb provided better discrimination of the presence of CVD in subjects with T2D than measurement of IMT in the common carotid artery. The factors most significantly associated with increased carotid IMT in T2D were age, disease duration, systolic blood pressure, impaired renal function and increased arterial stiffness, whereas there were no or weak independent associations with metabolic factors and endothelial dysfunction. CONCLUSIONS: Measures of atherosclerotic burden are associated with clinically manifest CVD in subjects with T2D. In addition, vascular changes that are not directly related to known metabolic risk factors are important in the development of both atherosclerosis and CVD in T2D. A better understanding of the mechanisms involved is crucial for enabling better identification of CVD risk in T2D.

A longitudinal study of Staphylococcus aureus colonization in pigs in Ireland.

The emergence of methicillin-resistant Staphylococcus aureus (MRSA) in livestock has refocused attention on S. aureus colonization and transmission in pigs. This study investigated the effect of the S. aureus colonization status of a sow on the colonization status of her piglets, and whether pigs carry the same strain of S. aureus throughout production. Nasal swabs were collected from the piglets of six healthy sows two days after birth and two days before and two days after they were moved into each production stage. The average prevalence of S. aureus colonization varied between 26% and 73%. The odds of being S. aureus positive were almost 12 times higher for piglets born to nasal-positive sows than for those born to nasal-negative sows, and three times higher again for piglets born to sows that were both nasal- and vaginal-positive. Isolates recovered from piglets immediately after birth were indistinguishable from those of the dam as determined by phenotypic and molecular typing, including microarray analysis and optical mapping. All isolates belonged to clonal complex 9 and the majority exhibited a novel spa type, t10449. The findings show that the S. aureus colonization status of the sow influences the colonization status of her piglets in the early production stages but strains carried by pigs change over time. Multiresistant S. aureus was detected, in particular post-weaning. Results suggest that sow status and management practices, including mixing of pigs and antimicrobial usage at weaning, should be considered when implementing control measures for S. aureus on a farm.