Comparing the epidemiology of community- and hospital-associated Clostridium difficile infections in Northern Ireland, 2012-2016: a population data linkage and case-case study.

The burden of community-associated Clostridium difficile infection (CA-CDI) has increased. We aimed to describe the epidemiology of CA-CDI to inform future interventions. We used population-based linked surveillance data from 2012 to 2016 to describe socio-demographic factors, ribotype and mortality for all CA (n = 1303) and hospital-associated (HA, n = 1356) CDI. For 483 community-onset (CO) CA-CDI and 287 COHA-CDI cases, a questionnaire on risk factors was completed and we conducted a case-case study using logistic regression models for univariate and multivariable analysis. CA-CDI cases had lower odds of being male (adjusted odds ratio (AOR) 0.71, 95% confidence interval (CI) 0.58-0.87; P < 0.001), and higher odds of living in rural rather than urban settlement (AOR 1.5, 95% CI 1.1-2.1; P = 0.05) compared with HA-CDI cases. The distribution of ribotypes was similar in both groups with RT078 being most prevalent. CDI-specific death was lower in CA-CDI than HA-CDI (7% vs. 11%, P < 0.001). COCA-CDI had lower odds of having had an outpatient appointment in the previous 4 weeks compared with COHA-CDI (AOR 0.61; 95% CI 0.41-0.9, P = 0.01) and lower odds of being in a care home or hospice when compared with their own home, than COHA-CDI (AOR 0.66; 95% CI 0.45-0.98 and AOR 0.35; 95% CI 0.13-0.92, P = 0.02). Exposure to gastric acid suppressants (50% in COCA-CDI and 55% in COHA-CDI) and antimicrobial therapy (18% in COCA-CDI and 20% in COHA-CDI) prior to CDI was similar. Our analysis of community-onset cases suggests that other risk factors for COHA-CDI may be equally important for COCA-CDI. Opportunities to safely reduce antibiotic and gastric acid suppressants use should be investigated in all healthcare settings.

The use of high-throughput sequencing to investigate an outbreak of glycopeptide-resistant Enterococcus faecium with a novel quinupristin-dalfopristin resistance mechanism.

High-throughput sequencing (HTS) has successfully identified novel resistance genes in enterococci and determined clonal relatedness in outbreak analysis. We report the use of HTS to investigate two concurrent outbreaks of glycopeptide-resistant Enterococcus faecium (GRE) with an uncharacterised resistance mechanism to quinupristin-dalfopristin (QD). Seven QD-resistant and five QD-susceptible GRE isolates from a two-centre outbreak were studied. HTS was performed to identify genes or predicted proteins that were associated with the QD-resistant phenotype. MLST and SNP typing on HTS data was used to determine clonal relatedness. Comparative genomic analysis confirmed this GRE outbreak involved two distinct clones (ST80 and ST192). HTS confirmed the absence of known QD resistance genes, suggesting a novel mechanism was conferring resistance. Genomic analysis identified two significant genetic determinants with explanatory power for the high level of QD resistance in the ST80 QD-resistant clone: an additional 56aa leader sequence at the N-terminus of the lsaE gene and a transposon containing seven genes encoding proteins with possible drug or drug-target modification activities. However, HTS was unable to conclusively determine the QD resistance mechanism and did not reveal any genetic basis for QD resistance in the ST192 clone. This study highlights the usefulness of HTS in deciphering the degree of relatedness in two concurrent GRE outbreaks. Although HTS was able to reveal some genetic candidates for uncharacterised QD resistance, this study demonstrates the limitations of HTS as a tool for identifying putative determinants of resistance to QD.

Relative resistance index (RRI) - a scoring system for antibiotic resistance in Pseudomonas aeruginosa.

BACKGROUND: There is a need to measure antibiotic resistance of Pseudomonas aeruginosa (PA) in cystic fibrosis (CF), either qualitatively or quantitatively, to inform patient management. The aim of this study was to develop a simple method by which resistance can be quantified by calculating a relative resistance index (RRI), and to assess correlation of RRIs with clinical variables. METHODS: In our model, RRIs were calculated based on resistance to aztreonam, ceftazidime, ciprofloxacin, colistin, meropenem, tazocin, temicillin and tobramycin. Eighty-five adults with CF and chronic PA colonisation were identified. For each, all PA cultures were allocated a score of 0 for susceptible, 0.5 for intermediate resistance or 1 for resistance for each antibiotic listed above, and the RRI calculated by dividing the sum of these by the number of antibiotics, giving a maximum score of 1. The mean RRIs for all cultures were correlated with key clinical variables monitored in CF patients (including age, FEV1, IV antibiotic days and BMI). RESULTS: RRIs for non-mucoid PA exhibited moderate positive correlation with total number of IV days (r = 0.405; p < 0.001) and moderate negative correlation with FEV1 % predicted (r = -0.437; p < 0.001). RRIs were not significantly correlated with duration of colonisation, typing (clonal vs other strain) or BMI. Median RRIs were significantly higher for females (0.26, IQR 0.13-0.54) than males (0.18, IQR 0.07-0.37) for non-mucoid PA only (p = 0.03). CONCLUSIONS: RRI is an easily calculated measure that correlates with other clinical variables in CF patients and enables quantitative monitoring of resistance.

Experimental demonstration of a soft x-ray self-seeded free-electron laser.

The Linac Coherent Light Source has added a self-seeding capability to the soft x-ray range using a grating monochromator system. We report the demonstration of soft x-ray self-seeding with a measured resolving power of 2000-5000, wavelength stability of 10(-4), and an increase in peak brightness by a factor of 2-5 across the photon energy range of 500-1000 eV. By avoiding the need for a monochromator at the experimental station, the self-seeded beam can deliver as much as 50-fold higher brightness to users.

Genetic susceptibility to invasive meningococcal disease: MBL2 structural polymorphisms revisited in a large case-control study and a systematic review.

Invasive infection caused by Neisseria meningitidis is a worldwide public health problem. Previous reports have indicated that carriage of common 'defective' structural polymorphisms of the host mannose-binding lectin gene (MBL2) greatly increases an individual's risk of developing the disease. We report the largest case-control study so far to investigate the effect of these polymorphisms in meningococcal disease (296 PCR-positive cases and 5196 population controls, all of European ancestry) and demonstrate that no change in risk is associated with the polymorphisms overall or in any age-defined subgroup. This finding contrasts with two smaller studies that reported an increase in risk. A systematic review of all studies of MBL2 polymorphisms in people of European ancestry published since 1999, including 24,693 individuals, revealed a population frequency of the combined 'defective'MBL2 allele of 0.230 (95% confidence limits: 0.226-0.234). The past reported associations of increased risk of meningococcal disease were because of low 'defective' allele frequencies in their study control populations (0.13 and 0.04) that indicate systematic problems with the studies. The data from our study and all other available evidence indicate that MBL2 structural polymorphisms do not predispose children or adults to invasive meningococcal disease.

Emergence of a non-sporulating secondary phenotype in Clostridium (Clostridioides) difficile ribotype 078 isolated from humans and animals.

Clostridium (Clostridioides) difficile is a Gram positive, spore forming anaerobic bacterium that is a leading cause of antibiotic associated diarrhoea in the developed world. C. difficile is a genetically diverse species that can be divided into 8 phylogenetically distinct clades with clade 5 found to be genetically distant from all others. Isolates with the PCR ribotype 078 belong to clade 5, and are often associated with C. difficile infection in both humans and animals. Colonisation of animals and humans by ribotype 078 raises questions about possible zoonotic transmission, and also the diversity of reservoirs for ribotype 078 strains within the environment. One of the key factors which enables C. difficile to be a successful, highly transmissible pathogen is its ability to produce oxygen resistant spores capable of surviving harsh conditions. Here we describe the existence of a non-sporulating variant of C. difficile ribotype 078 harbouring mutations leading to premature stop codons within the master regulator, Spo0A. As sporulation is imperative to the successful transmission of C. difficile this study was undertaken to investigate phenotypic characteristics of this asporogenous phenotype with regards to growth rate, antibiotic susceptibility, toxin production and biofilm formation.

Improving molecular detection of Candida DNA in whole blood: comparison of seven fungal DNA extraction protocols using real-time PCR.

The limitations of classical diagnostic methods for invasive Candida infections have led to the development of molecular techniques such as real-time PCR to improve diagnosis. However, the detection of low titres of Candida DNA in blood from patients with candidaemia requires the use of extraction methods that efficiently lyse yeast cells and recover small amounts of DNA suitable for amplification. In this study, a Candida-specific real-time PCR assay was used to detect Candida albicans DNA in inoculated whole blood specimens extracted using seven different extraction protocols. The yield and quality of total nucleic acids were estimated using UV absorbance, and specific recovery of C. albicans genomic DNA was estimated quantitatively in comparison with a reference (Qiagen kit/lyticase) method currently in use in our laboratory. The extraction protocols were also compared with respect to sensitivity, cost and time required for completion. The TaqMan PCR assay used to amplify the DNA extracts achieved high levels of specificity, sensitivity and reproducibility. Of the seven extraction protocols evaluated, only the MasterPure yeast DNA extraction reagent kit gave significantly higher total nucleic acid yields than the reference method, although nucleic acid purity was highest using either the reference or YeaStar genomic DNA kit methods. More importantly, the YeaStar method enabled C. albicans DNA to be detected with highest sensitivity over the entire range of copy numbers evaluated, and appears to be an optimal method for extracting Candida DNA from whole blood.

Comparison of serum and whole-blood specimens for the detection of Candida DNA in critically ill, non-neutropenic patients.

In contrast to the multitude of studies on fungal PCR assay methods, little work has been reported evaluating Candida PCR performance when using whole blood compared with serum in candidaemic patients. Here, a comparison of the performance of whole-blood and serum specimens using a set of real-time PCR Candida species assays is described. Specimens were collected prospectively from non-neutropenic adults who were recruited to a diagnostic clinical trial, the primary purpose of which was to verify the performance of the assays using serum; in all, 104 participants also had whole-blood specimens submitted for analysis in addition to the serum specimen. Of these participants, 10 had laboratory-confirmed candidaemia and 94 were categorized as being 'unlikely' to have invasive Candida infection. PCR results from the whole-blood specimens are presented here and compared with the results from serum specimens in this subgroup among whom both specimen types were obtained contemporaneously. All participants with candidaemia were PCR-positive from serum samples; however, only seven were PCR-positive from whole blood. All specimens from patients in the 'unlikely' category were PCR-negative in both types of specimen. Moreover, DNA extraction from serum required 1 h; extraction from whole blood required approximately 3 h. These data tentatively suggest that, overall, serum is an appropriate specimen for Candida PCR for detection of candidaemia in non-neutropenic adults.

Meningococcal Disease in Northern Ireland - Past, Present & Future: MeningoNI Forum.

Meningococcal disease has had devastating consequences in Northern Ireland since its first description locally in 1859. The incidence of this disease has significantly declined in recent years, however it is important to understand reasons for this changing epidemiology and to acknowledge the diagnostic and clinical management developments that have been made locally. This review aims to examine the changing face of this disease in Northern Ireland over the years, with particular reference to local disease prevention, epidemiology, diagnosis, clinical treatment and management, post-disease sequelae and the role of meningitis charities locally, in terms of patient support and research.

Effect of insulin-like growth factor-type I (IGF-I) and insulin on the secretion of sex hormone binding globulin and IGF-I binding protein (IBP-I) by human hepatoma cells.

Dietary factors are known to modulate concentrations of sex hormone-binding globulin (SHBG). In the present study we have investigated the possibility that insulin like growth factor-type I (IGF-I) may be an additional regulator of SHBG using cultured human hepatoma cells which secrete SHBG. The inhibitory effect of insulin on SHBG secretion by these cells was confirmed but, in addition, IGF-I was shown to inhibit SHBG secretion by about 40% at a concentration of 100 nmol/l. A similar degree of inhibition was achieved using insulin at a concentration of 10 mumol/l. Insulin, but not IGF-I, was also found to inhibit the secretion of a low molecular weight IGF-binding protein (IBP-I), which is also secreted by hepatoma cells. It is concluded that IGF-I is an additional regulator of SHBG secretion by these cells and that it may be involved in regulating SHBG secretion in vivo in response to dietary factors.

Daily mortality and air pollution in Santa Clara County, California: 1989-1996.

Since the last revision of the national particulate standards, there has been a profusion of epidemiologic research showing associations between particulates and health effects--mortality in particular. Supported by this research, the U.S. Environmental Protection Agency promulgated a national standard for particulate matter [less than/equal to] 2.5 microm in aerodynamic diameter (PM(2.5)). Nevertheless, the San Francisco Bay Area of California may meet this new standard. This study investigates the relationship between daily mortality and air pollution in Santa Clara County (a Bay Area county) using techniques similar to those utilized in earlier epidemiologic studies. Statistically significant associations persist in the early 1990s, when the Bay Area met national air pollution standards for every criteria pollutant. Of the various pollutants, the strongest associations occur with particulates, especially ammonium nitrate and PM(2.5). The continuing presence of associations between mortality and air pollutants calls into question the adequacy of national standards for protecting public health.

The relationship of daily mortality to suspended particulates in Santa Clara County, 1980-1986.

This paper explores the relationship between daily mortality and suspended particulates in Santa Clara County, CA, for years 1980 to 1986. An association was found between high particulate concentrations and increased mortality. This association persists after adjustment for temperature, relative humidity, year, and seasonality. Contrary to expectation, the magnitude of the particulate effect appears the same or larger than that estimated for London, despite Santa Clara County's cleaner air. The persistence of an effect at these lower particulate concentrations suggests that the particulate variable may be acting as a surrogate for some constituent particles, such as acid aerosols.

Sex hormone-binding globulin and female reproductive function.

Although sex steroids have long been known to influence serum concentrations of SHBG, it is now recognized that nutritional factors may be more important in the regulation of SHBG in women. Thus, SHBG concentrations are negatively correlated with body mass index (BMI) and, more particularly, to indices of central adiposity. Polycystic ovary syndrome (PCOS), the most common cause of anovulatory infertility, is associated with truncal obesity, hyperandrogenism and hyperinsulinaemia. There is evidence that insulin may be the humoral mediator of the weight-dependent changes in SHBG. Serum SHBG concentrations are inversely correlated with both fasting and glucose-stimulated insulin levels, and insulin has been shown to have a direct inhibitory effect on SHBG synthesis and secretion by hepatocytes in culture. However, the interrelationship of BMI, insulin and SHBG appears to be different in women with PCOS from that in normal subjects. The clinical importance of the weight-related suppression of SHBG is illustrated by the finding of a greater prevalence of hirsutism in obese women PCOS compared with their lean counterparts. Obese subjects with PCOS have similar total testosterone concentrations to lean PCO women but have lower SHBG and reciprocally higher free testosterone levels. Calorie restriction results in reduction of serum insulin followed by an increase in SHBG and a fall in free testosterone but an isocaloric, low-fat diet has no significant effect on SHBG concentrations. Weight reduction in obese, hyperandrogenaemic women with PCO is an important approach to the management of both anovulation and hirsutism.

The role of nutrition and insulin in the regulation of sex hormone binding globulin.

In an analysis of 263 women with polycystic ovary syndrome (PCOS), 91 (35%) of whom were obese (body mass index greater than 25 kg/m2), it was found that obese women with PCOS were more likely to be anovulatory and had a higher prevalence of hirsutism than the non-obese subgroup. Although serum concentrations of gonadotrophins, androstenedione and total testosterone were similar in obese and lean women with PCO, sex hormone binding globulin (SHBG) levels were significantly lower, and free testosterone correspondingly higher, in obese women. Serum concentrations of SHBG were inversely correlated with those of both fasting and glucose-stimulated insulin. A short-term, very-low-calorie diet resulted in a 2-fold increase in SHBG which was mirrored by a fall in serum insulin. Similar biochemical changes were also observed during a long-term (6-7 months) 1000 kcal diet and were associated with an improvement of menstrual function and fertility. This encourages the view that calorie restriction has an important part to play in the management of obese women with PCOS.

Obesity and polycystic ovary syndrome.

Our studies show that obese women with polycystic ovary syndrome are more likely to have hirsutism and menstrual disturbances than are lean women with PCOS. The most obvious biochemical differences between obese and lean women with PCOS is that SHBG concentrations are much lower in women with obesity. The SHBG levels are inversely related to insulin, and insulin has been shown to have a direct inhibitory action on SHBG secretion. Other factors, however, may contribute to the mechanism of the increased prevalence of hirsutism and anovulation in obese women with PCOS, such as a direct effect of insulin or increased activity of 5 alpha-reductase in peripheral tissues. Finally we have been able to show that weight reduction of more than 5% is associated with an improved biochemical profile and, importantly, with restoration of fertility.

A comparative, randomized study of low-dose human menopausal gonadotropin and follicle-stimulating hormone in women with polycystic ovarian syndrome.

Treatment with low-dose follicle-stimulating hormone (FSH) is associated with a high rate of ovulation in anovulatory women with polycystic ovarian syndrome (PCOS), but it is not clear whether the success of treatment is because of the use of pure FSH or the low dose of gonadotropin. We undertook a randomized controlled study to compare the effects of urinary FSH and human menopausal gonadotropin (hMG) using a low-dose regimen in 30 women with PCOS. Each subject received a maximum of three cycles of either FSH or hMG. Ovulation occurred in 75% of subjects and in 77% of cycles induced with FSH and in 94% of women, 85% of cycles of those treated with hMG. A single dominant follicle developed in 70% (FSH) and 65% (hMG) of cycles, respectively. Five singleton pregnancies occurred in each group. This study shows that low-dose FSH and hMG are equally successful in inducing ovulation, suggesting that the success of treatment depends on the low dose of gonadotropin used rather than the presence or absence of luteinizing hormone in the preparation.

The carbon dioxide rate of rise in awake apneic humans.

Currently available estimates of the PaCO2 rate of rise in resting humans with resting lung volume were gathered during general anesthesia. The PaCO2 rate of rise during apnea in awake subjects was determined to acquire a value that may be more applicable to awake, ventilator-dependent, critically ill patients. Clinically, apnea occurs at functional residual capacity. With FiO2 = 1.0, 20 volunteers held their breaths at functional residual capacity for 0, 10, and 20 seconds, and then for as long as possible. They exhaled through an infrared CO2 analyzer after each interval to determine end-tidal pCO2. An estimate of the logarithmic PaCO2 rise during breath holding at functional residual capacity was 7 mmHg during the first 10 seconds (43 mmHg/minute), 2 mmHg during the next 10 seconds (13 mmHg/minute), and 6 mmHg/minute thereafter. In conclusion, PaCO2 increases more rapidly in awake apneic humans than earlier thought. The values reported herein probably are better for estimating duration of apnea in conscious, critically ill patients than are values obtained during general anesthesia.

Managing miscarriage in early pregnancy assessment units.

For most women, pregnancy is a significant life event and the prospect of losing a baby causes anxiety, stress and grief. Modern treatment of miscarriage should provide rapid sympathetic diagnosis and adequate counselling. Early pregnancy assessment units benefit patients, staff and the NHS. Many clinicians use medical treatment or expectant management, rather than standard surgical evacuation of the uterus.