Neisseria gonorrhoeae false-positive result obtained from a pharyngeal swab by using the roche cobas 4800 CT/NG assay in New Zealand in 2012

The Roche cobas 4800 CT/NG assay is a commonly used commercial system for screening for Neisseria gonorrhoeae infection, and previous studies have shown the method to be highly sensitive and specific for urogenital samples. We present the first confirmed clinical N. gonorrhoeae false-positive result using the cobas 4800 NG assay, obtained from testing a pharyngeal swab sample and caused by cross-reaction with a commensal Neisseria strain

Evidence of false-positive results in a commercially available rotavirus assay in the vaccine era, Australia, 2011 to 2012

Concerns were raised about specificity of the VIKIA Rota-Adeno immunochromatographic kit. Only 28-37% of samples positive with the VIKIA kit could be confirmed using two real-time RT-PCR assays and three ELISA kits. On re-analysis of a subset of the positive samples, 86% remained positive with the VIKIA kit, however, 90% remained negative in the other assays. In a highly vaccinated population we found a high number of false-positive rotavirus tests with a widely-used commercial kit

Comparison of test specificities of commercial antigen-based assays and in-house PCR methods for detection of rotavirus in stool specimens

Seven commercial rotavirus antigen assays were compared with in-house PCR methods for detecting rotavirus in stool specimens. The assay sensitivities were 80% to 100%, while the specificities were 54.3% for one commercial immunochromatographic (ICT) method and 99.4% to 100% for other assays. Thus, except for one commercial ICT, all the assays were generally reliable for rotavirus detection

The evolution of the brightest cluster galaxies since z∼ 1 from the ESO Distant Cluster Survey (EDisCS)

We present K-band data for the brightest cluster galaxies (BCGs) from the ESO Distant Cluster Survey (EDisCS). These data are combined with the photometry published by Aragón-Salamanca, Baugh & Kauffmann and a low-redshift comparison sample built from the BCG catalogue of von der Linden et al. BCG luminosities are measured inside a metric circular aperture with 37 kpc diameter. In agreement with previous studies, we find that the K-band Hubble diagram for BCGs exhibits very low scatter (∼0.35) over a redshift range of 0 2 and evolved passively thereafter. In contrast with some previous studies, we do not detect any significant change in the stellar mass of the BCG since z∼ 1. These results do not seem to depend on the velocity dispersion of the parent cluster. We also find that there is a correlation between the 1D velocity dispersion of the clusters (σcl) and the K-band luminosity of the BCGs (after correcting for passive-evolution). The clusters with large velocity dispersions, and therefore masses, tend to have brighter BCGs, i.e. BCGs with larger stellar masses. This dependency, although significant, is relatively weak: the stellar mass of the BCGs changes only by ∼70 per cent over a two order of magnitude range in cluster mass. Furthermore, this dependency does not change significantly with redshift. We have compared our observational results with the hierarchical galaxy formation and evolution model predictions of De Lucia & Blaizot. We find that the models predict colours which are in reasonable agreement with the observations because the growth in stellar mass is dominated by the accretion of old stars. However, the stellar mass in the model BCGs grows by a factor of 3-4 since z= 1, a growth rate which seems to be ruled out by the observations. The models predict a dependency between the BCG's stellar mass and the velocity dispersion (mass) of the parent cluster in the same sense as the data, but the dependency is significantly stronger than observed. However, one major difficulty in this comparison is that we have measured magnitudes inside a fixed metric aperture while the models compute total luminositie

The Shapes of BCGs and normal Ellipticals in Nearby Clusters

We compare the apparent axial ratio distributions of Brightest Cluster Galaxies (BCGs) and normal ellipticals (Es) in our sample of 75 galaxy clusters from the WINGS survey. Most BCGs in our clusters (69%) are classified as cD galaxies. The sample of cDs has been completed by 14 additional cDs (non-BCGs) we found in our clusters. We find that: (i) Es have triaxial shape, the triaxiality sharing almost evenly the intrinsic axial ratios parameter space, with a weak preference for prolateness; (ii) the BCGs have triaxial shape as well. However, their tendence towards prolateness is much stronger than in the case of Es. Such a strong prolateness appears entirely due to the sizeable (dominant) component of cDs inside the WINGS sample of BCGs. In fact, while the 'normal'(non-cD) BCGs do not differ from Es, as far as the shape distribution is concerned, the axial ratio distribution of BCG_cD galaxies is found to support quite prolate shapes; (iii) our result turns out to be strongly at variance with the only similar, previous analysis by Ryden et al.(1993)(RLP93), where BCGs and Es were found to share the same axial ratio distribution; (iv) our data suggest that the above discrepancy is mainly caused by the different criteria that RLP93 and ourselves use to select the cluster samples, coupled with a preference of cDs to reside in powerful X-ray emitting clusters; (v) the GIF2 N-body results suggest that the prolateness of the BCGs (in particular the cDs) could reflect the shape of the associated dark matter halos.Comment: 18 pages, 9 figures, 2 tables. Accepted for publication in MNRA

The XMM Cluster Survey: The interplay between the brightest cluster galaxy and the intra-cluster medium via AGN feedback

Using a sample of 123 X-ray clusters and groups drawn from the XMM-Cluster Survey first data release, we investigate the interplay between the brightest cluster galaxy (BCG), its black hole, and the intra-cluster/group medium (ICM). It appears that for groups and clusters with a BCG likely to host significant AGN feedback, gas cooling dominates in those with Tx > 2 keV while AGN feedback dominates below. This may be understood through the sub-unity exponent found in the scaling relation we derive between the BCG mass and cluster mass over the halo mass range 10^13 < M500 < 10^15Msol and the lack of correlation between radio luminosity and cluster mass, such that BCG AGN in groups can have relatively more energetic influence on the ICM. The Lx - Tx relation for systems with the most massive BCGs, or those with BCGs co-located with the peak of the ICM emission, is steeper than that for those with the least massive and most offset, which instead follows self-similarity. This is evidence that a combination of central gas cooling and powerful, well fuelled AGN causes the departure of the ICM from pure gravitational heating, with the steepened relation crossing self-similarity at Tx = 2 keV. Importantly, regardless of their black hole mass, BCGs are more likely to host radio-loud AGN if they are in a massive cluster (Tx > 2 keV) and again co-located with an effective fuel supply of dense, cooling gas. This demonstrates that the most massive black holes appear to know more about their host cluster than they do about their host galaxy. The results lead us to propose a physically motivated, empirical definition of 'cluster' and 'group', delineated at 2 keV.Comment: Accepted for publication in MNRAS - replaced to match corrected proo

Comparison of the cobas 4800 CT/NG test with culture for detecting neisseria gonorrhoeae in genital and nongenital specimens in a low-prevalence population in New Zealand

To assess the clinical utility of replacing microbial culture for Neisseria gonorrhoeae with a nucleic acid amplification test (NAAT), we compared N. gonorrhoeae culture with the cobas 4800 CT/NG test for 18,247 urogenital and 666 nongenital samples. For urogenital specimens, the sensitivity, specificity, and positive and negative predictive values of the cobas N. gonorrhoeae PCR were 98.7%, 100%, 95.6%, and 100%, respectively, and for nongenital specimens, the values were 100%, 99.8%, 92.9%, and 100%, respectively. In our test population, 37% (10,185) of patients tested over the study period were screened for C. trachomatis by PCR but were not screened for gonorrhea by culture. Of these, 43 were N. gonorrhoeae positive by PCR and therefore went undiagnosed. The cobas 4800 CT/NG test diagnosed 33% (n=30) more urogenital and 25% (n=3) more rectal gonorrhea infections than culture and, based on the above performance indicators, does not require supplementary testing for urogenital or rectal specimens. The ability to test noninvasive specimens (such as urine and self-taken vulvovaginal swabs) for N. gonorrhoeae will enable more patients to be screened for infection, thus offering significant positive public health benefits. Copyrigh

Are COVID-19 conspiracies a threat to public health? Psychological characteristics and health protective behaviours of believers

We tested the link between COVID-19 conspiracy theories and health protective behaviours in three studies: one at the onset of the pandemic in the United Kingdom (UK), a second just before the first national lockdown, and a third during that lockdown (N = 302, 404 and 399). We focused on conspiracy theories that did not deny the existence of COVID-19 and evaluated the extent to which they predicted a range of health protective behaviours, before and after controlling for psychological and sociodemographic characteristics associated with conspiracy theory belief. COVID-19 conspiracy beliefs were positively correlated with beliefs in other unrelated conspiracies and a general conspiracy mind-set, and negatively correlated with trust in government and a tendency towards analytical thinking (vs. intuitive thinking). Unexpectedly, COVID-19 conspiracy believers adhered to basic health guidelines and advanced health protective measures as strictly as non-believers. Conspiracy believers were, however, less willing to install the contact-tracing app, get tested for and vaccinated against COVID-19, and were more likely to share COVID-19 misinformation – all of which might undermine public health initiatives. Study 3 showed conspiracy theory believers were less willing to undertake health protective behaviours that were outside of their personal control, perceiving these as having a negative balance of risks and benefits. We discuss models explaining conspiracy beliefs and health protective behaviours, and suggest practical recommendations for public health initiatives

Genetic relatedness of ceftriaxone-resistant and high-level azithromycin resistant Neisseria gonorrhoeae cases, United Kingdom and Australia, February to April 2018

Between February and April 2018, three ceftriaxone-resistant and high-level azithromycin-resistant Neisseria gonorrhoeae cases were identified; one in the United Kingdom and two in Australia. Whole genome sequencing was used to show that the isolates from these cases belong to a single gonococcal clone, which we name the A2543 clone

A real-time, quantitative PCR method using hydrolysis probes for the monitoring of Plasmodium falciparum load in experimentally infected human volunteers

Background: The accurate quantification of Plasmodium falciparum parasite numbers by PCR is an important tool for monitoring growth kinetics in subjects infected and subsequently treated with anti-malarial agents