Epidemiology and risk factors for Staphylococcus aureus colonization in children in the post-PCV7 era

<p>Abstract</p> <p>Background</p> <p>The incidence of community-associated methicillin-resistant <it>Staphylococcus aureus </it>(MRSA) has risen dramatically in the U.S., particularly among children. Although <it>Streptococcus pneumoniae </it>colonization has been inversely associated with <it>S. aureus </it>colonization in unvaccinated children, this and other risk factors for <it>S. aureus </it>carriage have not been assessed following widespread use of the heptavalent pneumococcal conjugate vaccine (PCV7). Our objectives were to (1) determine the prevalence of <it>S. aureus </it>and MRSA colonization in young children in the context of widespread use of PCV7; and (2) examine risk factors for <it>S. aureus </it>colonization in the post-PCV7 era, including the absence of vaccine-type <it>S. pneumoniae </it>colonization.</p> <p>Methods</p> <p>Swabs of the anterior nares (<it>S. aureus</it>) were obtained from children enrolled in an ongoing study of nasopharyngeal pneumococcal colonization of healthy children in 8 Massachusetts communities. Children 3 months to <7 years of age seen for well child or sick visits in primary care offices from 11/03–4/04 and 10/06–4/07 were enrolled. <it>S. aureus </it>was identified and antibiotic susceptibility testing was performed. Epidemiologic risk factors for <it>S. aureus </it>colonization were collected from parent surveys and chart reviews, along with data on pneumococcal colonization. Multivariate mixed model analyses were performed to identify factors associated with <it>S. aureus </it>colonization.</p> <p>Results</p> <p>Among 1,968 children, the mean age (SD) was 2.7 (1.8) years, 32% received an antibiotic in the past 2 months, 2% were colonized with PCV7 strains and 24% were colonized with non-PCV7 strains. The prevalence of <it>S. aureus </it>colonization remained stable between 2003–04 and 2006–07 (14.6% vs. 14.1%), while MRSA colonization remained low (0.2% vs. 0.9%, p = 0.09). Although absence of pneumococcal colonization was not significantly associated with <it>S. aureus </it>colonization, age (6–11 mo vs. ≥5 yrs, OR 0.39 [95% CI 0.24–0.64]; 1–1.99 yrs vs. ≥5 yrs, OR 0.35 [0.23–0.54]; 2–2.99 yrs vs. ≥5 yrs, OR 0.45 [0.28–0.73]; 3–3.99 yrs vs. ≥5 yrs, OR 0.53 [0.33–0.86]) and recent antibiotic use were significant predictors in multivariate models.</p> <p>Conclusion</p> <p>In Massachusetts, <it>S. aureus </it>and MRSA colonization remained stable from 2003–04 to 2006–07 among children <7 years despite widespread use of pneumococcal conjugate vaccine. <it>S. aureus </it>nasal colonization varies by age and is inversely correlated with recent antibiotic use.</p

The number of tree species on Earth

One of the most fundamental questions in ecology is how many species inhabit the Earth. However, due to massive logistical and financial challenges and taxonomic difficulties connected to the species concept definition, the global numbers of species, including those of important and well-studied life forms such as trees, still remain largely unknown. Here, based on global ground-sourced data, we estimate the total tree species richness at global, continental, and biome levels. Our results indicate that there are ∼73,000 tree species globally, among which ∼9,000 tree species are yet to be discovered. Roughly 40% of undiscovered tree species are in South America. Moreover, almost one-third of all tree species to be discovered may be rare, with very low populations and limited spatial distribution (likely in remote tropical lowlands and mountains). These findings highlight the vulnerability of global forest biodiversity to anthropogenic changes in land use and climate, which disproportionately threaten rare species and thus, global tree richness

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta