Comparison of the Respiratory Resistomes and Microbiota in Children Receiving Short versus Standard Course Treatment for Community-Acquired Pneumonia.

Pediatric community-acquired pneumonia (CAP) is often treated with 10 days of antibiotics. Shorter treatment strategies may be effective and lead to less resistance. The impact of duration of treatment on the respiratory microbiome is unknown. Data are from children (n = 171), ages 6 to 71 months, enrolled in the SCOUT-CAP trial (NCT02891915). Children with CAP were randomized to a short (5 days) versus standard (10 days) beta-lactam treatment strategy. Throat swabs were collected at enrollment and the end of the study and used for shotgun metagenomic sequencing. The number of beta-lactam and multidrug efflux resistance genes per prokaryotic cell (RGPC) was significantly lower in children receiving the short compared to standard treatment strategy at the end of the study (Wilcoxon rank sum test, P < 0.05 for each). Wilcoxon effect sizes were small for beta-lactam (r: 0.15; 95% confidence interval [CI], 0.01 to 0.29) and medium for multidrug efflux RGPC (r: 0.23; 95% CI, 0.09 to 0.37). Analyses comparing the resistome at the beginning and end of the trial indicated that in contrast to the standard strategy group, the resistome significantly differed in children receiving the short course strategy. Relative abundances of commensals such as Neisseria subflava were higher in children receiving the standard strategy, and Prevotella species and Veillonella parvula were higher in children receiving the short course strategy. We conclude that children receiving 5 days of beta-lactam therapy for CAP had a significantly lower abundance of antibiotic resistance determinants than those receiving standard 10-day treatment. These data provide an additional rationale for reductions in antibiotic use when feasible. IMPORTANCE Antibiotic resistance is a major threat to public health. Treatment strategies involving shorter antibiotic courses have been proposed as a strategy to lower the potential for antibiotic resistance. We examined relationships between the duration of antibiotic treatment and its impact on resistance genes and bacteria in the respiratory microbiome using data from a randomized controlled trial of beta-lactam therapy for pediatric pneumonia. The randomized design provides reliable evidence of the effectiveness of interventions and minimizes the potential for confounding. Children receiving 5 days of therapy for pneumonia had a lower prevalence of two different types of resistance genes than did those receiving the 10-day treatment. Our data also suggest that children receiving longer durations of therapy have a greater abundance of antibiotic resistance genes for a longer period of time than do children receiving shorter durations of therapy. These data provide an additional rationale for reductions in antibiotic use.

Voluntary sustainability standards could significantly reduce detrimental impacts of global agriculture.

Voluntary sustainability standards (VSS) are stakeholder-derived principles with measurable and enforceable criteria to promote sustainable production outcomes. While institutional commitments to use VSS to meet sustainable procurement policies have grown rapidly over the past decade, we still have relatively little understanding of the (i) direct environmental benefits of large-scale VSS adoption; (ii) potential perverse indirect impacts of adoption; and (iii) implementation pathways. Here, we illustrate and address these knowledge gaps using an ecosystem service modeling and scenario analysis of Bonsucro, the leading VSS for sugarcane. We find that global compliance with the Bonsucro environmental standards would reduce current sugarcane production area (-24%), net tonnage (-11%), irrigation water use (-65%), nutrient loading (-34%), and greenhouse gas emissions from cultivation (-51%). Under a scenario of doubled global sugarcane production, Bonsucro adoption would further limit water use and greenhouse gas emissions by preventing sugarcane expansion into water-stressed and high-carbon stock ecosystems. This outcome was achieved via expansion largely on existing agricultural lands. However, displacement of other crops could drive detrimental impacts from indirect land use. We find that over half of the potential direct environmental benefits of Bonsucro standards under the doubling scenario could be achieved by targeting adoption in just 10% of global sugarcane production areas. However, designing policy that generates the most environmentally beneficial Bonsucro adoption pathway requires a better understanding of the economic and social costs of VSS adoption. Finally, we suggest research directions to advance sustainable consumption and production.

Factors associated with persistent colonisation with methicillin-resistant Staphylococcus aureus.

We conducted a prospective cohort study between 1 January 2010 and 31 December 2012 at five adult and paediatric academic medical centres to identify factors associated with persistent methicillin-resistant Staphylococcus aureus (MRSA) colonisation. Adults and children presenting to ambulatory settings with a MRSA skin and soft tissue infection (i.e. index cases), along with household members, performed self-sampling for MRSA colonisation every 2 weeks for 6 months. Clearance of colonisation was defined as two consecutive negative sampling periods. Subjects without clearance by the end of the study were considered persistently colonised and compared with those who cleared colonisation. Of 243 index cases, 48 (19·8%) had persistent colonisation and 110 (45·3%) cleared colonisation without recurrence. Persistent colonisation was associated with white race (odds ratio (OR), 4·90; 95% confidence interval (CI), 1·38-17·40), prior MRSA infection (OR 3·59; 95% CI 1·05-12·35), colonisation of multiple sites (OR 32·7; 95% CI 6·7-159·3). Conversely, subjects with persistent colonisation were less likely to have been treated with clindamycin (OR 0·28; 95% CI 0·08-0·99). Colonisation at multiple sites is a risk factor for persistent colonisation and may require more targeted decolonisation efforts. The specific effect of clindamycin on MRSA colonisation needs to be elucidated.

Skeletal muscle and plasma concentrations of cefazolin during complex paediatric spinal surgery.

BACKGROUND: Surgical site infections (SSIs) can have devastating consequences for children who undergo spinal instrumentation. Prospective evaluations of prophylactic cefazolin in this population are limited. The purpose of this study was to describe the pharmacokinetics and skeletal muscle disposition of prophylactic cefazolin in a paediatric population undergoing complex spinal surgery. METHODS: This prospective pharmacokinetic study included 17 children with adolescent idiopathic scoliosis undergoing posterior spinal fusion, with a median age of 13.8 [interquartile range (IQR) 13.4-15.4] yr and a median weight of 60.6 (IQR 50.8-66.0) kg. A dosing strategy consistent with published guidelines was used. Serial plasma and skeletal muscle microdialysis samples were obtained during the operative procedure and unbound cefazolin concentrations measured. Non-compartmental pharmacokinetic analyses were performed. The amount of time that the concentration of unbound cefazolin exceeded the minimal inhibitory concentration for bacterial growth for selected SSI pathogens was calculated. RESULTS: Skeletal muscle concentrations peaked at a median of 37.6 (IQR 26.8-40.0) µg ml(-1) within 30-60 min after the first cefazolin 30 mg kg(-1) dose. For patients who received a second 30 mg kg(-1) dose, the peak concentrations reached a median of 40.5 (IQR 30.8-45.7) µg ml(-1) within 30-60 min. The target cefazolin concentrations for SSI prophylaxis for meticillin-sensitive Staphylococcus aureus (MSSA) and Gram-negative pathogens were exceeded in skeletal muscle 98.9 and 58.3% of the intraoperative time, respectively. CONCLUSIONS: For children with adolescent idiopathic scoliosis undergoing posterior spinal fusion, the cefazolin dosing strategy used in this study resulted in skeletal muscle concentrations that were likely not to be effective for intraoperative SSI prophylaxis against Gram-negative pathogens.

Reversing lipopolysaccharide toxicity by ligating the macrophage Fc gamma receptors.

Our laboratory has previously demonstrated that the ligation of phagocytic receptors on macrophages can influence cytokine production. In this study, we examine the cytokine responses to multiple inflammatory stimuli following FcgammaR ligation. Macrophages were stimulated in vitro with LPS, lipoteichoic acid, CD40 ligand, or low molecular mass hyaluronic acid. All of these stimuli were proinflammatory in character, inducing the production of high levels of IL-12, but only modest amounts of IL-10. The coligation of FcgammaR along with these stimuli resulted in an anti-inflammatory profile, abrogating IL-12 production and inducing high levels of IL-10. The modulation of these two cytokines occurred by two independent mechanisms. Whereas the abrogation of IL-12 biosynthesis was a property shared by several macrophage receptors, the induction of IL-10 was specific to the FcgammaR. The biological relevance of these observations was examined in murine models of endotoxemia, in which FcgammaR ligation induced the rapid production of IL-10 and prevented IL-12 synthesis. Mice could be passively immunized with Abs to LPS to reverse inflammatory cytokine production, and the transfer of macrophages whose FcgammaR had been ligated could rescue mice from lethal endotoxemia. Thus, the ligation of the macrophage FcgammaR can be exploited to prevent inappropriate inflammatory cytokine responses.

Stimulatory and inhibitory signals originating from the macrophage Fcgamma receptors.

The macrophage receptors for the Fc portion of immunoglobulin G (FcgammaR) have long been known to mediate a variety of effector functions that are vital to the adaptive immune response. Recent studies, however, have begun to stress potential regulatory roles that these receptors can play in modulating immune and inflammatory responses. In this article we discuss the activating and inhibitory properties of the individual macrophage FcgammaR and the conditions under which these heterologous responses can occur.

The intensity coherence function of time for partially saturated acoustic propagation through ocean internal waves.

The intensity coherence function of time for partially saturated acoustic propagation through internal waves is calculated with a method that is improved over previous treatments. Two specific improvements are introduced: the usual expansion in (1/lambdaphi2) is carried out to a higher order, and then the terms of that expansion are calculated with a new perturbative method. The method is applied to propagation without a sound channel, for both phase-screen and continuous-medium cases. The validity of the new perturbative method is estimated by calculating the next order error terms. Accuracies at the few-percent level are found. The new analytic formulas are also corroborated with numerical integration. Finally, the method is applied to a specific ocean-acoustic experiment [Azores Fixed Acoustic Range (AFAR)]. In order to achieve good agreement with experiment it will be necessary to add an accurate treatment of the sound channel to the present perturbation method.

An N-terminal mutation in the bacteriophage T4 motA gene yields a protein that binds DNA but is defective for activation of transcription.

The bacteriophage T4 MotA protein is a transcriptional activator of T4-modified host RNA polymerase and is required for activation of the middle class of T4 promoters. MotA alone binds to the -30 region of T4 middle promoters, a region that contains the MotA box consensus sequence [(t/a)(t/a)TGCTT(t/c)A]. We report the isolation and characterization of a protein designated Mot21, in which the first 8 codons of the wild-type motA sequence have been replaced with 11 different codons. In gel retardation assays, Mot21 and MotA bind DNA containing the T4 middle promoter P(uvsX) similarly, and the proteins yield similar footprints on P(uvsX). However, Mot21 is severely defective in the activation of transcription. On native protein gels, a new protein species is seen after incubation of the sigma70 subunit of RNA polymerase and wild-type MotA protein, suggesting a direct protein-protein contact between MotA and sigma70. Mot21 fails to form this complex, suggesting that this interaction is necessary for transcriptional activation and that the Mot21 defect arises because Mot21 cannot form this contact like the wild-type activator.

Characterization of pre-transcription complexes made at a bacteriophage T4 middle promoter: involvement of the T4 MotA activator and the T4 AsiA protein, a sigma 70 binding protein, in the formation of the open complex.

Bacteriophage T4 middle promoters have excellent matches to the -10 consensus sequence for the sigma 70 subunit of Escherichia coli RNA polymerase, but a binding site for the T4 transcriptional activator MotA replaces the sigma 70 -35 consensus. E. Coli RNA polymerase transcribes from middle promoters with or without the activator. In contrast, transcription by T4-modified E. coli RNA polymerase, which is present during T4 infection, requires NotA. We show that transcription by unmodified polymerase from the T4 middle promoter P uvsx is independent of the specific sequences within the -35 region, and the Dnase I footprint obtained with unmodified polymerase and P uvsx resembles those seen previously with E. coli extended -10" promoters. In contrast, although T4-modified polymerase alond binds P uvsx, promoter unwinding and detection of a Dnase I footprint requires MotA. This footprint is significantly different from that obtained with unmodified polymerase, starting upstream of around position -20. Previous work has indicated that the T4 AsiA protein, which binds tightly to sigma 70, is the phage modification required for MotA activation. We show that in the presence of AsiA, MotA, and otherwise unmodified polymerase, Dnase I protection of P uvsx is now similar to that obtained with the fully modified polymerase and MotA up to around position -40. However, protection upstream of -40 is still similar to that seen with unmodified polymerase. Our results support the idea that MotA-dependent activation requires AsiA binding to sigma 70 to achieve specific protein-DNA contacts within the -20 to -40 region of a middle promoter.