Mechanisms involved in acquisition of blaNDM genes by IncA/C2 and IncFIIY plasmids

blaNDM genes confer carbapenem resistance and have been identified on transferable plasmids belonging to different incompatibility (Inc) groups. Here we present the complete sequences of four plasmids carrying a blaNDM gene, pKP1-NDM-1, pEC2-NDM-3, pECL3-NDM-1, and pEC4-NDM-6, from four clinical samples originating from four different patients. Different plasmids carry segments that align to different parts of the blaNDM region found on Acinetobacter plasmids. pKP1-NDM-1 and pEC2-NDM-3, from Klebsiella pneumoniae and Escherichia coli, respectively, were identified as type 1 IncA/C2 plasmids with almost identical backbones. Different regions carrying blaNDM are inserted in different locations in the antibiotic resistance island known as ARI-A, and ISCR1 may have been involved in the acquisition of blaNDM-3 by pEC2-NDM-3. pECL3-NDM-1 and pEC4-NDM-6, from Enterobacter cloacae and E. coli, respectively, have similar IncFIIY backbones, but different regions carrying blaNDM are found in different locations. Tn3-derived inverted-repeat transposable elements (TIME) appear to have been involved in the acquisition of blaNDM-6 by pEC4-NDM-6 and the rmtC 16S rRNA methylase gene by IncFIIY plasmids. Characterization of these plasmids further demonstrates that even very closely related plasmids may have acquired blaNDM genes by different mechanisms. These findings also illustrate the complex relationships between antimicrobial resistance genes, transposable elements, and plasmids and provide insights into the possible routes for transmission of blaNDM genes among species of the Enterobacteriaceae family

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Exclusivity, Externalities & Easements: Dynamic Spectrum Access and Coasean Bargaining

Abstract — This paper explores the possibility of realising Coasean bargains to remove the presence of externalities in a libertarian system of exclusive spectrum rights through the creation of various economically motivated easements. We advocate that dynamic spectrum access (DSA) techniques can be used to enable rights holders reduce or eliminate the effects of externalities through local bargaining. Many of the objections to the promotion of marketbased exclusive-rights assignment systems concern the ability of rights holders to enforce their spectrum rights, so as to extract maximal value. In an increasingly fragmented and less-regulated spectrum landscape, there will be an inevitable chafing of rights at the boundaries between the users of neighbouring blocks of spectrum; the spectral activities of one network may impinge on the ability of a neighbouring network to extract maximum value from its exclusively assigned spectrum. Nonetheless, it is argued that it is possible to reduce, or eliminate, the existence of such externalities through the adjustment and exchange of rights through valueextraction-focussed bargaining. In essence, this represents a shift from a mindset of unilaterally enforcing rights to one of mutual remediation of any encroachment. Such an approach may offer a non-Pigouvian remedy to both the under-utilisation and over-utilisation of packages of exclusive rights to spectrum, allowing neighbours to find a tolerable level (a balance) of interference. This paper posits that DSA techniques will have a key role to play in the development of new DSA-based Coasean bargains which will be necessary to address a variety of coexistence issues that will arise between systems operating in neighbouring blocks of exclusively assigned spectrum. I

Spatial Stationarity of Link Statistics in Mobile Ad Hoc Network Modelling

The performance evaluation of ad hoc network components through simulation allows for isolation of parameters, easy access to global quantities and a statistically significant number of repeatable trials. In designing network protocols, it is important to investigate the relationship between global network performance and the underlying locally observed network characteristics. Mobility models are used to define the movement of nodes in the simulation space. A wide variety of mobility models exist, and the choice of mobility model has significant influence over locally observed metrics. Unfortunately, many mobility models exhibit spatial and temporal non-stationarity of important metrics, such that global averages of certain metrics are not representative of local observations. This finding impacts on the development of adaptive ad hoc architectures. This paper explores the spatial stationarity of frequently used mobility models. It focuses on the importance of stationarity in relation to the evaluation of performance studies. The spatial non-stationarity of link statistics, and the impact of this artefact on network performance evaluation is examined for the Toroidal Random Waypoint and Random Direction mobility models. We show that the Toroidal Random Waypoint model exhibits spatial stationarity of link statistics. Furthermore, we demonstrate that network performance studies in spatially stationary environments produce dissimilar results to those produced by non-stationary environments. This shows the importance of spatial stationarity when investigating global network performance and locally observed network characteristics.

Radiofrequency Ablation Is Associated With Decreased Neoplastic Progression in Patients With Barrett\u27s Esophagus and Confirmed Low-Grade Dysplasia.

BACKGROUND & AIMS: Barrett\u27s esophagus (BE) with low-grade dysplasia (LGD) can progress to high-grade dysplasia (HGD) and esophageal adenocarcinoma (EAC). Radiofrequency ablation (RFA) has been shown to be an effective treatment for LGD in clinical trials, but its effectiveness in clinical practice is unclear. We compared the rate of progression of LGD after RFA with endoscopic surveillance alone in routine clinical practice. METHODS: We performed a retrospective study of patients who either underwent RFA (n = 45) or surveillance endoscopy (n = 125) for LGD, confirmed by at least 1 expert pathologist, from October 1992 through December 2013 at 3 medical centers in the United States. Cox regression analysis was used to assess the association between progression and RFA. RESULTS: Data were collected over median follow-up periods of 889 days (interquartile range, 264-1623 days) after RFA and 848 days (interquartile range, 322-2355 days) after surveillance endoscopy (P = .32). The annual rates of progression to HGD or EAC were 6.6% in the surveillance group and 0.77% in the RFA group. The risk of progression to HGD or EAC was significantly lower among patients who underwent RFA than those who underwent surveillance (adjusted hazard ratio = 0.06; 95% confidence interval: 0.008-0.48). CONCLUSIONS: Among patients with BE and confirmed LGD, rates of progression to a combined end point of HGD and EAC were lower among those treated with RFA than among untreated patients. Although selection bias cannot be excluded, these findings provide additional evidence for the use of endoscopic ablation therapy for LGD

Transfer of scarlet fever-associated elements into the group A Streptococcus M1T1 clone

The group A Streptococcus (GAS) M1T1 clone emerged in the 1980s as a leading cause of epidemic invasive infections worldwide, including necrotizing fasciitis and toxic shock syndrome. Horizontal transfer of mobile genetic elements has played a central role in the evolution of the M1T1 clone, with bacteriophage-encoded determinants DNase Sda1 and superantigen SpeA2 contributing to enhanced virulence and colonization respectively. Outbreaks of scarlet fever in Hong Kong and China in 2011, caused primarily by emm12 GAS, led to our investigation of the next most common cause of scarlet fever, emm1 GAS. Genomic analysis of 18 emm1 isolates from Hong Kong and 16 emm1 isolates from mainland China revealed the presence of mobile genetic elements associated with the expansion of emm12 scarlet fever clones in the M1T1 genomic background. These mobile genetic elements confer expression of superantigens SSA and SpeC, and resistance to tetracycline, erythromycin and clindamycin. Horizontal transfer of mobile DNA conferring multi-drug resistance and expression of a new superantigen repertoire in the M1T1 clone should trigger heightened public health awareness for the global dissemination of these genetic elements