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BackgroundIndwelling pleural catheters (IPCs) offer symptom relief from pleural effusions. Usage is complicated by infection in ~5% of cases.1 IPCs can be colonised when bacteria grow from pleural fluid without infective features.2 The causes of colonisation are undescribed and its relationship with infection unexplored.AimsDescribe the incidence and microbiology of IPC colonisation.Identify clinical features associated with IPC colonisation.Compare asymptomatically colonising bacteria with those from infection.MethodsAll infected and non-infected IPCs were collected from four sites, along with associated metadata. Infected IPCs were identified clinically and non-infected IPCs categorised as ‘colonised’ if bacteria was cultured from them, and ‘clean’ if not. The genomes of all cultured organisms were sequenced, assembled and taxonomically classified. For Staphylococcus aureus isolates, a maximum likelihood phylogenetic tree was constructed from Snippy-core alignment using IQ-Tree, with S. aureus NCTC8325 as reference.ResultsOf 108 IPCs, 54 were ‘clean’, 34 colonised and 20 infected. Infected and colonised IPCs had longer mean insertion durations (197.6 and 181.3 days) compared with ‘clean’ ones (98 days).Of 34 colonised IPCs, 17 were colonised by multiple species. The most common causes were Coagulase-negative Staphylococci (CoNS n=18), Enterobacteriaceae (n=18), Corynebacteria spp (n=4) & S. aureus (n=4).Two of 20 infected IPCs were culture negative. We retrieved the same organism causing infection from 14/18 IPCs. The most common pathogens were S. aureus (n=8), Pseudomonas aeruginosa (n=3), Enterococcus spp (n=2) and Enterobacter cloacae (n=2). Figure 1 demonstrates clustering of S. aureus isolates from deep and superficial infection.Abstract S149 Figure 1Phylogenetic tree of Staphylococcus aureus isolates from colonised and infected IPCs. S. aureus NCTC8325 is the reference strain[Image Omitted. See PDF.]ConclusionA significant proportion of IPCs are colonised. Colonisation and infection are associated with longer insertion duration. Enterobacteriaceae and CoNS are the most common causes of colonisation, whereas S. aureus and Pseudomonas aeruginosa commonly cause infection. S. aureus isolates causing deep infection show higher genetic similarity versus colonising strains. This, and our phylogenetic analysis, suggests colonisation does not cause infection, but rather there is a virulent subset of isolates causing infection. Ongoing work will identify genes and markers associated with infection.ReferencesSundaralingam, et al. Chest 2022;161(5):1407–1425.Sethi, et al. Clinical & Translational Science 2023:1287–1288.

When faced with a shortage of oxygen, many bacterial species use nitrate to support respiration via the process of denitrification. This takes place extensively in nitrogen-rich soils and generates the gaseous products nitric oxide (NO), nitrous oxide (N sub(2)O) and dinitrogen (N sub(2)). The denitrifying bacteria protect themselves from the endogenous cytotoxic NO produced by converting it to N sub(2)O, which can be released into the atmosphere. However, N sub(2)O is a potent greenhouse gas and hence the activity of the enzyme that breaks down N sub(2)O has a crucial role in restricting its atmospheric levels. Here, we review the current understanding of the process by which N sub(2)O is produced and destroyed and discuss the potential for feeding this into new approaches for combating N sub(2)O release.

When faced with a shortage of oxygen, many bacterial species use nitrate to support respiration via the process of denitrification. This takes place extensively in nitrogen-rich soils and generates the gaseous products nitric oxide (NO), nitrous oxide (N@d2O) and dinitrogen (N@d2). The denitrifying bacteria protect themselves from the endogenous cytotoxic NO produced by converting it to N@d2O, which can be released into the atmosphere. However, N@d2O is a potent greenhouse gas and hence the activity of the enzyme that breaks down N@d2O has a crucial role in restricting its atmospheric levels. Here, we review the current understanding of the process by which N@d2O is produced and destroyed and discuss the potential for feeding this into new approaches for combating N@d2O release.

This paper introduces new insights into the hydrochemical functioning of lowland river systems using field-based spectrophotometric and electrode technologies. The streamwater concentrations of nitrogen species and phosphorus fractions were measured at hourly intervals on a continuous basis at two contrasting sites on tributaries of the River Thames – one draining a rural catchment, the River Enborne, and one draining a more urban system, The Cut. The measurements complement those from an existing network of multi-parameter water quality sondes maintained across the Thames catchment and weekly monitoring based on grab samples. The results of the sub-daily monitoring show that streamwater phosphorus concentrations display highly complex dynamics under storm conditions dependent on the antecedent catchment wetness, and that diurnal phosphorus and nitrogen cycles occur under low flow conditions. The diurnal patterns highlight the dominance of sewage inputs in controlling the streamwater phosphorus and nitrogen concentrations at low flows, even at a distance of 7 km from the nearest sewage treatment works in the rural River Enborne. The time of sample collection is important when judging water quality against ecological thresholds or standards. An exhaustion of the supply of phosphorus from diffuse and multiple septic tank sources during storm events was evident and load estimation was not improved by sub-daily monitoring beyond that achieved by daily sampling because of the eventual reduction in the phosphorus mass entering the stream during events. The results highlight the utility of sub-daily water quality measurements and the discussion considers the practicalities and challenges of in situ, sub-daily monitoring.

Correct identification of P sources in rural watersheds is critical for the development of cost-effective measures to combat agriculturally-driven eutrophication. The chemical composition of various storm runoff types (field surface runoff, field drain outfalls, roads, farmyards, and septic tanks) and the receiving streams in three micro (<10 km2) watersheds of varying agricultural intensity were monitored over a 2-yr period. Mean weekly stream soluble reactive phosphorus (SRP) and total phosphorus (TP) concentrations increased from 29 and 69 μg L-1, respectively in the watershed with the lowest intensity agriculture to 382 and 503 μg L-1, respectively in the watershed with high intensity agriculture and a village sewage treatment works. Concentrations of TP in storm runoff varied by up to two orders of magnitude reflecting the complex origins, routing, and composition of contributing source areas. Application of the DESPRAL test suggested field runoff TP concentrations were influenced by both P and organic matter in soil. However, runoff from impervious surfaces (farmyard and roads), and/or influenced by septic tank discharges, was significantly more concentrated (0.08-16 mg TP L-1, mean >>1 mg L-1) than surface and subsurface runoff from cultivated land and pasture (0.02-3.6 mg TP L-1, mean <1 mg L-1), and/or contained a significantly greater proportion (>50% vs. <50%) of P in dissolved forms. It is concluded that P sources associated with the functioning of rural communities (impervious surfaces, detergents, and wastewater) may be more ecologically relevant than those associated with agriculture and should be better quantified and controlled to avoid localized eutrophication impacts.

Background Marine sediments represent one of the planet’s largest carbon stores. Bottom trawl fisheries constitute the most widespread physical disturbance to seabed habitats, which exert a large influence over the oceanic carbon dioxide (CO 2 ) sink. Recent research has sparked concern that seabed disturbance from trawling can therefore turn marine sediments into a large source of CO 2 , but the calculations involved carry a high degree of uncertainty. This is primarily due to a lack of quantitative understanding of how trawling mixes and resuspends sediments, how it alters bioturbation, bioirrigation, and oxygenation rates, and how these processes translate into carbon fluxes into or out of sediments. Methods The primary question addressed by this review protocol is: how does mobile bottom fishing affect benthic carbon processing and storage? This question will be split into the following secondary questions: what is the effect of mobile bottom fishing on: (i) the amount and type of carbon found in benthic sediments; (ii) the magnitude and direction of benthic-pelagic carbon fluxes; (iii) the biogeochemical, biological, and physical parameters that control the fate of benthic carbon; and (iv) the biogeochemical, biological, and physical parameters that control the fate of resuspended carbon. Literature searches will be conducted in Web of Science, SCOPUS, PROQUEST, and a range of grey and specialist sources. An initial scoping search in Web of Science informed the final search string, which has been formulated according to Population Intervention Comparator Outcome (PICO) principles. Eligible studies must contain data concerning a change in a population of interest caused by mobile bottom fishing. Eligible study designs are Before and After, Control and Impact, and Gradient studies. Studies included at full-text screening will be critically appraised, and study findings will be extracted.Extracted data will be stored in an Excel spreadsheet. Results will be reported in narrative and quantitative syntheses using a variety of visual tools including forest plots. Meta-analysis will be conducted where sufficient data exists.

To-day a Naval Court enquiry, consisting of Captain E. E. Maxwell (H.M.S. Cockchafer), President, Mr. Geo. Brown, H.B.M.'s Vice-Consul, Captain Felgate, s.s. Lord of the Isles, and Captain Linton J. Hughes, s.s. Sooclww, sat in H.B.M.'s Lower Court to enquire out the circumstances attending the loss of the s.s.