Tradeoffs in Model Performance and Effort for Long-Term Phosphorus Leaching Based on In Situ Field Data

Phosphorus and N are critical nutrients for agriculture but are also responsible for surface water enrichment that leads to toxic algal growth. Although P loading to surface waters has traditionally been thought to occur primarily in surface runoff, contributions from subsurface transport can also be significant. The primary objectives of this research were to evaluate several methods of representing macropore flow and transport in a finite element model using plot-scale infiltration and leaching data and to compare several models of various levels of complexity to simulate long-term P leaching. To determine flow and transport parameters, single- and dual-porosity models in HYDRUS-2D were calibrated with infiltration, Cl−, and P data from a 22-h plot-scale leaching experiment on a silt loam mantle with gravel subsoil. Both homogeneous and heterogeneous gravel profiles were simulated. The dual-porosity model with heterogeneous hydraulic conductivity best matched experimental data, with physical nonequilibrium (dual porosity) being more important than two-dimensional (2D) heterogeneity. Long-term (9 yr) P leaching to the water table (3 m below the soil surface) at the field site was simulated with both one-dimensional (1D) and 2D models using the calibrated parameters. There was little difference between analogous 1D and 2D models, suggesting that HYDRUS-1D may be sufficient to model long-term P leaching. Overall, the most important elements for accurately simulating P leaching in this silt loam and gravel soil profile were found to be (i) field-measured hydraulic conductivity of the limiting soil layer, (ii) calibrated dispersivity, and (iii) dual-porosity, in some circumstances

Single- and Dual-Porosity Calibration and Long-Term Modeling of Highly Conductive Floodplain Soils in the Ozark Ecoregion

Phosphorus (P) is a critical nutrient for agriculture, but is also responsible for surface water enrichment that leads to algal growth. While P loading to surface waters has traditionally been thought to occur from surface runoff, contributions from subsurface transport can also be significant. Subsurface transport through gravelly soils in the Ozark ecoregion can have a significant, yet poorly-documented effect on P movement to groundwater. Long-term P modeling was performed in HYDRUS-1D and 2D using data collected from short-term plot experiments featuring gravelly soils. Seven model levels were developed to illustrate a wide variety of laboratory and field conditions. Calibration was performed in HYDRUS-2D using single- and dual-porosity models with both homogeneous and heterogeneous gravel profiles as well as a mesh macropore profile. The dual-porosity model with heterogeneous hydraulic conductivity best matched experimental data, although the dual-porosity model with homogenous soil layers also performed well. Long-term P transport to a 3 m-deep water table was simulated in HYDRUS-1D and 2D using nine years of both daily and modified 5 minute rainfall data with a P flux consistent with annual poultry litter applications. HYDRUS-1D models produced a wide range of long-term results, while HYDRUS-2D models produced a much narrower range of results. There was little difference between analogous 1D and 2D models, suggesting that HYDRUS-1D may be sufficient to model long-term transport. The lack of distinction between the single- and dual-porosity long-term models could be explained by the large P concentration gradient between the poultry litter leachate and the soil water. Advisor: Derek M. Heere

Finite element modeling of phosphorus leaching through floodplain soils dominated by preferential flow pathways

Phosphorus is a critical nutrient in soils, providing both positive and negative effects to different systems. While optimum crop growth requires a range of P above 0.2 mg/L, preventing surface water enrichment generally requires P to be below 0.03 mg/L. Proper application and control of phosphorus is important to increase farming efficiency and to protect freshwater systems from toxic algal growth. While the movement of phosphorus through many soil types has been well-documented, the presence of highly conductive, gravel outcrops and macropores in soil can have a significant, poorly-documented effect on phosphorus movement. In the Ozark ecoregion, for example, the erosion of carbonate bedrock (primarily limestone) by slightly acidic water has left a large residuum of chert gravel in Ozark soils, with floodplains generally consisting of coarse chert gravel overlain by a mantle (1 to 300 cm) of gravelly loam or silt loam. Highly conductive gravel outcrops and macropores may create preferential flow pathways for water moving through the soil column, along with any solutes in solution. In previous research, floodplain sites in Oklahoma and Arkansas were chosen due to the presence of cherty gravel outcrops that reached near the soil surface. Soil properties were evaluated, and two-dimensional electrical resistivity data were collected and correlated to hydraulic conductivity. Water was then applied to several plots (1, 10, and 100 m2) with known concentrations of phosphorus, Rhodamine WT, and chloride for up to 52 hours, and flow towards a nearby stream was monitored with observation wells. The objective of this research was to use finite element modeling to develop a long-term model for this phenomenon for future predictions. Results from the previous research were modeled with HYDRUS-3D, a three-dimensional, finite-element model for flow and contaminant transport (both equilibrium and physical/chemical nonequilibrium transport) through soils. HYDRUS-3D was setup to simulate the 1 m2 infiltration plot at the Barren Fork Creek site, with initial hydraulic conductivity data calculated from the 2013 ASABE Annual International Meeting Paper Page 1 plot scale infiltration experiment for the upper silt loam soil and from 2D geophysical data for the underlying gravel. The mobile-immobile (MIM) phase model within HYDRUS was also utilized, and MIM solute transport parameters were found iteratively using chloride tracer data taken from two wells. Results from this research will be used to predict phosphorus transport parameters and solve for long-term phosphorus transport through these soil profiles

Tradeoffs in Model Performance and Effort for Long-Term Phosphorus Leaching Based on In Situ Field Data

Phosphorus and N are critical nutrients for agriculture but are also responsible for surface water enrichment that leads to toxic algal growth. Although P loading to surface waters has traditionally been thought to occur primarily in surface runoff, contributions from subsurface transport can also be significant. The primary objectives of this research were to evaluate several methods of representing macropore flow and transport in a finite element model using plot-scale infiltration and leaching data and to compare several models of various levels of complexity to simulate long-term P leaching. To determine flow and transport parameters, single- and dual-porosity models in HYDRUS-2D were calibrated with infiltration, Cl−, and P data from a 22-h plot-scale leaching experiment on a silt loam mantle with gravel subsoil. Both homogeneous and heterogeneous gravel profiles were simulated. The dual-porosity model with heterogeneous hydraulic conductivity best matched experimental data, with physical nonequilibrium (dual porosity) being more important than two-dimensional (2D) heterogeneity. Long-term (9 yr) P leaching to the water table (3 m below the soil surface) at the field site was simulated with both one-dimensional (1D) and 2D models using the calibrated parameters. There was little difference between analogous 1D and 2D models, suggesting that HYDRUS-1D may be sufficient to model long-term P leaching. Overall, the most important elements for accurately simulating P leaching in this silt loam and gravel soil profile were found to be (i) field-measured hydraulic conductivity of the limiting soil layer, (ii) calibrated dispersivity, and (iii) dual-porosity, in some circumstances

Finite element modeling of long-term phosphorus leaching through macropores in the Ozark ecoregion

Phosphorus (P) is a critical nutrient for plant growth in agriculture, but is also responsible for surface water enrichment that leads to toxic algal growth. While P loading to surface waters has traditionally been thought to occur from surface runoff, contributions from subsurface transport can also be significant. While P transport through many soil types is well-documented, the presence of highly conductive gravel outcrops and macropore networks can have a significant, yet poorly-documented effect on P movement to the aquifer. Floodplain soils in the Ozark ecoregion generally contain coarse chert gravel layers that exhibit macropore behavior. Previous research has evaluated short-term P transport in plot trials ranging from 1 m2 to 100 m2 across many Ozark ecoregion floodplain sites. Traditional methods of estimating P loading and soil saturation do not account for macropore flow and likely underestimate P transport to the water table. To address this concern, long-term P modeling was performed in HYDRUS-2D/3D using data collected from short-term plot experiments. Calibration was performed using single- and dual-porosity models with both homogeneous and heterogeneous gravel profiles. The dual-porosity model with heterogeneous hydraulic conductivity best matched experimental data, although the dual-porosity model with homogenous soil layers also performed well. Long-term P transport to a 3 m-deep water table was simulated using 9 years of both daily and 5 minute rainfall data with a P flux consistent with yearly poultry litter applications. Long-term simulations with 5 minute rainfall data found that 113 kg ha-1 reached the water table over 9 years, or 21% of P applied

Validated risk score for predicting 6-month mortality in infective endocarditis

Background-Host factors and complications have been associated with higher mortality in infective endocarditis (IE). We sought to develop and validate a model of clinical characteristics to predict 6-month mortality in IE. Methods and Results-Using a large multinational prospective registry of definite IE (International Collaboration on Endocarditis [ICE]-Prospective Cohort Study [PCS], 2000-2006, n=4049), a model to predict 6-month survival was developed by Cox proportional hazards modeling with inverse probability weighting for surgery treatment and was internally validated by the bootstrapping method. This model was externally validated in an independent prospective registry (ICE-PLUS, 2008-2012, n=1197). The 6-month mortality was 971 of 4049 (24.0%) in the ICE-PCS cohort and 342 of 1197 (28.6%) in the ICE-PLUS cohort. Surgery during the index hospitalization was performed in 48.1% and 54.0% of the cohorts, respectively. In the derivation model, variables related to host factors (age, dialysis), IE characteristics (prosthetic or nosocomial IE, causative organism, left-sided valve vegetation), and IE complications (severe heart failure, stroke, paravalvular complication, and persistent bacteremia) were independently associated with 6-month mortality, and surgery was associated with a lower risk of mortality (Harrell's C statistic 0.715). In the validation model, these variables had similar hazard ratios (Harrell's C statistic 0.682), with a similar, independent benefit of surgery (hazard ratio 0.74, 95% CI 0.62-0.89). A simplified risk model was developed by weight adjustment of these variables. Conclusions-Six-month mortality after IE is 25% and is predicted by host factors, IE characteristics, and IE complications. Surgery during the index hospitalization is associated with lower mortality but is performed less frequently in the highest risk patients. A simplified risk model may be used to identify specific risk subgroups in IE

Impact of early valve surgery on outcome of Staphylococcus aureus prosthetic valve infective endocarditis: analysis in the international collaboration of Endocarditis-Prospective Cohort Study

Background. The impact of early valve surgery (EVS) on the outcome of Staphylococcus aureus (SA) prosthetic valve infective endocarditis (PVIE) is unresolved. The objective of this study was to evaluate the association between EVS, performed within the first 60 days of hospitalization, and outcome of SA PVIE within the International Collaboration on Endocarditis–Prospective Cohort Study. Methods. Participants were enrolled between June 2000 and December 2006. Cox proportional hazards modeling that included surgery as a time-dependent covariate and propensity adjustment for likelihood to receive cardiac surgery was used to evaluate the impact of EVS and 1-year all-cause mortality on patients with definite left-sided S. aureus PVIE and no history of injection drug use. Results. EVS was performed in 74 of the 168 (44.3%) patients. One-year mortality was significantly higher among patients with S. aureus PVIE than in patients with non–S. aureus PVIE (48.2% vs 32.9%; P = .003). Staphylococcus aureus PVIE patients who underwent EVS had a significantly lower 1-year mortality rate (33.8% vs 59.1%; P = .001). In multivariate, propensity-adjusted models, EVS was not associated with 1-year mortality (risk ratio, 0.67 [95% confidence interval, .39–1.15]; P = .15). Conclusions. In this prospective, multinational cohort of patients with S. aureus PVIE, EVS was not associated with reduced 1-year mortality. The decision to pursue EVS should be individualized for each patient, based upon infection-specific characteristics rather than solely upon the microbiology of the infection causing PVIE

Infective Endocarditis in Patients on Chronic Hemodialysis

295sinoneBackground: Infective endocarditis (IE) is a common and serious complication in patients receiving chronic hemodialysis (HD). Objectives: This study sought to investigate whether there are significant differences in complications, cardiac surgery, relapses, and mortality between IE cases in HD and non-HD patients. Methods: Prospective cohort study (International Collaboration on Endocarditis databases, encompassing 7,715 IE episodes from 2000 to 2006 and from 2008 to 2012). Descriptive analysis of baseline characteristics, epidemiological and etiological features, complications and outcomes, and their comparison between HD and non-HD patients was performed. Risk factors for major embolic events, cardiac surgery, relapses, and in-hospital and 6-month mortality were investigated in HD-patients using multivariable logistic regression. Results: A total of 6,691 patients were included and 553 (8.3%) received HD. North America had a higher HD-IE proportion than the other regions. The predominant microorganism was Staphylococcus aureus (47.8%), followed by enterococci (15.4%). Both in-hospital and 6-month mortality were significantly higher in HD versus non–HD-IE patients (30.4% vs. 17% and 39.8% vs. 20.7%, respectively; p < 0.001). Cardiac surgery was less frequently performed among HD patients (30.6% vs. 46.2%; p < 0.001), whereas relapses were higher (9.4% vs. 2.7%; p < 0.001). Risk factors for 6-month mortality included Charlson score (hazard ratio [HR]: 1.26; 95% confidence interval [CI]: 1.11 to 1.44; p = 0.001), CNS emboli and other emboli (HR: 3.11; 95% CI: 1.84 to 5.27; p < 0.001; and HR: 1.73; 95% CI: 1.02 to 2.93; p = 0.04, respectively), persistent bacteremia (HR: 1.79; 95% CI: 1.11 to 2.88; p = 0.02), and acute onset heart failure (HR: 2.37; 95% CI: 1.49 to 3.78; p < 0.001). Conclusions: HD-IE is a health care–associated infection chiefly caused by S. aureus, with increasing rates of enterococcal IE. Mortality and relapses are very high and significantly larger than in non–HD-IE patients, whereas cardiac surgery is less frequently performed.nonePericas J.M.; Llopis J.; Jimenez-Exposito M.J.; Kourany W.M.; Almirante B.; Carosi G.; Durante-Mangoni E.; Fortes C.Q.; Giannitsioti E.; Lerakis S.; Montagna-Mella R.; Ambrosioni J.; Tan R.-S.; Mestres C.A.; Wray D.; Pachirat O.; Moreno A.; Chu V.H.; de Lazzari E.; Fowler V.G.; Miro J.M.; Clara L.; Sanchez M.; Casabe J.; Cortes C.; Nacinovich F.; Oses P.F.; Ronderos R.; Sucari A.; Thierer J.; Altclas J.; Kogan S.; Spelman D.; Athan E.; Harris O.; Kennedy K.; Tan R.; Gordon D.; Papanicolas L.; Korman T.; Kotsanas D.; Dever R.; Jones P.; Konecny P.; Lawrence R.; Rees D.; Ryan S.; Feneley M.P.; Harkness J.; Post J.; Reinbott P.; Gattringer R.; Wiesbauer F.; Andrade A.R.; Passos de Brito A.C.; Guimaraes A.C.; Grinberg M.; Mansur A.J.; Siciliano R.F.; Varejao Strabelli T.M.; Campos Vieira M.L.; de Medeiros Tranchesi R.A.; Paiva M.G.; de Oliveira Ramos A.; Weksler C.; Ferraiuoli G.; Golebiovski W.; Lamas C.; Karlowsky J.A.; Keynan Y.; Morris A.M.; Rubinstein E.; Jones S.B.; Garcia P.; Cereceda M.; Fica A.; Mella R.M.; Fernandez R.; Franco L.; Gonzalez J.; Jaramillo A.N.; Barsic B.; Bukovski S.; Krajinovic V.; Pangercic A.; Rudez I.; Vincelj J.; Freiberger T.; Pol J.; Zaloudikova B.; Ashour Z.; El Kholy A.; Mishaal M.; Osama D.; Rizk H.; Aissa N.; Alauzet C.; Alla F.; Campagnac C.C.; Doco-Lecompte T.; Selton-Suty C.; Casalta J.-P.; Fournier P.-E.; Habib G.; Raoult D.; Thuny F.; Delahaye F.; Delahaye A.; Vandenesch F.; Donal E.; Donnio P.Y.; Flecher E.; Michelet C.; Revest M.; Tattevin P.; Chevalier F.; Jeu A.; Remadi J.P.; Rusinaru D.; Tribouilloy C.; Bernard Y.; Chirouze C.; Hoen B.; Leroy J.; Plesiat P.; Naber C.; Neuerburg C.; Mazaheri B.; Sophia Athanasia C.N.; Deliolanis I.; Giamarellou H.; Thomas T.; Mylona E.; Paniara O.; Papanicolaou K.; Pyros J.; Skoutelis A.; Papanikolaou K.; Sharma G.; Francis J.; Nair L.; Thomas V.; Venugopal K.; Hannan M.M.; Hurley J.P.; Wanounou M.; Gilon D.; Israel S.; Korem M.; Strahilevitz J.; Iossa D.; Orlando S.; Ursi M.P.; Pafundi P.C.; D'Amico F.; Bernardo M.; Cuccurullo S.; Dialetto G.; Covino F.E.; Manduca S.; Della Corte A.; De Feo M.; Tripodi M.F.; Cecchi E.; De Rosa F.; Forno D.; Imazio M.; Trinchero R.; Grossi P.; Lattanzio M.; Toniolo A.; Goglio A.; Raglio A.; Ravasio V.; Rizzi M.; Suter F.; Magri S.; Signorini L.; Kanafani Z.; Kanj S.S.; Sharif-Yakan A.; Abidin I.; Tamin S.S.; Martinez E.R.; Soto Nieto G.I.; van der Meer J.T.M.; Chambers S.; Holland D.; Morris A.; Raymond N.; Read K.; Murdoch D.R.; Dragulescu S.; Ionac A.; Mornos C.; Butkevich O.M.; Chipigina N.; Kirill O.; Vadim K.; Vinogradova T.; Edathodu J.; Halim M.; Liew Y.-Y.; Lejko-Zupanc T.; Logar M.; Mueller-Premru M.; Commerford P.; Commerford A.; Deetlefs E.; Hansa C.; Ntsekhe M.; Almela M.; Azqueta M.; Brunet M.; Castro P.; Falces C.; Fuster D.; Fita G.; Garcia- de- la- Maria C.; Garcia-Gonzalez J.; Gatell J.M.; Marco F.; Miro J.M.; Ortiz J.; Ninot S.; Pare J.C.; Pericas J.M.; Quintana E.; Ramirez J.; Rovira I.; Sandoval E.; Sitges M.; Tellez A.; Tolosana J.M.; Vidal B.; Vila J.; Anguera I.; Font B.; Guma J.R.; Bermejo J.; Bouza E.; Garcia Fernandez M.A.; Gonzalez-Ramallo V.; Marin M.; Munoz P.; Pedromingo M.; Roda J.; Rodriguez-Creixems M.; Solis J.; Fernandez-Hidalgo N.; Tornos P.; de Alarcon A.; Parra R.; Alestig E.; Johansson M.; Olaison L.; Snygg-Martin U.; Pachirat P.; Pussadhamma B.; Senthong V.; Casey A.; Elliott T.; Lambert P.; Watkin R.; Eyton C.; Klein J.L.; Bradley S.; Kauffman C.; Bedimo R.; Corey G.R.; Crowley A.L.; Douglas P.; Drew L.; Holland T.; Lalani T.; Mudrick D.; Samad Z.; Sexton D.; Stryjewski M.; Wang A.; Woods C.W.; Cantey R.; Steed L.; Dickerman S.A.; Bonilla H.; DiPersio J.; Salstrom S.-J.; Baddley J.; Patel M.; Peterson G.; Stancoven A.; Levine D.; Riddle J.; Rybak M.; Cabell C.H.Pericas, J. M.; Llopis, J.; Jimenez-Exposito, M. J.; Kourany, W. M.; Almirante, B.; Carosi, G.; Durante-Mangoni, E.; Fortes, C. Q.; Giannitsioti, E.; Lerakis, S.; Montagna-Mella, R.; Ambrosioni, J.; Tan, R. -S.; Mestres, C. A.; Wray, D.; Pachirat, O.; Moreno, A.; Chu, V. H.; de Lazzari, E.; Fowler, V. G.; Miro, J. M.; Clara, L.; Sanchez, M.; Casabe, J.; Cortes, C.; Nacinovich, F.; Oses, P. F.; Ronderos, R.; Sucari, A.; Thierer, J.; Altclas, J.; Kogan, S.; Spelman, D.; Athan, E.; Harris, O.; Kennedy, K.; Tan, R.; Gordon, D.; Papanicolas, L.; Korman, T.; Kotsanas, D.; Dever, R.; Jones, P.; Konecny, P.; Lawrence, R.; Rees, D.; Ryan, S.; Feneley, M. P.; Harkness, J.; Post, J.; Reinbott, P.; Gattringer, R.; Wiesbauer, F.; Andrade, A. R.; Passos de Brito, A. C.; Guimaraes, A. C.; Grinberg, M.; Mansur, A. J.; Siciliano, R. F.; Varejao Strabelli, T. M.; Campos Vieira, M. L.; de Medeiros Tranchesi, R. A.; Paiva, M. G.; de Oliveira Ramos, A.; Weksler, C.; Ferraiuoli, G.; Golebiovski, W.; Lamas, C.; Karlowsky, J. A.; Keynan, Y.; Morris, A. M.; Rubinstein, E.; Jones, S. B.; Garcia, P.; Cereceda, M.; Fica, A.; Mella, R. M.; Fernandez, R.; Franco, L.; Gonzalez, J.; Jaramillo, A. N.; Barsic, B.; Bukovski, S.; Krajinovic, V.; Pangercic, A.; Rudez, I.; Vincelj, J.; Freiberger, T.; Pol, J.; Zaloudikova, B.; Ashour, Z.; El Kholy, A.; Mishaal, M.; Osama, D.; Rizk, H.; Aissa, N.; Alauzet, C.; Alla, F.; Campagnac, C. C.; Doco-Lecompte, T.; Selton-Suty, C.; Casalta, J. -P.; Fournier, P. -E.; Habib, G.; Raoult, D.; Thuny, F.; Delahaye, F.; Delahaye, A.; Vandenesch, F.; Donal, E.; Donnio, P. Y.; Flecher, E.; Michelet, C.; Revest, M.; Tattevin, P.; Chevalier, F.; Jeu, A.; Remadi, J. P.; Rusinaru, D.; Tribouilloy, C.; Bernard, Y.; Chirouze, C.; Hoen, B.; Leroy, J.; Plesiat, P.; Naber, C.; Neuerburg, C.; Mazaheri, B.; Sophia Athanasia, C. N.; Deliolanis, I.; Giamarellou, H.; Thomas, T.; Mylona, E.; Paniara, O.; Papanicolaou, K.; Pyros, J.; Skoutelis, A.; Papanikolaou, K.; Sharma, G.; Francis, J.; Nair, L.; Thomas, V.; Venugopal, K.; Hannan, M. M.; Hurley, J. P.; Wanounou, M.; Gilon, D.; Israel, S.; Korem, M.; Strahilevitz, J.; Iossa, D.; Orlando, S.; Ursi, M. P.; Pafundi, P. C.; D'Amico, F.; Bernardo, M.; Cuccurullo, S.; Dialetto, G.; Covino, F. E.; Manduca, S.; Della Corte, A.; De Feo, M.; Tripodi, M. F.; Cecchi, E.; De Rosa, F.; Forno, D.; Imazio, M.; Trinchero, R.; Grossi, P.; Lattanzio, M.; Toniolo, A.; Goglio, A.; Raglio, A.; Ravasio, V.; Rizzi, M.; Suter, F.; Magri, S.; Signorini, L.; Kanafani, Z.; Kanj, S. S.; Sharif-Yakan, A.; Abidin, I.; Tamin, S. S.; Martinez, E. R.; Soto Nieto, G. I.; van der Meer, J. T. M.; Chambers, S.; Holland, D.; Morris, A.; Raymond, N.; Read, K.; Murdoch, D. R.; Dragulescu, S.; Ionac, A.; Mornos, C.; Butkevich, O. M.; Chipigina, N.; Kirill, O.; Vadim, K.; Vinogradova, T.; Edathodu, J.; Halim, M.; Liew, Y. -Y.; Lejko-Zupanc, T.; Logar, M.; Mueller-Premru, M.; Commerford, P.; Commerford, A.; Deetlefs, E.; Hansa, C.; Ntsekhe, M.; Almela, M.; Azqueta, M.; Brunet, M.; Castro, P.; Falces, C.; Fuster, D.; Fita, G.; Garcia- de- la- Maria, C.; Garcia-Gonzalez, J.; Gatell, J. M.; Marco, F.; Miro, J. M.; Ortiz, J.; Ninot, S.; Pare, J. C.; Pericas, J. M.; Quintana, E.; Ramirez, J.; Rovira, I.; Sandoval, E.; Sitges, M.; Tellez, A.; Tolosana, J. M.; Vidal, B.; Vila, J.; Anguera, I.; Font, B.; Guma, J. R.; Bermejo, J.; Bouza, E.; Garcia Fernandez, M. A.; Gonzalez-Ramallo, V.; Marin, M.; Munoz, P.; Pedromingo, M.; Roda, J.; Rodriguez-Creixems, M.; Solis, J.; Fernandez-Hidalgo, N.; Tornos, P.; de Alarcon, A.; Parra, R.; Alestig, E.; Johansson, M.; Olaison, L.; Snygg-Martin, U.; Pachirat, P.; Pussadhamma, B.; Senthong, V.; Casey, A.; Elliott, T.; Lambert, P.; Watkin, R.; Eyton, C.; Klein, J. L.; Bradley, S.; Kauffman, C.; Bedimo, R.; Corey, G. R.; Crowley, A. L.; Douglas, P.; Drew, L.; Holland, T.; Lalani, T.; Mudrick, D.; Samad, Z.; Sexton, D.; Stryjewski, M.; Wang, A.; Woods, C. W.; Cantey, R.; Steed, L.; Dickerman, S. A.; Bonilla, H.; Dipersio, J.; Salstrom, S. -J.; Baddley, J.; Patel, M.; Peterson, G.; Stancoven, A.; Levine, D.; Riddle, J.; Rybak, M.; Cabell, C. H

HACEK infective endocarditis: characteristics and outcomes from a large, multi-national cohort.

The HACEK organisms (Haemophilus species, Aggregatibacter species, Cardiobacterium hominis, Eikenella corrodens, and Kingella species) are rare causes of infective endocarditis (IE). The objective of this study is to describe the clinical characteristics and outcomes of patients with HACEK endocarditis (HE) in a large multi-national cohort. Patients hospitalized with definite or possible infective endocarditis by the International Collaboration on Endocarditis Prospective Cohort Study in 64 hospitals from 28 countries were included and characteristics of HE patients compared with IE due to other pathogens. Of 5591 patients enrolled, 77 (1.4%) had HE. HE was associated with a younger age (47 vs. 61 years; p<0.001), a higher prevalence of immunologic/vascular manifestations (32% vs. 20%; p<0.008) and stroke (25% vs. 17% p = 0.05) but a lower prevalence of congestive heart failure (15% vs. 30%; p = 0.004), death in-hospital (4% vs. 18%; p = 0.001) or after 1 year follow-up (6% vs. 20%; p = 0.01) than IE due to other pathogens (n = 5514). On multivariable analysis, stroke was associated with mitral valve vegetations (OR 3.60; CI 1.34-9.65; p<0.01) and younger age (OR 0.62; CI 0.49-0.90; p<0.01). The overall outcome of HE was excellent with the in-hospital mortality (4%) significantly better than for non-HE (18%; p<0.001). Prosthetic valve endocarditis was more common in HE (35%) than non-HE (24%). The outcome of prosthetic valve and native valve HE was excellent whether treated medically or with surgery. Current treatment is very successful for the management of both native valve prosthetic valve HE but further studies are needed to determine why HE has a predilection for younger people and to cause stroke. The small number of patients and observational design limit inferences on treatment strategies. Self selection of study sites limits epidemiological inferences