Risk Factors for Clostridioides Difficile Diarrhea In Solid Organ Transplantation Recipients.

BACKGROUND: There is limited knowledge about risk factors for Clostridioides difficile infection (CDI) and recurrent CDI in solid organ transplant (SOT) recipients. METHODS: A case-control study of CDI in SOT recipients compared with controls (SOT recipients who did not present CDI). RESULTS: Sixty-seven patients from 1089 SOT recipients (6.2%) suffered at least one episode of CDI. The mean age was 55 ± 12 years and 20 cases (69%) were men. The accumulated incidence was 8% in liver transplantation, 6.2% in lung transplantation, 5.4% in heart transplantation, and 4.7% in kidney transplantation. Twenty-nine cases (43.3%) were diagnosed during the first 3 months after SOT. Forty-one cases (61.2%) were hospital acquired. Thirty-one patients with CDI presented with mild-moderate infection (46.3%), 30 patients with severe infection (44.8%), and 6 patients with severe-complicated disease (9%). Independent variables found to be related with CDI were hospitalization in the previous 3 months (odds ratio: 2.99; [95% confidence interval 1.21-7.37]) and the use of quinolones in the previous month (odds ratio: 3.71 [95% confidence interval 1.16-11.8]). Eleven patients (16.4%) had at least one recurrence of CDI. Previous treatment with amoxicillin-clavulanate, severe-complicated index episode, and high serum creatinine were associated with recurrent CDI in the univariant analysis CONCLUSIONS: Liver transplant recipients presented the highest incidence of CDI among SOT recipients. Risk factors for CDI were hospitalization in the previous 3 months and the use of quinolones in the previous month.

A re-interpretation of the structure of the silver borate, Ag16B4O10, in the light of the extended Zintl-Klemm concept.

The borate Ag16B4O10 was synthesized at high temperature and at elevated oxygen pressures [Kovalevskiy et al. (2020). Chem. Sci. 11, 962-969]. Its structure consists of [B4O10]8- polyanions (isostructural to P4O10) embedded in an Ag matrix. According to the standard valences Ag+, B3+ and O2-, the formula has an excess of eight e- which the above authors proposed were located, pairwise, in four Ag4 tetrahedra within the silver substructure. That conclusion was based on the semiconducting and diamagnetic properties, as well as the very small `attractors' of the Electron Localization Function (ELF) found at the centre of these Ag4 tetrahedra. However, a large overlap of the projected density of states (DOS) of silver and oxygen indicated possible dispersion interactions between both atomic species. In this article, an alternative description is proposed based on the extended Zintl-Klemm concept. The anion [B4O10]8- can be formulated as Ψ-[N4O10] P4O10, if it is assumed that the eight e- are transferred to the four B atoms, so converting them into Ψ-N, this then makes sense of its similarity with P4O10, [N4(CH2)6], adamantane and tetraisopropyladamantane. When the Ag atoms connect to the O atoms, they arrange as the H atoms do in hexamethylenetetramine (HMTA). If the two lone pairs of each of the bridging O atoms in Ψ-[N4O10] are equated to the C-H bonds in HMTA, then, this same equivalence exists between the C-H bonds and the O-Ag bonds in the compound Ag16B4O10. The 24 Ag atoms surrounding each [B4O10]8- group prolong the sphalerite structure of the borate anion by means of Ag-O bonds which also fit the sphalerite structure formed of AgO. The eight excess electrons might then be distributed between the Ag and the O atoms, so making sense of the mixing of the Ag and O states. The Ag atoms bonded to the O atoms of the [B4O10]8- groups form a coat that interconnects the borate anions through Ag-O bonds. To establish the validity of this new proposal, the study needs to be extended to the compound Ag3B5O9.

Rationalization of the crystal structure of eudidymite Na2Be2[Si[4]6O15]·H2O in light of the extended Zintl-Klemm concept.

The structure of eudidymite is described in light of the extended Zintl-Klemm concept which considers that Na and Be atoms transfer their six valence electrons to the six Si atoms, converting them into Ψ-P which forms a skeleton characteristic of pentels (Group 15 elements) and is similar to that described in the compound (NH4)2Ge[6][Ge[4]6O15] when analysed in the same manner. The Si[4] skeleton is formed of bilayers that are connected through Be2O6 groups which are in fact fragments of the ß-BeO structure which bridge the two contiguous Si-bilayers by sharing O atoms. In this context, the Be atoms play a dual role, i.e. on the one hand converting the Si atoms into Ψ-P, on the other hand replicating fragments of its own ß-BeO structure. The Be atoms partially reproduce their own structure despite it being enclosed in a more complex network such as in Na2Be2[Si[4]6O15]·H2O. Calculations of the ionic strength I considering Si as Ψ-P is energetically more favourable than when I is calculated on the basis of tetravalent Si in the silicate, justifying this new approach of developing the theory of pseudo-structure generation. This approach offers a major new development in the study of crystal structures.

Epidemiología y clínica de las infecciones y colonizaciones causadas por enterobacterias productoras de carbapenemasas en un hospital de tercer nivel / Epidemiology and clinical of infections and colonizations caused by Enterobacterales producing carbapenemases in a tertiary hospital

OBJETIVOS: Describir la epidemiologia de las Enterobacterias portadoras de carbapenemasas (EPC) en un hospital de tercer nivel. MATERIAL Y MÉTODOS: Estudio observacional retrospectivo, se incluyeron todos los pacientes con muestra positiva para EPC atendidos en hospitalización o en el servicio de Urgencias, entre el 1 Enero de 2014 y el 31 de Diciembre de 2016. RESULTADOS: Se incluyeron 272 pacientes (316 muestras): 155 (57%) varones. Media de edad de 70,4 años (IC 95% 68,2-72,7). Media del índice de Charlson 3,6 (IC95% 3,4-3,8). En el 63,2% la adquisición fue nosocomial, en el 35,3% fue asociada a cuidados sanitarios (ACS). Presentaron infección el 55,1%, siendo la más frecuente la infección del tracto urinario (ITU) (58,7%). Las especies más frecuentes fueron Klebsiella pneumoniae (62,7%) y Enterobacter cloacae (10,1%). Los tipos de carbapenemasa más frecuente fueron OXA-48 (53,8%) y VIM (43%). La adquisición nosocomial se asoció con el género masculino, trasplante, inmunosupresión, ingreso en Unidad de Cuidados Intensivos (UCI) o Servicio Quirúrgico, tratamiento antibiótico previo, Enterobacter, VIM, infecciones respiratorias e intraabdominales. La adquisición ACS se asoció con mayor edad y comorbilidad, procedencia de residencia, sondaje vesical, mayor número de procedimientos ambulatorios, ingreso hospitalario previo, K. pneumoniae y E. coli, OXA-48, coproducción de betalactamasas de espectro extendido, ITU y sepsis. CONCLUSIONES: Los pacientes que adquieren la EPC en residencias presentan frecuentemente infección. Los pacientes con adquisición nosocomial se colonizan por EPC en la UCI, en relación a procedimientos invasivos y trasplante. Esta población presenta mayor mortalidad por desarrollar infecciones respiratorias por EPC

OBJECTIVE: To describe the epidemiology of Enterobacterales producing carbapenemases (EPC) in a tertiary hospital. MATERIAL AND METHODS: A retrospective observational study, all patients with a positive sample for EPC treated in hospitalization or in the Emergency Department were included, between January 1, 2014 and December 31, 2016. RESULTS: A total of 272 patients (316 samples) were included: 155 (57%) male. Mean age of 70.4 years (95% CI 68.2 -72.7). Mean Charlson index was 3.6 (95% CI 3.4-3.8). In 63.2% the acquisition was nosocomial, in 35.3% it was health-care associated (HA). 55.1% presented infection, the most frequent infection was urinary tract infection (UTI) (58.7%). The most frequent species were Klebsiella pneumoniae (62.7%) and Enterobacter cloacae (10.1%). The most frequent types of carbapenemase were OXA-48 (53.8%) and VIM (43%). The nosocomial acquisition was associated with the male gender, transplantation, immunosuppression, admission to the Intensive Care Unit (ICU) or surgical service, prior antibiotic treatment, Enterobacter, VIM, respiratory and intra-abdominal infections. The HA acquisition was associated with age and comorbidity, nursery home origin, bladder catheterization, greater number of outpatient procedures, previous hospital admission, K. pneumoniae and E. coli, OXA-48, coproduction of extended spectrum betalactamases, UTI and sepsis. CONCLUSIONS: Patients who acquire EPC in nursery homes frequently have an infection. Patients with nosocomial acquisition are colonized by EPC in the ICU, in relation to invasive procedures and transplantation. This population has a higher mortality due to developing respiratory infections by EPC

Generalized Stress-Redox Equivalence: A Chemical Link between Pressure and Electronegativity in Inorganic Crystals.

The crystal structure of many inorganic compounds can be understood as a metallic matrix playing the role of a host lattice in which the nonmetallic atomic constituents are located, the Anions in Metallic Matrices (AMM) model stated. The power and utility of this model lie in its capacity to anticipate the actual positions of the guest atoms in inorganic crystals using only the information known from the metal lattice structure. As a pertinent test-bed for the AMM model, we choose a set of common metallic phases along with other nonconventional or more complex structures (face-centered cubic (fcc) and simple cubic Ca, CsCl-type BaSn, hP4-K, and fcc-Na) and perform density functional theory electronic structure calculations. Our topological analysis of the chemical pressure (CP) scalar field, easily derived from these standard first-principles electronic computations, reveals that CP minima appear just at the precise positions of the nonmetallic elements in typical inorganic crystals presenting the above metallic subarrays: CaF2, rock-salt and CsCl-type phases of CaX (X = O, S, Se, Te), BaSnO3, K2S, and NaX (X = F, Cl, Br, I). A theoretical basis for this correlation is provided by exploring the equivalence between hydrostatic pressure and the oxidation (or reduction) effect induced by the nonmetallic element on the metal structure. Indeed, our CP analysis leads us to propose a generalized stress-redox equivalence that is able to account for the two main observed phenomena in solid inorganic compounds upon crystal formation: (i) the expansion or contraction experienced by the metal structure after hosting the nonmetallic element while its topology is maintained and (ii) the increasing or decreasing of the effective charge associated with the anions in inorganic compounds with respect to the charge already present in the interstices of the metal network. We demonstrate that a rational explanation of this rich behavior is provided by means of Pearson-Parr's electronegativity equalization principle.

Propuesta de una nueva calificación para determinar el riesgo de infección de dispositivos cardiacos implantables / Proposal for a novel score to determine the risk of cardiac implantable electronic device infection

Introducción y objetivos: El uso de dispositivos cardiacos implantables (DCI) se ha expandido en los últimos años. La infección relacionada con estos dispositivos es una de las principales complicaciones y se asocia con grandes morbilidad, mortalidad y costes. El objetivo del estudio es construir una puntuación predictiva del riesgo de infección del DCI. Métodos: Se diseñó un estudio retrospectivo de casos y controles anidado. Tanto los casos como los controles pertenecían a una cohorte que incluía a todos los pacientes sometidos a un procedimiento relacionado con un DCI entre enero de 2009 y diciembre de 2015. Los casos se definieron como pacientes con infección, y se seleccionó aleatoriamente a 3 controles de la cohorte por cada caso incluido. Resultados: Durante el periodo de estudio, se realizaron 2.323 procedimientos. Se identificaron en total 33 infecciones relacionadas con el DCI. Se seleccionó como controles a 99 pacientes. Se identificaron como factores de riesgo independientes el índice de Charlson (OR=1,33; IC95%, 1,07-1,67), la anticoagulación oral (OR=3,51; IC95%, 1,44-8,54), la revisión o el reemplazo de un dispositivo anterior (OR=2,75; IC95%, 1,12-6,71) y la presencia de más de 2 cables (OR=3,42; IC95%, 1,25-9,37). Se generó una escala de riesgo predictivo y se denominó CIED-AI (índice de Charlson, más de 2 cables/electrodos, revisión/reemplazo del dispositivo, anticoagulación oral, infección previa). Esta puntuación presentó un área bajo la curva receiver operating characteristic de 0,79 (IC95%, 0,71-0,88). Conclusiones: La puntuación CIED-AI puede ayudar a identificar a los pacientes con mayor riesgo de infección que serían candidatos a medidas de prevención intensivas

Introduction and objectives: The use of cardiac implantable electronic devices (CIEDs) has expanded in recent years. Infection related to these devices constitutes one of the main complications and is associated with high morbidity, mortality, and financial cost. The aim of this study was to construct a predictive risk score of acquiring CIED infection. Methods: We designed a retrospective, nested case-control study. Both cases and controls belonged to a cohort that included all patients who underwent a CIED-related procedure between January 2009 and December 2015. Cases were defined as patients with infection, and 3 infection-free controls were randomly selected from the cohort for each case included. Results: During the study period, 2323 procedures were performed. A total of 33 CIED-related infections were identified. Ninety-nine patients were selected as controls. Independent risk factors were the Charlson index (OR, 1.33; 95%CI, 1.07-1.67), oral anticoagulation (OR, 3.51; 95%CI, 1.44-8.54), revision or replacement of a previous device (OR, 2.75; 95%CI, 1.12-6.71) and the presence of more than 2 leads (OR, 3.42; 95%CI, 1.25-9.37). A predictive risk score was generated and denominated CIED-AI (Charlson Index, more than 2 leads/Electrodes, Device revision/replacement, oral Anticoagulation, previous Infection). This score had an area under the receiver operating characteristic curve of 0.79 (95%CI, 0.71-0.88). Conclusions: The CIED-AI score may help to identify patients at higher risk of infection, who could be candidates for intensive preventive measures

Proposal for a Novel Score to Determine the Risk of Cardiac Implantable Electronic Device Infection.

INTRODUCTION AND OBJECTIVES: The use of cardiac implantable electronic devices (CIEDs) has expanded in recent years. Infection related to these devices constitutes one of the main complications and is associated with high morbidity, mortality, and financial cost. The aim of this study was to construct a predictive risk score of acquiring CIED infection. METHODS: We designed a retrospective, nested case-control study. Both cases and controls belonged to a cohort that included all patients who underwent a CIED-related procedure between January 2009 and December 2015. Cases were defined as patients with infection, and 3 infection-free controls were randomly selected from the cohort for each case included. RESULTS: During the study period, 2323 procedures were performed. A total of 33 CIED-related infections were identified. Ninety-nine patients were selected as controls. Independent risk factors were the Charlson index (OR, 1.33; 95%CI, 1.07-1.67), oral anticoagulation (OR, 3.51; 95%CI, 1.44-8.54), revision or replacement of a previous device (OR, 2.75; 95%CI, 1.12-6.71) and the presence of more than 2 leads (OR, 3.42; 95%CI, 1.25-9.37). A predictive risk score was generated and denominated CIED-AI (Charlson Index, more than 2 leads/Electrodes, Device revision/replacement, oral Anticoagulation, previous Infection). This score had an area under the receiver operating characteristic curve of 0.79 (95%CI, 0.71-0.88). CONCLUSIONS: The CIED-AI score may help to identify patients at higher risk of infection, who could be candidates for intensive preventive measures.

Unique thermodynamic relationships for ΔfHo and ΔfGo for crystalline inorganic salts. I. Predicting the possible existence and synthesis of Na2SO2 and Na2SeO2. Addendum.

Addendum to Vegas et al. [(2012), Acta Cryst. B68, 511-527].

Characteristics of Clostridium difficile infection in patients with discordant diagnostic test results

Background: Clinical features of Clostridium difficile infection (CDI) cases diagnosed by detection of polymerase chain reaction (PCR), with negative toxin enzyme immunoassay results (EIA) have not been fully elucidated. The purpose of this study was to determine the magnitude of CDI patients who had negative EIA toxin determinations but positive PCR tests, and their differences in clinical presentation. Methods: We performed a retrospective study comparing the clinical features of CDI cases detected by EIA (toxins A + B) with cases detected by PCR (toxin negative, PCR positive) over a 16-month period. Only patients with an initial Clostridium difficile infection episode that fulfilled a standardized definition were included. Results: During the study period, 107 episodes of CDI were detected. Seventy-four patients (69%) had positive glutamate dehydrogenase (GDH) antigen and EIA determinations (EIA positive patients). Thirty-three patients (31%) had GDH positive, negative toxin EIA and positive PCR determination (PCR positive patients). PCR positive patients were younger, 57 (27) years (mean [SD]), than EIA positive patients, 71 (16) years, (p < 0.001). Fewer PCR positive patients were receiving proton pump inhibitors (21 patients, 64%) than EIA positive patients (61 patients, 82%, p = 0.034). The clinical presentation was similar in both groups. In the multivariate analysis, lower age was identified as the only independent variable associated with PCR positive patients. Conclusions: One third of Clostridium difficile infection patients present negative toxin EIA and PCR positive tests. Performing PCR determination after the negative EIA test is more relevant in younger patients (AU)

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Characteristics of Clostridium difficile infection in patients with discordant diagnostic test results.

BACKGROUND: Clinical features of Clostridium difficile infection (CDI) cases diagnosed by detection of polymerase chain reaction (PCR), with negative toxin enzyme immunoassay results (EIA) have not been fully elucidated. The purpose of this study was to determine the magnitude of CDI patients who had negative EIA toxin determinations but positive PCR tests, and their differences in clinical presentation. METHODS: We performed a retrospective study comparing the clinical features of CDI cases detected by EIA (toxins A + B) with cases detected by PCR (toxin negative, PCR positive) over a 16-month period. Only patients with an initial Clostridium difficile infection episode that fulfilled a standardized definition were included. RESULTS: During the study period, 107 episodes of CDI were detected. Seventy-four patients (69%) had positive glutamate dehydrogenase (GDH) antigen and EIA determinations (EIA positive patients). Thirty-three patients (31%) had GDH positive, negative toxin EIA and positive PCR determination (PCR positive patients). PCR positive patients were younger, 57 (27) years (mean [SD]), than EIA positive patients, 71 (16) years, (p < 0.001). Fewer PCR positive patients were receiving proton pump inhibitors (21 patients, 64%) than EIA positive patients (61 patients, 82%, p = 0.034). The clinical presentation was similar in both groups. In the multivariate analysis, lower age was identified as the only independent variable associated with PCR positive patients. CONCLUSIONS: One third of Clostridium difficile infection patients present negative toxin EIA and PCR positive tests. Performing PCR determination after the negative EIA test is more relevant in younger patients.

In-situ laser synthesis of Nd-Al-O coatings: the role of sublattice cations in eutectic formation.

Neodymium aluminate coatings have been prepared in-situ by the laser zone melting (LZM) method, using a CO2 SLAB-type laser emitting at 10.6 µm. Polycrystalline Al2O3 commercial plates have been used as substrates, and coatings were prepared from the corresponding mixtures of powdered neodymium and aluminium oxides as starting materials. Microstructure, studied by SEM and phase composition, studied by XRD, proved the in-situ formation of a NdAlO3/NdAl11O18 eutectic. As a result, a well integrated composite coating was formed. Nanoindentation tests are consistent with excellent integration between coating and substrate. Structural similarities between the eutectic components within the coating, as well as between these and the substrate, are consistent with the crystallographic concepts proposed by Vegas (Ramos-Gallardo & Vegas, 1997), where cation sub-arrays play an important role governing metal oxide structures. These structure sublattices are suggested as the driving force behind eutectic oxide formation.

Risk factors for Clostridium difficile diarrhea in patients with inflammatory bowel disease.

BACKGROUND: Despite the growing incidence of Clostridium difficile diarrhea (CCD) in patients with inflammatory bowel disease (IBD), little is known about the associated risk factors. METHOD: A retrospective study comparing cases of CCD in patients with IBD to IBD carriers who did not develop CCD. A comparison was also made with patients who developed CCD but did not suffer IBD. RESULTS: Three cases (20%) with IBD and CCD had received antibiotics during the previous three months versus none of the controls (IBD without CCD, p = 0.22). Ten cases (67%) received treatment with proton pump inhibitors (PPIs) versus 2 (13%) in the control group (IBD without CCD, p = 0.001). Seven cases underwent colonoscopy and pseudomembranes were seen in one (14%). Fourteen (93%) patients demonstrated a favourable response to metronidazole. Patients with IBD and CCD presented with younger age (36 ± 10 years), a higher degree of community-acquired infection (13 patients, 87%), immunosuppressive treatment (7 patients, 47%) and less patients had received previous antibiotic treatment (3 patients, 20%) than those with CCD without IBD. The proportion of patients who received treatment with PPIs was similar (66% and 80%, respectively p = 0.266). CONCLUSIONS: CCD in IBD carriers affects younger patients, the majority are community acquired (less nosocomial) and it is more related to previous treatment with PPIs than with the antibiotic treatment. Clinical evolution is also favourable.

Factores de riesgo de diarrea por Clostridium difficile en pacientes con enfermedad inflamatoria intestinal / Risk factors for Clostridium difficile diarrhea in patients with inflammatory bowel disease

INTRODUCCIÓN: a pesar de la incidencia creciente de diarrea por Clostridium difficile (DCD) en pacientes con enfermedad inflamatoria intestinal (EII) disponemos de un conocimiento limitado de factores de riesgo. MÉTODO: estudio retrospectivo comparando casos de DCD en pacientes con EEI con pacientes portadores de EEI que no desarrollaron DCD. También se realizó una comparación con pacientes que desarrollaron DCD, pero que no padecían EII. RESULTADOS: tres casos (20 %) con EII y DCD habían recibido antibióticos durante los tres meses previos frente a ninguno de los controles (EEI sin DCD, p = 0,22). Diez casos (67 %) estaban recibiendo tratamiento con un inhibidor de la bomba de protones (IBP) frente a dos (13 %) entre los controles (EEI sin DCD, p = 0,001). Se visualizaron pseudomembranas en uno (14 %) de los siete casos en los que se hizo colonoscopia. Hubo respuesta favorable a metronidazol en 14 pacientes (93 %). Los pacientes con EEI y DCD presentaron menor edad (36 ± 10 años), mayor grado de adquisición comunitaria de la infección (13 pacientes, 87 %) y tratamiento inmunosupresor (7 pacientes, 47 %) junto a menos pacientes con tratamiento antibiótico previo (3 pacientes, 20 %) que los pacientes con DCD pero sin EII. La proporción de pacientes que recibían tratamiento con un IBP era similar (66 % y 80 %, respectivamente; p = 0,266). CONCLUSIONES: los casos de DCD en portadores de EEI se caracterizan por afectar a pacientes más jóvenes, mayoritaria adquisición comunitaria (y menor nosocomial), guardar más relación con el tratamiento previo con IBP que con el tratamiento antibiótico y presentar evolución clínica favorable

BACKGROUND: Despite the growing incidence of Clostridium difficile diarrhea (CCD) in patients with inflammatory bowel disease (IBD), little is known about the associated risk factors. METHOD: A retrospective study comparing cases of CCD in patients with IBD to IBD carriers who did not develop CCD. A comparison was also made with patients who developed CCD but did not suffer IBD. RESULTS: Three cases (20 %) with IBD and CCD had received antibiotics during the previous three months versus none of the controls (IBD without CCD, p = 0.22). Ten cases (67 %) received treatment with proton pump inhibitors (PPIs) versus 2 (13 %) in the control group (IBD without CCD, p = 0.001). Seven cases underwent colonoscopy and pseudomembranes were seen in ne (14 %). Fourteen (93 %) patients demonstrated a favourable response to metronidazole. Patients with IBD and CCD presented with younger age (36 ± 10 years), a higher degree of communityacquired infection (13 patients, 87 %), immunosuppressive treatment (7 patients, 47 %) and less patients had received previous antibiotic treatment (3 patients, 20 %) than those with CCD without IBD. The proportion of patients who received treatment with PPIs was similar (66 % and 80 %, respectively p = 0.266). CONCLUSIONS: CCD in IBD carriers affects younger patients, the majority are community acquired (less nosocomial) and it is more related to previous treatment with PPIs than with the antibiotic treatment. Clinical evolution is also favourable

An alternative approach to rationalizing the structures of the cyclotrisilicates: Rb10[Si6O17], Cs8[Si6O16] and Na3Y[Si6O15] by viewing them in light of the extended Zintl-Klemm concept.

The structures of the three dimeric cyclotrisilicate anions [Si6O17](10-), [Si6O16](8-) and [Si6O15](6-) forming part of the compounds Rb10[Si6O17] or Rb14[Si4][Si6O17], Cs8[Si6O16] and Na3Y[Si6O15], respectively, have been described as different ways of condensing the more elemental cyclotrisilicate anions [Si3O9](6-) [Hlukhyy & Fässler (2013). Z. Anorg. Allg. Chem. 639, 231-233]. Such a description prevents a rational explanation of the connectivity between the Si atoms. So, in this article the Si skeletons of the above silicate anions are put on a common basis in light of the extended Zintl-Klemm concept. Their connectivity is directly related to the ratio Ψ-S/Ψ-P resulting from the number of electrons transferred from the electropositive Na, Y, Rb and Cs atoms, offering a new example of the fact that there exists a univocal link between chemical composition (in terms of pseudo-atoms) and structure: the generalized Zintl-Klemm concept. The three skeletons fit the connectivity of hypothetical Zintl polyanions of composition [Ψ-S4P2](10-), [Ψ-S2P4](8-) and [Ψ-P6](6-) respectively.

El estudio de prevalencia de las infecciones nosocomiales en España Epine-EPPS 2012 / No disponible

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Isoelectronic and isolobal O, CH2, CH3+ and BH3 as electron pairs; similarities between molecular and solid-state chemistry.

A topological analysis of the electron localization function (ELF) of a molecule of hexamethyldisiloxane, (H3C)3-Si-O-Si-(CH3)3, has been carried out, drawing a consistent picture of Si-O-Si bonding both in the linear and angular geometries. The ELF analysis confirms the idea that the O atom, in the linear geometry of (H3C)3-Si-O-Si-(CH3)3, is isolobal with the isoelectronic -CH3(+)- and -BH3- groups, the bonding in the Si-O-Si group being described as a two-electron, three-center (2e, 3c) bond. At the same time, the three oxygen lone pairs mirror the three C-H and B-H bonds, respectively. On the contrary, in the angular geometry the same O atoms form two Si-O bonds and its lone pairs mimic the geometry of the -CH2- group. In this model the O atoms would play the same role as the formally present O(2-) anions in the `so-called' ionic solids, such as in the skeletons of aluminate and silicate polyanions, thereby connecting molecular and solid-state chemistry as formulated by the `fragment formalism' or the `molecular unit-cell approach'. This unifying concept as well as the calculations we have carried out fully agree and also give support to earlier ideas developed by Bragg and Bent, among other authors. Bonding in the series of compounds P4, P4O6, P4O10, N4(CH2)6 (hexamethylenetetramine) and (CH)4(CH2)6 (adamantane) is discussed in the context of the isolobal model.

Unique thermodynamic relationships for ΔfHo and ΔfGo for crystalline inorganic salts. I. Predicting the possible existence and synthesis of Na2SO2 and Na2SeO2.

The concept that equates oxidation and pressure has been successfully utilized in explaining the structural changes observed in the M(2)S subnets of M(2)SO(x) (x = 3, 4) compounds (M = Na, K) when compared with the structures (room- and high-pressure phases) of their parent M(2)S `alloy' [Martínez-Cruz et al. (1994), J. Solid State Chem. 110, 397-398; Vegas (2000), Crystallogr. Rev. 7, 189-286; Vegas et al. (2002), Solid State Sci. 4, 1077-1081]. These structural changes suggest that if M(2)SO(2) would exist, its cation array might well have an anti-CaF(2) structure. On the other hand, in an analysis of the existing thermodynamic data for M(2)S, M(2)SO(3) and M(2)SO(4) we have identified, and report, a series of unique linear relationships between the known Δ(f)H(o) and Δ(f)G(o) values of the alkali metal (M) sulfide (x = 0) and their oxyanion salts M(2)SO(x) (x = 3 and 4), and the similarly between M(2)S(2) disulfide (x = 0) and disulfur oxyanion salts M(2)S(2)O(x) (x = 3, 4, 5, 6 and 7) and the number of O atoms in their anions x. These linear relationships appear to be unique to sulfur compounds and their inherent simplicity permits us to interpolate thermochemical data (Δ(f)H(o)) for as yet unprepared compounds, M(2)SO (x = 1) and M(2)SO(2) (x = 2). The excellent linearity indicates the reliability of the interpolated data. Making use of the volume-based thermodynamics, VBT [Jenkins et al. (1999), Inorg. Chem. 38, 3609-3620], the values of the absolute entropies were estimated and from them, the standard Δ(f)S(o) values, and then the Δ(f)G(o) values of the salts. A tentative proposal is made for the synthesis of Na(2)SO(2) which involves bubbling SO(2) through a solution of sodium in liquid ammonia. For this attractive thermodynamic route, we estimate ΔG(o) to be approximately -500 kJ mol(-1). However, examination of the stability of Na(2)SO(2) raises doubts and Na(2)SeO(2) emerges as a more attractive target material. Its synthesis is likely to be easier and it is stable to disproportionation into Na(2)S and Na(2)SeO(4). Like Na(2)SO(2), this compound is predicted to have an anti-CaF(2) Na(2)Se subnet.

On the charge transfer between conventional cations: the structures of ternary oxides and chalcogenides of alkali metals.

The structures of ternary oxides and chalcogenides of alkali metals are dissected in light of the extended Zintl-Klemm concept. This model, which has been successfully extended to other compounds different to the Zintl phases, assumes that crystal structures can be better understood if the cation substructures are contemplated as Zintl polyanions. This implies the occurrence of charge transfer between cations, even if they are of the same kind. In this article, the charge transfer between cations is even more illustrative because the two alkali atoms have different electronegativity, so that the less electropositive alkali metal and the O/S atom always form skeletons characteristic of the group 14 elements. Thus, partial structures of the zincblende-, wurtzite-, PbO- and SrAl(2)-type are found in the oxides/sulfides. In this work, such an interpretation of the structures remains at a topological level. The analysis also shows that this interpretation is complementary to the model developed by Andersson and Hyde which contemplates the structures as the intergrowth of structural slabs of more simple compounds.

Enteritis por Clostridium difficile / Clostridium difficile enteritis

La afectación del intestino delgado por Clostridium difficile constituye una entidad clínica infrecuente.MétodoSe presenta el primer caso de enteritis por C. difficile diagnosticado en España y se realiza una revisión de la literatura médica.ResultadosVarón de 30 años de edad intervenido por recidiva de un tumor germinal retroperitoneal. Siete días después presentó vómitos, diarrea y, finalmente, obstrucción intestinal por seudomembranas originadas por enteritis por C. difficile. En la literatura médica han sido descritos otros 57 casos de enteritis por C. difficile. La edad media era de 52±17 años con un rango desde 18 a 86 años. Veintinueve pacientes (50%) presentaban enfermedad inflamatoria intestinal. Cuarenta y siete (81%) tenían antecedentes de cirugía de colon o intestino delgado. La mortalidad fue más acusada en pacientes de mayor edad y en los que no presentaban enfermedad inflamatoria intestinal.ConclusiónLa enteritis por C. difficile se caracteriza por su elevada gravedad y morta(AU)

A 30-year-old man underwent surgery for recurrence of a retroperitoneal germ cell tumor. Seven days later the patient developed vomiting, diarrhea and, finally, intestinal obstruction due to pseudomembranes caused by CDE. Only 57 cases of CDE have been reported in the literature. The mean age was 52±17 years with a range of 18 to 86 years. Twenty-nine patients (50%) had inflammatory bowel disease. Forty-seven (81%) had a history of colon or small intestine surgery. Mortality was higher in older patients and in those without inflammatory bowel disease (AU)