Patient characteristics, clinical course and factors associated to ICU mortality in critically ill patients infected with SARS-CoV-2 in Spain: A prospective, cohort, multicentre study

Antecedentes

No se ha reportado plenamente la evolución clínica de los pacientes críticos de COVID-19 durante su ingreso en la unidad de cuidados intensivos (UCI), incluyendo las complicaciones médicas e infecciosas y terapias de soporte, así como su asociación con la mortalidad en UCI.

Objetivo

El objetivo de este estudio es describir las características clínicas y la evolución de los pacientes ingresados en UCI por COVID-19 y determinar los factores de riesgo de la mortalidad en UCI de dichos pacientes.

Métodos

Estudio prospectivo, multicéntrico y de cohorte, que incluyó a los pacientes críticos de COVID-19 ingresados en 30 UCI de España y Andorra. Se incluyó a los pacientes consecutivos del 12 de marzo al 26 de mayo del 2020 si habían fallecido o habían recibido el alta de la UCI durante el periodo de estudio. Se reportaron los datos demográficos, los síntomas, los signos vitales, los marcadores de laboratorio, las terapias de soporte, terapias farmacológicas y las complicaciones médicas e infecciosas, realizándose una comparación entre los pacientes fallecidos y los pacientes dados de alta.

Resultados

Se incluyó a un total de 663 pacientes. La mortalidad general en UCI fue del 31% (203 pacientes). Al ingreso en UCI los no supervivientes eran más hipoxémicos (SpO₂ con mascarilla de no reinhalación, de 90 [RIC 83-93] vs. 91 [RIC 87-94]; p < 0,001] y con mayor puntuación en la escala SOFA-Evaluación de daño orgánico secuencial (SOFA, 7 [RIC 5-9] vs. 4 [RIC 3-7]; p <0,001]). Las complicaciones fueron más frecuentes en los no supervivientes: síndrome de distrés respiratorio agudo (SDRA) (95% vs. 89%; p = 0,009), insuficiencia renal aguda (IRA) (58% vs. 24%; p < 10^–6), shock (42% vs. 14%; p < 10^–13) y arritmias (24% vs. 11%; p < 10^–4). Las superinfecciones respiratorias, infecciones del torrente sanguíneo y los shock sépticos fueron más frecuentes en los no supervivientes (33% vs. 25%; p = 0,03, 33% vs. 23%; p = 0,01 y 15% vs. 3%, p = 10^–7, respectivamente). El modelo de regresión multivariable reflejó que la edad estaba asociada a la mortalidad y que cada año incrementaba el riesgo de muerte en un 1% (IC del 95%: 1-10, p = 0,014). Cada incremento de 5 puntos en la escala APACHE II predijo de manera independiente la mortalidad (odds ratio [OR]: 1,508 [1,081, 2,104], p = 0,015). Los pacientes con IRA (OR: 2,468 [1,628, 3,741], p < 10^–4)], paro cardiaco (OR: 11,099 [3,389, 36,353], p = 0,0001] y shock séptico [OR: 3,224 [1,486, 6,994], p= 0,002) tuvieron un riesgo de muerte incrementado.

Conclusiones

Los pacientes mayores de COVID-19 con puntuaciones APACHE II más altas al ingreso, que desarrollaron IRA en grados ii o iii o shock séptico durante la estancia en UCI tuvieron un riesgo de muerte incrementado. La mortalidad en UCI fue del 31%.

Development of animal experimental model for bacterial peritonitis

Objetivo

Desarrollar un modelo de sepsis abdominal en animal de experimentación.

Material y métodos

Se utilizan ratas Sprague-Dawley®, machos de 5 semanas con pesos entre 270-280 g en el momento de la inoculación (N=39). Inicialmente se realiza un estudio piloto (N=9), distribuyéndolas en 3 grupos (3/3/3) con inóculo de 1cc de Escherichia coli ATCC 25922 intraperitoneal en concentraciones de 10⁸, 10⁹ y 10¹⁰ UFC. En un segundo estudio (N=6) con distribución en dos grupos (3/3) se utilizan 1cc una concentración de E. coli 10¹⁰ UFC que se diluyen en 10 y 15 ml de agua destilada para su inoculación. Por último se inicia un ensayo experimental con aleatorización de 24 ratas en tres grupos de tratamiento tras la infección intraperitoneal: Grupo I con suero fisiológico (N=6), Grupo II con antibiótico (ceftriaxona) (N=9), Grupo III con antibiótico más adyuvante (ceftriaxona más alicina) (N=9). Se realizan muestras microbiológicas de sangre y líquido peritoneal, así como estudio histopatológico de órganos intraperitoneales (hígado, diafragma y peritoneo).

Resultados

Se observa muerte en el 100% de las ratas infectadas con la concentración de E. coli 10¹⁰ UFC con la dilución de 15 ml de agua destilada y sin antibiótico. El hemocultivo y cultivo de líquido peritoneal es positivo a la misma cepa en todas ellas. Se observa la formación de abscesos en la superficie del hígado e infiltración por polimorfonucleares en los tejidos.

Conclusión

Se establece que la dosis letal de E. coli es 10¹⁰ UFC diluida en 15 ml agua destilada en inyección intraperitoneal.

Flavodoxin overexpression confers tolerance to oxidative stress in beneficial soil bacteria and improves survival in the presence of the herbicides paraquat and atrazine

AIM

To determine whether expression of a cyanobacterial flavodoxin in soil bacteria of agronomic interest confers protection against the widely used herbicides paraquat and atrazine.

METHODS AND RESULTS

The model bacterium Escherichia coli, the symbiotic nitrogen-fixing bacterium Ensifer meliloti and the plant growth-promoting rhizobacterium Pseudomonas fluorescens Aur6 were transformed with expression vectors containing the flavodoxin gene of Anabaena variabilis. Expression of the cyanobacterial protein was confirmed by Western blot. Bacterial tolerance to oxidative stress was tested in solid medium supplemented with hydrogen peroxide, paraquat or atrazine. In all three bacterial strains, flavodoxin expression enhanced tolerance to the oxidative stress provoked by hydrogen peroxide and by the reactive oxygen species-inducing herbicides, witnessed by the enhanced survival of the transformed bacteria in the presence of these oxidizing agents.

CONCLUSIONS

Flavodoxin overexpression in beneficial soil bacteria confers tolerance to oxidative stress and improves their survival in the presence of the herbicides paraquat and atrazine. Flavodoxin could be considered as a general antioxidant resource to face oxidative challenges in different micro-organisms.

SIGNIFICANCE AND IMPACT OF THE STUDY

The use of plant growth-promoting rhizobacteria or nitrogen-fixing bacteria with enhanced tolerance to oxidative stress in contaminated soils is of significant agronomic interest. The enhanced tolerance of flavodoxin-expressing bacteria to atrazine and paraquat points to potential applications in herbicide-treated soils.

Complications related to less-invasive haemodynamic monitoring

BACKGROUND

The aim of this study was to evaluate the type and incidence of complications during insertion, maintenance, and withdrawal of central arterial catheters used for transpulmonary thermodilution haemodynamic monitoring (PiCCO™).

METHODS

We conducted a prospective, observational, multicentre study in 14 European intensive care units (six countries). A total of 514 consecutive patients in whom haemodynamic monitoring by PiCCO™ was indicated were studied.

RESULTS

Five hundred and fourteen PiCCO catheters (475 in femoral, 26 in radial, nine in axillary, and four in brachial arteries) were inserted. Arterial access was obtained on the first attempt in 86.4% of the patients. Minor problems such as oozing after insertion (3.3%) or removal of the catheter (3.5%) were observed, but no episodes of serious bleeding (more than 50 ml) were recorded. Small local haematomas were observed after insertion (4.5%) and after removal (1.2%) of the catheter. These complications were not more frequent in patients with coagulation abnormalities. The incidence of site inflammation and catheter-related infection was 2% and 0.78%, respectively. Other complications such as ischaemia (0.4%), pulse loss (0.4%), or femoral artery thrombosis (0.2%) were rare, transient, and all resolved with catheter removal or embolectomy, respectively.

CONCLUSIONS

In this series of patients, central arterial catheters used for PiCCO™ monitoring were demonstrated to be a safe alternative for advanced haemodynamic monitoring.

[Acute myocardial infarction complicating radiofrequency catheter ablation in a girl]

Paroxysmal supraventricular tachycardia is the most common tachyarrhythmia in childhood and adolescence. The current treatment of choice for managing and preventing frequent recurrences is radiofrequency catheter ablation, which provides a definitive solution in most cases. This technique is very effective but not devoid of potential complications, particularly in children and adolescents. We report the case of a 3-year-old girl who suffered acute myocardial infarction after occlusion of the right coronary artery during this procedure. We describe intraoperative and postoperative management. Progress was good and the patient was discharged 14 days after ablation.

Transgenic Medicago truncatula plants that accumulate proline display nitrogen-fixing activity with enhanced tolerance to osmotic stress

Legume root nodule nitrogen-fixing activity is severely affected by osmotic stress. Proline accumulation has been shown to induce tolerance to salt stress, and transgenic plants over-expressing Delta(1)-pyrroline-5-carboxylate synthetase (P5CS), which accumulates high levels of proline, display enhanced osmotolerance. Here, we transformed the model legume Medicago truncatula with the P5CS gene from Vigna aconitifolia, and nodule activity was evaluated under osmotic stress in transgenic plants that showed high proline accumulation levels. Nitrogen fixation was significantly less affected by salt treatment compared to wild-type (WT) plants. To our knowledge, this is the first time that transgenic legumes have been produced that display nitrogen-fixing activity with enhanced tolerance to osmotic stress. We studied the expression of M. truncatula proline-related endogenous genes M. truncatulaDelta(1)-pyrroline-5-carboxylate synthetase 1 (MtP5CS1), M. truncatulaDelta(1)-pyrroline-5-carboxylate synthetase 2 (MtP5CS2), M. truncatula ornithine delta-aminotransferase (MtOAT), M. truncatula proline dehydrogenase (MtProDH) and a proline transporter gene in both WT and transgenic plants. Our results indicate that proline metabolism is finely regulated in response to osmotic stress in an organ-specific manner. The transgenic model allowed us to analyse some of the biochemical and molecular mechanisms that are activated in the nodule in response to high salt conditions, and to ascertain the essential role of proline in the maintenance of nitrogen-fixing activity under osmotic stress.

Biotransformation of tryptamine and secologanin into plant terpenoid indole alkaloids by transgenic yeast

A transgenic Saccharomyces cerevisiae was constructed containing the cDNAs coding for strictosidine synthase (STR) and strictosidine beta-glucosidase (SGD) from the medicinal plant Catharanthus roseus. Both enzymes are involved in the biosynthesis of terpenoid indole alkaloids. The yeast culture was found to express high levels of both enzymes. STR activity was found both inside the cells (13.2 nkatal/g fresh weight) and in the medium (up to 25 nkatal/l medium), whereas SGD activity was present only inside the yeast cells (2.5 mkatal/g fresh weight). Upon feeding of tryptamine and secologanin, this transgenic yeast culture produced high levels of strictosidine in the medium; levels up to 2 g/l were measured. Inside the yeast cells strictosidine was also detected, although in much lower amounts (0.2 mg/g cells). This was due to the low permeability of the cells towards the substrates, secologanin and tryptamine. However, the strictosidine present in the medium was completely hydrolyzed to cathenamine, after permeabilizing the yeast cells. Furthermore, transgenic S. cerevisiae was able to grow on an extract of Symphoricarpus albus berries serving as a source for secologanin and carbohydrates. Under these conditions, the addition of tryptamine was sufficient for the transgenic yeast culture to produce indole alkaloids. Our results show that transgenic yeast cultures are an interesting alternative for the production of plant alkaloids.