RESUMEN
Intestinal trematodes are among the most common types of parasitic worms. About 76 species belonging to 14 families have been recorded infecting humans. Infection commonly occurs when humans eat raw or undercooked foods that contain the infective metacercariae. These parasites are diverse in regard to their morphology, geographical distribution and life cycle, which make it difficult to study the parasitic diseases that they cause. Many of these intestinal trematodes have been considered as endemic parasites in the past. However, the geographical limits and the population at risk are currently expanding and changing in relation to factors such as growing international markets, improved transportation systems, new eating habits in developed countries and demographic changes. These factors make it necessary to better understand intestinal trematode infections. This chapter describes the main features of human intestinal trematodes in relation to their biology, epidemiology, host-parasite relationships, pathogenicity, clinical aspects, diagnosis, treatment and control.
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Parasitosis Intestinales , Trematodos , Infecciones por Trematodos , Animales , Infecciones por Trematodos/epidemiología , Infecciones por Trematodos/parasitología , Humanos , Parasitosis Intestinales/parasitología , Parasitosis Intestinales/epidemiología , Trematodos/patogenicidad , Trematodos/fisiología , Interacciones Huésped-Parásitos , Equinostomiasis/parasitología , Equinostomiasis/epidemiología , Echinostoma/fisiología , Echinostoma/patogenicidadRESUMEN
Digenetic trematodes form a major group of human parasites, affecting a large number of humans, especially in endemic foci. Over 100 species have been reported infecting humans, including blood, lung, liver and intestinal parasites. Traditionally, trematode infections have been diagnosed by parasitological methods based on the detection and the identification of eggs in different clinical samples. However, this is complicated due to the morphological similarity between eggs of different trematode species and other factors such as lack of sensitivity or ectopic locations of the parasites. Moreover, the problem is currently aggravated by migratory flows, international travel, international trade of foods and changes in alimentary habits. Although efforts have been made for the development of immunological and molecular techniques, the detection of eggs through parasitological techniques remains as the gold standard for the diagnosis of trematodiases. In the present chapter, we review the current status of knowledge on diagnostic techniques used when examining feces, urine, and sputum and also analyze the most relevant characteristics used to identify eggs with a quick key for the identification of eggs.
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Heces , Trematodos , Infecciones por Trematodos , Humanos , Infecciones por Trematodos/diagnóstico , Infecciones por Trematodos/parasitología , Animales , Heces/parasitología , Esputo/parasitología , Recuento de Huevos de Parásitos/métodosRESUMEN
Microbial hydrogen (H2) cycling underpins the diversity and functionality of diverse anoxic ecosystems. Among the three evolutionarily distinct hydrogenase superfamilies responsible, [FeFe] hydrogenases were thought to be restricted to bacteria and eukaryotes. Here, we show that anaerobic archaea encode diverse, active, and ancient lineages of [FeFe] hydrogenases through combining analysis of existing and new genomes with extensive biochemical experiments. [FeFe] hydrogenases are encoded by genomes of nine archaeal phyla and expressed by H2-producing Asgard archaeon cultures. We report an ultraminimal hydrogenase in DPANN archaea that binds the catalytic H-cluster and produces H2. Moreover, we identify and characterize remarkable hybrid complexes formed through the fusion of [FeFe] and [NiFe] hydrogenases in ten other archaeal orders. Phylogenetic analysis and structural modeling suggest a deep evolutionary history of hybrid hydrogenases. These findings reveal new metabolic adaptations of archaea, streamlined H2 catalysts for biotechnological development, and a surprisingly intertwined evolutionary history between the two major H2-metabolizing enzymes.
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Archaea , Hidrógeno , Hidrogenasas , Filogenia , Archaea/genética , Archaea/enzimología , Proteínas Arqueales/metabolismo , Proteínas Arqueales/química , Proteínas Arqueales/genética , Genoma Arqueal , Hidrógeno/metabolismo , Hidrogenasas/metabolismo , Hidrogenasas/genética , Hidrogenasas/química , Proteínas Hierro-Azufre/metabolismo , Proteínas Hierro-Azufre/genética , Proteínas Hierro-Azufre/química , Modelos Moleculares , Estructura Terciaria de ProteínaRESUMEN
Intestinal trematodes constitute a major group of helminths that parasitize humans and animals with relevant morbidity and mortality. Despite the importance of the intestinal trematodes in medical and veterinary sciences, immunology and pathology of these helminth infections have been neglected for years. Apart from the work focused on the members of the family Echnistomatidae, there are only very isolated and sporadic studies on the representatives of other families of digeneans, which makes a compilation of all these studies necessary. In the present review, the most salient literature on the immunology and pathology of intestinal trematodes in their definitive hosts in examined. Emphasis will be placed on members of the echinostomatidae family, since it is the group in which the most work has been carried out. However, we also review the information on selected species of the families Brachylaimidae, Diplostomidae, Gymnophallidae, and Heterophyidae. For most of these families, coverage is considered under the following headings: (i) Background; (ii) Pathology of the infection; (iii) Immunology of the infection; and (iv) Human infections.
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Parasitosis Intestinales , Trematodos , Infecciones por Trematodos , Animales , Humanos , Trematodos/fisiología , Trematodos/inmunología , Infecciones por Trematodos/parasitología , Infecciones por Trematodos/inmunología , Infecciones por Trematodos/veterinaria , Parasitosis Intestinales/inmunología , Parasitosis Intestinales/parasitología , Intestinos/parasitología , Intestinos/patología , Intestinos/inmunología , Interacciones Huésped-Parásitos/inmunologíaRESUMEN
BACKGROUND: Despite the fact that prison inmates are a population at higher risk than other groups of suffering from intestinal parasite infections in relation to their living conditions, information about these diseases in prison environments is still scarce. Herein, we analyze the status of intestinal parasite infections in a Spanish prison. METHODS: A cross-sectional study involving 528 inmates was conducted from April to June 2022 among inmates at Centro Penitenciario Picassent (Valencia, Spain). Stool specimens were examined using the direct wet mount technique, the formol-ether concentration technique, and the Ziehl-Neelsen staining method. We used STATA 16.1 for data analysis. We consider a p-value less than 0.05 significant at a 95% confidence level. RESULTS: Of the 528 inmates (471 men and 57 women; a mean age of 41.94 years) enrolled in the study, 83 (15.7%) were infected. Only six species of protozoa were detected. The gut potential microeukaryotic pathobiont Blastocystis sp. was the predominant parasite, accounting for 37 (44.6%) of the infections. Gut parasite amebas (6.6%) and pathobionts (5.3%) were more prevalent than flagellates (2.3%). The prevalence of infection with pathogenic species (8.9%) was similar to that of non-pathogenic species (8.7%). Infection among men (15.2%) was higher than in women (0.6%) (p < 0.0001). In multivariate analysis, the country of birth (AOR = 0.31, 95% CI = 0.18-0.52) and the time spent in prison (AOR = 1.83, 95% CI = 1.06-3.14) were statistically significant associated to intestinal parasite infections (p < 0.0001 and p = 0.028, respectively). CONCLUSION: This study found low levels of intestinal parasite infections in the CPP which could be indicative of the implementation of sanitary measures in prison environments in Spain. The less time spent in prison favor the risk of having infection while the Spanish nationality of inmates could reduce the risk of infection. The main recommendation would be to introduce routine parasitological tests upon foreigners entering prison.
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Parasitosis Intestinales , Prisioneros , Masculino , Humanos , Femenino , Adulto , España/epidemiología , Estudios Transversales , Prisiones , Parasitosis Intestinales/epidemiologíaRESUMEN
Ammonia oxidation, as the first step of nitrification, constitutes a critical process in the global nitrogen cycle. However, fundamental knowledge of its key enzyme, the copper-dependent ammonia monooxygenase, is lacking, in particular for the environmentally abundant ammonia-oxidizing archaea (AOA). Here the structure of the enzyme is investigated by blue-native gel electrophoresis and proteomics from native membrane complexes of two AOA. Besides the known AmoABC subunits and the earlier predicted AmoX, two new protein subunits, AmoY and AmoZ, were identified. They are unique to AOA, highly conserved and co-regulated, and their genes are linked to other AMO subunit genes in streamlined AOA genomes. Modeling and in-gel cross-link approaches support an overall protomer structure similar to the distantly related bacterial particulate methane monooxygenase but also reveals clear differences in extracellular domains of the enzyme. These data open avenues for further structure-function studies of this ecologically important nitrification complex.
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Archaea , Oxidorreductasas , Archaea/clasificación , Archaea/enzimología , Oxidorreductasas/química , Oxidorreductasas/genética , Oxidorreductasas/metabolismo , Nitrificación , Electroforesis en Gel de Poliacrilamida Nativa , Filogenia , Expresión GénicaRESUMEN
Asgard archaea are considered to be the closest known relatives of eukaryotes. Their genomes contain hundreds of eukaryotic signature proteins (ESPs), which inspired hypotheses on the evolution of the eukaryotic cell1-3. A role of ESPs in the formation of an elaborate cytoskeleton and complex cellular structures has been postulated4-6, but never visualized. Here we describe a highly enriched culture of 'Candidatus Lokiarchaeum ossiferum', a member of the Asgard phylum, which thrives anaerobically at 20 °C on organic carbon sources. It divides every 7-14 days, reaches cell densities of up to 5 × 107 cells per ml and has a significantly larger genome compared with the single previously cultivated Asgard strain7. ESPs represent 5% of its protein-coding genes, including four actin homologues. We imaged the enrichment culture using cryo-electron tomography, identifying 'Ca. L. ossiferum' cells on the basis of characteristic expansion segments of their ribosomes. Cells exhibited coccoid cell bodies and a network of branched protrusions with frequent constrictions. The cell envelope consists of a single membrane and complex surface structures. A long-range cytoskeleton extends throughout the cell bodies, protrusions and constrictions. The twisted double-stranded architecture of the filaments is consistent with F-actin. Immunostaining indicates that the filaments comprise Lokiactin-one of the most highly conserved ESPs in Asgard archaea. We propose that a complex actin-based cytoskeleton predated the emergence of the first eukaryotes and was a crucial feature in the evolution of the Asgard phylum by scaffolding elaborate cellular structures.
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Citoesqueleto de Actina , Archaea , Eucariontes , Filogenia , Citoesqueleto de Actina/metabolismo , Actinas/clasificación , Actinas/genética , Actinas/metabolismo , Archaea/clasificación , Archaea/citología , Archaea/genética , Archaea/crecimiento & desarrollo , Eucariontes/clasificación , Eucariontes/citología , Eucariontes/metabolismo , Anaerobiosis , Ribosomas/metabolismo , Estructuras de la Membrana Celular/metabolismo , Proteínas Arqueales/clasificación , Proteínas Arqueales/genética , Proteínas Arqueales/metabolismo , Evolución MolecularRESUMEN
Echinostoma caproni (Trematoda: Echinostomatidae) is an intestinal trematode with no tissue phases in the definitive host that has been extensively used as an experimental model to study the factors that determine resistance against intestinal helminths. In E. caproni infections in mice, interleukin-25 (IL-25) plays a critical role and it is required for the resistance to infection. However, little is known on the factors that determine its production. Primary E. caproni infection in mice is characterized by the development of chronic infections and elevated worm recovery, in relation to a local Th1 response with elevated production of interferon-γ. However, partial resistance against secondary E. caproni infections in ICR (Institute of Cancer Research) mice is developed after the chemotherapeutic cure of a primary infection and the innately produced IL-25 after pharmacological treatment. In this paper, we analyse the potential role of intestinal microbiota in the production of IL-25, and the subsequent resistance to infection. For this purpose, we analysed the production of IL-25 under conditions of experimental dysbiosis and also the changes in the resident microbiota in primary infections, pharmacological curation and secondary infections. The results obtained showed that resident microbiota play a major role in the production of IL-25 and the appearance of members of the phylum Verrucomicrobia as a consequence of the curation of the primary infection could be related to the partial resistance to secondary infection.
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Echinostoma , Echinostomatidae , Equinostomiasis , Microbiota , Infecciones por Trematodos , Ratones , Animales , Equinostomiasis/parasitología , Ratones Endogámicos ICR , Infecciones por Trematodos/parasitologíaRESUMEN
Background: A previous study reported the effectiveness and patient satisfaction in the dental emergency unit (DEU) of the Pitie Salpetrière Hospital in Paris before coronavirus disease 2019 (COVID-19). The same methodology was used during the COVID-19 pandemic to compare pain, anxiety, and patient satisfaction during the two periods. Methods: This prospective study was conducted in 2020 (NCT04354272) on adult patients. Data were collected on day zero (D0) on site and then by phone during the daytime on day one (D1), day three (D3), and day seven (D7). The primary objective was to assess the pain intensity at D1. Secondary objectives were to assess pain intensity at D3 and D7, anxiety intensity at D1, D3, and D7, and patient satisfaction. Patients were evaluated on a 0-10 numeric scale on D1, D3, and D7; mean scores were compared with non-parametric statistics (ANOVA, Dunn's). Results: A total of 445 patients were given the opportunity to participate in the study, and 370 patients consented. Seventy-one were lost during follow-up. Ultimately, 299 patients completed all the questionnaires and were included in the analysis. In the final sample (60% men, 40% women, aged 39 ± 14 years), 94% had health insurance. The mean pain scores were: D0, 6.1 ± 0.14; D1, 3.29 ± 0.16; D3, 2.08 ± 0.16; and D7, 1.07 ± 0.35. This indicates a significant decrease of 46%, 67%, and 82% at D1, D3, and D7, respectively, when compared to D0 (P < 0.0001). The mean anxiety scores were D0, 4.7 ± 0.19; D1, 2.6 ± 0.16; D3, 1.9 ± 0.61; and D7, 1.4 ± 0.15. This decrease was significant between D0 and D7 (ANOVA, P < 0.001). Perception of general health improved between D1 and D7. The overall satisfaction was 9.3 ± 0.06. Conclusion: DEU enabled a significant reduction in pain and anxiety with high overall satisfaction during COVID-19, which was very similar to levels observed pre-COVID-19 pandemic.
RESUMEN
Background: The Dental Emergency Unit (DEU) of the Pitié Salpêtrière Hospital receives mainly painful emergencies. This study aimed at evaluating the suppression of pain and anxiety as well as the patient's satisfaction after a visit to the DEU. Patients and Methods. A prospective study was carried out in 2019 (NCT03819036) in adult patients. Data was collected on D0 on site and then on D1, D3, and D7 by phone, during daytime. The main objective and secondary objectives were, respectively, to assess the intensity of pain on D1; the intensity of pain on D3 and D7; the evolution of anxiety on D1, D3, and D7; and the patients' satisfaction. They were evaluated with a 0-10 numeric scale (NS) on D1, D3 and D7; mean scores were compared with nonparametric statistics (ANOVA, Dunn's test). Results: 814 patients were contacted and 581 patients included; 87 were lost to follow-up. 376 patients completed all the questionnaires. In the final sample (59% men, 40 ± 16 y.o.), 86% had health insurance. The mean pain scores were as follows: D0: 6.36 ± 0.12; D1: 3.49 ± 0.13; D3: 2.23 ± 0.13; D7: 1.07 ± 0.11-indicating a significant decrease of 45%, 65%, and 93% on D1, D3, and D7, respectively, compared to D0 (p < 0.0001) between D0 and D1, D3, D7. The mean NS anxiety scores were as follows: D0: 3.32 ± 0.15; D1: 3.69 ± 0.16; D3: 2.75 ± 0.16; D7: 1.98 ± 0.15. The decrease was significant between D0 and D7 (p < 0.0001). The perception of general heath improved between D1 and D7. The overall score of satisfaction was 8.64 ± 0.06. Conclusion: DEU enabled a significant reduction in pain and anxiety with high overall satisfaction.
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There is a lack of epidemiological information concerning intestinal parasitic infections, and especially in soil-transmitted helminths, occurring in some departments of Nicaragua. Up to now, this is the first study involving two nearby areas (Puerto Cabezas and Siuna municipalities) of the Región Autónoma Atlántico Norte (R.A.A.N.). One stool sample was analyzed by Kato-Katz, formaldehyde-ethyl acetate concentration method and modified Ziehl-Neelsen technique, and a simple questionnaire concerning demographic, sanitary and behavioral data was distributed among 735 children and evaluated. Overall prevalence of infection reached 97.0%, being the highest prevalences detected in all Nicaragua. The higher protozoan prevalence appears in Siuna (94.5%), a rural interior municipality, with a typical tropical monsoon climate, while the higher helminths rates were reached in Puerto Cabezas (92.8%), the urbanized coastal capital, with a typical tropical rainforest climate. No statistical differences were found with regard to sex. However, the 6-11-year age-group children presented the highest prevalences. Most T. trichiura infections (59.4%) were of light intensity, while 51.7% of Ascaris lumbricoides were of moderate intensity. Multivariable logistic regression analysis indicated that those who drink rainwater and walk barefoot were 2.9 and 2.5 times more likely to have helminth infections, respectively. Results from one geographical setting might not be applied to other nearby with different climatic conditions. The use of anthelmintic drugs only will not be sufficient to bring prevalence to low levels. It is necessary to design geographically more specific intervention, with communication and interaction between different disciplines (e.g. parasitology, biochemistry, molecular biology, epidemiology, public health, etc.) being imperative to reduce STH infection.
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Helmintiasis , Helmintos , Parasitosis Intestinales , Animales , Ascaris lumbricoides , Niño , Heces/parasitología , Helmintiasis/epidemiología , Helmintiasis/parasitología , Humanos , Parasitosis Intestinales/epidemiología , Parasitosis Intestinales/parasitología , Nicaragua/epidemiología , Prevalencia , Suelo/parasitologíaRESUMEN
In the present paper, we review two of the most neglected intestinal food-borne trematodiases: echinostomiasis, caused by members of the family Echinostomatidae, and gastrodiscoidiasis produced by the amphistome Gastrodiscoides hominis. Both parasitic infections are important intestinal food-borne diseases. Humans become infected after ingestion of raw or insufficiently cooked molluscs, fish, crustaceans, amphibians or aquatic vegetables. Thus, eating habits are essential to determine the distribution of these parasitic diseases and, traditionally, they have been considered as minor diseases confined to low-income areas, mainly in Asia. However, this scenario is changing and the population at risk are currently expanding in relation to factors such as new eating habits in developed countries, growing international markets, improved transportation systems and demographic changes. These aspects determine the necessity of a better understanding of these parasitic diseases. Herein, we review the main features of human echinostomiasis and gastrodiscoidiasis in relation to their biology, epidemiology, immunology, clinical aspects, diagnosis and treatment.
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Echinostomatidae , Equinostomiasis , Enfermedades Parasitarias , Trematodos , Infecciones por Trematodos , Animales , Equinostomiasis/epidemiología , Humanos , Infecciones por Trematodos/diagnóstico , Infecciones por Trematodos/epidemiología , Infecciones por Trematodos/veterinariaRESUMEN
BACKGROUND: Rwanda is a sub-Saharan country, where intestinal parasite infections, anemia and undernutrition coexist. The purpose of this research is to study the relationship between intestinal parasite infections and undernutrition/anemia to clarify the priorities of intervention in the rural area of Gakenke district in the Northern Province of Rwanda. MATERIALS AND METHODS: A total of 674 students from Nemba I School, participated in a cross-sectional study, in which their parasitological and nutritional status were analysed. Statistical analysis was performed by χ2 test, univariate analysis and Odds ratios (OR). RESULTS: A total of 95.3% of children presented intestinal parasitism, most of whom (94.5%) infected by protozoa and 36.1% infected by soil-transmitted helminths (STH), with Trichuris trichiura (27.3%) being the most prevalent. Multiple infections were found to be high (83.8%), with protozoa and STH co-infections in 30.6%. STH infections were mainly of low/moderate intensity. Neither infection nor STH infection of any intensity profile, was significantly related to anemia. In addition, STH infection, regardless of the intensity profile, was not associated with stunting, underweight or thinness. There was no difference between genders nor among ages in odds of anemia and nutritional status in STH-infected schoolchildren. CONCLUSION: Multiparasitism remains high among Rwandan schoolchildren and is likely to cause nutritional problems. This work emphasizes the importance of keeping up health programs to reduce the prevalence of infection.
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Anemia/epidemiología , Desnutrición/epidemiología , Adolescente , Animales , Niño , Preescolar , Estudios Transversales , Heces/parasitología , Femenino , Trastornos del Crecimiento/epidemiología , Trastornos del Crecimiento/parasitología , Helmintiasis/epidemiología , Helmintos/patogenicidad , Humanos , Parasitosis Intestinales/epidemiología , Parasitosis Intestinales/parasitología , Masculino , Estado Nutricional/fisiología , Prevalencia , Rwanda/epidemiología , Suelo/parasitología , Delgadez/epidemiología , Delgadez/parasitología , Tricuriasis/epidemiología , Trichuris/patogenicidadRESUMEN
The autonomous Valencian Community (Spain) has experienced intense population growth with economic difficulties or deprivation in basic goods, ranking as the sixth Spanish autonomous region with the highest percentage of a population at risk of poverty or social exclusion. The objective of this work is to assess the level of enteroparasites in a Valencian population that meets certain deprivation conditions. A coproparasitological analysis was carried out in 460 users (children and adult relatives) of the 3 Casa Caridad schools in the province of Valencia. The parasite prevalence reached 31.7%, with a higher frequency of pathogens/potentially pathogenic species (66.4%) than non-pathogenic species (33.5%), although symptoms only appeared in 10.3% of those with pathogens/potentially pathogenic species. Of those parasitized, the presence of pathogens/potentially pathogenic species reached 20.6% in individuals living in crowded conditions and 17.5% in those living with pets. Presenting pathogens/potentially pathogenic species infection increased almost fourfold in those of southern European origin. In family groups, infection occurred among all their members, showing interpersonal parasitic transmission linked to both material deprivation and a lack of health education. Improving epidemiological surveillance, health education, and hygiene/sanitation facilities is essential to reduce or eliminate parasitic transmission among those who suffer from certain deprivation conditions.
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Parasitosis Intestinales/epidemiología , Adolescente , Adulto , Anciano , Niño , Preescolar , Heces/parasitología , Femenino , Humanos , Lactante , Parasitosis Intestinales/economía , Parasitosis Intestinales/parasitología , Masculino , Persona de Mediana Edad , Áreas de Pobreza , Prevalencia , España/epidemiología , Adulto JovenAsunto(s)
Humanos , Alergia e Inmunología/ética , Alergia e Inmunología/tendencias , Pandemias/prevención & control , Infecciones por Coronavirus/epidemiología , Infecciones por Coronavirus/inmunología , Infecciones por Coronavirus/prevención & control , Infecciones por Coronavirus/terapia , Infecciones por Coronavirus/transmisiónRESUMEN
Three recent studies of Blastocystis epidemiology in mammalian hosts identified four novel sequences that appeared to share B. lapemi as the most similar sequence. However, full-length ssu rRNA gene sequences were not available to confirm the validity of these new subtypes. In the present study, Nanopore MinION sequencing was used to obtain full-length reference sequences for each of the new subtypes. Additionally, phylogenetic analyses and pairwise distance comparisons were performed to confirm the validity of each of these new subtypes. We propose that the novel sequences described in this study should be assigned the subtype designations ST35-ST38. The full-length reference sequences of ST35-ST38 will assist in accurate sequence descriptions in future studies of Blastocystis epidemiology and subtype diversity.
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New information technologies have transformed the way care is delivered within health services, permeating almost every aspect of health care. As the complexity of the system increases, it becomes more difficult to work optimally without the assistance of new technologies. Although its implementation represents a breakthrough, either because of the advancement involved in the proper use of any technology in health care, or because of the development of specific applications that improve patient safety, other factors such as incorrect design, implementation and poor maintenance, inadequate training, along with overconfidence and dependency, can make technologies compromise patient safety. This article describes the beneficial effects, and those that are not so, of the introduction in our country of the electronic medical record and the electronic prescription on the healthcare quality and safety.
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Registros Electrónicos de Salud , Calidad de la Atención de Salud , Atención a la Salud , Humanos , Prescripciones , Medición de RiesgoRESUMEN
A highly resolved taxonomy for ammonia-oxidizing archaea (AOA) based on the alpha subunit of ammonia monooxygenase (amoA) was recently established, which uncovered novel environmental patterns of AOA, challenging previous generalizations. However, many microbiome studies target the 16S rRNA gene as a marker; thus, the usage of this novel taxonomy is currently limited. Here, we exploited the phylogenetic congruence of archaeal amoA and 16S rRNA genes to link 16S rRNA gene classification to the novel amoA taxonomy. We screened publicly available archaeal genomes and contigs for the co-occurring amoA and 16S rRNA genes and constructed a 16S rRNA gene database with the corresponding amoA clade taxonomy. Phylogenetic trees of both marker genes confirmed congruence, enabling the identification of clades. We validated this approach with 16S rRNA gene amplicon data from peatland soils. We succeeded in linking 16S rRNA gene amplicon sequence variants belonging to the class Nitrososphaeria to seven different AOA (amoA) clades, including two of the most frequently detected clades (Nitrososphaerales γ and δ clades) for which no pure culture is currently available. Water status significantly impacted the distribution of the AOA clades as well as the whole AOA community structure, which was correlated with pH, nitrate, and ammonium, consistent with previous clade predictions. Our study emphasizes the need to distinguish among AOA clades with distinct ecophysiologies and environmental preferences, for a better understanding of the ecology of the globally abundant AOA. IMPORTANCE The recently established phylogeny of amoA provides a finer resolution than previous studies, allowing clustering of AOA beyond the order level and thus revealing novel clades. While the 16S rRNA gene is mostly appreciated in microbiome studies, this novel phylogeny is in limited use. Here, we provide an alternative path to identifying AOA with this novel and highly resolved amoA taxonomy by using 16S rRNA gene sequencing data. We constructed a 16S rRNA gene database with the associated amoA clade taxonomy based on their phylogenetic congruence. With this database, we were able to assign 16S rRNA gene amplicons from peatland soils to different AOA clades, with a level of resolution provided previously only by amoA phylogeny. As 16S rRNA gene amplicon sequencing is still widely employed in microbiome studies, our database may have a broad application for interpreting the ecology of globally abundant AOA.
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Marine sediments represent a vast habitat for complex microbiomes. Among these, ammonia oxidizing archaea (AOA) of the phylum Thaumarchaeota are one of the most common, yet little explored, inhabitants, which seem extraordinarily well adapted to the harsh conditions of the subsurface biosphere. We present 11 metagenome-assembled genomes of the most abundant AOA clades from sediment cores obtained from the Atlantic Mid-Ocean ridge flanks and Pacific abyssal plains. Their phylogenomic placement reveals three independently evolved clades within the order Nitrosopumilales, of which no cultured representative is known yet. In addition to the gene sets for ammonia oxidation and carbon fixation known from other AOA, all genomes encode an extended capacity for the conversion of fermentation products that can be channeled into the central carbon metabolism, as well as uptake of amino acids probably for protein maintenance or as an ammonia source. Two lineages encode an additional (V-type) ATPase and a large repertoire of DNA repair systems that may allow to overcome the challenges of high hydrostatic pressure. We suggest that the adaptive radiation of AOA into marine sediments occurred more than once in evolution and resulted in three distinct lineages with particular adaptations to this extremely energy-limiting and high-pressure environment.