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Pathobionts have been implicated in various chronic diseases, including Crohn's disease (CD), a multifactorial chronic inflammatory condition that primarily affects the gastrointestinal tract, causing inflammation and damage to the digestive system. While the exact cause of CD remains unclear, adherent-invasive Escherichia coli (AIEC) strains have emerged as key contributors to its pathogenesis. AIEC are characterized by their ability to adhere to and invade intestinal epithelial cells and survive and replicate inside macrophages. However, the mechanisms underlying the virulence and persistence of AIEC within their host remain the subject of intensive research. Toxin-antitoxin systems (TAs) play a potential role in AIEC pathogenesis and may be therapeutic targets. These systems generally consist of two components: a toxin harmful to the cell and an antitoxin that neutralizes the toxin's effects. They contribute to bacterial survival in adverse conditions and regulate bacterial growth and behavior, affecting various cellular processes in bacterial pathogens. This review focuses on the current information available to determine the roles of TAs in the pathogenicity of AIEC. Their contribution to the AIEC stress response, biofilm formation, phage inhibition, the maintenance of mobile genetic elements, and host lifestyles is discussed.
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Quinolone resistance has been largely related to the presence of specific point mutations in chromosomal targets, with an accessory role of impaired uptake and enhanced pump-out. Meanwhile the relevance of transferable mechanisms of resistance able to protect the target of pump-out or inactivate quinolones has been increasingly reported since 1998. Nevertheless, bacteria have other strategies and mechanisms allowing them to survive and even proliferate in the presence of quinolones, which might be qualified as resistance or resilience mechanisms. These include decreasing levels of quinolone target production, transient amoeba protection, benthonic lifestyle, nutrient-independent slow growth, activation of stringent response, inactivation or degradation of quinolones as well as apparently unrelated or forgotten chromosomal mutations. These mechanisms have been largely overlooked, either because of the use of classical approaches to antibiotic resistance determination or due to the low increase in final minimum inhibitory concentration levels. This article is devoted to a review of a series of these mechanisms.
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Toxin/antitoxin (TA) systems have been scarcely studied in Brucella abortus, the causative agent of brucellosis, which is one of the most prevalent zoonotic diseases worldwide. In this study, the roles of a putative type II TA system composed by a Zinc-dependent metalloproteinase (ZnMP) and a transcriptional regulator HTH-Xre were evaluated. The deletion of the open reading frame (ORF) BAB1_0270, coding for ZnMP, used to produce a mutant strain, allowed us to evaluate the survival and gene expression of B. abortus 2308 under oxidative conditions. Our results showed that the B. abortus mutant strain exhibited a significantly reduced capacity to survive under hydrogen peroxide-induced oxidative stress. Furthermore, this mutant strain showed a decreased expression of genes coding for catalase (katE), alkyl hydroperoxide reductase (ahpC) and transcriptional regulators (oxyR and oxyR-like), as well as genes involved in the general stress response, phyR and rpoE1, when compared to the wild-type strain. These findings suggest that this type II ZnMP/HTH-Xre TA system is required by B. abortus to resist oxidative stress. Additionally, previous evidence has demonstrated that this ZnMP also participates in the acidic stress resistance and virulence of B. abortus 2308. Therefore, we propose a hypothetical regulatory function for this ZnMP/HTH-Xre TA system, providing insight into the stress response and its potential roles in the pathogenesis of B. abortus.
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Brucella abortus , Metaloporfirinas , Zinco , Animais , Camundongos , Brucella abortus/genética , Brucella abortus/metabolismo , Virulência/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Estresse Oxidativo , Metaloproteases/metabolismo , Camundongos Endogâmicos BALB CRESUMO
Mycobacterium bovis BCG is the only vaccine against tuberculosis. The variable forms of cultivation throughout the years, before seed-lots were developed, allowed in vitro evolution of the original strain, generating a family of vaccines with different phenotypic and genotypic characteristics. Molecular studies revealed regions of difference (RDs) in the genomes of the various BCG strains. This work aims to characterize the gene pair rv3407-rv3408 (vapB47-vapC47), coding for a toxin-antitoxin system of the VapBC family, and to evaluate possible transcriptional effects due to the adjacent BCG Moreau-specific genomic deletion RD16. We show that these genes are co-transcribed in BCG strains Moreau and Pasteur, and that the inactivation of an upstream transcriptional repressor (Rv3405c) due to RD16 has a polar effect, leading to increased vapBC47 expression. Furthermore, we detect VapB47 DNA binding in vitro, dependent on a 5' vapB47 sequence that contributes to a palindrome, spanning the promoter and coding region. Our data shed light on the regulation of VapBC systems and on the impact of the BCG Moreau RD16 deletion in the expression of adjacent genes, contributing to a better understanding of BCG Moreau physiology.
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Bacterial plasmids and chromosomes widely contain toxin-antitoxin (TA) loci, which are implicated in stress response, growth regulation and even tolerance to antibiotics and environmental stress. Type I TA systems consist of a stable toxin-expressing mRNA, which is counteracted by an unstable RNA antitoxin. The Long Direct Repeat (LDR-) D locus, a type I TA system of Escherichia Coli (E. coli) K12, encodes a 35 amino acid toxic peptide, LdrD. Despite being characterized as a bacterial toxin, causing rapid killing and nucleoid condensation, little was known about its function and its mechanism of toxicity. Here, we show that LdrD specifically interacts with ribosomes which potentially blocks translation. Indeed, in vitro translation of LdrD-coding mRNA greatly reduces translation efficiency. The structure of LdrD in a hydrophobic environment, similar to the one found in the interior of ribosomes was determined by NMR spectroscopy in 100% trifluoroethanol solution. A single compact α-helix was found which would fit nicely into the ribosomal exit tunnel. Therefore, we conclude that rather than destroying bacterial membranes, LdrD exerts its toxic activity by inhibiting protein synthesis through binding to the ribosomes.
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Antitoxinas , Toxinas Bacterianas , Escherichia coli/genética , Escherichia coli/metabolismo , Toxinas Bacterianas/genética , Toxinas Bacterianas/química , Toxinas Bacterianas/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Sequências Repetitivas de Ácido Nucleico , Biossíntese de Proteínas , Antitoxinas/química , Antitoxinas/genética , Antitoxinas/metabolismo , Proteínas de Bactérias/químicaRESUMO
The PumAB type-II toxin-antitoxin (TA) system is encoded by pumAB genes that are organized into an operon. This system is encoded by the pUM505 plasmid, isolated from a Pseudomonas aeruginosa clinical strain. The pumA gene encodes a putative RelE toxin protein (toxic component), whereas the pumB gene encodes a putative HTH antitoxin protein. The expression of the PumAB system in Escherichia coli confers plasmid stability. In addition, PumA toxin overexpression in P. aeruginosa possesses the capability to increase bacterial virulence, an effect that is neutralized by the PumB antitoxin. The aim of this study was to establish the mechanism of regulation of the PumAB toxin-antitoxin system from pUM505. By an in silico analysis of the putative regulatory elements, we identified two putative internal promoters, PpumB and PpumB-AlgU (in addition to the already reported PpumAB), located upstream of pumB. By RT-qPCR assays, we determined that the pumAB genes are transcribed differentially, in that the mRNA of pumB is more abundant than the pumA transcript. We also observed that pumB could be expressed individually and that its mRNA levels decreased under oxidative stress, during individual expression as well as co-expression of pumAB. However, under stressful conditions, the pumA mRNA levels were not affected. This suggests the negative regulation of pumB by stressful conditions. The PumB purified protein was found to bind to a DNA region located between the PpumAB and the pumA coding region, and PumA participates in PumB binding, suggesting that a PumA-PumB complex co-regulates the transcription of the pumAB operon. Interestingly, the pumA mRNA levels decreased after incubation in vitro with PumB protein. This effect was repressed by ribonuclease inhibitors, suggesting that PumB could function as an RNAse toward the mRNA of the toxin. Taken together, we conclude that the PumAB TA system possesses multiple mechanisms to regulate its expression, as well as that the PumB antitoxin generates a decrease in the mRNA toxin levels, suggesting an RNase function. Our analysis provides new insights into the understanding of the control of TA systems from mobile plasmid-encoded genes from a human pathogen.
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Antitoxinas , Toxinas Bacterianas , Sistemas Toxina-Antitoxina , Humanos , Antitoxinas/genética , Antitoxinas/metabolismo , Toxinas Bacterianas/genética , Sistemas Toxina-Antitoxina/genética , Proteínas Reguladoras de Apoptose/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Endorribonucleases/genética , Endorribonucleases/metabolismo , RNA Mensageiro , Ribonucleases/genética , Ribonucleases/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Regulação Bacteriana da Expressão GênicaRESUMO
SUMMARY OBJECTIVE: Toxin-antitoxin genes RelBE and HigBA are known to be involved in the formation of biofilm, which is an important virulence factor for Pseudomonas aeruginosa. The purpose of this study was to determine the presence of toxin-antitoxin genes and exoenzyme S and exotoxin A virulence genes in P. aeruginosa isolates and whether there is a relationship between toxin-antitoxin genes and virulence genes as well as antibiotic resistance. METHODS: Identification of the isolates and antibiotic susceptibilities was determined by a VITEK 2 (bioMérieux, France) automated system. The presence of toxin-antitoxin genes, virulence genes, and transcription levels were detected by real-time polymerase chain reaction. RESULTS: RelBE and HigBA genes were detected in 94.3% (82/87) of P. aeruginosa isolates, and exoenzyme S and exotoxin A genes were detected in all of the isolates (n=87). All of the isolates that harbor the toxin-antitoxin and virulence genes were transcribed. There was a significant increase in the RelBE gene transcription level in imipenem- and meropenem-sensitive isolates and in the HigBA gene transcription level in amikacin-sensitive isolates (p<0.05). There was a significant correlation between RelBE and exoenzyme S (p=0.001). CONCLUSION: The findings suggest that antibiotic resistance may be linked to toxin-antitoxin genes. Furthermore, the relationship between RelBE and exoenzyme S indicates that toxin-antitoxin genes in P. aeruginosa isolates are not only related to antibiotic resistance but also play an influential role in bacterial virulence. Larger collections of comprehensive studies on this subject are required. These studies should contribute significantly to the solution of the antibiotic resistance problem.
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Resumen El botulismo del lactante (BL), es la forma más frecuente del botulismo humano en la actualidad, es una enfermedad "rara" o "huérfana" ya que afecta a menos del 0,05 % de la población. El objetivo del presente trabajo es determinar la Incidencia del BL en la Argentina, evaluar el diagnóstico y tratamiento realizado, comparar la evolución y las secuelas al alta en pacientes con y sin tratamiento específico y, considerar las características climáticas (precipitaciones y vientos) y los estudios de muestras de suelos de las provincias con mayor cantidad de casos de BL. Presentamos un estudio multicéntrico, de cohorte (longitudinal) observacional, retrospectivo analizando las historias clínicas de los pacientes con BL, que ingresaron a Unidades de Cuidados Intensivos Pediátricos con asistencia respiratoria mecánica, desde el 1 de enero de 2010 hasta 31 de diciembre de 2013. Se consideró: edad, sexo, días previos al ingreso hasta diagnóstico por laboratorio, total internación en Unidades de Cuidados Intensivos Pediátricos con asistencia respiratoria mecánica, alimentación por sonda nasogástrica, tratamiento y secuelas. En Argentina entre 2010 al 2013 se registraron 216 casos de BL. En este trabajo se analizaron 79 pacientes provenientes de 11 provincias, que ingresaron a Unidades de Cuidados Intensivos Pediátricos. La edad promedio de los pacientes ingresados fue de 4 meses, de los cuales 90% recibía alimentación materna. Dieciocho pacientes de seis provincias recibieron antitoxina botulínica equina. El promedio de días de enfermedad previos al ingreso fue de 2 días en los pacientes que recibieron tratamiento con antitoxina botulínica equina y 4 días en los pacientes no tratados. Diagnóstico de laboratorio (Toxina A y Clostridium botulinum) a los 5 días en los tratados con antitoxina botulínica equina, y a los 11,5 en los no tratados. En los pacientes tratados con antitoxina botulínica equina, el promedio de días de internación fue de 30 versus 70 días en los no tratados (p=0,0001). El promedio días en las Unidades de Cuidados Intensivos Pediátricos de los pacientes tratados fue de 20 versus 54 días en los no tratados (p=0,0001). Los días de asistencia respiratoria mecánica en los tratados fue de 16 versus 43 días en los no tratados (p=0,0001) y los tratados requirieron 29 días de alimentación por sonda nasogástrica versus 70 días en los no tratados (p=0,0001). El 40% de los pacientes tratados presentaron neumonía asociada a respirador versus el 56% de los no tratados (p=0,0038), sepsis el 11% versus el 34% (p=0,005) y secuelas al alta 6% versus 64% (p=0,0001), respectivamente. En zonas con mayor número de casos, se observó una alta frecuencia de esporas en los suelos, asociado a clima seco y ventoso. Los resultados sugieren que el tratamiento precoz con antitoxina botulínica equina es una alternativa hasta disponer de inmuno-globulina botulínica humana. Los climas secos y ventosos favorecen la enfermedad.
Abstract Infant botulism (BL), the most common form of human botulism today, is a "rare" or "orphan" disease as it affects less than 0.05% of the population. The objective of this work is to determine the incidence of BL in Argentina. Evaluate the diagnosis and treatment performed. To compare evolution and sequelae at discharge in patients with and without specific treatment. Consider the climatic characteristics (precipitations and winds) and the studies of soil samples from the provinces with the highest number of BL cases. We present a retrospective, observational, multicenter, cohort (longitudinal) study analyzing the medical records of patients with BL, who were admitted to Pediatric Intensive Care Units with mechanical ventilation, from January 1,2010 to December 31,2013. The following were considered: age, sex, days prior to admission, until laboratory diagnosis, Pediatric Intensive Care Units, me-chanical respiratory assistance, average hospital days, nasogastric tube feeding, treatment and sequelae. In the country, 216 cases of BL were registered between 2010 and 2013. We analyzed 79 who were admitted to Pediatric Intensive Care Units from 11 provinces. Average age 4 months. Maternal nutrition 90%. Eighteen patients (6 provinces) received equine botulinum antitoxin .Mean days of illness prior to admission: 2 in those treated with equine botulinum antitoxin and 4 in those not treated. Laboratory diagnosis (Toxin A and Clostridium botulinum) at 5 days in treated with equine botulinum antitoxin, at 11.5 in untreated. Patients with equine botulinum antitoxin average hospital days 30 vs 70 in untreated patients (p=0.0001). Mean Pediatric Intensive Care Unit days 20 vs 54 (p=0.0001) of mechanical respiratory assistance 16 vs 43 (p=0.0001) and nasogastric tube feeding 29 vs 70 (p=0.0001). Those treated presented ventilator-associated pneumonia 40% vs 56% (p=0.0038) and sepsis 11% vs 34% (p=0.005). Sequelae at discharge 6% vs 64% (p=0.0001) in those not treated. In areas with a higher number of cases, high frequency of spores in soils, dry and windy weather. The results suggest that early treatment with equine botulinum antitoxin is an alternative until human botulinum immunoglobulin is available. The dry and windy climates favor the disease.
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Humanos , Lactente , Botulismo/diagnóstico , Botulismo/tratamento farmacológico , Antitoxina Botulínica/uso terapêutico , Toxinas Botulínicas Tipo A , Argentina/epidemiologiaRESUMO
Tetanus is a distressing and often fatal disease caused by exotoxins released by the bacterium Clostridium tetani. Clostridium tetani is a commensal of the gastrointestinal tract of humans and domestic animals, and its spores are highly resistant to environmental changes, acid, and alkali and may persist in the soil for many years. The disease is characterized by generalized muscular rigidity and spasms, hyperesthesia, convulsions, respiratory arrest, and death. Horses are the most susceptible domestic animals. Treatment is typically directed towards elimination of the source of the toxin, neutralization of any unbound toxin, establishment of antitoxin immunity, control of neuromuscular derangements, and relief of pain. This study described the clinical findings and therapeutic protocols of 17 horses with tetanus, treated between March 2012 and December 2021. The diagnosis of tetanus was based on the history and clinical examination findings of the animals. All horses received a treatment pattern composed of the administration of tetanus serum (50,000 UI, intravenously, followed by three injections of the same dose at 48-h intervals), procaine penicillin (25,000 UI kg, intramuscularly, BID, for 10 days), and muscle relaxant (acepromazine 0.02-0.05 mg/kg, intramuscularly, BID, for 8 days). Support therapy based on hydroelectrolytic replacements, feeding via a nasogastric tube, and assistance in the maintenance of the quadrupedal position were performed when needed. The mortality rate observed in this report was 23.52%. Early diagnosis associated with the instituted treatment contributed the most to the animal recovery.
O tétano é uma doença angustiante e frequentemente fatal, causada por exotoxinas liberadas pela bactéria Clostridium tetani. Clostridium tetani é um microrganismo comensal do trato gastrointestinal do homem e de animais domésticos, e seus esporos são altamente resistentes às mudanças ambientais, ácidas e alcalinas, podendo persistir no solo por muitos anos. A doença é caracterizada por rigidez muscular generalizada e espasmos, hiperestesia, convulsões, parada respiratória e morte. O cavalo é a espécie de animal doméstico mais suscetível. O tratamento é tipicamente direcionado à eliminação da fonte da toxina, neutralização de qualquer toxina não ligada, estabelecimento de imunidade à antitoxina, controle de distúrbios neuromusculares e alívio da dor. Os achados clínicos e protocolos terapêuticos de 17 cavalos com tétano tratados durante o período de março de 2012 a dezembro de 2021 são descritos. O diagnóstico de tétano baseou-se na história e nos achados do exame clínico dos animais. Todos os cavalos receberam padrão de tratamento, composto pela administração de soro tetânico (50.000UI, por via intravenosa, seguido de três outras aplicações da mesma dose em intervalos de 48 horas), penicilina procaína (25.000UI kg, intramuscular, BID, por 10 dias) e relaxante muscular (acepromazina 0,02-0,05 mg kg, por via intramuscular, BID, por oito dias). Foram realizadas terapia de suporte baseada em reposições hidroeletrolíticas, alimentação por sonda nasogástrica e auxílio na manutenção da posição quadrúpede, quando necessário. A mortalidade observada neste estudo foi de 23,52%. O diagnóstico precoce associado ao tratamento instituído foram os fatores que mais contribuíram para a recuperação dos animais.
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Resumen El botulismo del lactante (BL) es una enfermedad neuroparalítica potencialmente grave que afecta a niños menores de un año, ocasio nada por la ingesta y germinación de esporas de la bacteria del género Clostridium en tubo digestivo y la producción in situ de toxina botulínica (TB). Ésta se absorbe de manera intermitente y puede ser sostenida en el tiempo, condicionando una mayor exposición a la TB respecto a otras formas de botulismo. La TB representa el agente más letal conocido para el ser humano, con capacidad de producir parálisis flácida descendente, insuficiencia respiratoria y la muerte. Los lactantes representan la población más susceptible a esta toxiinfección. El eje central del manejo del BL radica en el diagnóstico precoz y tratamiento de sostén adecuado y oportuno. Si bien en la bibliografía consultada se describe que el tratamiento específico con antitoxina botulínica humana (BabyBIG® reduce el tiempo de hospitalización y estadía en Unidad de Cuidados Intensivos, la misma no se encuentra disponible en muchos países, incluida la Argentina. En nuestro país se encuentra disponible la antitoxina botulínica de origen equino (AtBE) bivalente A-B. La misma no posee indicación formal para el tratamiento del BL por la escasa experiencia en esta población, su corta vida media y los efectos adversos descritos, como son la sensibilización a antígenos equinos de por vida y posibles reacciones anafilácticas más graves en lactantes, basados en trabajos de la década de 1980 y opiniones de expertos. Se presenta el caso de una paciente de 5 meses asistida en el Hos pital de Niños "Superiora Sor María Ludovica" con BL severo, con requerimientos de asistencia ventilatoria mecánica y deterioro clínico durante la internación. Recibió AtBE a los 48 días de enfermedad, con respuesta favorable, a partir de una búsqueda bibliográfica sobre la eficacia y el perfil de seguridad de la AtBE en BL grave y la eficacia de su administración luego de 5 días de inicio del cuadro. A pesar de no haberse hallado bibliografía que avale la eficacia de la AtBE pasados 5 días de evolución, se plantea su uso en pacientes con BL grave e indicadores compatibles con presencia de TB en circulación, como la intensificación de la hipotonía muscular o la identificación de TB en materia fecal o suero. La búsqueda realizada arrojó datos sobre posibles beneficios de su uso, tanto antes como después de los 5 días de evolución del cuadro, y la ausencia de reportes de reacciones adversas severas en lactantes. Se concluye que el uso de la AtBE podría ser una opción terapéutica frente a la ausencia de BabyBIG® en pacientes con BL grave confirmado que requieran cuidados intensivos con soporte ventilatorio mecánico, frente a indicadores compatibles con TB circulante, independientemente del tiempo de evolución.
Abstract Infant botulism (BL) is a potentially serious neuroparalytic disease that affects children under one year old, caused by the ingestion and germination of spores of the Clostridium genus bacterium in the digestive tract and the in situ production of botulinum toxin (TB), which is absorbed intermittently and can be sustained over time, with longer exposure time to TB than other botulism forms. The TB represents the most lethal toxin known to humans and can cause descending flaccid paralysis, respiratory failure and death. Infants represent an especially susceptible population. Early diagnosis and supportive care are the cornerstone of BL management. Although specific treatment with human botulinum antitoxin (BabyBIG® has shown to reduce the hospitalization time and Intensive Care Unit stay in the consulted bibliography, it is not currently available in many countries, including Argentina. Botulinum antitoxin of equine origin (AtBE) bivalent A-B is available in our country. This antitoxin has not a formal indication in BL due to the limited experience of its use in this population, its short half-life and the adverse effects described, such as lifelong sensitization to equine antigens and possible more severe anaphylactic reactions in infants, based on studies from the 1980s and expert opinions. We present the case of a 5 month old patient assisted at the Children's Hospital "Superiora Sor María Ludovica" with severe BL, in need of mechanical ventilatory assistance and worsening of her clinical state during hospitalization, who received ATBE at 48 days of illness with a favorable response. A bibliographic search was carried out on the efficacy and safety profile of AtBE in severe BL and the efficacy of its administration after 5 days of illness onset. Even though bibliography on efficacy of ATBE after 5 days of evolution was not found, its use is proposed in patients with compatible indicators of circulating TB, such as worsening of muscular hypotonia or TB presence in feces or serum in severe ill patients. The carried out search has shown data of the possible benefits of its use, both before and after 5 days of disease onset, and the absence of severe adeverse reaction reports in infants. We concluded that the use of AtBE could be a therapeutic option in absence of BabyBIG® in patients with confirmed severe BL who require intensive care with mechanical ventilatory support and compatible indicators with circulating TB, regardless of the evolution time.