Bacteriófagos, los virus come-bacterias: historia de dos mentes científicas

El descubrimiento de los bacteriófagos (virus come bacterias) está lleno de discusiones, ya que algunos autores consideran a Felix d’Herelle como su único descubridor oficial, debido a que pudo comprobar, en 1917, que esos entes totalmente diferentes a todos los que se conocían eran los responsables de la actividad lítica (acción destructiva). En contraste, otros autores proponen a Frederick W. Twort como su verdadero descubridor, ya que, en 1915, reportó una actividad lítica; sin embargo, no pudo determinar su origen. En este artículo se relatan las observaciones, planteamientos e ideas de dos personajes que fueron pilares en el descubrimiento de los bacteriófagos, virus que actualmente son considerados como una propuesta para combatir efectivamente enfermedades mortales de origen bacteriano

Monitoreo de la resistencia a los antibióticos utilizando Escherichia coli en aves de combate en el norte del Estado de México

La clínica veterinaria relacionada con las aves de combate es cada vez más frecuente en la atención por parte del Médico Veterinario Zootecnista, sin embargo los tratamientos mal empleados con antibióticos debido al desconocimiento del manejo de la especie o por el mal uso en la posología han originado la presencia de cepas resistentes a los antibióticos en la mayoría de las especies animales productivas incluyendo a las aves de combate

Caracterização de sistemas, simulação e otimização de etapas da planta de processamento de gas natural

Orientador: Maria Regina Wolf MacielTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia QuimicaResumo: O gás natural, assim como o petróleo, é uma fonte de energia não renovável e tem sido usado comercialmente como combustível há mais de cem anos. Não existe uma composição única para o gás natural, ele é uma mistura de hidrocarbonetos leves, principalmente metano, e algumas outras substãncias orgãnicas e inorgánicas em menor quantidade, que em alguns casos precisam ser removidas. Com a ajuda do simulador HYSYS e o software estatístico MINITAB, foram desenvolvidos, neste trabalho, estudos de caracterização, tratamento e otimização de processos de gás natural. A caracterização consiste em determinar as propriedades tanto de componentes puros quanto de uma corrente de gás, elaborar diagramas termodinâmicos e predizer se há formação de hidratos. No tratamento, primeiramente os gases ácidos têm que ser removidos num processo que é conhecido como "adoçamento". Posteriormente, água líquida ou em forma de vapor tem que ser removida, num processo de desidratação. Estes processos são fundamentais para o tratamento de gás natural pois, para sua comercialização, o gás tem que cumprir com rigorosas especificações de conteúdo de H2S e água. Técnicas de Planejamento Fatorial e Análise de Superficie de Respostas foram usadas para a otimização dos processos de tratamento do gás natural. Estas técnicas permitem predizer com um elevado grau de confiança as regiões de operação para cada variável, nas quais se atingem as especificações requeridas para o gásAbstract: Natural gas, like petroleum, is a non-renewable energy resource and has been used commercially for more than a century. Natural gas does not have a unique composition, it is a mixture of light hydrocarbons, mainly methane, and other organic and inorganic substances in smaller quantities, that in some cases need to be removed. With the aid of the HYSYS process simulator and the MINITAB statistical software, it was possible to develop studies for characterization, treatment and optimization of natural gas processes. The characterization consists in determining the properties of both pure components and a natural gas stream, elaborate thermodynamic diagrams and predict if there is hydrate formation or noto For the treatment, first, the acid gases need to be removed in a process known as "sweetening". Next, liquid water, or in the form of steam, has to be removed in a dehydration processo These processes are fundamental for natural gas treatment because, for its commercialization, the gas has to meet rigorous specifications of H2S and water contento Factorial design and Response Surface techniques were used for the optimization of the natural gas treatment processes. These techniques allow one to predict, with a high degree of confidence, the operating regions for each variable, in which the required specifications for the gasDoutoradoDesenvolvimento de Processos QuímicosDoutor em Engenharia Químic

Resistencia a antibi ticos betalact micos y quinolonas en Escherichia coli aislada de pollos broiler

ArtículoEl objetivo del estudio fue determinar la resistencia antimicrobiana de 176 cepas de Escherichia. coli aisladas de  órganos de pollos broiler. Las cepas fueron desafiadas con antibi ticos betalact micos, quinolonas y fluoroquinolonas, observ ndose resistencia a antibióticos betalactámicos (97.7%) y a quinolonas (86.7%). El 71.6% de los aislados también expresaron fenotípicamente la producción de betalactamasas de espectro extendido (ESLB). Mediante PCR se determinaron genes de resistencia para betalactámicos blaTEM, blaSHV, blaCTX-M1 y Amp-C y genes de resistencia para quinolonas qnrA, qnrB, qnrS. Se encontraron los genes Amp-C (74%), blaCTX-M (65%), blaSHV (65%), blaTEM (50%), qnrB (86.4%) y qnrS (11.9%). No se evidencia  el gen qnrA en las muestras analizadas. Los resultados obtenidos revelaron un gran porcentaje de resistencia a los antibióticos estudiados y la presencia de genes de resistencia en aislados de aves para consumo humano, lo cual constituye un riesgo para la salud pública

Serotypes and Stx2 subtyping of Shiga toxin producing Escherichia coli isolates from cattle carcasses and feces

ArticuloShiga toxin E. coli (STEC) is an important pathogen responsible for foodborne illness, this have been related with epidemic outbreaks in the past, mainly because of consumption of bovine meat. The objective of this study was identify the serotypes and Stx2 subtypes and associate them with their possible epidemiology. There were analyzed a total of 65 isolates from the collection of the Centro de Investigación y Estudios Avanzados en Salud Animal, Facultad de Medicina Veterinaria y Zootecnia of the Universidad Autónoma del Estado de México, from carcasses and feces of bovines at three different Municipal slaughterhouses. The identification of Stx2 gene by PCR at final point, sequencing and analyzed with the help of BLAST software. There were found O157:H7, O70:H16, O91:H10, O112ac:H2, O128ac:H26 serotypes, which have been reported to be present at infectious outbreaks previously by foodborne worldwide; 63.07% (41/65) of the Escherichia coli strains got amplified for Stx2 and after BLAS analysis it was confirmed its presence and a hypothetic protein. The presence of this serotypes in combination with different subtype’s, Stx2a, Stx2c, Stx2d, in carcasses and feces of bovine in must be considered as a potential risk for diseases an important problem of the public health

Serotypes, virulence genes profiles and antimicrobial resistance patterns of Escherichia coli recovered from feces of healthy lambs in Mexico

Articulo que habla de la resistencia a los antibióticos en corderosHealthy lambs are one of the major reservoirs of Shiga toxin-producing Escherichia coli (STEC) and it is known as the cause of foodborne diseases (FBD). The work objective is to characterize (STEC) isolates obtained from rectal swabs of healthy lambs herds, a total of 183 samples were obtained from sheep production units of the State of Mexico. E. coli isolates were confirmed through the amplification of the uid A gene. antimicrobial sensitivity pattern was determined through Kirby-Bauer (CLSI, 2012) test and the presence stx1, stx2 and eae genes from isolates by multiplex PCR. Serotyping was performed using specific anti-O and anti-H sera (SERUNAM, Mexico) for 185 Somatic and 56 flagellar antigens. 126 isolates biochemically and molecularly identified as E. coli were obtained, of which 80 did not express any virulence factor and 46 expressed at least some (STEC) virulence factor. The highest percentage of E. coli resistance was for tetracycline 48.7% (39/80), followed by nalidixic acid 13.7% (11/80), gentamicin 6.2% (5/80) and Ciprofloxacin 3.7% (3/80). Resistance to amikacin, cefotaxime and ceftazidime were not detected. A frequency of 46 STEC isolates (36.2%) were obtained, of which 28/46 (22.0%) expressed stx1, stx2 3/46 (6.5%), stx1, stx2 13/46 (10.2%) and eae 2/46 (1.6%). Thirty different serotypes were obtained. The three serotypes with the highest number of isolates (four each) were: O76:H19, O118:H27 and O146:H21 which have been identified as a cause of diarrhea in human population. An isolate of serogroup O104 was obtained, with a significant importance for European public health. In virtue of the discovered serotypes and the virulence factors distribution, we can affirm that the obtained isolates from lambs in the State of Mexico are classifiable as atypical STEC of low virulence

Phenotypic and genotypic profile of clinical and animal multidrug-resistant Salmonella enterica isolates from Mexico

Descripción de Salmonella enterica multirresistenteAims: The objective of this study was to obtain a phenotypic and genotypic profile of Salmonella enterica including multidrug-resistant (MDR) isolates from food-producing animals and clinical isolates, as well as their genetic relatedness in two different States of Mexico (Jalisco and State of Mexico). Methods and Results: A total of 243 isolates were evaluated in terms of antimicrobial resistance (AMR) and related genes through a disk diffusion method and PCR respectively; we found 16 MDR isolates, all of them harbouring the blaCMY gene but not qnr genes, these isolates represent less than 10% of the collection. The pulsed-field gel electrophoresis revealed a higher genotypic similitude within isolates of State of Mexico than Jalisco. Conclusions: A low percentage of Salmonella isolates were resistant to relevant antibiotics in human health, nevertheless, the AMR and involved genes were similar despite the different serovars and origin of the isolates. Significance and Impact of the Study: This investigation rovided an insight of the current status of AMR of Salmonella isolates in two States of Mexico and pinpoint the genes involved in AMR and their epidemiological relationship, the information could help to determine an adequate therapy in human and eterinary medicine

CARACTERIZACIÓN DE Escherichia coli AISLADOS DE HISOPADOS RECTALES DE CORDEROS DEL ESTADO DE MÉXICO.

E. coli es uno de los microorganismos más difundidos en la naturaleza y además el integrante principal de la flora intestinal normal, pero consistentemente la bacteria es uno de los agentes etiológicos más importantes de las diarreas neonatales de los mamíferos, concretamente cuando intervienen determinadas cepas de E. coli que poseen una peculiar capacidad de adhesión selectiva de las células epiteliales del intestino (Gallego y Pérez, 1993). Las diferentes investigaciones realizadas señalan que E. coli está presente en el 30% al 40% de los focos de diarrea neonatal de los corderos, pero en concordancia con el principio etiológico del síndrome diarreico neonatal, la presentación de la diarrea colibacilar, al igual que la producida por otros microorganismos, no va a depender en exclusiva de las complejas características antigénicas, serológicas y de los factores de virulencia de las cepas de E. coli. La edad del cordero, con una mayor susceptibilidad cuanto más temprana, y el nivel de inmunidad pasiva aportado por el calostro, son igualmente determinantes, asimismo, varios de los elementos del factor entorno van a condicionar la presentación de la enfermedad; en concreto los aspectos que se engloban en lo que habitualmente se denomina manejo, como deficiencias en higiene, humedad, temperatura ambiente, hacinamiento y coexistencia de edades muy diferentes (Gallego y Pérez 1993). Las infecciones sistémicas causadas por E. coli son bastantes frecuentes en terneros, corderos y pollos. Las cepas septicémicas de E. coli presentan mecanismos especiales para superar las defensas del hospedador. Son capaces de alcanzar la corriente sanguínea tras penetrar por el intestino, los pulmones o el tejido umbilical (Quinn et al., 2005).E. coli es uno de los microorganismos más difundidos en la naturaleza y uno de los integrantes principales de la flora intestinal normal, pero algunos serotipos son agentes causales de diarreas neonatales en los mamíferos. Las diferentes investigaciones realizadas señalan que E. coli está presente en el 30% al 40% de los focos de diarrea neonatal de los corderos. La resistencia a los antimicrobianos es un problema importante que va en aumento en humanos como en animales. El amplio uso y a veces indiscriminado de estos compuestos da lugar a una selección de bacterias que son hereditariamente resistentes. El objetivo de este trabajo es evaluar la resistencia a los antibióticos β-lactámicos, quinolonas, tetraciclinas y aminoglucósidos en cepas de Escherichia coli aisladas de corderos con y sin diarrea y madres. Se tomaron 182 muestras de hisopados rectales en ocho unidades de producción del estado de México, se realizó la siembra en agar EMB para el aislamiento de E. coli, a las colonias sospechosas se les realizaron pruebas bioquímicas para su identificació

Aislamiento e identificación fenotípica y genotípica de Moraxella ovis de casos clínicos de queratoconjuntivitis ovina en el Estado de México

La queratoconjuntivitis contagiosa ovina (QCO) es una enfermedad infectocontagiosa que produce ceguera temporal o permanente en ovinos y caprinos, se encuentra asociada a un conjunto de agentes infecciosos como Moraxella ovis, Mycoplasma conjunctivae y Chlamydia psittaci, el diagnóstico se realiza mediante un examen clínico y pruebas de laboratorio. De un total de 861 animales examinados, 209 presentaron algún tipo de lesión ocular resultando en una prevalencia del 24.27% de animales con lesiones compatibles con QCO. De las 209 muestras remitidas al laboratorio se lograron identificar 58 como Moraxella ovis mediante bacteriología y por la amplificación de los genes 16S rRNA y RxtA por PCR. En virtud de los resultados podemos concluir que Moraxella ovis esta involucrada en los casos de QCO en establecimientos productores de ovinos en el Estado de México

Microbial Contamination in Milk Quality and Health Risk of the Consumers of Raw Milk and Dairy Products

d market. Milk quality and food safety concern in the consumers’ health and nutrition in public health surveillance prevent food-borne diseases, food poisoning, and zoonosis risk by raw milk and fresh dairy products. The aim of this work is focused on milk microbial contamination and its impacts on milk production and dairy industry with their implications in milk product quality, food-borne diseases from raw milk, and unpasteurized milk by food-borne pathogen microbial contamination and milk and dairy product spoilage. The microbial milk contamination source comes from herd hygiene and health status, mastitis prevalence, production environment, and milking parlor and milk conserving practices in dairy farm. Moreover, these facts are implicated in milk quality and milk spoilage and unsafe dairy products. The milk production system and the dairy plant operations keep track in pasteurized milk and fresh dairy products reviewing the traceability in field situational diagnosis report