Caracterización epidemio-molecular de la infección por Clostridioides difficile en pacientes hospitalizados con cuadro diarreico en instituciones de salud. 2019

La infección por Clostridioides difficile es una de las principales causas de diarrea nosocomial en hospitales del mundo, asociada a antibióticos de amplio espectro. Estudio descriptivo, retrospectivo, de corte transverso, de tipo censal. Se estudiaron 281 muestras de pacientes hospitalizados con la infección, se analizaron características socio-demográficas, clínicas y se caracterizó molecularmente al patógeno. Como resultado, se obtuvieron pacientes con la infección con una mediana de edad de 64 años siendo el 61,5 % del sexo masculino. El promedio de presentación del cuadro diarreico fue de 5 días, con tratamiento antimicrobiano de 8 días e internación de 15 días. El 94% tuvo tratamiento antimicrobiano previo, y el 6% estuvo expuesto a algún factor de riesgo. Los antimicrobianos más utilizados solos o en combinación fueron betalactámicos, fluoroquinolonas, vancomicina y carbapenémicos. Las áreas de internación con mayor frecuencia de presentación de la infección fueron las unidades de Clínica Médica, Traumatología, Geriatría y Unidad de Terapia Intensiva. La prevalencia de C. difficile toxigénico fue de 14%, y de esta frecuencia el 100% presentó toxinas TcdA y TcdB, con ausencia de toxinas binarias y deleción del gen tcdC. Se constató la presencia grupos clonales en la misma unidad de internación y misma institución de salud. El 100% de las cepas resultaron susceptibles a los antibióticos de elección para la infección. La prevalencia de la infección y presencia de perfiles clonales detectadas revelan la necesidad de un mejoramiento en el sistema de control de infecciones, así como del fortalecimiento y vigilancia de la resistencia antimicrobiana.

Clostridioides difficile infection is one of the main causes of nosocomial diarrhea in hospitals worldwide, associated with broad-spectrum antibiotics. Descriptive, retrospective, cross-sectional, census-type study. Two hundred eighty-one samples from patients hospitalized with the infection were studied, sociodemographic and clinical characteristics were analyzed and the pathogen was characterized molecularly. As a result, patients with the infection had a median age of 64 years and 61.5% male. The average presentation of diarrhea was 5 days, antimicrobial treatment 8 days and hospitalization 15 days. Ninety four percent had previous antimicrobial treatment, and 6% were exposed to some risk factor. The most commonly used antimicrobials alone or in combination were beta-lactams, fluoroquinolones, vancomycin, and carbapenems. The hospitalization areas with the highest frequency of presentation of the infection were the Clinical Medicine, Traumatology, Geriatrics and Intensive Care Unit units. The prevalence of toxigenic C. difficile was 14%, and of this frequency, 100% presented TcdA and TcdB toxins, with the absence of binary toxins and deletion of the tcdC gene. The presence of clonal groups was verified in the same hospitalization unit and the same health institution. All the strains were susceptible to the antibiotics of choice for the infection. The prevalence of infection and the presence of clonal profiles detected reveal the need for improvement of the infection control system, as well as of the strengthening and surveillance of antimicrobial resistance.

Antifungal potential of biosurfactants produced by strains of Bacillus spp. (Bacillales: Bacillaceae) selected by molecular screening / Potencial antifúngico de biosulfactantes producidos por cepas de Bacillus spp. (Bacillales: Bacillaceae) seleccionadas por tamizaje molecular

Introduction: Bacillus species are used as biological controllers for phytopathogenic fungi, and the mechanisms to produce controllers include biosynthesis of lipopeptide biosurfactants with antifungal activity. Objective: To evaluate the antifungal potential of the biosurfactants produced by Bacillus strains, selected by molecular screening, on Fusarium oxysporum. Methods: We selected four molecular markers, related to the biosynthesis of surfactin, fengicin, and lichenysin (srfA, spf, fenB, LichAA) in nine Bacillus strains. We used two mineral media with several culture conditions, for biosurfactant production, and a well diffusion test for antifungal potential. Results: Only the biosurfactant produced by UFAB25 inhibits the mycelial growth of F. oxysporum (44 % ± 13): this biosurfactant was positive for srfA, spf, and fenB genes involved in the synthesis of surfactin and fengicine. Antifungal activity depends on culture conditions and the strain. Conclusions: Genetic markers are useful to detect strains with antifungal potential, facilitating the selection of bio-controllers. The biosurfactant profile is influenced by the strain and by culture conditions.

Introducción: Especies de Bacillus han sido empleadas como controladores biológicos contra hongos fitopatógenos. Entre los mecanismos utilizados se destaca la biosíntesis de biosurfactantes lipopeptídicos con actividad antifúngica. Objetivo: Evaluar el potencial antifúngico de los biosurfactantes producidos por cepas Bacillus nativas, previamente seleccionadas mediante tamizaje molecular, sobre Fusarium oxysporum. Métodos: Se utilizaron cuatro marcadores moleculares, relacionados con la biosíntesis de surfactina, fengicina y liquenisina (srfA, spf, fenB, LichAA) sobre nueve cepas de Bacillus. Se utilizaron dos medios minerales con diferentes condiciones de cultivo para la producción del biosurfactante. Se evaluó el potencial antifúngico de los biosurfactantes mediante la prueba de difusión en pozos. Resultados: Se determinó que solo el biosurfactante producido por UFAB25 actúa como inhibidor del crecimiento micelial de Fusarium oxysporum (43.6 % ± 13), esta cepa es positiva para los genes srfA, spf y fenB, involucrados en la síntesis de surfactina y fengicina. La actividad antifúngica depende de las condiciones de cultivo y la cepa. Conclusiones: Los marcadores genéticos ayudan a detectar cepas con potencial antifúngico, facilitando la selección de biocontroladores. El perfil del biosurfactante está influenciado no solo por la cepa, sino también por las condiciones del cultivo.

Creación del primer biorrepositorio nacional de bacterias multirresistentes disponible para el estudio de la resistencia bacteriana en Chile

La disponibilidad de cepas bacteriana para el estudio de la resistencia bacteriana es clave para los avances en la investigación básica y clínica respecto del tema. Existen pocos biorrepositorios o bancos de bacterias con mecanismos de resistencia conocidos, aisladas de infecciones clínicamente significativas. Una revisión de la literatura revela que sólo en los Estados Unidos de América existe un biobanco de aislados resistentes disponibles para estudios. En esta publicación se cuenta cómo se creó el primer biorrepositorio de bacterias resistentes en Chile asociados a la Red de Laboratorios MICROB-R, con la participación de 11 centros distribuidos a lo largo del país, que a la fecha cuenta con más de 3.500 aislados bacterianos estudiados fenotípica y genotípicamente, disponibles para la comunidad científica chilena.

The availability of bacterial strains for the study of bacterial resistance is key to advances in basic and clinical research. There are few biobanks of bacteria with known resistance mechanisms, isolated from clinically significant infections. A review of the literature reveals that only in the United States of America is there a biobank of resistant isolates. This publication shows the creation of the first biorepository of resistant bacteria Chile associated with the MICROB-R Laboratory Network, with the participation of 11 centers distributed throughout the country, which to date has more than 3,500 bacterial isolates studied phenotypically and genotypically, available to the Chilean scientific community.

Organoides: fundamentos, presente y futuro / Organoids: fundamentals, present and future

RESUMEN Los organoides son estructuras miniaturizadas, generadas principalmente a partir de células madre pluripotentes inducidas, que se cultivan en el laboratorio conservando sus características innatas o adquiridas. Tienen el potencial de reproducir procesos de desarrollo biológico, modelar procesos patológicos que permitirán el descubrimiento de nuevos fármacos y propicien la medicina regenerativa. Sin embargo, estas experiencias requieren perfeccionamiento constante porque pueden haberse realizado variaciones en la constitución de estos órganos. Por ello, el presente artículo tiene como objetivo revisar la información actualizada sobre organoides y sus procesos experimentales básicos y recientes, empezando por la gastrulación, para tratar de imitar, en lo posible, la formación de las tres capas: ectodermo, mesodermo y endodermo, incluyendo los factores que intervienen en la inducción, diferenciación y maduración en la generación de estos organoides. Asimismo, el diseño y preparación de medios de cultivo altamente especializados que permitan obtener el órgano seleccionado con la mayor precisión y seguridad. Se realizó una búsqueda de artículos originales y de revisión publicados en PubMed, Nature y Science. Los artículos se seleccionaron por sus resúmenes y por su texto completo. Las conclusiones de este articulo destacan las ventajas futuras en el uso y aplicaciones de los organoides.

ABSTRACT Organoids are tiny structures, mainly generated from induced pluripotent stem cells, which are cultured in the laboratory while retaining their innate or acquired characteristics. They have the potential to reproduce biological development processes, model pathological processes that will enable the discovery of new drugs and promote regenerative medicine. However, these processes require constant improvement because variations may have occurred in the constitution of the organs. Therefore, this article aims to review updated information on organoids and their basic and recent experimental processes, starting with gastrulation, in an attempt to mimic, as much as possible, the formation of the three layers: ectoderm, mesoderm and endoderm; as well as the information regarding the factors involved in the induction, differentiation and maturation during the generation of organoids. Likewise, the design and preparation of highly specialized culture media that allow obtaining the selected organ with the highest precision and safety. We searched for original and review articles published in PubMed, Nature and Science. Articles were selected for their abstracts and full text. The conclusions of this article highlight the future advantages in the use and applications of organoids.

Phenotypic and molecular characterization of erythromycin resistance in Campylobacter jejuni and Campylobacter coli strains isolated from swine and broiler chickens / Caracterização fenotípica e molecular da resistência à eritromicina em cepas de Campylobacter jejuni e Campylobacter coli isoladas de suínos e frangos de corte

Campylobacter spp. is a bacterial agent that causes gastroenteritis in humans and may trigger Guillain-Barré Syndrome (GBS) and is also considered one of the main foodborne diseases in developed countries. Poultry and pigs are considered reservoirs of these microorganisms, as well as raw or undercooked by-products are often incriminated as a source of human infection. Treatment in human cases is with macrolide, such erythromycin, that inhibits the protein synthesis of the microorganism. This study aimed to isolate Campylobacter jejuni and Campylobacter coli from intestinal content samples of broiler chickens (n=20) and swine (n=30) to characterize the erythromycin resistance profile of the strains and to detect molecular mechanisms involved in this resistance. The minimum inhibitory concentration was determined by agar dilution. The Mismatch Amplification Mutation Assay-Polymerase Chain Reaction (MAMA-PCR) was performed to detect mutations at positions 2074 and 2075 of 23S rRNA region, in addition to PCR test to detect the erm(B) gene. From the intestinal content of broiler chickens, 18 strains of C. jejuni and two strains of C. coli were isolated, whereas, from swine samples, no C. jejuni strain and 14 strains of C. coli were isolated. All C. coli strains were resistant, and three C. jejuni strains from broilers chickens were characterized with intermediate resistance to erythromycin. The MIC of the strains ranged from ≤0.5mg/μL to ≥128mg/μL. All resistant strains had the A2075G mutation, and one strain with intermediate resistance had the A2075G mutation. However, the A2074C mutation and the erm(B) gene were not detected. High resistance levels were detected in C. coli strains isolated from swine. The MAMA-PCR is a practical tool for detecting the erythromycin resistance in Campylobacter strains.(AU)

Campylobacter spp. é um agente bacteriano causador de gastroenterite em humanos e associado à síndrome de Guillain-Barré, sendo a campilobacteriose considerada uma das principais enfermidades de origem alimentar. Aves e suínos são importantes reservatórios desses microrganismos e seus produtos derivados crus ou mal cozidos são muitas vezes incriminados como fonte de infecção humana. A primeira escolha para o tratamento em casos humanos são os antimicrobianos da classe dos macrolídeos como à eritromicina. Dentro desse contexto, o objetivo deste estudo foi isolar Campylobacter jejuni e C. coli a partir de 20 amostras de conteúdo intestinal de frangos de corte e de 30 de suínos ao abate e investigar a resistência à eritromicina das estirpes obtidas e os possíveis mecanismos moleculares envolvidos nesta resistência. A concentração inibitória mínima foi determinada pela diluição em ágar e a técnica MAMA-PCR foi utilizada para detecção de mutações nas posições 2074 e 2075 da região 23s rRNA, foi pesquisado também a presença do gene erm(B) pela PCR. A partir do conteúdo intestinal de frangos de corte foram isoladas 18 estirpes de C. jejuni e duas de C. coli, enquanto de suínos foram obtidas 14 estirpes de C. coli e nenhuma estirpe de C. jejuni. Todas as estirpes de C. coli de suínos foram identificadas como resistentes e três estirpes de C. jejuni de frangos foram caracterizadas com resistência intermediária. A CIM das estirpes variou de ≤0,5mg/μL a ≥128mg/μL. Todas as estirpes resistentes tinham a mutação A2075G e uma cepa com resistência intermediária também apresentou a mutação A2075G. Não foi detectada a mutação A2074C ou a presença do gene erm(B) em nenhuma das estirpes obtidas. Os resultados revelam um alto nível de resistência em estirpes de C. coli isoladas de suínos frente a eritromicina. A técnica MAMA PCR utilizada se constitui em uma ferramenta prática para detecção da resistência à eritromicina em estirpes de C. jejuni e C. coli.(AU)

Pathogenic potential of Brucella ovis field isolates with different genotypic profile and protection provided by the vaccine strain B. ovis ΔabcBA against B. ovis field isolates in mice / Vacina viva atenuada Brucella ovis Δ abcBA encapsulada protege camundongos frente a desafios de B. ovis isoladas de campo

Brucella ovis causes economic and reproductive losses in sheep herds. The goal of this study was to characterize infection with B. ovis field isolates in a murine model, and to evaluate protection induced by the candidate vaccine strain B. ovis ΔabcBA in mice challenged with these field isolates. B. ovis field strains were able to colonize and cause lesions in the liver and spleen of infected mice. After an initial screening, two strains were selected for further characterization (B. ovis 94 AV and B. ovis 266 L). Both strains had in vitro growth kinetics that was similar to that of the reference strain B. ovis ATCC 25840. Vaccination with B. ovis ΔabcBA encapsulated with 1% alginate was protective against the challenge with field strains, with the following protection indexes: 0.751, 1.736, and 2.746, for mice challenged with B. ovis ATCC25840, B. ovis 94 AV, and B. ovis 266 L, respectively. In conclusion, these results demonstrated that B. ovis field strains were capable of infecting and inducing lesions in experimentally infected mice. The attenuated vaccine strain B. ovis ΔabcBA induced protection in mice challenged with different B. ovis field isolates, resulting in higher protection indexes against more pathogenic strains.(AU)

Brucella ovis é responsável por perdas econômicas e reprodutivas em rebanhos ovinos. O objetivo deste trabalho foi caracterizar a infecção com as cepas isoladas de campo de B. ovis em modelo murino e avaliar a eficiência vacinal da mutante B. ovis ΔabcAB para proteção contra desafio com as cepas isoladas de campo. Foram utilizadas sete cepas isoladas de campo foram capazes de colonizar e provocar lesões no fígado e no baço de camundongos após sete dias pós-infecção. Após triagem, duas cepas foram selecionadas para a melhor caracterização (B. ovis 94 AV and B. ovis 266L). Ambas apresentaram crescimento em placa de cultivo semelhante ao da cepa de referência B. ovis ATCC 25840. A vacinação com a cepa de Brucella ovis ΔabcBA encapsulada com alginato a 1% foi capaz de proteger camundongos desafiados com as cepas isoladas de campo, com os seguintes índices de proteção: 0,751, 1,736 e 2,746, para camundongos desafiados com B. ovis ATCC 25840, B. ovis 94 AV e B. ovis 266 L, respectivamente. Estes resultados demonstraram que as cepas isoladas de campo de B. ovis são capazes de infectar e induzir lesão em camundongos experimentalmente infectados. O uso da cepa mutante atenuada B. ovis ΔabcBA para vacinação de fêmeas C57BL/6 desafiados com diferentes cepas de B. ovis induziu proteção nos camundongos desafiados com diferentes cepas de B. ovis. Deste modo, mostrando-se eficiente na proteção das cepas de campo de B. ovis.(AU)

Identificación de Bacillus toyonensis en hecesde ganado cebú en el Departamento de Sucre, Colombia / Identification of Bacillus toyonensis in faeces of zebu cattle in the Sucre Department, Colombia

RESUMEN Se evaluaron las características probióticas de cepas nativas aisladas de ganado cebú y se realizó identificación molecular de una de estas cepas, para considerar su posterior aplicación como aditivos microbianos en la alimentación bovina. Se usaron muestras de estiércol de terneros de levante, se aislaron bacterias y levaduras, determinándose la capacidad probiótica de estas cepas mediante pruebas como; resistencia a sales biliares (0.05, 0.1, 0.1 5 y 0.3 %), resistencia a pH ácido (pH 3, 4, 5.6, 7), tolerancia a NaCl (2, 4, 6, 8,10 %), actividad antagónica (Salmonella spp., y Escherichia coli), producción de gas a partir de la glucosa, y crecimiento a diferentes temperaturas (37 y 40 °C). La identificación preliminar de las cepas se realizó mediante: tinción de Gram, tinción de endosporas (método de Wirtz), prueba de la catalasa, prueba de oxidasa. Se seleccionó una de las cepas que superó las pruebas pro-bióticas para su identificación mediante métodos moleculares y se realizó el análisis filogenético de la misma utilizando la base de datos NCBI Reference Sequence (RefSeq). Los ensayos se organizaron en un diseño completamente al azar, los resultados obtenidos por triplicado se sistematizaron en el software Statgraphics Centurion XVI y el efecto de los diferentes tratamientos se analizó estadísticamente mediante análisis de varianza. Se aislaron 10 cepas nativas, identificándose molecularmente a Bacillus toyonensis. Esta investigación representa el primer reporte molecular de B. toyonensis en estiércol de terneros de levante cebú en el Departamento de Sucre, el cual ha sido ampliamente utilizado como probiótico en la nutrición animal.

ABSTRACT Probiotic characteristics of isolated native strains from zebu cattle were evaluated and molecular identification of one of these strains was performed to consider their subsequent application as microbial additives for bovine feeding. Manure samples were collected from growing zebu calves. Bacteria and yeasts were isolated and the probiotic capacity of these strains was determined by means of tests such as; resistance to bile salts (0.05, 0.1, 0.15 and 0.3 %), resistance to acid pH (pH 3, 4, 5.6, 7) tolerance to NaCl (2, 4, 6, 8, 10 %), antagonistic activity (Salmonella sp. and Escherichia coli), gas production from glucose, and growth at different temperatures (37 and 40 °C). Preliminary identification of the strains was performed by techniques such as: Gram staining, endospore staining (Wirtz method), catalase and oxidase test. One of the strains that exceeded the probiotic probes was selected for its identification employing molecular methods and the phylogenetic analysis was performed using the NCBI Reference Sequence (RefSeq) database. The trials were organized in a Completely Randomized Design, whose results obtained in triplicate were systematized in the Statgraphics Centurion XVI software and the effect of the different treatments was analyzed statistically through an analysis of variance. 10 native strains were isolated, identifying Bacillus toyonensi molecularly. This research represents the first molecular report of B. toyonensis in manure from growing zebu calves in the Sucre Department, which has been widely used as a probiotic in animal nutrition.

Detection of efflux pump CmeABC in enrofloxacin resistant Campylobacter spp. strains isolated from broiler chickens (Gallus gallus domesticus) in the state of Rio de Janeiro, Brazil / Detecção da bomba de efluxo CmeABC em cepas de Campylobacter spp. resistentes à enrofloxacina isoladas de frangos de corte (Gallus gallus domesticus) no Estado do Rio de Janeiro, Brasil

Fowls are the main reservoirs of the highly important food-originating pathogen called Campylobacter spp. and broilers' meat and byproducts are the main vehicles of this microorganism. Increasing of Campylobacter spp. resistant strains to fluorquinolones, an antimicrobial class often employed in poultry farming and in human medicine has become a great concern to poultry breeders. In fact, several studies evaluated increasing bacterial resistance against these antimicrobial agents. The role of CmeABC efflux system has been underscored among the resistance mechanisms in Campylobacter spp. to fluorquinolones. This study investigated the occurrence of CmeABC efflux pump in 81 and 78 enrofloxacin resistant strains of Campylobacter jejuni and C. coli respectively, isolated from broilers collected from six abattoirs situated at São José do Vale do Rio Preto/RJ poultry center and from two commercial abattoirs situated at Metropolitan Region of Rio de Janeiro, from 2013 to 2016. The resistance to enrofloxacin was assessed by agar dilution to determine minimum inhibitory concentration (MIC). The CmeABC efflux system was investigated through the detection of genes genes cmeA, cmeB and cmeC by PCR. The activity of CmeABC efflux pump was investigated in 20 strains by using the efflux pump inhibitor Phenylalanine-Arginine ß-Naphthylamide (PAßN). The three genes cmeA, cmeB and cmeC were detected in 94.3% of the strains (C. jejuni = 80 and C. coli = 70), whereas the system was absent or incomplete in 5.7% of strains (C. jejuni = 1 and C. coli = 8). MIC varied between 0.5µg/ml and 64µg/ml, and 88.7% of strains were enrofloxacin resistant and 11.3% featuring intermediate resistance. The inhibition of the efflux pump by PAßN reduced the MIC to enrofloxacin up to eight times in fifteen strains (75%). These results indicate that this system is frequent and active in Campylobacter spp. Resistant strains in the presence of enrofloxacin.(AU)

As aves são os principais reservatórios de Campylobacter spp., importante patógeno de origem alimentar e a carne de frango e produtos derivados são os principais veículos desse microrganismo. O aumento de cepas de Campylobacter spp. resistentes às fluorquinolonas, uma classe antimicrobiana frequentemente empregada na avicultura e na medicina humana, tornou-se uma grande preocupação para os produtores de aves e vários estudos avaliaram o aumento da resistência bacteriana a esses antimicrobianos. O papel do sistema de efluxo CmeABC tem sido enfatizado entre os mecanismos de resistência em Campylobacter spp. à fluorquinolonas. O presente estudo investigou a ocorrência da bomba de efluxo CmeABC em 81 cepas de Campylobacter jejuni e 78 cepas de Campylobacter coli resistentes à enrofloxacina, isoladas de frangos de corte coletados em seis abatedouros situados no polo avícola de São José do Rio Preto/RJ e de dois abatedouros comerciais situados na Região Metropolitana do Rio de Janeiro, de 2013 a 2016. A resistência à enrofloxacina foi avaliada pelo método de diluição em ágar para determinar a concentração inibitória mínima (CIM). O sistema de efluxo CmeABC foi investigado através da detecção dos genes cmeA, cmeB e cmeC por PCR. A atividade da bomba de efluxo CmeABC foi investigada em 20 cepas utilizando o inibidor da bomba de efluxo Phenylalanine-Arginine ß-Naftilamida (PAßN). Os três genes cmeA, cmeB e cmeC foram detectados em 94,3% das cepas (C. jejuni = 80 e C. coli = 70), enquanto o sistema estava ausente ou incompleto em 5,7% das cepas (C. jejuni = 1 e C coli = 8). A CIM variou entre 0,5µg/ml e 64µg/ml e 88,7% das cepas foram resistentes à enrofloxacina, enquanto 11,3% apresentaram resistência intermediária. A inibição da bomba de efluxo pelo PAßN reduziu a CIM da enrofloxacina até oito vezes em quinze cepas (75%). Estes resultados indicam que este sistema é frequente e ativo em cepas resistentes de Campylobacter spp. na presença de enrofloxacina.(AU)

Antimicrobial and antibiofilm activity of the essential oil from dried leaves of Eucalyptus staigeriana / Atividade antimicrobiana e antibiofilme do óleo essencial de folhas secas de Eucalyptus staigeriana

In recent years, compounds with biological properties produced by plants have received attention as an alternative to control microorganisms. Essential oils extracted from green leaves of Eucalyptus sp. have been demonstrated to have antimicrobial activities, but so far there are no reports of antimicrobial activity of essential oils extracted from dried leaves of Eucalyptus staigeriana. So, the objectives of this study were to determine the chemical composition of the essential oils obtained from dried leaves of E. staigeriana (EOdlES) and to evaluate in vitro antimicrobial and antibiofilm activities of EOdlES against gram-positive and gram-negative, resistance and multiresistant Enterococcus faecalis isolated from food and clinical samples. The characterization of EOdlES was performed by gas chromatography-mass spectrometry (GC/MS). For this study, 26 bacterial strains were used, which included 11 reference strains and 15 antibiotic resistant and multiresistant E. faecalis strains. Antimicrobial activities of EOdlES against gram-positive and gram-negative were determined using the disc diffusion method. The minimum inhibitory concentration (MIC) value was evaluated by a microbroth dilution technique. The antibiofilm effects were assessed by microtiter plate method. As a result, 21 compounds were identified, being oxygenated monoterpenes (69.58%) the major chemical family. EOdlES showed only antimicrobial activity against gram-positive strains. E. faecalis resistant and multiresistant strains show the lowest MIC (3.12 to 6.25%), when compared with reference E. faecalis strain. EOdlES has the ability to inhibit the biofilm formation, but little or none ability to inhibit the preformed biofilm. This study demonstrates that EOdlES is a promising alternative to control important foodborne and clinic gram-positive resistant bacteria.(AU)

Nos últimos anos, compostos com propriedades biológicas produzidas por plantas têm recebido atenção como alternativa de controle de micro-organismos. Óleos essenciais extraídos de folhas verdes de Eucalyptus sp. têm demonstrado atividades antimicrobianas. No entanto, até o momento não há nenhum relato de atividade antimicrobiana de óleos essenciais extraídos de folhas secas de Eucalyptus staigeriana. O objetivo deste estudo foi determinar a composição química dos óleos essenciais obtidos de folhas secas de E. staigeriana e avaliar in vitro a sua atividade antimicrobiana e de antibiofilme contra gram-positivas e gram-negativas e também resistentes e multirresistentes de Enterococcus faecalis isolados de amostras de alimentos e clínicas. A caracterização de E. staigeriana foi realizada por CG-EM. Para este estudo foram utilizadas 26 cepas bacterianas, que incluíram 11 cepas referência e 15 cepas de E. faecalis resistentes a antibióticos. A atividade antimicrobiana de E. staigeriana contra gram-positivas e gram-negativas foi determinada utilizando o método de disco-difusão. Os valores da concentração inibitória mínima foram avaliados pela técnica de microdiluição. Os efeitos de antibiofilme foram avaliados pelo método de placa de microtitulação. Como resultado, 21 compostos foram identificados, sendo monoterpenos oxigenados (69,58%) a grande família química. E. staigeriana mostrou apenas atividade antimicrobiana contra cepas gram-positivas. Cepas de E. faecalis resistentes e multirresistentes mostraram a menor concentração inibitória mínima (3,12 para 6,25%) quando comparado com a cepa referência de E. faecalis. E. staigeriana apresentou a capacidade de inibir a formação de biofilme, mas pouca ou nenhuma capacidade de inibir o biofilme pré-formado. Este estudo demonstra que o óleo essencial obtido de folhas secas de E. staigeriana é uma alternativa promissora para controle importante de bactérias gram-positivas resistentes de origem alimentar e clínicas.(AU)

Resistencia Bacteriana por beta lactamasas de epectro extendido: un problema creciente / BACTERIAL RESISTANCE BY EXTENDED SPECTRUM BETA LACTAMASE: A GROWING PROBLEM

Las ß-lactamasas de espectro extendido (BLEE) son enzimas que generan resistencia a la mayoría de los b-lactámicos, incluyendo a penicilinas, cefalosporinas de primera, segunda, tercera generación, monobactámicos, excepto a la cefamicina y carbapenémicos. Esta resistencia se vio incrementada por el indiscriminado uso de cefalosporinas para infecciones incluso leves. También cuentan con frecuencia con genes para otros antimicrobianos como ser aminoglucosidos, tetraciclinas y cotrimoxazol. Además, las cepas BLEE (+) son más frecuentemente resistentes a quinolonas que las cepas no productoras de BLEE. La resistencia actual que existe a las betalactamasas de espectro extendido aumenta las tasas de mortalidad, ya que en pacientes con infecciones se inician tratamientos empíricos, que al no tener buena respuesta ocasionan que el cuadro clínico llegue a evolucionar hasta la sepsis. El tratamiento de elección en estos casos es el uso de carbapenémicos, recomendación que se basa principalmente en el resultado de resistencia observada in vitro. Los nuevos carbapenémicos, como ertapenem o doripenem parecen tener una excelente actividad. Se realiza una revisión de los aspectos básicos de la aparición de cepas BLEE y su importancia en el manejo de pacientes con cuadros infecciosos, que son de frecuente presentación en los Hospitales de referencia

Control del deterioro microbiológico de filetes de tilapia mediante la aplicación de bacterias lácticas / Control Microbiological Deterioration of Tilapia Fillets by the Application of Lactic Acid Bacteria / Controle de Deterioração Microbiológica da Tilápia Arquiva Através da Aplicação de Bactérias Láticas

Resumen En los últimos años se ha reconocido el potencial de las bacterias ácido lácticas (BAL) como agentes bioconservantes de productos cárnicos, incluido el pescado, al reducir el deterioro microbiológico y químico. El objetivo de este trabajo fue determinar el efecto bioconservante de dos cepas de BAL y el tiempo de impregnación en la calidad microbiológica y química de filetes de tilapia. Se evaluaron dos tiempos de impregnación (1h y 2h) y las BAL Lactobacillus plantarum JCM 1149 y Lactobacillus acidophilus ATCC4356. Los filetes bioconservados (FB) se almacenaron a 5°C y se evaluaron los cambios en el recuento de BAL, mesófilos, psicrófilos y coliformes totales durante 30 días. Los recuentos en los FB fueron de 5.94 de Log UFC/g. de BAL, y <2.7 log UFC/g de coliformes y psicrófilos. Los filetes control presentaron recuentos de 1.2 log UFC/g de BAL mientras los coliformes totales y psicrófilos superaron el límite permitido para consumo humano luego de 10 días. Luego de 10 días. El tratamiento que mantuvo la calidad microbiológica y química de los FB por más tiempo fue L. plantarum con inmersión de una hora. Las BAL estudiadas mostraron un efecto inhibitorio de la microflora deteriorante del pescado y una reducción en la formación de nitrógeno volátil, siendo un método viable para la conservación del pescado.

Abstract In recent years, it has recognized the potential of lactic acid bacteria (LAB) as biopreservatives agents for meat products, including fish, by reducing the microbiological and chemical spoilage. The aim of this study was to determine the effect of two strains biopreservative LAB and impregnation time on the microbiological and chemical quality of tilapia fillets. Two impregnation time (1h and 2h) and two LAB (Lactobacillus plantarum JCM 1149 and Lactobacillus acidophilus ATCC4356 were evaluated. The biopreserved fillets (BF) were stored at 5 ° C and the changes of the LAB count, mesophilic, psychrophilic and total coliforms., were evaluated for 30 days. The microbiological analysis show for the BF 5.94 log CFU / g. of LAB and <2.7 log CFU / g of coliform and psychrophilic bacteria. The control Fillets showed 1.2 log CFU / g of LAB while the psychrophile and total coliforms exceeded the allowed limit for human consumption after 10 days. The treatment kept the microbiological and chemical quality of the BF longer was L. plantarum with one hour of impregnation. The LAB studied showed an inhibitory effect of the spoilage microflora of fish and a reduction in the formation of volatile nitrogen compounds, being a viable fish preservation method.

Resumo Nos últimos anos tem se reconhecido o potencial das bactérias ácido lácticas (BAL) como agentes bioconservantes de pro dutos carnicos, incluído o peixe ao diminuir o deterioro microbiológico e químico. O propósito deste estudo foi determinar o efeito bioconservante de duas cepas de BAL e a avaliação do tempo de impregnação requerido para obter uma boa qua lidade microbiológica e química de filetes de tilapia. Foram avaliados dois tempos de impregnação (1h e 2h) com as BAL Lactobacillus plantarum JMC 1149 e Lactobacillus acidophilus ATCC4356. Os filetes biopreservados (FB) foram estocados a 5oC e valoradas as modificações na contagem de microorganismos BAL, mesófilos, psicrófilos, coliformes totais durante 30 dias. As contagens microbianas nos FB foram de 5.94 de log UFC/g e <2.7 log UFC/g de coliformes e psicrofilos. Os filetes controle apresentaram valores de 1.2 log UFC/g de BAL, não entanto os coliformes totais e psicrófilos superaram o limite permitido para consumo humano após 10 dias de estocagem. O tratamento que manteve a qualidade microbiológica e química dos FB por maior tempo foi de imersão com Lactobacillus plantarum por uma hora. As BAL estudadas amostraram um efeito inibitório da microflora deteriorante dos peixes e uma redução na formação de nitrogênio volátil se apresentan do como um método viável para a preservação de filete de peixe

Nanopartículas de CuO y su propiedad antimicrobiana en cepas intrahospitalarias / CuO nanoparticles and their antimicrobial activity against nosocomial strains / Nanopartículas de CuO e sua propriedade antimicrobiana frente a cepas intrahospitalares

Resumen Empleando un prototipo de reactor, se sintetizaron nanopartículas (NPs) de CuO a través del método de precipitación a partir de CuSO25H2O y de Cu(CH3COO)2H2O. Las NPs obtenidas fueron caracterizadas mediante XRD, FT-IR, TEM y SEM. La actividad antimicrobiana de las NPs se determinó mediante el método de difusión en placa, colocando 20 mg de NPs de CuO sobre cuatro cepas intrahospitalarias o nosocomiales aisladas de la Unidad de Cuidados Intensivos de un hospital nacional de Lima norte (Staphylococcus epidermidis, Aerococcus viridans, Ochrobactrum anthropi y Micrococcus lylae). La caracterización de las NPs de CuO demostró que las sintetizadas a partir de acetato (CuO-Acet) presentaron una fase pura de CuO, mientras que las sintetizadas a partir de sulfato (CuO-Sulf) presentaron dos fases, donde la de CuO representó más del 84%. Los dominios cristalinos del CuO-Acet y CuO-Sulf fueron 15 y 19 nm, respectivamente. Los halos de inhibición de las cepas estudiadas fueron mayores para las NPs de CuO-Sulf que para las NPs de CuO-Acet; solo para la cepa Ochrobactrum anthropi se presentaron halos similares para ambos tipos de NPs.

Abstract Using a prototype reactor, CuO nanoparticles (NPs) were synthetized through the precipitation method, starting from CuSO2 5H2O and Cu(CH3COO)2H2O. The obtained NPs were characterized by XDR, FT-IR, SEM, and TEM. The antimicrobial activity of the NPs was determined by the plate diffusion method, placing 20 mg of NPs onto four nosocomial strains obtained from north Lima national hospital Intensive-Care Unit (Staphylococcus epidermidis, Aerococcus viridans, Ochrobactrum anthropic, and Micrococcus lylae). NPs characterization revealed that those synthetized from acetate (CuO-Acet) shown pure CuO phase, while those synthetized from sulphate CuO-Sulf shown two phases where CuO was the predominant one, having more than 84%. The crystal domains for CuO-Acet and CuO-Sulf were 15 and 19 nm, respectively. The inhibition halos for the studied strains were larger for CuO-Sulf NPs than CuO-Acet NPs, only Ochrobactrum anthropi displayed similar inhibition halos for both types of NPs.

Resumo Usando um protótipo de reator, sintetizaram-se nanopartículas (NPs) de CuO pelo método de precipitação a partir de CuSO25H2O e de Cu(CH3COO)2H2O. As NPs obtidas foram caracterizadas por meio das seguintes técnicas: XRD, FT-IR, TEM e SEM. A atividade antimicrobiana das NPs foi determinada pelo método de difusão em placa, colocando 20 mg de NPs de CuO sobre quatro cepas nosocomiais isoladas de uma Unidade de Terapia Intensiva no hospital nacional de Lima norte (Staphylococcus epidermidis, Aerococcus viridans, Ochrobactrum anthropic e Micrococcus lylae). A caracterização das NPs de CuO mostrou que as nanopartículas sintetizadas a partir do acetato (CuO-Acet) apresentavam uma fase pura de CuO, enquanto que as sintetizadas a partir do sulfato (CuO-Sulf), apresentaram duas fases sendo a fase maior de CuO, com mais de 84%. Os domínios cristalinos de CuO-Acet y CuO-Sulf foram 15 e 19 nm, respectivamente. Os halos de inibição das cepas estudadas foram maiores para as NPs de CuO-Sulf do que as NPs de CuO-Acet somente para a cepa Ochrobactrum anthropi, apresentaram-se halos de inibição parecidos.

Variability study of entomopathogenic nematode populations (Heterorhabditidae) from Argentina / Estudo da variabilidade entomopatogênicos nematóides populações (Heterorhabditidae) da Argentina

Abstract Entomopathogenic nematodes (EPN) belonging to the Heterorhabditidae family are lethal parasites of soil-dwelling insects. Two species were reported in Argentina: Heterorhabditis argentinensis and Heterorhabditis bacteriophora characterized mainly by morphometric features. In this work a comparative and phylogenetic study between five Heterorhabditis populations from Argentina was conducted to analyze the variability between strains and to evaluate the taxonomic position of Heterorhabditis argentinensis. The PCA analyses of morphometric characters separated the larger juvenile, female and male H. argentinensis from H. bacteriophora populations. The juvenile (IJs) stage provided the clearest separation of Heterorhabditis populations presenting the least variability between strains. The variable L and MBW were highly related to H. argentinensis IJs. Three groups were separated by this stage considering PC1 and PC2: one formed by H. bacteriophora OLI, RIV and RN strains, (isolates from Córdoba and Río Negro province), one for H. bacteriophora VELI strain (Buenos Aires province) and one for H. argentinensis (Santa Fe province). Heterorhabditis bacteriophora VELI and H. argentinensis isolated from regions with more rainfalls and humidity presented larger values for morphometric features. Molecular analyses showed the Argentinian populations (H. bacteriophora VELI strain and H. argentinensis), forming a same clade, with six other H. bacteriophora populations (not from Argentina) with a genetic similarity between them of 99%. Heterorhabditis argentinensis presented one unique nucleotide that was not present in any of the other species of the clade. Considering the results of this study H. argentinensis would be conspecific to H. bacteriophora, constituting a strain with a great morphometric variation where the host and climatic conditions could have influenced on the measurements.

Resumo Nematóides entomopatogênicos (EPN) pertencentes à família Heterorhabditidae são parasitas letais de insetos que vivem no solo. Duas espécies foram relatados na Argentina: Heterorhabditis argentinensis e Heterorhabditis bacteriophora, caracterizada principalmente por características morfométricas. Neste trabalho um estudo comparativo e filogenética entre cinco populações do Heterorhabditis da Argentina foi conduzido para analisar a variabilidade entre as linhagens e avaliar a posição taxonômica das Heterorhabditis argentinensis. Características morfométricas de Heterorhabditis bacteriophora VELI e H. argentinensis isoladas de regiões com mais chuvas e umidade apresentaram dimensões maiores. Analisa o PCA de personagens morfométricas separou a maior juvenil, feminino e masculino H. argentinensis de H. bacteriophora populações. A fase juvenil (JIs) fornece a mais clara separação de populações Heterorhabditis apresentando a menor variação entre as cepas. A L variável e MBW foram altamente relacionada com H. argentinensis JIs. Três grupos foram separados por esta fase considerando PC1 e PC2: um formado por H. bacteriophora OLI, RIV e estirpes RN, (isolados de Córdoba e província de Rio Negro), um para a estirpe H. bacteriophora VELI (província de Buenos Aires) e um para H. argentinensis (província de Santa Fe). Heterorhabditis bacteriophora VELI e H. argentinensis isolado a partir de regiões com mais chuvas e umidade apresentaram maiores valores para as características morfométricas. A análise molecular mostrou as populações da Argentina (estirpe H. bacteriophora VELI e H. argentinensis), formando um mesmo subtipo, com seis outras populações H. bacteriophora (não da Argentina), com uma similaridade genética entre eles de 99%. Heterorhabditis argentinensis apresentado um único nucleótido que não estava presente em nenhum dos outros espécies do clado. Considerando os resultados deste estudo H. argentinensis seria conspecific a H. bacteriophora, constituindo uma estirpe com uma grande variação morfométrica onde o anfitrião e as condições climáticas podem ter influenciado nas medições.

Synthesis, characterization and in vitro antimicrobial screening studies of some pyridyl-coumarin compounds / Síntesis, caracterización y evaluación antimicrobiana in vitro de algunos derivados de piridil-coumarina

SUMMARY In vitro antimicrobial screening of some pyridyl-coumarin compounds were done against some bacterial and fungal strains in DMF and DMSO. These pyridyl-coumarin compounds were synthesized in the laboratory and their structure was confirmed by different spectroscopic techniques such as IR, 1H NMR, 13C NMR and mass. Some of these compounds exhibited excellent antibacterial activity in both the solvents.

RESUMEN La actividad antimicrobiana in vitro de algunos compuestos derivados de piridil-coumarina se evaluó frente a algunas cepas bacterianas y fúngicas en DMF y DMSO. Las piridil-cumarinas se sintetizaron en el laboratorio y sus estructuras se confirmaron por diferentes técnicas espectroscópicas, tales como IR, 1H NMR, 13C NMR y masas. Algunos de los compuestos que se obtuvieron presentaron buena actividad antibacteriana en ambos solventes.

The chilean network of microbial culture collections: establishment and operation / Red chilena de colecciones de cultivos microbianos: establecimiento y operación

According to the data available at the World Data Center for Microorganism-WDCM from the World Federation for Culture Collection-WFCC, Chile has four registered culture collections that preserve 2777 microbial strains. At the global point of view, the culture collections in Chile are in different level of operation regarding its own infrastructure and compliancy with quality standards for preservation of strains and for services provide. The absence of funding to support the preservation of the Chilean microbial assets is a key issue for the development of the Chilean bioeconomy. Considering this, the Chilean culture collections started working together to establish the Chilean Network of Microbial Culture Collections (RCCCM, acronym in Spanish). In this note, the establishment and operation of the RCCCM is presented and discussed.

De acuerdo con los datos disponibles en el World Data Center for Microorganism-WDCM de la Federación Mundial para la Colección de Cultivos - WFCC, Chile tiene cuatro colecciones de cultivos registradas que preservan 2777 cepas microbianas. Desde el punto de vista global, las colecciones de cultivos en Chile se encuentran en diferentes niveles de operación con respecto a su propia infraestructura y cumplimiento con estándares de calidad para la preservación de las cepas y para los servicios que proporcionan. La ausencia de financiamiento para apoyar la preservación de los activos microbianos chilenos es un tema clave para el desarrollo de la bioeconomía chilena. Considerando esto, las colecciones chilenas de cultivos comenzaron a trabajar conjuntamente para establecer la Red Chilena de Colecciones de Cultivos Microbianos (RCCCM). En esta nota se presenta y discute el establecimiento y funcionamiento de la RCCCM.

Frecuencia y perfil de sensibilidad in vitro de aislamientos del Complejo Candida parapsilosis provenientes de pacientes con candidemias / Frequency and in vitro susceptibility profile of Candida parapsilosis Complex isolates from patients with candidemia

El objetivo de este trabajo fue conocer la frecuencia y el perfil de sensibilidad in vitro de aislamientos del Complejo Candida parapsilosis provenientes de casos de candidemias. Se estudiaron 754 cepas (Periodo 2008-2011), de la Red de Vigilancia de Candidemia del Instituto Nacional de Higiene “Rafael Rangel”. La identificación de las cepas se realizó por pruebas fenotípicas. La sensibilidad in vitro a los antifúngicos se evaluó por el método de Etest® y se determinó la concentración mínima inhibitoria a anfotericina B (AB), caspofungina (CS), fluconazol (FZ), y voriconazol (VZ). Se calcularon los puntos de corte epidemiológicos (PCE) y los rangos de cepas salvajes (PS) para cada antifúngico. El 43,6% de las cepas (n=328) fueron identificadas como Complejo C. parapsilosis; todas fueron sensibles a AB y presentaron bajos porcentajes de resistencia a FZ (4,3%), VZ (1,2%) y CS (0,6%). Los PCE y los rangos de PS (en µg/mL) fueron: FZ: 2/0,03-2; VZ y AB: 0,06/0,002-0,06 y CS: 0,5/0,002-0,5 respectivamente. Los resultados de este estudio aportaron información importante sobre el comportamiento del Complejo C. parapsilosis frente a los antifúngicos más utilizados en el tratamiento de las candidemias.

The aim of this study was to determine the frequency and in vitro susceptibility profile of Candida parapsilosis Complex isolates from patients with candidemia. Seven hundred and fifty four (754) strains (Period 2008-2011), from the Candidemia Surveillance Network of the Instituto Nacional de Higiene “Rafael Rangel” were studied. The strains identification was performed by phenotypic methods. In vitro antifungal susceptibility was evaluated by the Etest® method and minimum inhibitory concentration for amphotericin B (AB), caspofungin (CS), fluconazole (FZ), and voriconazole (VZ) was determined. Epidemiological cut off values (ECV) and ranges for wild type strains (WT) were also calculated for each antifungal. Forty three point six (43.6%) of the isolates (n=328) belonged to C. parapsilosis Complex; all of them were susceptible to AB and showed low resistance percentages to FZ (4.3%), VZ (1.2%) and CS (0.6%). The ECV and WT strains ranges (in mcg/mL) were: FZ: 2/0.03-2; VZ and AB: 0.06/0.002-0.06 and CS: 0.5/0.002-0.5 respectively. The results of this study provided important information about the behavior of the C. parapsilosis Complex against the most commonly antifungal agents used for the treatment of candidemias.

Bioprospección de los hiperparásitos cicinobolus cesatii de bary y eudarluca caricis (Biv.) O.E. Erikss sobre cultivos y plantas adyacentes en la región central de Guatemala / Bioprospecting of fungal hyperparasites cicinobolus cesatii de bary and eudarluca caricis (Biv.) O.E. Erikss on crops and adjacent plants in central region of Guatemala

Se realizó una bioprospección para detectar los hiperparásitos Cicinobolus cesatii y Eudarluca caricis en la región central de Guatemala para establecer la presencia y la obtención de cepas prometedoras para control biológico. Setecientos seis muestras de plantas silvestres y cultivadas fueron analizadas, en 16 se detectó C. cesatii y en 46 E. caricis. Las regiones con más detecciones de ambos hiperparásitos fueron San Juan Comalapa y Tecpán Guatemala del departamento de Chimaltenango, emergiendo como una región con alto potencial biológico y variabilidad. Se obtuvieron aislamientos e hicieron comparaciones de estructuras reproductivas y se estableció que existe variabilidad a través de análisis estadístico que marcó diferencias significativas al 5% de significancia al comparar entre cepas de la misma localidad y entre localidades, además de la diferencia entre origen vegetal. También se estableció que hay cepas promisorias de C. cesatii aislado de Physalis sp. y E. caricis aislado de Prunus sp., Zea mays y Phaseolus vulgaris. El estudio pone de manifiesto el potencial de presencia de ambos agentes sobre plantas silvestres o áreas sin aplicación de fungicidas.

Bioprospecting was performed to detect hyperparasites Cicinobolus cesatii and Eudarluca caricis in central region of Guatemala to establish their presence and obtain promising strains to be use in biological control. Seven hundred and six samples from wild and cultivated plants were analyzed; C. cesatii was detected in 16 samples, and 46 cases of E. caricis. Both hyperparasites were identified in San Juan Comalapa and Tecpan of Chimaltenango County, having high biological potential and variability. Reproductive structures comparison of the different isolates was made and its variability was established through statistical analysis showing significant differences when they were compare between strains from the same site and between sites, also they showed difference between plant origins. These strains such as C. cesatii from Physalis sp. and E. caricis from Prunus sp., Zea mays and Phaseolus vulgaris have a high potential. This research showed a high presence of both agents on wild plants or areas without application of fungicides.

Antibacterial activity of the Piper aduncum oil and dillapiole, its main constituent, against multidrug-resistant strains / Actividad antibacteriana del aceite de Piper aduncum y dillapiole, su componente principal, frente a cepas resistentes a múltiples fármacos

The study aimed to evaluate the bactericidal activity of oil essential and dillapiole from P. aduncum against standard and multidrug-resistant strains of Staphylococcus spp. The oil showed antimicrobial action against these strains, but better results were obtained for the standards strains of S. epidermidis and S. aureus, with MIC of 250 and 500 ug/mL, respectively. Dillapiolle was less effective than the oil against the same standard and multi-drug resistant strains (MIC =1000 ug/mL). However, when dillapiolle was tested in combination with myristicin, another component of the oil, it increased its bactericidal activity and showed a synergistic action...

El objetivo del estudio fue evaluar la actividad bactericida de los aceites esenciales y dillapiole de P. aduncum contra cepas estándar y multirresistentes de Staphylococcus spp. El aceite mostró acción antimicrobiana frente a estas cepas, pero se obtuvo mejores resultados para las cepas de S. epidermidis y S. aureus, con MIC de 250 y 500 ug/ml, respectivamente. Dillapiolle fue menos eficaz que el aceite contra cepas estándar y multirresistentes (MIC = 1000 ug/ml). Sin embargo, cuando dillapiolle fue probado en combinación con la miristicina, otro componente del aceite, que aumentó su actividad bactericida y mostró una acción sinérgica...

Evaluación de la peptona papaínica de corazón de res para el enriquecimiento selectivo de Enterococcus / Evaluation of beef heart papainic peptone for selective enrichment of Enterococcus

Introducción: el control microbiológico de aguas y alimentos ha motivado el desarrollo de medios de cultivo selectivos capaces de detectar Enterococcus, los cuales necesitan de una fuente de energía apropiada para garantizar la recuperación de estos. Objetivos: comparar diferentes bases nutritivas elaboradas a partir de productos y subproductos alimenticios según su capacidad de promoción de crecimiento del género Enterococcus y evaluar la exactitud del medio de cultivo caldo azida dextrosa. Métodos: para el ensayo se seleccionaron 80 cepas de diferentes géneros. Se prepararon dos variantes experimentales del caldo azida dextrosa (una tamponada) y se inocularon los microorganismos seleccionados a una concentración estandarizada. El incremento de la biomasa se determinó midiendo la densidad óptica en un espectrofotómetro a 640 nm cada una hora. La evaluación microbiológica del medio de cultivo se realizó utilizando diferentes géneros microbianos a distintas concentraciones. Se determinó la sensibilidad, especificidad, exactitud diagnóstica y relativa y el índice Kappa del diagnosticador. Como medio de referencia se utilizó el caldo azida glucosa proveniente de la firma comercial Merck (Alemania). ..

Introduction: microbiological control of water and food has motivated the development of selective culture media capable of detecting Enterococcus, which need an appropriate source of energy to ensure the recovery of microorganisms. Objectives: compare different nutrient bases produced from food products and by-products according to their growth promotion capacity for the genus Enterococcus, and evaluate the accuracy of dextrose azide broth culture medium. Methods: eighty strains of different genera were selected for the test. Two experimental variants of dextrose azide broth were prepared (one buffered) and the microorganisms selected were inoculated at a standardized concentration. Biomass increase was determined by measuring optical density in a spectrophotometer at 640 nm every 1 h. Microbiological evaluation of the culture medium was carried out using different microbial genera at different concentrations. Diagnostic and relative sensitivity, specificity and accuracy, and the Kappa index were determined for the culture medium. Glucose azide broth (Merck, Germany)ss production than the other genera...

Efecto de dos probióticos que contienen cepas de Lactobacillus casei variedad rhamnosus y lactobacillus johnsonii sobre el crecimiento in vitro de Streptococcus mutans / Effect of two probiotics containing lactobacillus casei rhamnosus and lactobacillus johnsonii variety on the in vitro growth of treptococcus mutans

La caries dental es una de las enfermedades mas prevalentes en la población mundial y más aún en los países en desarrollo, por lo que se necesitan nuevas medidas para su prevención. Estudios previos señalan que el efecto de cepas probióticas inhibe la colonización de los patógenos responsables de la caries dental como el Streptococcus mutans, previniendo la aparición de la caries dental. El objetivo fue medir el efecto de las cepas probióticas Lactobacillus casei variedad rhamnosus (LCR32) y Lactobacillus johnsonii (LA1) sobre le crecimiento in vitro de Streptococcus mutans. Se midió el efecto in vitro de las cepas de dos probióticos comercializados en Chile; Lactobacillus casei variedad rhamnosus (LCR32) contenidas en Lactil® y Lactobacillus johnsonii (LA1) contenidas en Chamyto, sobre el crecimiento in vitro de Streptococcus mutans. Se realizaron medios de cultivo selectivos para Streptococcus mutans a los cuales se les adicionaron cuatro diluciones diferentes de cada probiótico y se midió el halo de inhibición de los Streptococcus mutans con un pie de metro. Los probióticos con las cepas Lactobacillus casei variedad rhamnosus (LCR32) y Lactobacillus johnsonii (LA1) inhiben el crecimiento sobre Streptococcus mutans. Ambos probióticos en las dos concentraciones más altas no obtuvieron diferencias significativas en relación a los halos de inhibición. Sin embargo, el probiótico con la cepa Lactobacillus casei variedad rhamnosus (LCR35), mostró halos de inhibición más significativos en comparación a la cepa Lactobacillus johnsonii (LA1). Las cepas probióticas Lactobacillus casei variedad rhamnosus (LCR35) y Lactobacillus Johnosonii (LA1) disminuyen la colonización de las principales bacterias productoras de caries dental, de tal forma estos probióticos podrían ser utilizados como apoyo en la prevención y profilaxis de la enfermedad en pacientes de alto riesgo cariogénico, en forma adicional a otros medios de prevención.

Dental caries is one of the most prevalent diseases in the world and even more in the population of developing countries, so it is necessary to use new measures for prevention. Previous studies indicate that the effect of probiotic strains inhibit colonization of pathogens responsible for dental caries such as Streptococcus mutans, preventing the onset of dental caries. The aim was to measure the effect of the probiotic strains Lactobacillus casei variety rhamnosus (LCR32) and Lactobacillus johnsonii (LA1) on in vitro growth will Streptococcus mutans. We measured the effect in vitro of two probiotic strains marketed in Chile; Lactobacillus casei variety rhamnosus (LCR32) contained in Lactyl ® and Lactobacillus johnsonii (LA1) contained in Chamyto on in vitro growth of Streptococcus mutans. Culture media were made selective for Streptococcus mutans to which were added four different dilutions of each probiotic and measured the zone of inhibition of Streptococcus mutans with a foot tube. The probiotic strains Lactobacillus casei variety rhamnosus (LCR32) and Lactobacillus johnsonii (LA1) inhibit the growth of Streptococcus mutans. Both probiotics in the two higher concentrations no significant differences in relation to the zones of inhibition. However, the probiotic strain Lactobacillus casei rhamnosus variety (LCR35) showed the most significant zones of inhibition compared to the strain Lactobacillus johnsonii (LA1). The probiotic strains Lactobacillus casei rhamnosus variety (LCR35) and Lactobacillus Johnosonii (LA1) decreased the colonization of the main dental caries producing bacteria, so these probiotic could be used as support in the prevention and prophylaxis of the disease in high-risk cariogenic patients, additionally in other means of prevention.