Inativação fotodinâmica de bactérias patogênicas de interesse alimentar utilizando o fotossensibilizador protoporfirina IX / Photodynamic inactivation of pathogenic bacteria of food interest using the photosensibilizer protoporfirin IX

Salmonella enterica é um importante patógeno na indústria de alimentos, relacionado com gastroenterites alimentares. Staphylococcus aureus é causador de infecção intestinal. Neste cenário, a inativação fotodinâmica (IFD) surge como uma alternativa de desinfecção desses patógenos. A IFD consiste na interação de três elementos: um agente fotossensibilizador (FS) , luz e oxigênio molecular. Esta interação promove espécies reativas de oxigênio, causando danos irreparáveis à célula . Estes microrganismos possuem morfologia celular diversa, portanto uma concentração ideal de FS para cada cepa se faz necessária para o sucesso da técnica. O comprimento de onda absorvido pelo FS Protoporfirina IX corresponde ao vermelho do espectro eletromagnético (630 nm). Concentrações de 10 e 20 μM do pró-fármaco ácido aminolevulínico (ALA), observou-se a inativação de S. aureus em 20 μM, S. enterica manteve-se em crescimento. A IFD mostrou-se como uma promissora técnica para controle microbiano.

Salmonella Panama: genetic diversity of the isolates collected from human and non-human sources

Abstract INTRODUCTION Salmonella enterica serovar Panama belongs to the D1 serogroup and is frequently associated with nontyphoidal salmonellosis in humans. This study aimed to characterize isolates collected from Northeast Brazil by phenotypic and molecular methods. METHODS Forty four S. Panama strains were examined for antimicrobial susceptibility, virulence genes, and pulsed field gel electrophoresis (PFGE) types. RESULTS All strains were susceptible to antibiotics (except for streptomycin), presented classical virulence factors, and could be clustered into four groups and 18 pulsotypes. CONCLUSIONS This work calls for continuous surveillance for the emergence of antibiotic resistance and new clones in a geographical area.

Inactivation of phoPQ genes attenuates Salmonella Gallinarum biovar Gallinarum to susceptible chickens

Abstract Salmonella Gallinarum is a host-restrict pathogen that causes fowl typhoid, a severe systemic disease that is one of the major concerns to the poultry industry worldwide. When infecting the bird, SG makes use of evasion mechanisms to survive and to replicate within macrophages. In this context, phoPQ genes encode a two-component regulatory system (PhoPQ) that regulates virulence genes responsible for adaptation of Salmonella spp. to antimicrobial factors such as low pH, antimicrobial peptides and deprivation of bivalent cations. The role of the mentioned genes to SG remains to be investigated. In the present study a phoPQ-depleted SG strain (SG ΔphoPQ) was constructed and its virulence assessed in twenty-day-old laying hens susceptible to fowl typhoid. SG ΔphoPQ did cause neither clinical signs nor mortality in birds orally challenged, being non-pathogenic. Furthermore, this strain was not recovered from livers or spleens. On the other hand, chickens challenged subcutaneously with the mutant strain had discreet to moderate pathological changes and also low bacterial counts in liver and spleen tissues. These findings show that SG ΔphoPQ is attenuated to susceptible chickens and suggest that these genes are important during chicken infection by SG.

Comparison of three diagnostic methods for Salmonella enterica serovars detection in chicken rinse / Comparação de três métodos diagnósticos para detecção de Salmonella enterica em lavados de carcaça de frango

Salmonella detection is a key point in food safety testing, because of the frequent association of this pathogen with food poisoning in humans. The standard bacteriological tests currently used for Salmonella-detection are time-consuming; therefore, there is a need to develop alternative methods to accelerate the detection. In order to accelerate Salmonella diagnosis, we used the immunomagnetic separation assay associated with bacteriophage P22 for the rapid detection of the following Salmonella serovars in chicken rinses of drumsticks, artificially contaminated with 5, 10, and 100 CFU/25mL of bacteria: Salmonella enterica subsp. enterica serovar Heidelberg (S. Heidelberg), Salmonella enterica subsp. enterica serovar Enteritidis (S. Enteritidis) and Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium). The efficiency of the technique, represented by the time required for detection of positive and negative samples, was compared with that of the standard diagnostic tests used for this pathogen, the bacteriological assay and the polymerase chain reaction (PCR)-based test. This study confirmed the ability of the bacteriophage-associated immunomagnetic separation assay to identify 99.6% of Salmonella-positive samples of the three serovars tested. In contrast, the bacteriological assay and PCR-based test detected 95.1% and 98.5% of the Salmonella-positive samples respectively.(AU)

A detecção de Salmonella é um ponto crucial para a segurança alimentar, devido a frequente associação deste patógeno com infecções alimentares em humanos. O método padrão para detecção de Salmonella é o bacteriológico, mas o tempo requerido para o processamento das amostras e o diagnóstico final é longo, por isso existe a necessidade de desenvolvimento de métodos alternativos que visem acelerar esta etapa. Para isto utilizamos a separação imunomagnética associada ao bacteriófago P22 como técnica de detecção rápida para os seguintes sorovares de Salmonella: Salmonella enterica subsp. enterica sorovar Heidelberg (S. Heidelberg), Salmonella enterica subsp. enterica sorovar Enteritidis (S. Enteritidis) e Salmonella enterica subsp. enterica sorovar Typhimurium (S. Typhimurium), os quais foram inoculados artificialmente em lavados de sobre-coxas de frango nas seguintes concentrações: 5, 10 e 100 UFC/25mL. A eficiência da técnica, representada pelo tempo requerido para detecção de amostras positivas ou negativas, foi comparado com os testes rotineiramente utilizados para detecção de Salmonella, o exame bacteriológico e a reação em cadeia da polimerase (PCR). Este estudo confirmou a capacidade do teste de separação imunomagnética associado a bacteriófago, o qual identificou 99,6% das amostras positivas para Salmonella, dos três sorovares testados. Já o bacteriológico e PCR identificaram respectivamente 95,1% e 98,5% das amostras positivas.(AU)

O pombo (Columba livia) como agente carreador de Salmonella spp. e as implicações em saúde pública / The pigeon (Columba livia) as a carrier agent of Salmonella spp. and public health implications

Os pombos domésticos e silvestres estão distribuídos por todo o mundo e carreiam micro-organismos patogênicos ao homem e a outros animais, podendo ser um dos responsáveis pela disseminação de Salmonella spp. Este patógeno gera grande preocupação para a economia mundial, uma vez que cria transtornos para a indústria avícola quando ocorre contaminação dos plantéis e ônus para a saúde pública devido a surtos de infecção alimentar causados por esta bactéria. Dessa forma, objetivou-se realizar um levantamento acerca da participação do pombo doméstico na possível disseminação de Salmonella spp.(AU)

Domestic and wild pigeons are distributed throughout the world and carrie micro-organisms that are pathogenic to humans and other animals. They can be one of the animals in charge of the dissemination of Salmonella spp., pathogen of great concern for the world economy as it creates inconvenience to the poultry industry when there is contamination of herds and impacts on public health due to outbreaks of foodborne infection caused by this bacterium. Therefore, the objective was to conduct a survey about the participation of the domestic pigeon in the possible dissemination of Salmonella spp.(AU)

Primera detección de CMY-2 en Salmonella Heidelberg en Sudamérica / First detection of CMY-2 plasmid mediated ß-lactamase in Salmonella Heidelberg in South America

Salmonellaenterica serovar Heidelberg es uno de los principales agentes causantes de salmonelosis en humanos en Estados Unidos y Canadá, sin embargo, resulta infrecuente en los países de Sudamérica y Europa. En este trabajo se caracterizó un aislamiento de S. Heidelberg resistente a oximino-cefalosporinas recuperado de un paciente internaen un hospital de la Ciudad de Buenos Aires. Se evidenció la presencia de un plásmido de 97 kbperteneciente al grupo de incompatibilidad IncN, portador del gen blaCMY-2. ISEcp1 fue localizado corriente arriba de blaCMY-2, promoviendo su expresión y movilización.El aislamiento de S. Heidelberg correspondió al secuenciotipo 15 y en la virotipifi cación se detectó el gen sopE. En este trabajo describimos por primera vez la producción de CMY-2 en una cepa de S. Heidelberg en nuestro país y América Latina

Salmonellaenterica serovar Heidelberg ranks among the most prevalent causes of human salmonellosis in the United States and Canada, although it has been infrequently reported in South American and European countries.Most Salmonella infections are self-limiting; however, some invasive infections require antimicrobial therapy. In this work we characterized an oxyimino-cephalosporin resistant S. Heidelberg isolate recovered from an inpatient in a Buenos Aires hospital. CMY-2 was responsible for the ß-lactam resistance profi le. S. Heidelberg contained a 97 kb plasmid belonging to the Inc N groupharboring blaCMY-2. ISEcp1 was located upstream blaCMY-2 driving its expression and mobilization.The isolate belonged to sequence type 15 and virotyping revealed the presence of sopE gene. In this study we identifi ed the fi rst CMY-2 producing isolate of S. Heidelberg in Argentina and even in South Americ

Construcción de mutantes de salmonella enterica por inactivación de los genes invG/invE y ssaJ/ssaK de las islas de patogenicidad 1 y 2 / Construction of mutants of salmonella enterica for inactivation of invG/invE y ssaJ/ssaK genes of pathogenicity islands 1 and 2

Para la comprensión de las bases genéticas de los mecanismos de patogenicidad de Salmonella se han descrito diversas metodologías para manipular el ADN genómico y generar mutantes con características particulares. En este estudio se reporta la construcción de mutantes a partir de varios serotipos de S. enterica, por sustitución e inactivación de los genes invG/invE en SPI-1 y de los genes ssaJ/ssaK en SPI-2 mediante la técnica de recombinasa Red del fago λ descrita por Datsenko y Wanner (2000). Los genes delecionados en las SPI-1 y SPI-2 codifican para las proteínas que participan en la formación de los sistemas de secreción tipo III, responsables de la invasión y supervivencia intracelular de S. enterica en las células hospedadoras. Los resultados de este trabajo permitirán realizar estudios futuros in vivo para evaluar la posible atenuación de la virulencia de las cepas mutantes, así como aportar nuevos conocimientos sobre los mecanismos genéticos involucrados en la fisiopatogenia de las enfermedades producidas por los serovares estudiados. Además, esta técnica se recomienda para generar de manera eficiente mutantes de diferentes serotipos de S. enterica con la finalidad de estudiar los genes cromosómicos y sus productos.

To understand the genetic basis of Salmonella pathogenicity mechanisms, various methods have been described to manipulate and generate mutant genomic DNA with specific characteristics. In this study we report the construction of mutants from several serotypes of S. enterica, substitution and inactivation of genes invG/invE in SPI-1 gene and ssaJ/ssaK in SPI-2 by the technique of phage λ Red recombinase, as described by Datsenko and Wanner (2000). The gene deletion in SPI-1 and SPI-2 encodes proteins involved in the formation of type III secretion systems responsible for the invasion and intracellular survival of S. enterica in the host cells. The results of this work will allow in vivo studies to evaluate the possible attenuation of virulence of the mutant strains, as well as to provide new insights into the genetic mechanisms involved in the pathogenesis of diseases caused by these bacteria. Moreover, this technique is recommended to efficiently generate mutants of different serotypes of S. enterica in order to study the chromosomal genes and their products.

Infecção experimental por Salmonella enterica subespécie enterica sorotipo Panama e tentativa de transmissão nasonasal em leitões desmamados / Experimental infection by Salmonella enterica ssp. enterica serovar Panama and tentative of nose-to-nose transmission in weaned pigs

O objetivo deste experimento foi produzir uma infecção experimental de Salmonella enterica subespécie. enterica sorotipo Panama e verificar a importância da via nasonasal na transmissão entre leitões desmamados. Foram utilizados seis leitões recém-desmamados, adquiridos de granja livre de Salmonella spp. Utilizaram-se baias isoladoras, que proporcionavam o contato nasonasal e eliminavam a possibilidade de outras vias de transmissão e de contaminação externa. Três grupos foram formados: controle, sentinela e infectado. Não foram encontradas amostras positivas para Salmonella spp. em leitões do grupo-controle e sentinelas, e nos animais infectados foi isolada Salmonella Panama em suabes retais e tecidos necropsiados. Os resultados revelaram não haver a transmissão pela via nasonasal entre leitões desmamados, pois, em nenhum momento, o agente foi isolado dos animais sentinelas.

Experimental infection of Salmonella enterica ssp. enterica serovars Panama was proceeded to establish the importance of nose-to-nose contact in the transmission among weaned pigs. Six recently-weaned pigs were acquired from a farm previously selected, free from Salmonella spp. Isolation stalls allowing nose-to-nose contact and eliminating other transmission routes as well outside contamination were used. Three groups were formed: control, sentinel, and infected. Piglets of control and sentinel groups were not positive for Salmonella spp., however, Salmonella Panama was isolated in infected animals in rectal swabs and necropsied tissues. It was concluded that there was not transmission by nose-to-nose contact among weaned pigs, since Samonella Panama was not isolated in the sentinel group at any moment.

Mecanismos moleculares utilizados por Salmonella para causar infecciones del tracto digestivo / Molecular mechanisms used by Salmonella to cause infections in the digestive tract

Salmonella enterica es uno de los principales causantes de gastroenteritis infecciosa en el mundo, debido al consumo de alimentos y aguas contaminadas con esta bacteria. Este grupo de bacterias Gram negativas se caracteriza por tener la capacidad de invadir células eucariontes y sobrevivir en el interior de ellas, evento fundamental para que la bacteria cause una enfermedad tanto localizada como sistémica. Las proteínas de virulencia que este agente utiliza para invadir y sobrevivir en células eucariontes son codificadas por genes presentes en islas de patogenicidad, que corresponden a grandes bloques de material genético integrados en el cromosoma bacteriano y que fueron posiblemente adquiridos a través de transferencia lateral de genes desde otros microorganismos. Estudios recientes han permitido identificar el rol que poseen estas proteínas de virulencia en el proceso infectivo de Salmonella y su impacto en el funcionamiento de la célula eucarionte. De este modo, ha sido posible entender de mejor manera los mecanismos moleculares utilizados para infectar a su hospedero y se han identificado posibles blancos terapéuticos para el tratamiento de los cuadros infecciosos causados por este patógeno.

Salmonella enterica is one of the main ethiological agents of infectious gastroenteritis in the world, due the consumption of food and water contaminated with these bacteria. This group of Gram negative bacterials characterized by its capacity to invade eukaryotic cells and survive inside them, an event that is fundamental for the bacteria to cause a localized as well as a systemic disease. The virulence proteins that this bacterium uses to invade and survive within eukaryotic cells are encoded by genes found in pathogenicity islands, big blocks of genetic material integrated in the bacterial chromosome, that were probably acquired through lateral gene transfer from other microorganisms. Recent studies have identified the role that these virulence proteins play in the infective process of Salmonella, and their impact in the function of the eukaryotic cell. This way, it has been possible to better understand the molecular mechanisms used by Salmonella to infect their hosts, and potential therapeutic targets have been identified to improve the treatment of the infection caused by this pathogen.

Pathogenic effects of Salmonella enterica subspecies enterica serovar Typhimurium on sprouting and growth of maize.

The study was undertaken to understand effects and survival of S. enterica subspecies enterica serovar Typhimurium (S. Typhimurium), a zoonotic serovar, on maize seed germination and plant growth. All the four strains of S. enterica subspecies enterica serovar Typhimurium significantly reduced germination of maize seeds in sprouting plates as well as in soil. About > or =2.7x10(3) Salmonella cfu ml(-1) of soaking water, while > or =2.7x10(7) Salmonella cfu g(-1) soil were required to significantly inhibit germination of maize. Similar inhibition of germination could be observed using > or = 16 mg of bacteria free Salmonella cell lysate (CL) protein per g of soil or > or =0.5 mg of CL protein per ml of soaking water in sprouting plates. At the constant dose of 3.6x10(7) to 3.8x10(7) Salmonella cfu or 5 mg cell lysate protein ml(-1) of soaking water, four strains of Salmonella significantly reduced germination, however difference between strains was insignificant. After germination too, maize growth was affected both by Salmonella organism and CL with little strain-to-strain variation. All Salmonella persisted in growing plants from 15 to 35 days of plant age and up to 190 days in soil. Maize plants once grown for a week in sterile soil were resistant to invasion of S. enterica subspecies enterica serovar Typhimurium in their leaves even in doses as high as 7.6x10(9) cfu g(-1) of soil. Salmonella persisted better and longer in plants grown from contaminated seed sown in loam soil, but rarely in plants grew in sandy soil. All maize plants had Salmonella in their stumps even after 35 days of sowing irrespective of kind of soil, primary source of infection (soil or seed) and type of S. enterica subspecies enterica serovar Typhimurium strain. The study revealed that Salmonella is not only zoonotic but a phytopathogen also.

Protection by Lactobacillus acidophilus UFV-H2B20 against experimental oral infection with Salmonella enterica subsp. Enterica Ser. Typhimurium in gnotobiotic and conventional mice

The ability of Lactobacillus acidophilus UFV-H2B20 to antagonize Salmonella enterica subsp. enterica ser. Typhimurium and to reduce the pathological consequences for the host was determining using conventional and gnotobiotic animals. Conventional NIH mice received daily by gavage a 0.1 ml suspension containing about 10(8) cfu L. acidophilus UFV-H2B20 and germfree animals received a single 0.1 ml dose. The gnotobiotic and conventional groups were infected orally with 10(2) and 10(5) cfu of S. Typhimurium, respectively, 7 days after the beginning of treatment. Control groups were treated with sterile saline instead of Lactobacillus. Survival data showed a protective effect against the pathogenic bacteria in both conventional and gnotobiotic Lactobacillus-treated mice. L. acidophilus UFV-H2B20 colonized the digestive tract of gnotobiotic mice and the number of viable cells ranged from 10(9) to 10(10) cfu/g of faeces. In both experimental and control gnotobiotic animals, S. Typhimurium became rapidly established at a level ranging from 108 to 1010 cfu/g of faeces and remained at high levels until the animals died or were sacrificed. In conclusion, the previous treatment of mice with L. acidophilus UFV-H2B20 protects the animals against the experimental infection with S. Typhimurium but this protection was not due to the reduction of the pathogenic populations in the intestines.(au)

Resistencia a antimicrobianos y perfil plasmídico de Salmonella enterica de origen pediátrico / Bacterial resistance and plamid profile of pediatricïs origin Salmonella enterica

El género Salmonella es un grupo de microorganismos ubicuos en humanos y animales. En los primeros puede ocasionar cuadros clínicos del tipo de la gastroenteritis, aunque ocasionalmente es causa de infecciones sistémicas que ponen en peligro la vida del paciente. La participación de Salmonella se ha incrementado a nivel mundial, ocasionando brotes epidémicos en unidades de atención pediátrica, en las que se han aislando cepas resistentes a más de un antimicrobiano. El objetivo de este trabajo fue determinar la sensibilidad a un grupo de antimicrobianos y el perfil plasmídico de cepas de Salmonella aisladas de pacientes pediátricos. Los resultados obtenidos mostraron alta resistencia a estreptomicina, ampicilina, cefalotina y tetraciclina. Se observó un plásmido de 20.5 Md en cepas de Salmonella enterica, subespecie typhimurium, heidelberg y derby, en cuyas transconjugantes se logró la transferencia fenotípica de resistencia a ampicilina.

Salmonella Freetown: primer aislamiento en Argentina / Salmonella Freetown: first report in Argentina

En el presente trabajo se comunica el primer aislamiento de Salmonella Freetown en Argentina. Se obtuvo a partir de un coprocultivo de una paciente de 1 mes y 7 días, cuya madre consultó por un cuadro de diarrea aguda en el Hospital de Niños Dr. Ricardo Gutiérrez de la ciudad de Santa Fe. Por sus características bioquímicas y su fórmula antigénica, esta nueva serovariedad se ubica dentro de la especie Salmonella enterica subespecie enterica