Water samples were collected at four sites on the White River, Muncie, Indiana, on a biweekly basis from April 1980 to April 1981, to determine seasonal variation in A. hydrophila density. In conjunction with water sampling, temperature, dissolved oxygen, conductivity and pH were determined at each site. During this period a yearly mean of 589 colony forming units (CFU) per ml was obtained with a range of 0-6350. Peaks in mean A. hydrophila numbers occurred during the summer (1808 CFU ml-1) and early spring (3946 CFU ml-1) with lows occurring in winter (42 CFU ml-1). No significant correlations could be found between CFU values and the physico-chemical parameters studied over the calendar year. However, the compiling of data from May 1979 to April 1981 did yield a significant correlation between A. hydrophila density values and the following water quality parameters: temperature, conductivity, and dissolved oxygen.Fish were collected during June through October 1980 at various sites along the White River, Delaware County, Indiana, for the determination of past or present exposure to A. hydrophila infection by serological and direct isolation methods. Of 102 different fish sera tested, 36% (37/102) had a detectable titer to A. hydrophila (isolate #113). However, the direct isolation method only yielded seventeen percent (8/47) of the fishes sampled to be positive forA. hydrophila systemically. Agglutinins to A. hydrophila were demonstrated in eleven different fish species, whereas five different species revealed no detectable antibody to the specific particulate antigen employed. Estimated CFU ml-1 of A. hydrophila was the only parameter which correlated with the presence of agglutinating antibody to this organism in river fish populations.Ball State UniversityMuncie, IN 47306

Temperature, conductivity, and Aeromonas hydrophila density were determined bimonthly at six sites in the White River drainage system, Delaware County, Indiana, from April, 1984 through December, 1984. Fish were collected from four of the six sites. Fish were identified to species, examined for gross pathology, and their blood collected. Titers against A. hydrophila antigen 157 were determined for all carp (Cyprinus carpio) captured. Certain carp serum samples were also tested against three additional A. hydrophila antigens.Aerononas hydrophila densities appeared to be related to temperature and conductivity, primary producers, and runoff/effluent. Aeromonas hydrophila densities were higher in areas affected by urban runoff/ effluent than in areas affected by rural runoff/effluent. Aeromonas hydrophila densities increased as one progressed through the city of Muncie.Only five percent of all fish captured exhibited signs of gross pathology. Diseased fish typically demonstrated low titers against antigen 157. Several A. hydrophila serotypes were apparently infectious for the carp studied. Thirty-two percent of the carp sampled exhibited a positive titer response against antigen 157. Considerable variation in titer response existed between individuals.Ball State UniversityMuncie, IN 47306

The type II secretion system is used by many pathogenic and non-pathogenic bacteria for the extracellular secretion of enzymes and toxins. <i>Aeromonas hydrophila</i> is a Gram-negative pathogen that secretes proteins via the type II secretion system.<p> In the studies described here, a series of yeast two-hybrid assays was performed to identify protein-protein interactions in the type II secretion system of <i>A. hydrophila</i>. The periplasmic domains of ExeA and ExeB were assayed for interactions with the periplasmic domains of Exe A, B, C, D, K, L, M, and N. Interactions were observed for both ExeA and ExeB with the secretin ExeD in one orientation. In addition, a previously identified interaction between ExeC and ExeD was observed. In order to further examine and map these interactions, a series of eight two-codon insertion mutations in the amino terminal domain of ExeD was screened against the periplasmic domains of ExeA and ExeB. As a result, the interactions were verified and mapped to subdomains of the ExeD periplasmic domain. To positively identify the region of ExeD involved in the interactions with ExeA, B, C and D, deletion mutants of ExeD were constructed based on the two-codon insertion mutation mapping of subdomains of the ExeD periplasmic domain, and yeast two-hybrid assays were carried out. The results showed that a fragment of the periplasmic domain of ExeD, from amino acid residue 26 to 200 of ExeD, was involved in the interactions with ExeA, B and C. As an independent assay for interactions between ExeAB and the secretin, His-tagged derivatives of the periplasmic domains of ExeA and ExeB were constructed and co-purification on Ni-NTA agarose columns was used to test for interactions with untagged ExeD. These experiments confirmed the interaction between ExeA and ExeD, although there was background in the co-purification test.<p> These results provide support for the hypothesis that the ExeAB complex functions to organize the assembly of the secretin through interactions between both peptidoglycan and the secretin that result in its multimerization into the peptidoglycan and outer membrane layers of the envelope.

The bacterium Aeromonas hydrophila is a known fish and opportunistic human pathogen commonly occurring in surface waters supplying drinking water distribution systems. The major concern of government and drinking water providers is that A. hydrophila may invade and become established in the biofilm of a distribution system, thus potentially leading to outbreaks of disease. The purpose of this study was to survey source water, distribution system biofilm, and to establish a simulated distribution system to explore the possibility of A. hydrophila invading and becoming established under normal and disrupted treatment conditions. A. hydrophila (AH) medium and the API-20E system were used for identification, while Ampicillin-Dextrin Agar (ADA) was used for enumeration. Presumptive counts were high in source water approaching 103 CFU/ml during summer months. Biofiim from an actual distribution system showed the presence of A. hydrophila in 10 % of the samples. In the simulated distribution system A. hydrophila was never found in the bulk water or biofilm under normal treatment condition, showing disinfectant efficiency. Under disrupted treatment conditions A. hydrophila was not able to colonize a pre-established biofilm over a 14 week period. / Department of Biology

Recently the EPA placed Aeromonas hydrophila on the Candidate Contaminant List (CCL). It has long been known to be a pathogen of cold blooded animals and now is a suspected human opportunistic pathogen as well. Among the various virulence factors produced by A. hydrophila, the cytolytic enterotoxin (AHCYTOEN) is by far one of the most important contributors to the pathogenicity of the organism. This factor is also produced by other pathogenic Aeromonas spp. In this study, PCR technology was used to detect AHCYTOEN gene from a simulated water distribution system. A set of primers was selected to amplify the unique sequence of a pathogenic island, AHCYTOEN gene. To examine the sensitivity of the PCR, serial dilutions of pure A. hydrophila culture were tested. The PCR technique used was sensitive enough to detect samples containing less than 10.0 cells/ml. Source water, bulk water, and simulated distribution biofilm samples were examined for the gene. Biofilm and bulk water samples exposed to raw source water were collected on 4 occasions during a 24-day period. PCR technology detected the AHCYTOEN gene from 100 % of the bulk water samples and 85% of tightly bound biofilm (TB) samples from a simulated water distribution system while no positive results were observed in loosely bound biofilm samples (LB). After the inlet line of the system was changed to normally treated distribution water, 11 biofilm samples were collected on 3 occasions during 15 day sampling period along with bulk water samples. No positive results were observed from the bulk water and LB samples while 91% of TB samples tested for the presence of the gene. No significant difference was observed in detection by PCR from biofilm samples before and after the switch to chloraminated water. / Department of Biology

El género "Aeromonas" pertenece a la familia "Vibrionaceas". Dentro de este généro podemos diferenciar dos grupos: un primer grupo formado por microorganismos psicrófilos no mótiles en el que únicamente hallamos la especie "Aeromonas salmonicida" y un segundo grupo formado por microorganismos mesófilos mótiles en el que hallamos las especies "Aeromonas hydrophila", "Aeromonas sobria" y "Aeromonas caviae". Las cepas de "Aeromonas" mesófilas mótiles son microorganismos que se caracterizan por su elevada diversidad en cuanto al grado de virulencia. Estas diferencias se hallan estrechamente relacionadas con las estructuras moleculares presentes a nivel de la superficie bacteriana. La incidencia y variabilidad de este grupo hizo que obtuviesen a partir de muestras de agua diferentes bacteriófagos específicos para las estructuras superficiales bacterianas, los cuales pudiesen emplearse como marcadores biológicos que permitiesen diferenciar a un serotipo de los restantes dentro del grupo de "Aeromonas" mótiles. De este modo, se aislaron los bacteriófagos PM1, PM2 y PM3.El bacteriófago PM1 presenta doble cadena de DNA, capside poliédrica y una placa con fibras en la cola. Además, posee como receptor el antígeno O del lipopolisacárido (LPS) de las cepas de serotipo 0:34 y, en consecuencia, los mutantes espontáneos resistentes al citado bacteriófago carecen de antígeno 0 del LPS, aunque presentan sensibilidad a bacteriófagos de "Aeromonas" cuyo receptor es el núcleo del LPS. El bacteriófago PM2 presenta doble cadena de DNA, cápside poliédrica y una placa basal con espinas. Además, posee como receptor el núcleo del LPS de diferentes cepas de serotipo 0:34 y 0:11 (así como "A. salmonicida"); en consecuencia, los mutantes resistentes al mismo presentan alteraciones en los oligosacáridos del núcleo del LPS, careciendo en todos los casos de antígeno 0 del LPS. El bacteriófago PM3 presenta doble cadena de DNA y posee como receptor el flagelo monopolar de diferentes serotipos de "A. hydrophila" tanto con lámina S como sin lámina. Los mutantes resistentes a este bacteriófago presentan alteraciones en el flagelo o en la motilidad de dichas cepas bacterianas. Estos bacteriófagos han permitido la agrupación de diferentes cepas de "Aeromonas" mesófilas que luego han correspondido a serotipos distintos. Así, las cepas sensibles al bacteriófago PM1 pertenecen al serogrupo 0:34 y presentan las siguientes características:1.- Un perfil de proteínas de membrana externa tremendamente homogéneo.2.- Un LPS heterogéneo, químicamente formado por KDO, L-heptosas, glucosa y hesoxaminas, y carente en D-heptosas, galactosa, rhamnosa y pentosas.3.- Una DL(50) a 20ºC menos elevada que a 37°C, tanto en ratón como en pez, lo cual indica que son más virulentas a 20ºC que a 37°C. Este hecho se debe a la producción de antígeno 0 del LPS a 20ºC y a la práctica ausencia del mismo a 37°C. Todo ello implica al antigeno 0 del LPS en la virulencia de estas cepas.Uno de los serotipos más importantes dentro de las "Aeromonas" mesófilas a causa de su elevado grado de virulencia es el denominado serotipo 0:11. Este serotipo presenta:1. Un LPS homogéneo, formado químicamente por KDO y L-heptosas en el núcleo del LPS y glucosa, galactosa, mañosa y hexosaminas en el antígeno 0 del LPS. 2. Una lámina proteínica de estructura tetragonal, denominada lámina S, que recubre prácticamente la superficie celular haciendo que el LPS quede totalmente recubierto. Esta poca accesibilidad del antígeno 0 del LPS hace difícil encontrar marcadores biológicos (bacteriófagos) para este serotipo. 3. Todas las cepas de serotipo 0: 11 al igual que las de "A. salmonicida" poseen la propiedad de autoaglutinar. Dicha propiedad está ligada fundamentalmente a la presencia de lámina S y de flagelo.4. La DL(50) de este serotipo es dos logaritmos inferior a la existente en las cepas de serotipo 0:34 y además es muy similar en todos los mutantes isogénicos obtenidos para las diferentes estructuras superficiales. Una vez estudiados los serotipos 0:34 y 0:11 de las "Aeromonas" mesófilas se obtuvieron mutantes isogénicos, bien por resistencia a bacteriófagos específicos para las diferentes estructuras superficiales o bien mediante mutagénesis con un agente alquilante y contraselección con anticuerpos especificos frente a 1as estructuras superficiales a alterar.Con el uso de los citados mutantes se determinó que la vía clásica del complemento es la responsable en las "Aeromonas" pertenecientes al serotipo 0:34 y 0:11 de la activación del complemento y por consiguiente, de la actividad bactericida del suero. Además, se obeservó que la lámina S peresente en las cepas de serotipo 0:11 no activaba la acción del complemento (a diferencia de la lámina A de "A. salmonicida"), sino que el determinante a nivel de las estructuras superficiales de la resistencia a la actividad bactericida del suero en ambos serotipos son los oligosacáridos del núcleo del LPS. Finalmente se demostró que el LPS de todas las "Aeromonas" mesófilas es capaz de activar el complemento, y la razón de ser sensible o resistente a la actividad bactericida del suero se debe a la fijación o no de C3b pegado a la membrana y la consiguiente formación de los complejos C5b-9. / The motile "Aeromonas" group is characterized by their high diversity degree of virulence. These differences are related with molecular structures located on the bacterial surface.Several bacteriophages of motile "Aeromonas" were isolated and characterized from water samples. Thus, it was obtained bacteriophages whose receptors are: the 0 antigen lipopolisaccharide (LPS) of 0:34 serotype strains, the core LPS of 0:34 and 0:11 serotype strains (as soon as "Aeromonas salmonicida" and the monopolar flagellum of motile "Aeromonas".Then, motile "Aeromnas" 0:34 and 0:11 isogenic mutants were obtained by resistance to the specific bacteriophages for different structures, or by mutagenesis with an alquilant agent and contraselection with specific antibodies.Using the different isogenic mutants it was possible to determinate: a) the complement activation pathway in the 0:34 and 0:11 serotypes motile "Aeromonas" is the classical pathway, b) the S-layer present on the 0:11 serotype strains not activate the complement action; but, in contrast, the A-layer present on the "Aeromonas salmonicida" strains active this action, c) the complement activation determinant at the structural bacterial surface are the core LPS oligosaccharides, and d) the LPS present at all motile "Aeromonas" strains activate the classical complement pathway; and the sensibility or resistance from the bactericidal action was due to the presence or absence of C3b linked on the membranes and the subsequence formation of C5b-9 complexes.

Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 5 uppsatser.

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xvi, 105 p.; also includes graphics (some col.) Includes bibliographical references (p. 95-105). Available online via OhioLINK's ETD Center

Thesis (Ph. D.)--Miami University, Dept. of Chemistry and Biochemistry, 2007. / Title from second page of PDF document. Includes bibliographical references.

Orientador: Helio Langoni / Resumo: EBERHARDT, B.G. Avaliação de micro-organismos zoonóticos em filés de tilápia do Nilo (Oreochromis niloticus). Botucatu, 2018. 71p. Tese (Doutorado) – Faculdade de Medicina Veterinária e Zootecnia, Campus de Botucatu, Universidade Estadual Paulista. RESUMO Cinquenta filés de tilápia do Nilo (Oreochromis niloticus) obtidos em mercado de peixes no município de Ourinhos, Estado de São Paulo, foram analisados quanto à prevalência para Aeromonas hydrophila, Edwardsiella tarda, Mycobacterium spp. e Cianobactérias. Amostras de músculo foram avaliadas por PCR para Aeromonas hydrophila, Edwardsiella tarda e Mycobacterium spp., enquanto que as amostras para cianobactérias foram analisadas por PCR em Tempo Real (qPCR). Os resultados obtidos demonstraram ausência de Aeromonas hydrophila e Edwardsiella tarda nas amostras de filés. A prevalência para Mycobacterium spp. foi de 100% (50/50). Realização posterior de sequenciamento revelou Mycobacterium gordonae. Esta bactéria é considerada um colonizador comum, normalmente não patogênico, porém, há relatos de literatura que demonstram risco de infecção em indivíduos imunossuprimidos e até mesmo imunocompetentes. A taxa de prevalência para cianobactérias foi de 48% (24/50). As cianobactérias (algas azuis) produzem grande quantidade de metabólitos bioativos ou mesmo tóxicos, incluindo toxinas associadas a problemas ambientais e de saúde pública. Considerando a natureza e o papel das cianobactérias como patógenos emergentes, a elevada prevalência... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor