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Hydrophila
Kinds of Hydrophila Selected AbstractsDevelopment of a bacterial challenge test for gnotobiotic sea bass (Dicentrarchus labrax) larvaeENVIRONMENTAL MICROBIOLOGY, Issue 2 2009K. Dierckens Summary The use of probiotic microorganisms in aquaculture is gaining a lot of interest. Gnotobiotic model systems are required in order to fully understand the effects and modes-of-action of these microorganisms, as the native microbial communities present in non-sterile animals can lead to false conclusions. In this study, a gnotobiotic sea bass larvae (Dicentrarchus labrax) test system was developed. In order to obtain bacteria-free animals, the eggs were disinfected with glutaraldehyde and subsequently incubated in a solution of rifampicin and ampicillin. Axenity was confirmed using culture-dependent and -independent techniques. The gnotobiotic larvae were fed axenic Artemia sp. from 7 days after hatching onwards. In the challenge test, one of the three opportunistic pathogens, Aeromonas hydrophila, Listonella anguillarum serovar O1 and O2a, was added to the model system via the water and encapsulated in Artemia sp. Only serovar O2a led to increased mortality in the sea bass larvae. The presented gnotobiotic model can be used for research on, among others, reciprocal metabolic effects between microorganisms and the host (e.g. as measured by gene expression), immunostimulants, pharmacological research and the histological development of the gastrointestinal tract and growth of larvae. [source] Acute effects of the antibiotic oxytetracycline on the bacterial community of the grass shrimp, Palaemonetes pugio,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2009Miguel Uyaguari Abstract The toxicity of oxytetracycline (OTC) was evaluated in adult grass shrimp, Palaemonetes pugio. Initially, static acute (96 h) toxicity tests were conducted with shrimp exposed from 0 to 1,000 mg/L OTC. A calculated lethal concentration 50% value of 683.30 mg/L OTC (95% confidence interval 610.85,764.40 mg/L) was determined from these tests, along with a lowest-observable-effect concentration of 750 mg/L and no-observable-effect concentration of 500 mg/L. Moreover, chronic sublethal effects of OTC exposure on grass shrimp intestinal bacterial population were assessed using doses from 0 to 32 mg/L OTC. The total viable counts in digestive tract content had levels between 5.2 and 1 × 104 colony-forming units per gram of tissue at times 0 and 96 h, respectively. Aeromonas hydrophila were the most resistant isolates (27.78%) to OTC exposure. Vibrio alginolyticus showed significant positive growth following exposure to OTC, whereas other bacterial species abundance declined over time. A total of 268 bacterial isolates were screened using antibiotic resistance analysis from a library containing 459 isolates. Among the tested isolates from the OTC treatments, 15.4% were resistant to OTC and 84.6% were OTC sensitive. Oxytetracycline was generally not consistently quantifiable with liquid chromatography-mass spectroscopy technique in shrimp homogenates. The only peak detected was at the 32 mg/L dose of OTC at 96 h. Nevertheless, OTC had a significant biological effect on the bacterial population. Antibiotic resistance to five other antibiotics (penicillin G, sulfathiazole, trimethoprim, trimethoprim and sulfamethoxazole, and tetracycline) was strongly associated with OTC exposures. The present study indicates that OTC toxicity effects in P. pugio and changes in the shrimp microbial community would only be expected under special circumstances. [source] Cytotoxins of the human pathogen Aeromonas hydrophila trigger, via the NLRP3 inflammasome, caspase-1 activation in macrophagesEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 10 2010Andrea J. McCoy Abstract Aeromonas hydrophila is a Gram-negative pathogen that causes serious infectious disease in humans. A. hydrophila induces apoptosis in infected macrophages, but the host proinflammatory responses triggered by macrophage death are largely unknown. Here, we demonstrate that the infection of mouse macrophages with A. hydrophila triggers the activation of caspase-1 and release of IL-1,. Caspase-1 activation was abrogated in macrophages deficient in Nod-like receptor family, pyrin domain containing 3 (NLRP3) and apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), but not NLR family, CARD domain containing 4 (NLRC4). The activation of the NLRP3 inflammasome was mediated by three cytotoxins (aerolysin, hemolysin and multifunctional repeat-in-toxin) produced by A. hydrophila. Our results indicated that the NLRP3 inflammasome senses A. hydrophila infection through the action of bacterial cytotoxins. [source] ORIGINAL ARTICLE: Echinacea purpurea and Allium sativum as immunostimulants in fish culture using Nile tilapia (Oreochromis niloticus)JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 5 2010S. M. Aly Summary The study was conducted to evaluate the efficiency of echnicacea (E) and garlic (G) supplemented diets as immunostimulant for tilapia (Oreochromis niloticus). Seven treatments were designed including a control (C). Fish were fed on 35% protein diet at a rate of 3% body weight per day. Echinacea (1.0 ppt) and garlic (3%) were incorporated in the feed, which was administered for periods of 1, 2 and 3 months (summer season), followed by basal diet for 4 more months (winter season). Neutrophil adherence and haematocrit values increased in both supplemented groups with prolonging period of application. The neutrophils adherence was significantly increased in all treatments except group administered echinacea for 1 month. The lymphocytic counts were significantly (p < 0.004) elevated that resulted in a significant increase in the total leucocytic count in groups administered echinacea for 1 and 2 months when compared with the control and/or other treatments. The gain in the body weight and specific growth rate was significantly increased in all supplemented groups (p < 0.004) during summer, but remained without any significant increase after winter. The survival rate was significantly high (>85%) in all the supplemented groups. The percentage of protection, after challenge infection using pathogenic Aeromonas hydrophila was the highest in groups supplemented with echinacea and garlic for 3 months after summer and winter seasons. It could be concluded that echinacea and garlic improve the gain in body weight, survival rate and resistance against challenge infection. Both compounds showed extended effects after withdrawal and improved resistance to cold stress during the winter season. However, a full commercial cost benefit analysis is necessary before recommending their application in aquaculture. [source] Isolation and selection of Bacillus spp. as potential biological agents for enhancement of water quality in culture of ornamental fishJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2007R. Lalloo Abstract Aims:, To isolate, select and evaluate Bacillus spp. as potential biological agents for enhancement of water quality in culture of ornamental fish. Methods and Results:, Natural isolates obtained from mud sediment and Cyprinus carpio were purified and assessed in vitro for efficacy based on the inhibition of growth of pathogenic Aeromonas hydrophila and the decrease in concentrations of ammonium, nitrite, nitrate and phosphate ions. Based on suitability to predefined characteristics, the isolates B001, B002 and B003 were selected and evaluated in vitro in the presence of Aer. hydrophila and in a preliminary in vivo trial with C. carpio. The inhibitory effect on pathogen growth and the decrease in concentrations of waste ions was demonstrated. Based on 16S RNA sequence homology, the isolates were identified as Bacillus subtilis, Bacillus cereus and Bacillus licheniformis, respectively. Isolate B002 did not contain the anthrax virulence plasmids pOX1, pOX2 or the B. cereus enterotoxin. Conclusions:, Selected isolates effected synergistic reduction in pathogen load and the concentrations of waste ions in vitro and in vivo and are safe for use in ornamental aquaculture. Significance and Impact of the Study:, A new approach for assessment of biological agents was demonstrated and has yielded putative isolates for development into aquaculture products. [source] The effects of temperature, water activity and pH on the growth of Aeromonas hydrophila and on its subsequent survival in microcosm waterJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2003M. Sautour Abstract Aims: The influence of temperature, water activity and pH on the growth of Aeromonas hydrophila, and on its survival after transfer in nutrient-poor water were assessed. Methods and Results: Experiments were carried out according to a Box,Behnken matrix at 10,30°C, 0·95,0·99 water activity (aw) and pH 5,9. The effect of each factor on the kinetic parameters of growth (i.e. the maximal specific growth rate, ,max, and the lag time, ,) and on the decline of the bacteria in microcosm water (time to obtain a reduction of 5 log, T5 log) were studied by applying central composite design. Conclusions: The major effect of temperature and water activity on the growth of A. hydrophila was highlighted, whereas the effect of pH in these experimental conditions was not significant. Models describing the effect of environmental parameters on the growth of A. hydrophila were proposed. The effect of the growth environment, and particularly the incubation temperature, have an influence on the survival ability of the bacteria in nutrient-poor water. Significance and Impact of the Study: The Box,Behnken design was well suited to determine the influence of environmental factors on the growth of A. hydrophila and to investigate the effect of previous growth conditions on its survival in microcosm water. [source] Phenotypic study by numerical taxonomy of strains belonging to the genus AeromonasJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2002L. Valera Aims: ,This study was undertaken to cluster and identify a large collection of Aeromonas strains. Methods and Results: ,Numerical taxonomy was used to analyse phenotypic data obtained on 54 new isolates taken from water, fish, snails, sputum and 99 type and reference strains. Each strain was tested for 121 characters but only the data for 71 were analysed using the `SSM' and `SJ' coefficients, and the UPGMA clustering algorithm. At SJ values of , 81·6% the strains clustered into 22 phenons which were identified as Aer. jandaei, Aer. hydrophila, Aer. encheleia, Aer. veronii biogroup veronii, Aer. trota, Aer. caviae, Aer. eucrenophila, Aer. ichthiosmia, Aer. sobria, Aer. allosaccharophila, Aer. media, Aer. schubertii and Aer. salmonicida. The species Aer. veronii biogroup sobria was represented by several clusters which formed two phenotypic cores, the first related to reference strain CECT 4246 and the second related to CECT 4835. A good correlation was generally observed among this phenotypic clustering and previous genomic and phylogenetic data. In addition, three new phenotypic groups were found, which may represent new Aeromonas species. Conclusions: ,The phenetic approach was found to be a necessary tool to delimitate and identify the Aeromonas species. Significance and Impact of the Study: ,Valuable traits for identifying Aeromonas as well as the possible existence of new Aeromonas species or biotypes are indicated. [source] Occurrence of Staphylococcus and enteropathogens in soft cheese commercialized in the city of Rio de Janeiro, BrazilJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2002V.S. Araújo Aims: To investigate the presence of Staphylococcus aureus, enteropathogenic Escherichia coli (EPEC), Aeromonas spp. and Yersinia spp. in soft cheese commercialized in Rio de Janeiro, Brazil. Methods and Results: A total of 45 samples of cheese from three different brands marketed in Rio de Janeiro city were analysed for faecal coliform levels using the Most Probable Number (MPN) technique. The samples were also analysed using conventional methodology for the investigation of food-borne pathogens. High levels of faecal contamination were detected in 95·5% of cheese samples. Staphylococcus aureus was isolated from 20% of samples, of which 17·7% were above the limits allowed by Brazilian legislation. Aeromonas hydrophila and Aer. caviae were detected in 17·7% of the samples. Yersinia spp. were not found in this study. EPEC was isolated from 21·1% of the samples and the most frequently found serogroups were O127, followed by O55 and O26. Conclusions: Our results showed that 95·5% of cheese samples had high levels of faecal coliforms. The isolation of Staph. aureus, serogroups of EPEC and Aeromonas spp. suggested that the soft cheese commercialized in the city of Rio de Janeiro may represent a health risk for the consumers. Significance and Impact of the Study: These results suggest that soft cheese may act as an important vehicle of transmission for well-established pathogens. [source] Prevalence and virulence properties of Vibrio cholerae non-O1, Aeromonas spp. and Plesiomonas shigelloides isolated from Cambé Stream (State of Paraná, Brazil)JOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2000A. Gibotti The incidence of Vibrio cholerae, Aeromonas spp. and Plesiomonas shigelloides was determined in water samples from Cambé Stream. The samples were collected from seven different sites. The serogroups, virulence markers and drug resistance profiles were also evaluated. Twelve Aer. hydrophila, 12 Aer. caviae, eight Aer. sobria, seven Ple shigelloides and two V. cholerae non-O1 were isolated. They belonged to different serogroups and all produced haemolysis in different assays. Five of the Aeromonas strains and one of V. cholerae non-O1 were positive for enterotoxin activity. Haemagglutination and its inhibition, using erythrocytes of different origins, was variable for Aeromonas spp. and V. cholerae, while none of the Ple. shigelloides haemagglutinated in association with any type of erythrocyte. All isolates exhibited multiple drug resistance. These results indicate that the occurrence of V. cholerae non-O1, Aeromonas spp. and Ple. shigelloides, in water used for vegetable irrigation, human recreation and animal consumption, among others, represents a potential risk for humans. [source] The response of Aeromonas hydrophila to oxidative stress induced by exposure to hydrogen peroxideJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2000J.P.B. Landre Aeromonas hydrophila, an opportunist human pathogen of low virulence, was shown to display a high degree of sensitivity upon exposure to hydrogen peroxide. As with other species, Aer. hydrophila is able to develop the capacity to resist loss of viability induced by such oxidative stress. Development of stress resistance follows the archetypal profile where pre-exposure of a population to sub-lethal levels of H2O2 stimulates onset of tolerance to further exposure. Acquisition of tolerance critically requires nascent protein synthesis. Further analysis demonstrated population growth phase influences the degree of sensitivity of the organism. Late stationary phase cultures demonstrate a decreased sensitivity compared with younger populations. Significantly, it was also determined that stock culture age influenced the level of sensitivity of the derived experimental culture, where an increased stock culture age corresponded with enhanced resistance to H2O2. These data show that Aer. hydrophila population phenotype is influenced by the phenotype of the donor stock culture. [source] Experimental challenge studies in Vietnamese catfish, Pangasianodon hypophthalmus (Sauvage), exposed to Edwardsiella ictaluri and Aeromonas hydrophilaJOURNAL OF FISH DISEASES, Issue 9 2010M Crumlish Abstract The two main diseases in the pangasius catfish industry are bacillary necrosis of Pangasianodon (BNP) and motile aeromonas septicaemia (MAS), where the aetiological agents have been identified as Edwardsiella ictaluri and Aeromonas hydrophila, respectively. In this study, apparently healthy Pangasianodon hypophthalmus were exposed to E. ictaluri, A. hydrophila or both bacterial species by intraperitoneal injection or immersion. There were 20 fish per treatment group, and the bacterial isolates used for the study were recovered from natural infections of BNP or MAS in farmed Vietnamese P. hypophthalmus. The results of the experimental infections mimicked the natural disease outbreaks reported from these pathogens in P. hypophthalmus. Furthermore, it was clearly demonstrated that E. ictaluri was only recovered from the fish exposed to the bacterium and not recovered from the animals receiving A. hydrophila. [source] The garlic component, allicin, prevents disease caused by Aeromonas hydrophila in rainbow trout, Oncorhynchus mykiss (Walbaum)JOURNAL OF FISH DISEASES, Issue 4 2010E J Nya Abstract Allicin was fed at 0 (= control), 0.5 and 1.0 mL of Allimed® liquid 100 g,1 of feed for 14 days to rainbow trout, Oncorhynchus mykiss (Walbaum), fingerlings before infection with Aeromonas hydrophila with a resultant reduction in mortalities from 80% in the controls to 8% [relative percentage survival (RPS) = 90%] and 0% (RPS = 100%) among the treated fish. Allicin was strongly antibacterial compared to the control, with a minimum inhibitory concentration (MIC) of >400 ,L mL,1 of Allimed® liquid. Use of allicin led to a lower number of white blood cells (132.0 ± 0.4 × 103) compared to 175.0 ± 0.1 × 103 in the controls, but elicited increased phagocytic activity, i.e. a phagocytic value of 39.2% compared to 13.6% in the controls, and serum lysozyme activity, which showed significant (P > 0.05) differences compared to the control at 15 and 30 min after the first reading at 0 min of incubation. [source] Microbial levan in the diet of Labeo rohita Hamilton juveniles: effect on non-specific immunity and histopathological changes after challenge with Aeromonas hydrophilaJOURNAL OF FISH DISEASES, Issue 9 2008S K Gupta Abstract A 60-day feeding trial was conducted to study the immuno-protective effect of microbial levan on Labeo rohita juveniles challenged with Aeromonas hydrophila. Six purified diets were prepared with different levels of microbial levan: control (no levan), T1 (Basal + 0.25%), T2 (Basal + 0.50%), T3 (Basal + 0.75%), T4 (Basal + 1%) and T5 (Basal + 1.25%), fed to six groups of fish in triplicate. Among the treatment groups the haemoglobin content and total leucocyte count were increased with a dietary supplementation of levan at 1% or more. An increasing trend for total erythrocyte count was observed with increasing level of dietary levan. Lower levan-supplemented groups showed a higher albumin/globulin ratio. As the levan supplementation was increased, there was a gradual increase in serum lysozyme activity and respiratory burst activity [nitroblue tetrazolium (NBT) assay] reduction values. The highest lysozyme activity and NBT were observed in the T5 group although this was similar to the T4 group (P > 0.05). No significant histo-architectural changes were associated with dietary levan levels. After challenge with A. hydrophila, moderately degenerated hepatocytes, oedema and leucocytic infiltration in parenchymatous tissues, and extensive haemorrhage and haemosiderosis in the kidney were observed in the control group. However, the T5 group supplemented with 1.25% levan showed infiltrating leucocytes in the liver while the kidney showed only moderate degeneration of renal tubules. The relative survival per cent of juveniles after challenge with A. hydrophila was the highest in the T5 group followed by T4. This suggests that microbial levan at 1.25% can be used as dietary immunostimulant for L. rohita juveniles. [source] Adjuvant effect of mushroom glucan and bovine lactoferrin upon Aeromonas hydrophila vaccination in catla, Catla catla (Hamilton)JOURNAL OF FISH DISEASES, Issue 6 2006D Kamilya Abstract Mushroom glucan and bovine lactoferrin (Lf), known for their immunostimulatory potential, were used as adjuvant in conjunction with a formalin-killed Aeromonas hydrophila vaccine in catla, Catla catla. In vitro antigen-specific responsiveness of catla leucocytes and protective responses against experimental challenge with homologous antigen were monitored following immunization. Antigen-specific proliferation, ,macrophage activating factor' (MAF) production and antibody production were significantly higher in fish injected with glucan adjuvanted vaccine. Lf adjuvanted preparations showed a weak proliferative response and MAF production, although the antibody production was significantly higher than the controls. A good degree of protection was achieved with the glucan adjuvanted vaccine. However, in spite of producing significant anti- A. hydrophila antibody, Lf adjuvanted vaccine did not confer any protection following challenge with A. hydrophila. The potential of adjuvanticity of mushroom glucan and bovine Lf in intraperitoneal vaccination is discussed. [source] Competition for attachment of aquaculture candidate probiotic and pathogenic bacteria on fish intestinal mucusJOURNAL OF FISH DISEASES, Issue 6 2004N G Vine Abstract Probiotics for aquaculture are generally only selected by their ability to produce antimicrobial metabolites; however, attachment to intestinal mucus is important in order to remain within the gut of its host. Five candidate probiotics (AP1,AP5), isolated from the clownfish, Amphiprion percula (Lacepéde), were examined for their ability to attach to fish intestinal mucus and compete with two pathogens, Aeromonas hydrophila and Vibrio alginolyticus. Two different radioactive isotopes were used to quantify competition between pathogens and probionts. Attachment of the pathogens was enhanced by the presence of the candidate probiotics. However, the addition of the candidate probiotics after the pathogens resulted in reduced pathogen attachment. Only AP5 caused lower attachment success of V. alginolyticus when added before the pathogen. When AP5 was added first, the average attachment change was 41% compared with 72% when added after V. alginolyticus, suggesting that the probiotic is displaced but that enhanced attachment of the pathogen does not occur. Conversely, when V. alginolyticus was added first, followed by AP5, attachment change was 37% while AP5 had 92% attachment change when added second. This implies that the pathogen was displaced by the candidate probiotic and therefore it appeared that, based on the ability of probiont AP5 to attach to mucus, the growth of the pathogen in the digestive tract might be suppressed by the candidate probiont's presence. [source] Use of probiotics to control furunculosis in rainbow trout, Oncorhynchus mykiss (Walbaum)JOURNAL OF FISH DISEASES, Issue 6 2002A Irianto Aerobic heterotrophic bacteria were isolated from the intestinal contents of Atlantic salmon, Salmo salar, rainbow trout, Oncorhynchus mykiss, and turbot, Scophthalmus maximus, on tryptone soya agar and De Man Rogosa and Sharpe agar, of which 11 of 177 (6% of the total) of the isolates were antagonistic to Aeromonas salmonicida. Four of these cultures, which were identified tentatively as A. hydrophila, Vibrio fluvialis, Carnobacterium sp. and an unidentified Gram-positive coccus, were beneficial to fish when fed singly or as an equi-mixture. Feed supplemented with the putative probiotics indicated survival of the organisms in the gastrointestinal tract for 7 days. Feeding with the probiotics for 7 and 14 days led to better survival following challenge with A. salmonicida. There was no indication of serum or mucus antibodies to A. salmonicida, but there was an increased number of erythrocytes, macrophages, lymphocytes and leucocytes, and enhanced lysozyme activity in the fish. [source] PURIFICATION AND CHARACTERIZATION OF BACTERIOCIN FROM WEISSELLA PARAMESENTEROIDES DFR-8, AN ISOLATE FROM CUCUMBER (CUCUMIS SATIVUS)JOURNAL OF FOOD BIOCHEMISTRY, Issue 5 2010AJAY PAL ABSTRACT Bacteriocin from Weissella paramesenteroides DFR-8 isolated from cucumber (Cucumis sativus) was purified by using only two steps, viz., pH-mediated cell adsorption,desorption method and gel permeation chromatography. A single peak observed in the purity check by analytical Reverse Phase-High Performance Liquid Chromatography (Waters 600 analytical HPLC system, Milford, MA) and a single band (molecular weight,3.74 kDa) shown on SDS-PAGE analysis strongly indicated the homogeneity of the bacteriocin preparation. Treatment with proteolytic enzymes abolished the antimicrobial activity indicating the proteinaceous nature of bacteriocin. The purified bacteriocin exhibited a broad inhibitory spectrum against foodborne pathogens and spoilage microorganisms, including gram-negative bacteria such as Salmonella typhimurium, Vibrio parahaemolyticus, Aeromonas hydrophila and Listeria monocytogenes. Response surface methodology was employed to study the interactive effect of temperature and pH on bacteriocin activity, and a regression equation was developed. The bacteriocin retained full activity after storage at,20C for 90 days, while partial and complete activity loss was observed when stored at 4 and 37C, respectively. PRACTICAL APPLICATION In recent years, bacteriocins of lactic acid bacteria have gained much attention as food biopreservatives because of their origin from generally regarded as safe organisms. In spite of various bacteriocins studied worldwide, studies on bacteriocins of Weissella paramesenteroides remain rare. The present work involves the purification of bacteriocin up to absolute homogeneity from W. paramesenteroides, an isolate first time reported from cucumber (Cucumis sativus). The purified bacteriocin (molecular weight ,3.74 kDa) was found to inhibit a large number of foodborne pathogens, including Listeria monocytogenes, which is resistant to commercially available bacteriocin, i.e., nisin. The application of central composite rotatable design enabled us to design a regression equation from which the residual activity of bacteriocin can be predicted at any given conditions of temperature and pH within the experimental domain. The broad inhibitory spectrum and thermostability of bacteriocin suggest its potential application in food preservation. [source] GROWTH AND CHARACTERIZATION OF THE HISTAMINE-FORMING BACTERIA OF JACK MACKEREL (TRACHURUS SYMMETRICUS)JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 6 2003ALINA BERMEJO ABSTRACT Consumption of fish with high histamine poses health hazards. The isolation, identification and viable counts of the histamine-forming bacteria from jack mackerel in batch cultures in trypticase soy broth with 2 % histidine at 25, 15 and 5C were performed. Proteus vulgaris, Aeromonas hydrophila and Photobacterium damsela were the most histamine producing population. The community had a maximal specific growth rate (,max) of 0.304, 0.217 and 0.048 h,1 at 25, 15 and 5C, respectively. Mulchandani's model, with an exponential value of 5.21, predicted bacterial growth. Histamine production was proportional to growth rate; proportionality coefficients were 1.987, 0.436 and 1.439 and the community's maximal spefic rates for histamine production were 0.604, 0.095 and 0.068 [g histamine (g dry cells h),1] af 25, 15 and SC, respectively. Lesser histamine production at 15C needs further investigation in whole fish, as it is a relevant result forfish handling. [source] OCCURRENCE OF HEMOLYSIN-PRODUCING AEROMONADS IN MEAT AND OFFAL SOLD IN PORT HARCOURT, NIGERIAJOURNAL OF FOOD SAFETY, Issue 3 2005E.N. AMADI ABSTRACT Fresh, different meat types and offal were examined for the occurrence of Aeromonas species by the direct-plating and enrichment methods. The enrichment method (coefficient of variation = 15.1%) enhanced the recovery of Aeromonas species. The major Aeromonas species identified were A. sobria (67.3%) and A. hydrophila (21.2%). Other species occurred in minor proportions and were A. caviae, A. proteolytica and A. salmonicida. Out of the 52 isolates, 50 were motile species except two which were not motile and identified as the species A. proteolytica. Sixteen motile species occurred in cow, 18 in goat and 16 in lamb. The motile species and the two nonmotile species were hemolytic. They were all sensitive to chloramphenicol (30 mg) and resistant to ampicillin (10 mg). The nonmotile A. proteolytica were all resistant to tetracycline. Aeromonas caviae, A. salmonicida, A. hydrophila and A. sobria were killed after exposure to 50C (decimal reduction time, D10 = 30 s). Aeromonads are unlikely to pose a public health problem in Nigeria where meat undergoes prolonged cooking. Meat is a possible factor in the epidemiology of Aeromonas -associated gastroenteritis in man. [source] CALCOFLUOR AS A FLUORESCENT PROBE TO DETECT BIOFILMS OF FOODBORNE PATHOGENSJOURNAL OF FOOD SAFETY, Issue 1 2003C.L. ERIKSSON DE REZENDE ABSTRACT Biofilms enable foodborne pathogens to resist removal from surfaces, survive disinfection and elude detection. This study evaluated the use of Calcofluor, which binds to polysaccharides containing ,-D-glucans, to detect biofilms produced by Salmonella enterica serovar Berta and Salmonella enterica serovar Typhimurium DT104 (St DT104), Escherichia coli, Aeromonas hydrophila, Vibrio cholerae O139 and Hyphomonas adhaerens. Biofilms produced by St DT104, S. berta and V. cholerae on five types of surfaces (glass, polypropylene, TeflonÔ, stainless steel and aluminum) were detected by Calcofluor. Results suggest the potential use of Calcofluor as probes of foodborne pathogens in biofilms. [source] ENUMERATION OF AEROMONAS FOR VERIFICATION OF THE HYGIENIC ADEQUACY OF SWINE CARCASS DRESSING PROCESSES,JOURNAL OF FOOD SAFETY, Issue 1 2000SHEW-LING YU ABSTRACT Populations of Aeromonas spp. and aerobic bacteria from dehairing equipment and from carcasses passing through different processing steps in a swine slaughtering plant were evaluated to identify the hygienic risks of each operation. Sponge samples were taken from the scraper flails in dehairing machines and the surface of the shackling table at pre- and post-operation times, with 20 samples from each location being collected at each time. Increased post-operation levels of Aeromonas spp. indicated a buildup and possible spread of these bacteria to carcasses. The belly skins of 40 dehaired carcasses were each sampled at five points along the process line which were after the shackling, after the final singeing, after the final polishing, after the final wash and after chilling. The levels of microbial contaminants on carcasses varied at each processing step. The heaviest contamination of carcasses with Aeromonas (1.88 log CFU/cm2) and aerobic bacteria (2.66 log CFU/cm2) occurred after shackling. Counts were reduced at other steps as a result of singeing, washing and chilling operations. However, singed carcasses were recontaminated with Aeromonas and aerobic bacteria during the polishing operation. Aeromonas hydrophila were the most prominent motile aeromonads (74.1%) recovered at the plant. The findings for Aeromonas spp. were similar to those for aerobic bacteria (r2= 0.9995) which suggested that Aeromonas spp. are appropriate indicators for assessing carcass dressing processes. [source] Antibacterial activities and total phenolic contents of grape pomace extractsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2004Gülcan Özkan Abstract The aim of this study was to determine the total phenolic contents and antibacterial effects of grape pomace extracts (cultivars Emir and Kalecik karasi) against 14 bacteria, and the effects of the extracts on the growth and survival of two of the bacteria during storage. The total phenolic contents of grape pomace of Emir and Kalecik karasi cultivars extracted with acetone/water/acetic acid (90:9.5:0.5) were 68.77 and 96.25 mg GAE g,1, respectively. The agar well diffusion method was used to test the antibacterial activity of the extracts at 1, 2.5, 5, 10 and 20% (w/v) concentrations in methanol on spoilage and pathogenic bacteria including Aeromonas hydrophila, Bacillus cereus, Enterobacter aerogenes, Enterococcus faecalis, Escherichia coli, Escherichia coli O157:H7. Mycobacterium smegmatis, Proteus vulgaris, Pseudomonas aeruginosa, Pseudomonas fluorescens, Salmonella enteritidis, Salmonella typhimurium, Staphylococcus aureus and Yersinia enterocolitica. All the bacteria tested were inhibited by extract concentrations of 2.5, 5, 10 and 20%, except for Y enterocolitica which was not inhibited by the 2.5% concentration. However, pomace extracts at 1% concentration had no antibacterial activity against some of the bacteria. According to the agar well diffusion method, E coli O157:H7 was the most sensitive of the bacteria. Generally, using the serial dilution method, while the extracts at 0.5% concentration had bacteriostatic activities on E coli O157:H7 and S aureus, the extracts appeared to have bactericidal effects at 1 and 2.5% concentrations. In accordance with this method, S aureus was more sensitive than E coli O157:H7 to the extracts. Copyright © 2004 Society of Chemical Industry [source] Competitive exclusion as a mode of action of a novel Bacillus cereus aquaculture biological agentLETTERS IN APPLIED MICROBIOLOGY, Issue 6 2010R. Lalloo Abstract Aims:, To determine the contribution of potential modes of action of a Bacillus cereus aquaculture biological control agent in inhibition of the fish pathogen, Aeromonas hydrophila. Methods and Results:, When B. cereus was tested in plate well inhibition studies, no production of antimicrobial compounds was detected. Bacillus cereus had a high growth rate (0·96 h,1), whereas Aer. hydrophila concentration decreased by c. 70% in co-culture experiments. In nutrient limitation studies, B. cereus had a significantly higher growth rate when cultured under glucose (P < 0·05) and iron (P < 0·01) limitation in comparison with Aer. hydrophila. Bacillus cereus glucose (0·30 g l,1 h,1) and iron (0·60 mg l,1 h,1) uptake rates were also significantly higher (P < 0·01) than the Aer. hydrophila glucose (0·14 g l,1 h,1) and iron (0·43 mg l,1 h,1) uptake rates. Iron uptake was facilitated by siderophore production shown in time profile studies where relative siderophore production was c. 60% through the late exponential and sporulation phases. Conclusions:, Competitive exclusion by higher growth rate, competition for organic carbon and iron, facilitated by siderophore production, could be identified as mechanisms of pathogen growth inhibition by B. cereus. Significance and Impact of the Study:, This study is the first elucidation of the mechanism of action of our novel B. cereus biological agent in growth attenuation of pathogenic Aer. hydrophila. This study enhances the application knowledge and attractiveness for adoption of B. cereus NRRL 100132 for exploitation in aquaculture. [source] Detection of metallo-,-lactamases-encoding genes in environmental isolates of Aeromonas hydrophila and Aeromonas jandaeiLETTERS IN APPLIED MICROBIOLOGY, Issue 1 2009L.C. Balsalobre Abstract Aims:, To determine the prevalence and expression of metallo-,-lactamases (MBL)-encoding genes in Aeromonas species recovered from natural water reservoirs in southeastern Brazil. Methods and Results:, Eighty - seven Aeromonas isolates belonging to Aeromonas hydrophila (n = 41) and Aer. jandaei (n = 46) species were tested for MBL production by the combined disk test using imipenem and meropenem disks as substrates and EDTA or thioglycolic acid as inhibitors. The presence of MBL genes was investigated by PCR and sequencing using new consensus primer pairs designed in this study. The cphA gene was found in 97·6% and 100% of Aer. hydrophila and Aer. jandaei isolates, respectively, whereas the acquired MBL genes blaIMP, blaVIM and blaSPM-1 were not detected. On the other hand, production of MBL activity was detectable in 87·8% and 10·9% of the cphA -positive Aer. hydrophila and Aer. jandaei isolates respectively. Conclusions:, Our results indicate that cphA seems to be intrinsic in the environmental isolates of Aer. hydrophila and Aer. jandaei in southeastern Brazil, although, based on the combined disk test, not all of them are apparently able to express the enzymatic activity. Significance and Impact of the Study:, These data confirm the presence of MBL-producing Aeromonas species in natural water reservoirs. Risk of waterborne diseases owing to domestic and industrial uses of freshwater should be re-examined from the increase of bacterial resistance point of view. [source] Interactions of clinical and environmental Aeromonas isolates with Caco-2 and HT29 intestinal epithelial cellsLETTERS IN APPLIED MICROBIOLOGY, Issue 4 2007C.R.A. Couto Abstract Aim:, Evaluation of adherence and invasion of Aeromonas spp. to human colon carcinoma cell lines Caco-2 and HT29 and assessment of cytotoxic activity. Methods and Results:, A number of 27 strains of Aeromonas caviae and 23 strains of Aeromonas hydrophila was analysed. All strains were capable to adhere to sub-confluent monolayers of Caco-2 and HT29 cell types, presenting aggregative and diffuse adherence patterns cells, respectively. In the cytotoxic assays all strains showed cytopathic and/or cytotoxic activities to Vero cells. The evaluation of the tetrazolium salt (MTT test) reduction capability was carried out in Vero, Caco-2, and HT29 cells. MTT test showed that Vero cell line was the most sensitive cell type. In the invasion test, 13 strains were analysed on Caco-2 and HT29 monolayers. Only two (15%) of the 13 strains, A. hydrophila and A. caviae species, both isolated from vegetables were invasive to Caco-2 cells. No strains were able to invade the HT29 cells. Conclusions:,A. hydrophila and A. caviae isolated from human diarrhoeic faeces, vegetables, and water, were able to adhere to and produce cytotoxic/cytopathic effects in intestinal epithelial cell lines. Significance and Impact of the Study:, The presence of Aeromonas spp. in food and water samples expressing virulence factors suggest that these sources may act as dissemination vehicles of human pathogen with implication in the public health. [source] Aeromonas hydrophila Folliculitis Associated with an Inflatable Swimming Pool: Mimicking Pseudomonas aeruginosa InfectionPEDIATRIC DERMATOLOGY, Issue 5 2009Marc Juliŕ Manresa M.D. Skin and soft-tissue infections, including cellulitis and wound infections, are the second most frequent location of isolations of Aeromonas spp. in clinical samples, after the gastrointestinal tract. All three major Aeromonas species (A. hydrophila, A. caviae, and A. veroni biotype sobria) have been associated with wound infections, but A. hydrophila predominates. Typically, infection occurs after trauma and subsequent exposure to contaminated fresh water or soil. However, Aeromonas folliculitis has been rarely reported. We report the first two pediatric cases of Aeromonas hydrophila folliculitis associated with the use of recreational water facilities that clinically and epidemiologically mimic Pseudomonas folliculitis. Clinical and microbiological studies may be necessary to clarify the role of Aeromonas spp. in this newly-reported infection. [source] Antibacterial activity of plant extracts from azuki beans (Vigna angularis) in vitroPHYTOTHERAPY RESEARCH, Issue 2 2006Y. Hori Abstract This study was undertaken to examine the antimicrobial property of azuki beans (Vigna angularis). The water extracts of green, black and red colored azuki beans showed antibacterial effects against Staphylococcus aureus, Aeromonas hydrophila and Vibrio parahaemolyticus. In contrast, the extract of white azuki beans showed no inhibition towards any of the microorganisms examined. The extracts of colored azuki beans contained larger amounts of polyphenols including proanthocyanidins than the extracts of white azuki beans. The counts of S. aureus cells, inoculated in the medium containing the extracts of colored azuki beans, were signicantly reduced in comparison with those of control and white azuki beans after 24 h (p < 0.05). These results suggest that polyphenols including proanthocyanidins in colored azuki beans may be responsible for their antibacterial activity. Copyright © 2006 John Wiley & Sons, Ltd. [source] Factors Affecting Preference Responses of the Freshwater Ciliate Uronema nigricans to Bacterial PreyTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 2 2009BEGOŃA AYO ABSTRACT. To enhance our understanding of the factors affecting feeding selectivity of bacterivorous protists in aquatic systems, we examined the preference responses of the freshwater ciliate Uronema nigricans towards three bacterial prey taxa, Pseudomonas luteola, Serratia rubidaea, and Aeromonas hydrophila. Potential factors influencing the predator,prey contact rate included the previous feeding history of the ciliate and physiological state of bacteria. Preference indexes were obtained from multiple-choice mazes in which ciliates moved preferentially towards alternative bacteria or the prey species on which they had been feeding. Uronema nigricans showed differential attraction towards the offered prey types, and these preferences varied as a function of the ciliate feeding history: U. nigricans growing on P. luteola showed lower preference responses towards the offered bacteria than U. nigricans growing on S. rubidaea. The bacteria in stationary phase elicited a higher degree of attraction than bacteria in exponential phase, probably due to a higher concentration of carbohydrates in the former. Therefore, this protist will preferentially swim towards bacteria in stationary growth phase, although the degree of this response will be affected by the recent feeding history of the ciliate. [source] Immune response, disease resistance and intestinal microflora of juvenile Jian carp (Cyprinus carpio var. Jian) fed graded levels of pantothenic acidAQUACULTURE NUTRITION, Issue 4 2010Z.-P. WEN Abstract This study was to investigate the effect of dietary pantothenic acid (PA) on the disease resistance, immune response and intestinal microflora on juvenile Jian carp (Cyprinus carpio var. Jian). Seven diets (4.0, 15.5, 25.6, 36.1, 45.9, 56.1 and 65.9 mg PA kg,1) were fed to Jian carp (12.95 ± 0.03 g) for 9 weeks. After 9-week feeding trial, the challenge experiment with Aeromonas hydrophila was conducted to determine the impact of PA on fish disease resistance. Survival rate after challenge was promoted with the increasing PA levels (P < 0.05). Blood counts also significantly increased up to the dietary PA level of 25.6 mg PA kg,1 (P < 0.05). Leucocyte phagocytic activity, lectin potency, lysozyme and acid phosphatase activity, and total iron-binding capacity were improved with increasing PA levels (P < 0.05). Serum immunoglobulin M level and agglutination antibody titre to A. hydrophila were increased (P < 0.05) in fish fed the diets with the dietary PA levels between 56.1 and 65.9 mg kg,1. PA also promoted the growth and reproduction of Lactobacillus and depressed Escherichia coli and A. hydrophila (P < 0.05). These results suggested that pantothenic acid could improve disease resistance, immune response, and the balance of intestinal microflora in juvenile Jian carp. [source] Effects of dietary pyridoxine on disease resistance, immune responses and intestinal microflora in juvenile Jian carp (Cyprinus carpio var. Jian)AQUACULTURE NUTRITION, Issue 3 2010L. FENG Abstract This experiment was conducted to evaluate the effects of dietary pyridoxine on disease resistance, immune responses and intestinal microflora of fish. A total of 1050 Jian carp (11.71 ± 0.05 g) were randomly distributed into seven groups, feeding diets containing graded levels of pyridoxine (0.2, 1.7, 3.2, 5.0, 6.3, 8.6 and 12.4 mg kg,1 diet). After 80 days of feeding, a challenge trial was conducted by injection of Aeromonas hydrophila for 17 days. Results indicated that with increasing dietary pyridoxine concentration up to 5.0 mg kg,1 diet, survival rate after challenge with A.hydrophila and phagocytic activity of leukocyte were improved (P < 0.05), and plateaued thereafter (P > 0.05). Red blood cell and white blood cell counts were lowest when fed the diet containing 1.7 mg pyridoxine kg,1 diet. Haemagglutination titre, lysozyme activity, acid phosphatase activity, total iron-binding capacity, antibody titre and immunoglobulin M content followed the similar pattern to that observed with survival rate. Aeromonas hydrophila, Escherichia coli and Lactobacillus counts in intestine were not affected by dietary pyridoxine concentration (P > 0.05). These results suggested that pyridoxine could enhance immune response of fish. [source] | |||||||||||||||||||