Publications by authors named "Félix Acosta"

26 Publications

  • Page 1 of 1

Dietary Phytogenics and Galactomannan Oligosaccharides in Low Fish Meal and Fish Oil-Based Diets for European Sea Bass () Juveniles: Effects on Gill Structure and Health and Implications on Oxidative Stress Status.

Front Immunol 2021 12;12:663106. Epub 2021 May 12.

Grupo de Investigación en Acuicultura (GIA), IU-ECOAQUA, Universidad de Las Palmas de Gran Canaria, Las Palmas, Spain.

An effective replacement for fish meal (FM) and fish oil (FO) based on plant-based raw materials in the feed of marine fish species is necessary for the sustainability of the aquaculture sector. However, the use of plant-based raw materials to replace FM and FO has been associated with several negative health effects, some of which are related to oxidative stress processes that can induce functional and morphological alterations in mucosal tissues. This study aimed to evaluate the effects of dietary oligosaccharides of plant origin (5,000 ppm; galactomannan oligosaccharides, GMOS) and a phytogenic feed additive (200 ppm; garlic oil and labiatae plant extract mixture, PHYTO) on the oxidative stress status and mucosal health of the gills of juvenile European sea bass (). The experimental diets, low FM and FO diets (10%FM/6%FO) were supplemented with GMOS from plant origin and PHYTO for 63 days. GMOS and PHYTO did not significantly affect feed utilization, fish growth, and survival. GMOS and PHYTO downregulated the expression of , , , , and in the gills of the fish compared with that in fish fed the control diet. The expression of and was upregulated and downregulated, respectively, in the GMOS group compared with that in the control group, whereas the expression of downregulated in the PHYTO group compared with that in the GMOS group. The morphological, histopathological, immunohistochemical, and biochemical parameters of the fish gills were mostly unaffected by GMOS and PHYTO. However, the PHYTO group had lower incidence of lamellar fusion than did the control group after 63 days. Although the tissular distribution of goblet cells was unaffected by GMOS and PHYTO, goblet cell size showed a decreasing trend (-11%) in the GMOS group. GMOS and PHYTO significantly reduced the concentration of PCNA+ in the epithelium of the gills. The above findings indicated that GMOS and PHYTO in low FM/FO-based diets protected the gill epithelia of . from oxidative stress by modulating the expression of oxidative enzyme-related genes and reducing the density of PCNA+ cells in the gills of the fish.
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http://dx.doi.org/10.3389/fimmu.2021.663106DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8149968PMC
May 2021

Identification of the Pseudomonas fluorescens group as being responsible for blue pigment on fresh cheese.

J Dairy Sci 2021 Jun 8;104(6):6548-6558. Epub 2021 Apr 8.

Department of Morphology, Faculty of Veterinary, Universidad de Las Palmas de Gran Canaria, Arucas, 35413 Las Palmas, Spain.

New cases of blue cheese discoloration has led to recent research to identify the causal agent and factors that favor blue pigment appearing. Nonetheless, very few reports have described the source of contamination and the measurements to eradicate the microbiological source on cheese farms by determining the relation between blue discoloration on fresh cheese and the Pseudomonas fluorescens group. Thus, 60 samples from a cheese farm (cheese, equipment surfaces, tap water, and raw and pasteurized milk) were analyzed by phenotypical, MALDI-TOF, 16S rRNA sequencing and pulsed-field gel electrophoresis tests to determine the causal agent. The results obtained by pulsed-field gel electrophoresis with restriction enzymes XbaI and SpeI confirmed tap water as the initial contaminated source. The above-mentioned result was essential to avoid Pseudomonas contamination due to the most residual microorganisms being inactivated through a new disinfection program.
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http://dx.doi.org/10.3168/jds.2020-19517DOI Listing
June 2021

Isolation and Characterization of a Bacillus velezensis D-18 Strain, as a Potential Probiotic in European Seabass Aquaculture.

Probiotics Antimicrob Proteins 2021 Apr 3. Epub 2021 Apr 3.

Grupo de Investigación en Acuicultura (GIA), Instituto Ecoaqua, Universidad de Las Palmas de Gran Canaria, Las Palmas, Spain.

Within the food-producing sectors, aquaculture is the one that has developed the greatest growth in recent decades, currently representing almost 50% of the world's edible fish. The diseases can affect the final production in intensive aquaculture; in seabass, aquaculture vibriosis is one of the most important diseases producing huge economical losses in this industry. The usual methodology to solve the problems associated with the bacterial pathology has been the use of antibiotics, with known environmental consequences. This is why probiotic bacteria are proposed as an alternative fight against pathogenic bacteria. The aim of this study was to analyse a strain of Bacillus velezensis D-18 isolated from a wastewater sample collected from a fish farm, for use as probiotics in aquaculture. The strain was evaluated in vitro through various mechanisms of selection, obtaining as results for growth inhibition by co-culture a reduction of 30%; B. velezensis D-18 was able to survive at 1.5-h exposure to 10% seabass bile, and at pH 4, its survival is 5% and reducing by 60% the adhesion capacity of V. anguillarum 507 to the mucus of seabass and in vivo by performing a challenge. Therefore, in conclusion, we consider B. velezensis D-18 isolate from wastewater samples collected from the farms as a good candidate probiotic in the prevention of the infection by Vibrio anguillarum 507 in European seabass after in vitro and biosafety assays.
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http://dx.doi.org/10.1007/s12602-021-09782-8DOI Listing
April 2021

Proteomic profile and protease activity in the skin mucus of greater amberjack (Seriola dumerili) infected with the ectoparasite Neobenedenia girellae - An immunological approach.

Fish Shellfish Immunol 2021 Mar 11;110:100-115. Epub 2021 Jan 11.

Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Internacional Agroalimentario CeiA3, Universidad de Córdoba, Campus de Rabanales, Edificio Severo Ochoa, E-14071, Córdoba, Spain. Electronic address:

Skin mucus is considered the first barrier against diseases in fish. The skin mucus protein profile of the greater amberjack (Seriola dumerili) and its changes due to experimental infection with Neobenedenia girellae were studied by combining 2-DE-MS/MS and gel-free LC-MS/MS proteomic approaches. The 2-DE results led to the identification of 69 and 55 proteins in noninfected and infected fish, respectively, and revealed that keratins were specifically cleaved in parasitized fish. Therefore, the skin mucus of the infected fish showed a higher protease activity due to, at least in part, an increase of metal-dependent protease and serine-type protease activities. Additionally, through a gel-free LC-MS/MS analysis, 1377 and 1251 different proteins were identified in the skin mucus of healthy and parasitized fish, respectively. The functional analysis of these proteins demonstrated a statistical overrepresentation of ribosomal proteins (a well-known source of antimicrobial peptides) in N. girellae-infected fish. In contrast, the components of membranes and protein transport GO categories were underrepresented after infection. Immune system process-related proteins constituted 2.5% of the total skin mucosal proteins. Among these skin mucosal proteins, 14 and 15 proteins exclusive to non-parasitized and parasitized fish were found, respectively, including specific serine-type proteases and metalloproteases in the parasitized fish. Moreover, the finding of tryptic peptides exclusive to some bacterial genera, obtained by gel-free LC-MS/MS, allowed us to construct a preliminary map of the microbiota living in the mucus of S. dumerili, with Pseudomonas and Paracoccus the most represented genera in both noninfected and infected fish.
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http://dx.doi.org/10.1016/j.fsi.2021.01.001DOI Listing
March 2021

Dietary phytogenics and galactomannan oligosaccharides in low fish meal and fish oil-based diets for European sea bass (Dicentrarchus labrax) juveniles: Effects on gut health and implications on in vivo gut bacterial translocation.

PLoS One 2019 18;14(9):e0222063. Epub 2019 Sep 18.

Grupo de Investigación en Acuicultura (GIA), IU-ECOAQUA, Universidad de Las Palmas de Gran Canaria, Crta. Taliarte s/n, Telde, Las Palmas, Canary Islands, Spain.

European sea bass were fed four low FM/FO (10%/6%) diets containing galactomannan oligosaccharides (GMOS), a mixture of garlic oil and labiatae plants oils (PHYTO), or a combination of both functional products (GMOSPHYTO) for 63 days before exposing the fish to an intestinal Vibrio anguillarum infection combined with crowding stress. In order to evaluate functional diets efficacy in terms of gut health maintenance, structural, cellular, and immune intestinal status were evaluated by optical and electron microscopy and gene expression analyses. A semi-automated software was adapted to determine variations in goblet cell area and mucosal mucus coverage during the challenge test. Feeding with functional diets did not affect growth performance; however, PHYTO and GMOS dietary inclusion reduced European sea bass susceptibility to V. anguillarum after 7 days of challenge testing. Rectum (post-ileorectal valve) showed longer (p = 0.001) folds than posterior gut (pre-ileorectal valve), whereas posterior gut had thicker submucosa (p = 0.001) and higher mucus coverage as a result of an increased cell density than rectum. Functional diets did not affect mucosal fold length or the grade of granulocytes and lymphocytes infiltration in either intestinal segment. However, the posterior gut fold area covered by goblet cells was smaller in fish fed GMOS (F = 14.53; p = 0.001) and PHYTO (F = 5.52; p = 0.019) than for the other diets. PHYTO (F = 3.95; p = 0.049) reduced posterior gut goblet cell size and increased rodlet cell density (F = 3.604; p = 0.068). Dietary GMOS reduced submucosal thickness (F = 51.31; p = 0.001) and increased rodlet cell density (F = 3.604; p = 0.068) in rectum. Structural TEM analyses revealed a normal intestinal morphological pattern, but the use of GMOS increased rectum microvilli length, whereas the use of PHYTO increased (p≤0.10) Ocln, N-Cad and Cad-17 posterior gut gene expression. After bacterial intestinal inoculation, posterior gut of fish fed PHYTO responded in a more controlled and belated way in terms of goblet cell size and mucus coverage in comparison to other treatments. For rectum, the pattern of response was similar for all dietary treatments, however fish fed GMOS maintained goblet cell size along the challenge test.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0222063PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6750610PMC
March 2020

An insight into piscidins: The discovery, modulation and bioactivity of greater amberjack, Seriola dumerili, piscidin.

Mol Immunol 2019 10 23;114:378-388. Epub 2019 Aug 23.

Scottish Fish Immunology Research Centre, School of Biological Sciences, University of Aberdeen, Aberdeen, AB24 2TZ, UK. Electronic address:

Antimicrobial peptides (AMPs) play an important role in the innate immune response of vertebrates by creating a hostile environment for any invading pathogens. Piscidins are potent teleost specific AMPs, which have a broad spectrum activity. We have identified a novel piscidin active peptide, in the greater amberjack, Seriola dumerili, that consists of 25 aa, which forms an amphipathic helix with distinct hydrophobic and positively charged regions. Following homology and phylogenetic analysis the greater amberjack piscidin was deemed to belong to the group 3 family of piscidins. Piscidin was expressed constitutively at immune sites, with transcript level highest in the spleen and gut, at an intermediate level in the gills and lowest in the head kidney. Following in vivo stimulation with PAMPs (poly I:C, LPS and flagellin) piscidin transcript level increased in gills in response to flagellin, in gut and spleen in response to poly I:C, and in head kidney in response to poly I:C, LPS and flagellin. Head kidney and spleen cells were then isolated from greater amberjack and incubated with each of the PAMPs for 4, 12 and 24 h. Piscidin expression was unchanged at 4 and 12 h post PAMP stimulation in head kidney cells but at 24 h transcript level was markedly upregulated compared to control (unstimulated) cells, especially with the bacterial PAMPs. In contrast, spleen cells upregulated piscidin expression by 4 h post stimulation with poly I:C and flagellin, and remained upregulated to 24 h with flagellin exposure, but had returned to baseline levels by 12 h using poly I:C. To determine if piscidin expression could be modulated by diet, greater amberjack were fed diets supplemented with MOS and cMOS for 30 days when transcript level was determined. It was found that MOS supplemented diets increased expression in the spleen, cMOS supplemented diets upregulated transcript levels in the gills and head kidney, whilst a diet containing both MOS and cMOS upregulated transcript in the gut, when compared to fish fed the control diet. Finally, a synthetic greater amberjack piscidin was produced and showed bacteriostatic activity against a number of bacterial strains, including both Gram positive and Gram negative fish pathogens.
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http://dx.doi.org/10.1016/j.molimm.2019.08.005DOI Listing
October 2019

Welcome to ISFSI2019.

Fish Shellfish Immunol 2019 07 30;90:274. Epub 2019 Apr 30.

Instituto Universitario ECOAQUA, Universidad de Las Palmas de Gran Canaria (ULPGC), Grupo de Investigación en Acuicultura (GIA), Parque Científico Tecnológico Marino, Muelle de Taliarte s/n, Telde, 35200 Las Palmas, Canary Islands, Spain.

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http://dx.doi.org/10.1016/j.fsi.2019.04.068DOI Listing
July 2019

Increased parasite resistance of greater amberjack (Seriola dumerili Risso 1810) juveniles fed a cMOS supplemented diet is associated with upregulation of a discrete set of immune genes in mucosal tissues.

Fish Shellfish Immunol 2019 Mar 16;86:35-45. Epub 2018 Oct 16.

Grupo de Investigación en Acuicultura (GIA), Instituto Universitario Ecoaqua, Universidad de Las Palmas de Gran Canaria, Crta. Taliarte s/n, 35214, Telde, Las Palmas, Canary Islands, Spain.

The main objective of this study was to determine the effect of two forms of mannan oligosaccharides (MOS: Bio-Mos and cMOS: Actigen, Alltech Inc, USA) and their combination on greater amberjack (Seriola dumerili) growth performance and feed efficiency, immune parameters and resistance against ectoparasite (Neobenedenia girellae) infection. Fish were fed for 90 days with 5 g kg MOS, 2 g kg cMOS or a combination of both prebiotics, in a Seriola commercial base diet (Skretting, Norway). At the end of the feeding period, no differences were found in growth performance or feed efficiency. Inclusion of MOS also had no effect on lysozyme activity in skin mucus and serum, but the supplementation of diets with cMOS induced a significant increase of serum bactericidal activity. Dietary cMOS also reduced significantly greater amberjack skin parasite levels, parasite total length and the number of parasites detected per unit of fish surface following a cohabitation challenge with N. girellae, whereas no effect of MOS was detected on these parameters. Of 17 immune genes studied cMOS dietary inclusion up-regulated hepcidin, defensin, Mx protein, interferon-γ (IFNγ), mucin-2 (MUC-2), interleukin-1β (IL-1B), IL-10 and immunoglobulin-T (IgT) gene expression in gills and/or skin. MOS supplementation had a larger impact on spleen and head kidney gene expression, where piscidin, defensin, iNOS, Mx protein, interferons, IL-1β, IL-10, IL-17 and IL-22 were all upregulated. In posterior gut dietary MOS and cMOS both induced IL-10, IgM and IgT, but with MOS also increasing piscidin, MUC-2, and IL-1β whilst cMOS induced hepcidin, defensin and IFNγ. In general, the combination of MOS and cMOS resulted in fewer or lower increases in all tissues, possibly due to an overstimulation effect. The utilization of cMOS at the dose used here has clear benefits on parasite resistance in greater amberjack, linked to upregulation of a discrete set of immune genes in mucosal tissues.
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http://dx.doi.org/10.1016/j.fsi.2018.10.034DOI Listing
March 2019

Susceptibility of Malassezia pachydermatis to aminoglycosides.

Mycoses 2017 Dec 19;60(12):796-799. Epub 2017 Sep 19.

Instituto Universitario de Sanidad Animal y Seguridad Alimentaria (IUSA), Universidad de Las Palmas de Gran Canaria, Arucas, Las Palmas, Spain.

Previous studies have evaluated the action of gentamicin against Malassezia pachydermatis. The aim of this study was to evaluate in vitro susceptibility of M. pachydermatis to the aminoglycosides- gentamicin, tobramycin, netilmicin and framycetin. The minimum inhibitory concentration (MIC) of gentamicin was determined following methods M27-A3 microdilution and Etest . The Etest was used to determine the minimum inhibitory concentration (MIC) of the tobramycin and netilmicin. The Kirby-Bauer test was used to determine the antibiotic susceptibility to the framycetin. The MIC50 and MIC90 were 8.12 μg/mL and 32.5 μg/mL by microdilution method for gentamicin. The MIC50, determined by the Etest , was 8 μg/mL for gentamicin and netilmicin and 64 μg/mL for tobramycin. The MIC90 was 16 and 32 μg/mL for gentamicin and netilmicin respectively. The MIC90 was outside of the detectable limits for tobramycin. To framycetin, 28 strains (40%) of the 70 M. pachydermatis isolates tested showed a diameter of 22 mm, 22 strains (31.42%) showed a diameter of 20 mm, 16 strains showed a diameter of ≤ 18 mm, and only 5.71% of the isolates showed a diameter of ≥ 22 mm. This study provides evidence of high in vitro activity of the aminoglycosides-gentamicin, tobramycin, netilmicin and framycetin against M. pachydermatis. For gentamicin Etest showed similar values of MIC50 y MIC90 that the obtained by microdilution method. We considered Etest method could be a good method for these calculations with aminoglycosides.
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http://dx.doi.org/10.1111/myc.12665DOI Listing
December 2017

Human neutrophils phagocytose and kill Acinetobacter baumannii and A. pittii.

Sci Rep 2017 07 4;7(1):4571. Epub 2017 Jul 4.

Instituto de Investigación Valdecilla IDIVAL, Santander, 39011, Spain.

Acinetobacter baumannii is a common cause of health care associated infections worldwide. A. pittii is an opportunistic pathogen also frequently isolated from Acinetobacter infections other than those from A. baumannii. Knowledge of Acinetobacter virulence factors and their role in pathogenesis is scarce. Also, there are no detailed published reports on the interactions between A. pittii and human phagocytic cells. Using confocal laser and scanning electron microscopy, immunofluorescence, and live-cell imaging, our study shows that immediately after bacteria-cell contact, neutrophils rapidly and continuously engulf and kill bacteria during at least 4 hours of infection in vitro. After 3 h of infection, neutrophils start to release neutrophil extracellular traps (NETs) against Acinetobacter. DNA in NETs colocalizes well with human histone H3 and with the specific neutrophil elastase. We have observed that human neutrophils use large filopodia as cellular tentacles to sense local environment but also to detect and retain bacteria during phagocytosis. Furthermore, co-cultivation of neutrophils with human differentiated macrophages before infections shows that human neutrophils, but not macrophages, are key immune cells to control Acinetobacter. Although macrophages were largely activated by both bacterial species, they lack the phagocytic activity demonstrated by neutrophils.
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http://dx.doi.org/10.1038/s41598-017-04870-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5496873PMC
July 2017

Erratum to: Identification of some main Streptococcus iniae associated proteins: relationship.

Vet Res Commun 2017 06;41(2):97

University Institute of Animal Health, University of Las Palmas de Gran Canaria, 35413, Arucas, Spain.

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http://dx.doi.org/10.1007/s11259-017-9688-7DOI Listing
June 2017

Identification of some main Streptococcus iniae associated proteins: relationship.

Vet Res Commun 2017 06 14;41(2):85-95. Epub 2017 Jan 14.

University Institute of Animal Health, University of Las Palmas de Gran Canaria, 35413, Arucas, Spain.

The surface-associated proteins play a key role in bacterial physiology and pathogenesis, and are the major targets in the development of new vaccines. These proteins contribute to the adaptation of bacteria to different hosts and environments. To study differences at the genomic level, we first sequenced the whole genome of Streptococcus iniae from fish (IUSA-1 strain) and compared it to Streptococcus iniae from human (9117 strain), revealing a high similitude between both strains. To gain further insights into host- and environment-specific differences, we then studied proteins in silico and by High Performance Liquid Chromatography. This approach successfully identified 54 secreted and surface proteins, including several proteins involved in cell wall synthesis and transport of solutes, as well as proteins with yet unknown function. These proteins highlight as interesting targets for further investigation in the interaction between Streptococcus iniae and its environment. Results reported in this study have shown a first analysis about the predicted and experimental associated proteins of Streptococcus iniae isolated from two different hosts: human and fish.
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http://dx.doi.org/10.1007/s11259-017-9675-zDOI Listing
June 2017

Synthetic hepcidin from fish: Uptake and protection against Vibrio anguillarum in sea bass (Dicentrarchus labrax).

Fish Shellfish Immunol 2016 Aug 29;55:662-70. Epub 2016 Jun 29.

Grupo de Marcadores Inmunológicos, Laboratorio de Genética e Inmunología Molecular, Instituto de Biología, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile. Electronic address:

The generation of a variety of new therapeutic agents to control and reduce the effects of pathogen in aquaculture is urgently needed. The antimicrobial peptides (AMPs) are one of the major components of the innate defenses and typically have broad-spectrum antimicrobial activity. However, absorption and distributions of exogenous AMPs for therapeutics application on farmed fish species need to be studied. Previous studies in our laboratory have shown the properties of hepcidin as an effective antimicrobial peptide produced in fish in response to LPS and iron. Therefore, we decided to investigate the antimicrobial activity of four synthetic variants of hepcidin against Vibrio anguillarum in vitro, and using the more effective peptide we demonstrated the pathogen's ability to protect against the infection in European Sea bass. Additionally the uptake of this peptide after ip injection was demonstrated, reaching its distribution organs such as intestine, head kidney, spleen and liver. The synthetic peptide did not show cytotoxic effects and significantly reduced the accumulated mortalities percentage (23.5%) compared to the European Sea bass control (72.5%) at day 21. In conclusion, synthetic hepcidin shows antimicrobial activity against V. anguillarum and the in vivo experiments suggest that synthetic hepcidin was distributed trough the different organs in the fish. Thus, synthetic hepcidin antimicrobial peptide could have high potential for therapeutic application in farmed fish species.
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http://dx.doi.org/10.1016/j.fsi.2016.06.035DOI Listing
August 2016

Whole-Genome Sequence of Hafnia alvei HUMV-5920, a Human Isolate.

Genome Announc 2016 Jun 16;4(3). Epub 2016 Jun 16.

Servicio de Microbiología, Hospital Universitario Marqués de Valdecilla, Santander, Cantabria, Spain Instituto de Investigación Sanitaria Valdecilla (IDIVAL), Santander, Cantabria, Spain Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain

A clinical isolate of Hafnia alvei (strain HUMV-5920) was obtained from a urine sample from an adult patient. We report here its complete genome assembly using PacBio single-molecule real-time (SMRT) sequencing, which resulted in a chromosome with 4.5 Mb and a circular contig of 87 kb. About 4,146 protein-coding genes are predicted from this assembly.
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http://dx.doi.org/10.1128/genomeA.00556-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4911478PMC
June 2016

Acinetobacter baumannii and A. pittii clinical isolates lack adherence and cytotoxicity to lung epithelial cells in vitro.

Microbes Infect 2016 09 24;18(9):559-64. Epub 2016 May 24.

Instituto de Investigación Valdecilla IDIVAL, Santander, Cantabria, Spain; Servicio de Microbiología, Hospital Universitario Marqués de Valdecilla, Santander, Cantabria, Spain; Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain. Electronic address:

The molecular and genetic basis of Acinetobacter baumannii and Acinetobacter pittii virulence remains poorly understood, and there is still lack of knowledge in host cell response to these bacteria. In this study, we have used eleven clinical Acinetobacter strains (A. baumannii n = 5; A. pittii n = 6) to unravel bacterial adherence, invasion and cytotoxicity to human lung epithelial cells. Our results showed that adherence to epithelial cells by Acinetobacter strains is scarce and cellular invasion was not truly detected. In addition, all Acinetobacter strains failed to induce any cytotoxic effect on A549 cells.
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http://dx.doi.org/10.1016/j.micinf.2016.05.002DOI Listing
September 2016

Effects of Subinhibitory Concentrations of Ceftaroline on Methicillin-Resistant Staphylococcus aureus (MRSA) Biofilms.

PLoS One 2016 22;11(1):e0147569. Epub 2016 Jan 22.

Servicio de Microbiología, Hospital Universitario Marqués de Valdecilla and Instituto de Investigación Marqués de Valdecilla (IDIVAL), Santander, Cantabria, Spain.

Ceftaroline (CPT) is a novel cephalosporin with in vitro activity against Staphylococcus aureus. Ceftaroline exhibits a level of binding affinity for PBPs in S. aureus including PBP2a of methicillin-resistant S. aureus (MRSA). The aims of this study were to investigate the morphological, physiological and molecular responses of MRSA clinical strains and MRSA biofilms to sub-MICs (1/4 and 1/16 MIC) of ceftaroline by using transmission, scanning and confocal microscopy. We have also used quantitative Real-Time PCR to study the effect of sub-MICs of ceftaroline on the expression of the staphylococcal icaA, agrA, sarA and sasF genes in MRSA biofilms. In one set of experiments, ceftaroline was able to inhibit biofilm formation in all strains tested at MIC, however, a strain dependent behavior in presence of sub-MICs of ceftaroline was shown. In a second set of experiments, destruction of preformed biofilms by addition of ceftaroline was evaluated. Ceftaroline was able to inhibit biofilm formation at MIC in all strains tested but not at the sub-MICs. Destruction of preformed biofilms was strain dependent because the biofilm formed by a matrix-producing strain was resistant to a challenge with ceftaroline at MIC, whereas in other strains the biofilm was sensitive. At sub-MICs, the impact of ceftaroline on expression of virulence genes was strain-dependent at 1/4 MIC and no correlation between ceftaroline-enhanced biofilm formation and gene regulation was established at 1/16 MIC. Our findings suggest that sub-MICs of ceftaroline enhance bacterial attachment and biofilm formation by some, but not all, MRSA strains and, therefore, stress the importance of maintaining effective bactericidal concentrations of ceftaroline to fight biofilm-MRSA related infections.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0147569PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4723258PMC
July 2016

Whole-Genome Sequence of Serratia liquefaciens HUMV-21, a Cytotoxic, Quorum-Sensing, and Biofilm-Producing Clinical Isolate.

Genome Announc 2015 May 28;3(3). Epub 2015 May 28.

A clinical isolate of Serratia liquefaciens (strain HUMV-21) was obtained from a skin ulcer of an adult patient. We report here its complete genome assembly using PacBio single-molecule real-time (SMRT) sequencing, which resulted in a single circular chromosome with 5.3 Mb. About 5,844 protein-coding genes are predicted from this assembly.
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http://dx.doi.org/10.1128/genomeA.00533-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4447907PMC
May 2015

New aspects in the biology of Photobacterium damselae subsp. piscicida: pili, motility and adherence to solid surfaces.

Vet Microbiol 2014 Nov 15;174(1-2):247-54. Epub 2014 Aug 15.

Servicio de Microbiología, Hospital Universitario Marqués de Valdecilla, Instituto de Investigación Marqués de Valdecilla IDIVAL, Santander, Cantabria, Spain. Electronic address:

We describe for the first time the presence of pilus-like structures on the surface of Photobacterium damselae subsp. piscicida (Phdp). The hint to this discovery was the ability of one strain to hemagglutinate human erythrocytes. Further analysis of several Phdp strains ultrastructure by electron microscopy revealed the presence of long, thin fibers, similar to pili of other Gram-negative bacteria. These appendages were also observed and photographed by scanning, transmission electron microscopy and immunofluorescence. Although this fish pathogen has been described as non-motile, all strains tested exhibit twitching motility, a flagella-independent type IV-dependent form of bacterial translocation over surfaces. As far as we are aware, the movement of Phdp bacteria on semi-solid or solid surfaces has not been described previously. Moreover, we speculate that Phdp twitching motility may be involved in biofilm formation. Microscopic examination of Phdp biofilms by microscopy revealed that Phdp biofilm architecture display extensive cellular chaining and also bacterial mortality during biofilm formation in vitro. Based on our results, standardized analyses of Phdp surface appendages, biofilms, motility and their impact on Phdp survival, ecology and pathobiology are now feasible.
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http://dx.doi.org/10.1016/j.vetmic.2014.08.005DOI Listing
November 2014

Interactions of Streptococcus iniae with phagocytic cell line.

Microbes Infect 2015 Apr 21;17(4):258-65. Epub 2014 Jun 21.

Institute of Animal Health (IUSA), University of Las Palmas de Gran Canaria, Arucas 35413, Spain. Electronic address:

Streptococcus iniae has become one of the most serious aquatic pathogens in the last decade, causing large losses in wild and farmed fish worldwide. There is clear evidence that this pathogen is capable not only of causing serious disease in fish but also of being transferred to and infecting humans. In this study, we investigate the interaction of S. iniae with two murine macrophage cell lines, J774-A1 and RAW 264.7. Cytotoxicity assay demonstrated significant differences between live and UV-light killed IUSA-1 strains. The burst respiratory activity decreased to baseline after 1 and 4 h of exposure for J774-A1 and RAW 264.7, respectively. Immunofluorescent and ultrastructural study of infected cells confirmed the intracellular localization of bacteria at 1 h and 24 h post-infection. Using qRT-PCR arrays, we investigated the changes in the gene expression of immune relevant genes associated with macrophage activation. In this screening, we identified 11 of 84 genes up-regulated, we observed over-expression of pro-inflammatory response as IL-1α, IL-1β, and TNF-α, without a good anti-inflammatory response. Present findings suggest a capacity of S. iniae to modulate a mammalian macrophages cell lines to their survival and replication intracellular, which makes this cell type as a reservoir for continued infection.
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http://dx.doi.org/10.1016/j.micinf.2014.06.006DOI Listing
April 2015

Experimental Lactococcus garvieae infection in zebrafish and first evidence of its ability to invade non-phagocytic cells.

Vet Microbiol 2014 Jun 30;171(1-2):248-54. Epub 2014 Mar 30.

Department of Animal Health, Faculty of Veterinary Sciences, Complutense University, 28040 Madrid, Spain. Electronic address:

Zebrafish has been used for studying infections and host-pathogen interactions in different bacterial fish pathogens. In the present study we evaluated the ability of Lactococcus garvieae to infect zebrafish when inoculated intraperitoneally with 2 × 10(7)UFC of this pathogen. L. garvieae can colonize and invade zebrafish at multiple anatomical sites causing a lethal acute septicemic infection with clinical signs and lesions consistent with those observed in lactococcosis outbreaks. Immunohistochemical studies showed the presence of L. garvieae into macrophages as well as into non-phagocytic zebrafish cells of liver (hepatocytes). The internalization capacity showed by L. garvieae in zebrafish cells was confirmed in the rainbow trout cell line RTG-2. Our results provide the first evidence that L. garvieae is able to invade non-phagocytic host cells.
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http://dx.doi.org/10.1016/j.vetmic.2014.03.029DOI Listing
June 2014

Interaction of macrophages with a cytotoxic Serratia liquefaciens human isolate.

Microbes Infect 2013 Jun 22;15(6-7):480-90. Epub 2013 Mar 22.

Servicio de Microbiología, Hospital Universitario Marqués de Valdecilla-IFIMAV, Santander, Cantabria, Spain.

Macrophages play key roles in host defense by recognizing, engulfing, and killing microorganisms. Understanding the response of macrophages to pathogens may provide insights into host defenses and the tactics used by pathogens to circumvent these defenses. In the present study, we investigated the interaction between a clinical isolate of Serratia liquefaciens and macrophages. S. liquefaciens strain HUMV-3250 triggers a fast and potent cytotoxic effect upon infection. This process requires the presence of live bacteria, adherence, and protein synthesis but not phagocytosis/bacterial internalization. Moreover, cytotoxicity assays, analysis of DNA integrity, immunofluorescence, and confocal, scanning, and time-lapse microscopy revealed that macrophage viability decreased rapidly with time upon challenge, and depends on the MOI used. Treatment of macrophages with caspase-1 inhibitors, or with specific inhibitors of phagocytosis, did not alter the infection outcome. Moreover, human macrophages exhibited similar cytotoxic changes after infection with this strain. Macrophages responded to this cytotoxic strain with a robust pattern of pro-inflammatory gene expression. However, phagocytosis attempts to engulf live bacteria were unsuccessful, and the phagocytes were unable to kill the bacteria. We conclude that macrophage cell death occurs rapidly as a result of necrotic events after close contact with S. liquefaciens. These results likely have important implications for understanding Serratia pathogenesis and host response to infection.
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http://dx.doi.org/10.1016/j.micinf.2013.03.004DOI Listing
June 2013

Whole-Genome Sequence of the Fish Virulent Strain Streptococcus iniae IUSA-1, Isolated from Gilthead Sea Bream (Sparus aurata) and Red Porgy (Pagrus pagrus).

Genome Announc 2013 Mar 14;1(2):e0002513. Epub 2013 Mar 14.

Institute of Animal Health (IUSA), University of Las Palmas de Gran Canaria, Arucas, Arucas, Spain.

Streptococcus iniae is a major fish pathogen that produces invasive infections that result in economic losses in aquaculture. In this study, the draft genome sequence of Streptococcus iniae strain IUSA-1, isolated from a natural outbreak affecting gilthead sea bream (Sparus aurata) and red porgy (Pagrus pagrus), is presented.
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http://dx.doi.org/10.1128/genomeA.00025-13DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3622967PMC
March 2013

Infectious pancreatic necrosis virus suppresses type I interferon signalling in rainbow trout gonad cell line but not in Atlantic salmon macrophages.

Fish Shellfish Immunol 2007 Jan-Feb;22(1-2):44-56. Epub 2006 Mar 28.

Marine Laboratory, 375 Victoria Road, Aberdeen AB11 9DB, Scotland, UK.

RTG-P1 cells are a rainbow trout fibroblastic cell line permanently transfected with the luciferase gene under the control of the Mx promoter. On exposure to interferon (IFN) or IFN inducing agents, the cells produce luciferase. IPNV did not induce luciferase production up to 24h post-infection but did not suppress constitutive luciferase production. Furthermore, IPNV suppressed luciferase production induced by poly I:C. RT-PCR analysis of IPNV infected cells showed IFN gene transcription from 6h post-infection with increasing expression up to 24h. Housekeeping genes beta-actin and GAPDH were also expressed along with upregulation of IRF1 and slight upregulation of STAT1. When RTG-P1 cells were stimulated with IFN, Mx transcripts, measured by qRT-PCR, peaked at 3-6h and thereafter fell to low levels, but in the presence of IPNV, Mx transcription at this time was significantly suppressed but continued to rise gradually. Luciferase production was lower in infected cells at 12h post-infection but not significantly after 24h. These results indicate that, in non-stimulated RTG-P1 cells, while IPNV induces IFN transcription, activation of Mx expression is suppressed. Furthermore, when stimulated by IFN, the rate of Mx transcription is significantly suppressed by the virus. This would probably give time for the virus to replicate rapidly in the early phases of infection. Contrary to the fibroblastic cell line, IPNV stimulated IFN production by salmon macrophages in vitro at least as strongly as poly I:C, with no suppression of the IFN response to poly I:C, and the virus persisted for up to 9 days without causing CPE.
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http://dx.doi.org/10.1016/j.fsi.2006.03.011DOI Listing
June 2008

Behavior of an Aeromonas hydrophila aroA live vaccine in water microcosms.

Appl Environ Microbiol 2004 May;70(5):2702-8

Department of Cell Biology, Faculty of Biological and Environmental Sciences, Arucas, Spain.

Genetically modified auxotrophic mutants of different fish pathogens have been used as live vaccines in laboratory experiments, but the behavior of the strains after release into aquatic ecosystems has not been characterized. We previously constructed and characterized an aroA mutant of Aeromonas hydrophila and studied the protection afforded by this mutant as a live vaccine in rainbow trout. In this work, we describe the survival of this strain in aquatic microcosms prepared from fish water tanks. The aroA mutant disappeared rapidly in nonfiltered, nonautoclaved fish tank water, declining below detection levels after 15 days, suggesting an inhibitory effect of the autochthonous microflora of the water. When the aroA strain was used to inoculate sterilized water, its culturability was lower than that of wild-type strain A. hydrophila AG2; after long periods of incubation, aroA cells were able to enter a viable but nonculturable state. Entry into this nonculturable state was accompanied by changes in the cell morphology from rods to spheres, but the cells appeared to remain potentially viable, as assessed by the preservation of cell membrane integrity. Supplementation of the culture medium with sodium pyruvate favored the culturability and resuscitation of the two A. hydrophila strains at low temperatures (6 and 16 degrees C). These results contribute to a better understanding of the behavior of the aroA strain in natural environments and suggest that the inactivation of the aroA gene may be beneficial for the safety of this live vaccine for aquacultures.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC404459PMC
http://dx.doi.org/10.1128/AEM.70.5.2702-2708.2004DOI Listing
May 2004
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