Escuela de Medicina Veterinaria

URI permanente para esta comunidadhttp://10.0.96.45:4000/handle/11056/14561

Escuela de Medicina Veterinaria:
Misión:

La Escuela de Medicina Veterinaria es el centro académico de formación profesional y de referencia a nivel nacional regional, para el abordaje de la medicina veterinaria, la salud pública y producción animal que contribuye al bienestar humano, social, animal y al desarrollo integral en armonía con la naturaleza.

Visión:

Generar conocimiento y formar profesionales en medicina veterinaria, con una formación integral en salud pública y otras disciplinas de las ciencias de la salud y la producción animal, así como con una sólida formación humanística, científica y tecnológica para el abordaje integral de los problemas mediante la investigación, la docencia, la extensión y la producción y sirvan como punto de apoyo a las investigaciones que cada día se desarrollan en éste campo.

Biblioteca Escuela de Medicina Veterinaria:
Misión:

Brindar a la comunidad de usuarios de la Escuela de Medicina Veterinaria información y servicios que sirvan como punto de apoyo a las investigaciones que cada día se desarrollan en éste campo.

Ubicación:

Segundo piso de la Escuela de Medicina Veterinaria de la Universidad Nacional de Costa Rica, Campus Benjamín Núñez, Barreal de Heredia

Horario de atención:

Lunes a viernes de 7:30 a.m. a 4:30 p.m.

Correo electrónico: biblio.medvet@una.ac.cr

Teléfono: 2562-4573 / 2562-4519

Personal de la Biblioteca:

Mag. María Carlina Rojas Badilla
Licda. Francina Gonzalo Thomas

URL: https://www.medvet.una.ac.cr/biblioteca/

Examinar

Mostrando 1 - 18 de 18

A novel host-adapted strain of Salmonella Typhimurium causes renal disease in olive ridley turtles (Lepidochelys olivacea) in the Pacific
(Springer Nature, 2019-06-27) Thierry, Work; Dagenais, Julie; Stacy, Brain; Ladner, Jason; Lorch, Jeffrey; Balazs, George; BARQUERO-CALVO, ELIAS; Breeden, Renee; Corrales Gómez, Natalia; Berlowski-Zier, Brenda; Gonzalez-Barrientos, Rocio; Harris, Heather; Hernández-Mora, Gabriela; Herrera-Ulloa, Ángel; Hesami, Shoreh; Jones, Todd; Morales, Juan Alberto; Norton, Terry M.; Rameyer, Robert A.; Taylor, Daniel; Waltzek, Thomas
Salmonella spp. are frequently shed by wildlife including turtles, but S. enterica subsp. enterica serovar Typhimurium or lesions associated with Salmonella are rare in turtles. Between 1996 and 2016, we necropsied 127 apparently healthy pelagic olive ridley turtles (Lepidochelys olivacea) that died from drowning bycatch in fisheries and 44 live or freshly dead stranded turtles from the west coast of North and Central America and Hawaii. Seven percent (9/127) of pelagic and 47% (21/44) of stranded turtles had renal granulomas associated with S. Typhimurium. Stranded animals were 12 times more likely than pelagic animals to have Salmonella-induced nephritis suggesting that Salmonella may have been a contributing cause of stranding. S. Typhimurium was the only Salmonella serovar detected in L. olivacea, and phylogenetic analysis from whole genome sequencing showed that the isolates from L. olivacea formed a single clade distinct from other S. typhimurium. Molecular clock analysis revealed that this novel clade may have originated as recently as a few decades ago. The phylogenetic lineage leading to this group is enriched for non-synonymous changes within the genomic area of Salmonella pathogenicity island 1 suggesting that these genes are important for host adaptation.
Application of multiplex quantitative Polymerase chain reaction methods to detect common bacterial fish pathogens in Nile tilapia, Oreochromis niloticus, hatcheries in Costa Rica
(WILEY, 2018-09-29) Kenelty, Kirsten; Barum, Samantha; Soto, Esteban; López-Porras, Adrián; Elizondo-Ovares, Carolina; Chaves Hernández, Aida J.; Camus, Alvin; Griffin, Matt; BARQUERO-CALVO, ELIAS
Edwardsiella spp., Streptococcus spp., and Francisella noatunensis subsp. orientalis are some of the most important fish pathogens affecting global tilapia, Oreochromis spp., aquaculture. In Costa Rica, the aquaculture industry is dominated by freshwater‐cultured Nile tilapia, Oreochromis niloticus, which are raised in all seven national provinces. At present, little is known regarding the diversity of pathogens present in these facilities, and definitive identification of agents associated with disease outbreaks are rare. To evaluate the prevalence of common bacterial pathogens in these systems, this study used multiplex quantitative polymerase chain reaction (qPCR) assays targeting Edwardsiella, Streptococcus, and Francisella species as a diagnostic and surveillance tool. In 2017, seven different tilapia hatcheries were visited, and 350 fingerlings were subjected to necropsy and molecular diagnostic evaluation. Fish exhibiting gross signs of disease were subjected to histological and microbiological analysis. For the first time, Edwardsiella anguillarum was recovered and molecularly confirmed from diseased tilapia in Costa Rica. In addition, F. noatunensis subsp. orientalis was identified in a region of Costa Rica where it had not been previously reported
Brucella abortus ornithine lipids are dispensable outer membrane components devoid of a marked pathogen-associated molecular pattern
(PLoS One, 2011-01-07) Palacios-Chaves, Leyre; Conde-Álvarez, Raquel; Gil-Ramírez, Yolanda; Zúñiga-Ripa, Amaia; BARQUERO-CALVO, ELIAS; Chacón-Díaz, Carlos; Chaves-Olarte, Esteban; Arce-Gorvel, Vilma; Gorvel, Jean-Pierre; Moreno, Edgardo; de Miguel, María-Jesús; Grilló, María-Jesús; Moriyon, Ignacio; Iriarte, Maite
The brucellae are a-Proteobacteria facultative intracellular parasites that cause an important zoonosis. These bacteria escape early detection by innate immunity, an ability associated to the absence of marked pathogen-associated molecular patterns in the cell envelope lipopolysaccharide, lipoproteins and flagellin. We show here that, in contrast to the outer membrane ornithine lipids (OL) of other Gram negative bacteria, Brucella abortus OL lack a marked pathogen-associated molecular pattern activity. We identified two OL genes (olsB and olsA) and by generating the corresponding mutants found that olsB deficient B. abortus did not synthesize OL or their lyso-OL precursors. Liposomes constructed with B. abortus OL did not trigger IL-6 or TNF-a release by macrophages whereas those constructed with Bordetella pertussis OL and the olsB mutant lipids as carriers were highly active. The OL deficiency in the olsB mutant did not promote proinflammatory responses or generated attenuation in mice. In addition, OL deficiency did not increase sensitivity to polymyxins, normal serum or complement consumption, or alter the permeability to antibiotics and dyes. Taken together, these observations indicate that OL have become dispensable in the extant brucellae and are consistent within the trend observed in a-Proteobacteria animal pathogens to reduce and eventually eliminate the envelope components susceptible of recognition by innate immunity.
Brucella ceti and brucellosis in cetaceans
(Frontiers in cellular and infection microbiology, 2012-02-06) Guzman-Verri, Caterina; González-Barrientos, Rocio; Hernández-Mora, Gabriela; Morales, Juan Alberto; BARQUERO-CALVO, ELIAS; Chaves-Olarte, Esteban; Moreno, Edgardo
Since the first case of brucellosis detected in a dolphin aborted fetus, an increasing number of Brucella ceti isolates has been reported in members of the two suborders of cetaceans: Mysticeti and Odontoceti. Serological surveys have shown that cetacean brucellosis may be distributed worldwide in the oceans. Although all B. ceti isolates have been included within the same species, three different groups have been recognized according to their preferred host, bacteriological properties, and distinct genetic traits: B. ceti dolphin type, B. ceti porpoise type, and B. ceti human type. It seems that B. ceti porpoise type is more closely related to B. ceti human isolates and B. pinnipedialis group, while B. ceti dolphin type seems ancestral to them. Based on comparative phylogenetic analysis, it is feasible that the B. ceti ancestor radiated in a terrestrial artiodactyl host close to the Raoellidae family about 58 million years ago. The more likely mode of transmission of B. ceti seems to be through sexual intercourse, maternal feeding, aborted fetuses, placental tissues, vertical transmission from mother to the fetus or through fish or helminth reservoirs. The B. ceti dolphin and porpoise types seem to display variable virulence in land animal models and low infectivity for humans. However, brucellosis in some dolphins and porpoises has been demonstrated to be a severe chronic disease, displaying significant clinical and pathological signs related to abortions, male infertility, neurobrucellosis, cardiopathies, bone and skin lesions, strandings, and death.
Brucellosis caused by the wood rat pathogen Brucella Neotomae: two case reports
(Journal of Medical Case Reports, 2017-12-19) Arnuy, Ernesto; Rojas, Norman; Villalobos-Vindas, Juan M.; BARQUERO-CALVO, ELIAS; Chacón-Díaz, Carlos; Chaves-Olarte, Esteban; Guzman-Verri, Caterina; Moreno, Edgardo
Background: Brucellosis is a chronic bacterial disease caused by members of the genus Brucella. Among the classical species stands Brucella neotomae, until now, a pathogen limited to wood rats. However, we have identified two brucellosis human cases caused by B. neotomae, demonstrating that this species has zoonotic potential. Cases presentation: Within almost 4 years of each other, a 64-year-old Costa Rican white Hispanic man and a 51-year-old Costa Rican white Hispanic man required medical care at public hospitals of Costa Rica. Their hematological and biochemical parameters were within normal limits. No adenopathies or visceral abnormalities were found. Both patients showed intermittent fever, disorientation, and general malaise and a positive Rose Bengal test compatible with Brucella infection. Blood and cerebrospinal fluid cultures rendered Gram-negative coccobacilli identified by genomic analysis as B. neotomae. After antibiotic treatment, the patients recovered with normal mental activities. Conclusions: This is the first report describing in detail the clinical disease caused by B. neotomae in two unrelated patients. In spite of previous claims, this bacterium keeps zoonotic potential. Proposals to generate vaccines by using B. neotomae as an immunogen must be reexamined and countries housing the natural reservoir must consider the zoonotic risk.
Chromobacterium violaceum infection in a free ranging howler monkey in Costa Rica
(Wildlife Disease Association, 2010) Baldi, Mario; Morales, Juan Alberto; Hernandez, Giovanna; Jiménez-Soto, Mauricio; Alfaro-Alarcón, Alejandro; BARQUERO-CALVO, ELIAS
Chromobacterium violaceum is a gram-negative saprobe bacterium that is a rare opportunistic pathogen in mammals. There are numerous reports in humans including fatalities, but no record exists in free-ranging nonhuman primates. Here we report an infection by C. violaceum in a wild adult male howler monkey (Alouatta palliata) captured at Ballena Marine National Park, in southwestern Costa Rica. The individual had severe skin lesions over its extremities; gross findings included multiple skin ulcers, white foci in liver, and lymphoid hyperplasia. Histologic results included deep dermatitis with presence of necrotic epithelial cells where clusters of coccoid-shaped bacteria were detected. In the liver, numerous neutrophils forming microabscesses, telangiectasia, and focal necrotic areas were observed. Necrotic liver tissue sampled for bacteriologic culture resulted in the isolation of C. violaceum. We could not ascertain the source or mechanism of infection in this case, although infection through skin microabrasions is suspected. To the best of our knowledge, this is the first report for this pathogen in a wild, nonhuman primate. This report also draws attention to this infectious agent as a potential emerging wildlife disease and consideration should be paid by regional veterinary and epidemiologic vigilance services.
Depletion of complement enhances the clearance of Brucella abortus in mice
(American Society for Microbiology, 2018-08-06) González-Espinoza, Gabriela; BARQUERO-CALVO, ELIAS; Lizano-González, Esteban; Alfaro-Alarcón, Alejandro; Arias-Gómez, Berny; Chaves-Olarte, Esteban; Moreno, Edgardo; Lomonte, Bruno; Chacón-Díaz, Carlos
Brucellosis is a bacterial disease of animals and humans. Brucella abortus barely activates the innate immune system at the onset of infection, and this bacterium is resistant to the microbicidal action of complement. Since complement stands as the first line of defense during bacterial invasions, we explored the role of complement in B. abortus infections. Brucella abortus-infected mice depleted of complement with cobra venom factor (CVF) showed the same survival rate as mice in the control group. The complement-depleted mice readily eliminated B. abortus from the spleen and did so more efficiently than the infected controls after 7 days of infection. The levels of the proinflammatory cytokines tumor necrosis factor alpha and interleukin-6 (IL-6) remained within background levels in complement-depleted B. abortus-infected mice. In contrast, the levels of the immune activator cytokine gamma interferon and the regulatory cytokine IL-10 were significantly increased. No significant histopathological changes in the liver and spleen were observed between the complement-depleted B. abortus-infected mice and the corresponding controls. The action exerted by Brucella on the immune system in the absence of complement may correspond to a broader phenomenon that involves several components of innate immunity.
Es erróneo hacer una asociación directa entre la detección de Helicobacter spp.y gastritis en caninos
(Revista de Ciencias Veterinarias, 2017-12-03) Suárez-Esquivel, Marcela; BARQUERO-CALVO, ELIAS
It has been proposed that Helicobacter may play a significant role in the generation of gastritis and cancer in dogs. However, despite several independent efforts, there is still controversy regarding the true ability of Helicobacter to cause gastric lesions in these animals. The foregoing is due in part to the fact that gastritis is a multifactorial disease. Studies focused on naturally acquired infections have been unable to establish a positive correlation between Helicobacter colonization and gastritis. Establishing a clear association between the presence of Helicobacter and gastritis may be difficult due to the following reasons: (i) taxonomy of the genus Helicobacter remains unclear, (ii) virulence factors of Helicobacter species that colonize dogs are not well known, and (iii) simultaneous infections have been reported with several species of Helicobacter. Current knowledge in taxonomy and pathogenesis of Helicobacter species is insufficient to differentiate between pathogenic and non-pathogenic strains. Therefore, no direct association should be made between the detection of Helicobacter and gastritis.
Francisella marina Sp. nov., etiologic agent of systemic disease in cultured spotted rose snapper (Lutjanus Guttatus) in Central America
(American Society for Microbiology, 2018-06-18) Soto, Esteban; Morales, Juan Alberto; Sebastiao, Fernanda de Alexandre; García, Julio; Griffin, Matt; BARQUERO-CALVO, ELIAS; López-Porras, Adrián; Víquez-Rodríguez, Xindy; Reichley, Stephen; Rosser, Thomas; Ware, Cynthia; Byrne, Barbara; LaFrentz, Benjamin; Camus, Alvin
Historically, piscine francisellosis in various warm-, temperate-, and cold-water fish hosts has been attributed to Francisella noatunensis From 2015 to 2016, an undescribed Francisella sp. was recovered during mortality events in cultured spotted rose snapper (Lutjanus guttatus) off the Pacific coast of Central America. Despite high mortality and emaciation, limited gross findings were observed in affected fish. Histological examination revealed multifocal granulomatous lesions, with the presence of numerous small, pleomorphic coccobacilli, predominantly in the peritoneum, spleen, kidneys, liver, pancreas, heart, and intestine. Sequencing of an ∼1,400-bp fragment of the 16S rRNA gene demonstrated these isolates to be most similar (99.9% identity) to Francisella sp. isolate TX077308 cultured from seawater in the Gulf of Mexico, while sharing <99% similarity to other Fransicella spp. Biochemical analysis, multilocus sequence comparisons of select housekeeping genes, repetitive extragenic palindromic PCR fingerprinting, matrix-assisted laser desorption ionization-time of flight mass spectrometry, and fatty acid methyl ester analysis revealed marked differences between these isolates and other described members of the genus. Koch's postulates were fulfilled by experimental intracoelomic injection and immersion trials using Nile (Oreochromis niloticus) and blue (Oreochromis aureus) tilapia. Based on observed phenotypic and genotypic differences from recognized Francisella spp., the name Francisellamarina sp. nov. (NRRL B-65518) is proposed to accommodate these novel strains.IMPORTANCE Finfish aquaculture is the fastest growing global food production sector. Infectious disease, particularly emergent pathogens, pose a significant threat to established and nascent aquaculture industries worldwide. Herein, we characterize a novel pathogen isolated from mortality events in cultured spotted rose snapper in Central America. The bacteria recovered from these outbreaks were genetically and phenotypically dissimilar from other known Francisella spp. from fish, representing a previously unrecognized member of the genus Francisella, for which the name Francisella marina sp. nov. is proposed.
Frecuency and species of Campylobacter spp. in broiler at three levels of the poultry production chain of Costa Rica
(International Journal of Current Research, 2019-02-28) Zumbado Gutiérrez, Leana; Romero-Zúñiga, Juan José; BARQUERO-CALVO, ELIAS; Abarca Gómez, Jessica; Jiménez Mora, Mónica; Ravery Morovati, Vandad; Arias Echandi, María Laura
Campylobacter spp. is one of the main bacteria that cause food borne illness. Many of these cases are caused by C. jejuni and C. coli, which are transmitted mainly by poultry. A cross-sectional study, conducted between March and July 2015, demonstrates the national frequency of Campylobacter spp. and the species C. jejuni and C. coli in broilers for human consumption using a simultaneous sampling design in three levels of Costa Rican poultry production chain. For this research, 152 samples of cecal content (CC) (87 farms), 104 samples of carcass rinse after chiller (CA) (six processing plants), and 96 carcass rinses from 96 retail stores (RS) were collected. The samples were analyzed by microbiological culture and PCR species specific. The overall frequency of Campylobacter spp obtained was 59.37% (209/352, 95% CI 54.24%-64.51%), for C. jejuni was 42.59% (95% CI 37.45%-48.26%), for C. coli was 3.09% (95% CI 1.21%-5.00%) and 8.64% (95% CI 5.62%-11.77%) for contamination with both species. The frequency of Campylobacter spp. in CC was 57.23% (95% CI 49.37%-65.10%), in CA was 61.53% (95% CI 52.19%-70.89%) and 60.42% (95% CI 50.63%-70.20%) for RS. The frequency of Campylobacter spp. found in this study is high, and it represents a risk for public health in Costa Rica. Preventive measures for this agent are few and inadequate, thus leading to high levels of contamination.
Multidrug-resistant Clostridium Difficile Ribotypes 078 and 014/5-FLI01 in Piglets From Costa Rica
(Elsevier, 2018-11-08) Seyboldt, Christian; Tzoc, Edgardo; Rodríguez, César; Andino-Molina, Mauricio Alejandro; BARQUERO-CALVO, ELIAS; Schmoock, Gernot; Neubauer, Heinrich; Quesada-Gómez, Carlos
Though an overlap of Clostridium difficile PCR ribotypes (RT) in humans and animals has been noted -particularly in piglets-information regarding C. difficile isolates from swine is scarce in Latin America. A characterization of 10 C. difficile isolates obtained from this origin in Costa Rica revealed the presence of the RT078 (n = 4) and RT014/5-FLI01 (n = 6) ribotypes. Unlike two previous reports from the region, all isolates were multidrug resistant (MDR). According to a minimum spanning tree (MST) analysis, our RT078 isolates formed a clonal complex with some German RT078 isolates and the already noted overlap of RT078 strains in humans and animals. This unanticipated high level of genetic relatedness confirms the transcontinental spread and geographically unlimited clustering of RT078.
Neutrophils as Trojan Horse vehicles for Brucella abortus macrophage infection
(Universidad Nacional, Costa Rica, 2019-05-07) Gutiérrez-Jiménez, Cristina; Mora-Cartín, Ricardo; Altamirano-Silva, Pamela; Chacón-Díaz, Carlos; Chaves-Olarte, Esteban; Moreno, Edgardo; BARQUERO-CALVO, ELIAS
Brucella abortus is a stealthy intracellular bacterial pathogen of animals and humans. This bacterium promotes the premature cell death of neutrophils (PMN) and resists the killing action of these leukocytes. B. abortus-infected PMNs presented phosphatidylserine (PS) as "eat me" signal on the cell surface. This signal promoted direct contacts between PMNs and macrophages (Mϕs) and favored the phagocytosis of the infected dying PMNs. Once inside Mϕs, B. abortus replicated within Mϕs at significantly higher numbers than when Mϕs were infected with bacteria alone. The high levels of the regulatory IL-10 and the lower levels of proinflammatory TNF-α released by the B. abortus-PMN infected Mϕs, at the initial stages of the infection, suggested a non-phlogistic phagocytosis mechanism. Thereafter, the levels of proinflammatory cytokines increased in the B. abortus-PMN-infected Mϕs. Still, the efficient bacterial replication proceeded, regardless of the cytokine levels and Mϕ type. Blockage of PS with Annexin V on the surface of B. abortus-infected PMNs hindered their contact with Mϕs and hampered the association, internalization, and replication of B. abortus within these cells. We propose that B. abortus infected PMNs serve as "Trojan horse" vehicles for the efficient dispersion and replication of the bacterium within the host.
Neutrophils dampen adaptive immunity in Brucellosis
(American Society For Microbiology, 2019-04-23) Mora-Cartín, Ricardo; Gutiérrez-Jiménez, Cristina; Alfaro-Alarcón, Alejandro; Chaves-Olarte, Esteban; Chacón-Díaz, Carlos; BARQUERO-CALVO, ELIAS; Moreno, Edgardo
Brucella organisms are intracellular stealth pathogens of animals and humans. The bacteria overcome the assault of innate immunity at early stages of an infection. Removal of polymorphonuclear neutrophils (PMNs) at the onset of adaptive immunity against Brucella abortus favored bacterial elimination in mice. This was associated with higher levels of interferon gamma (IFN-γ) and a higher proportion of cells expressing interleukin 6 (IL-6) and inducible nitric oxide synthase (iNOS), compatible with M1 macrophages, in PMN-depleted B. abortus-infected (PMNd-Br) mice. At later times in the acute infection phase, the amounts of IFN-γ fell while IL-6, IL-10, and IL-12 became the predominant cytokines in PMNd-Br mice. IL-4, IL-1β, and tumor necrosis factor alpha (TNF-α) remained at background levels at all times of the infection. Depletion of PMNs at the acute stages of infection promoted the premature resolution of spleen inflammation. The efficient removal of bacteria in the PMNd-Br mice was not due to an increase of antibodies, since the immunoglobulin isotype responses to Brucella antigens were dampened. Anti-Brucella antibodies abrogated the production of IL-6, IL-10, and IL-12 but did not affect the levels of IFN-γ at later stages of infection in PMNd-Br mice. These results demonstrate that PMNs have an active role in modulating the course of B. abortus infection after the adaptive immune response has already developed.
Pansusceptible Escherichia Coli isolates obtained from faeces of free-ranging baird's tapirs (Tapirus Bairdii) suggests a low selective pressure for resistance determinants in the Northwestern Region of the Talamanca Mountain Range, Costa Rica
(Elsevier, 2018-09-27) Rojas-Jiménez, Jorge; Brenes-Mora, Esteban; Alcázar García, Paloma Elizabeth; Arguedas, Randall; BARQUERO-CALVO, ELIAS
Objectives The main objective of this study was to analyse the antimicrobial susceptibility profile of Escherichia coli isolates obtained from faecal samples of free-ranging Baird’s tapirs (Tapirus bairdii) in the northwestern region of the Talamanca Mountain Range, Costa Rica. Methods Faecal samples were collected by opportunistic search of the study area from February–September 2017 during seven field expeditions. Escherichia coli isolates were recovered using selective and differential MacConkey agar medium and were subjected to biochemical identification and antimicrobial susceptibility testing using a VITEK®2 Compact automated system and the AST-N279 card. Results A total of 60 E. coli isolates were obtained from 63 faecal samples. Following evaluation of nine different antimicrobial classes, 98% (59/60) of the isolates were characterised as pansusceptible; only 1 isolate presented resistance to nalidixic acid. Conclusion We propose that the commensal intestinal microbiota of free-ranging Baird’s tapirs in this area remains isolated from antibiotic selective pressure, probably because seven different protected areas converge, thus giving a possible low anthropogenic activity to the region.
Persistence of Brucella abortus in the bone marrow of infected mice
(Journal of Immunology Research, 2018-12-03) Gutiérrez-Jiménez, Cristina; HYSENAJ, LISIENA; Alfaro-Alarcón, Alejandro; Mora-Cartín, Ricardo; Gorvel, Jean-Pierre; Arce-Gorvel, Vilma; Moreno, Edgardo; BARQUERO-CALVO, ELIAS
Brucellosis is a zoonotic bacterial infection that may persist for long periods causing relapses in antibiotic-treated patients. The ability of Brucella to develop chronic infections is linked to their capacity to invade and replicate within the mononuclear phagocyte system, including the bone marrow (BM). Persistence of Brucella in the BM has been associated with hematological complications such as neutropenia, thrombocytopenia, anemia, and pancytopenia in human patients. In the mouse model, we observed that the number of Brucella abortus in the BM remained constant for up to 168 days of postinfection. This persistence was associated with histopathological changes, accompanied by augmented numbers of BM myeloid GMP progenitors, PMNs, and CD4+ lymphocytes during the acute phase (eight days) of the infection in the BM. Monocytes, PMNs, and GMP cells were identified as the cells harboring Brucella in the BM. We propose that the BM is an essential niche for the bacterium to establish long-lasting infections and that infected PMNs may serve as vehicles for dispersion of Brucella organisms, following the Trojan horse hypothesis. Monocytes are solid candidates for Brucella reservoirs in the BM.
Persistence of Brucella abortus lineages revealed by genomic characterization and phylodynamic analysis
(PLOS Neglected Tropical Diseases, 2020-04-14) Suárez-Esquivel, Marcela; Henández-Mora, Gabriela; Ruiz-Villalobos, Nazareth; BARQUERO-CALVO, ELIAS; Chacón-Díaz, Carlos; LadnerI, JasonT.; Oviedo-Sánchez, Gerardo; Foster, JeffreyT.; Rojas-Campos, Norman; Chaves-Olarte, Esteban; Thomson, Nicholas; Moreno, Edgardo; Guzman-Verri, Caterina
Brucellosis, caused by Brucella abortus, is a major disease of cattle and humans worldwide distributed. Eradication and control of the disease has been difficult in Central and South America, Central Asia, the Mediterranean and the Middle East. Epidemiological strategies combined with phylogenetic methods provide the high-resolution power needed to study relationships between surveillance data and pathogen population dynamics, using genetic diversity and spatiotemporal distributions. This information is crucial for prevention and control of disease spreading at a local and worldwide level. In Costa Rica (CR), the disease was first reported at the beginning of the 20th century and has not been controlled despite many efforts. We characterized 188 B. abortus isolates from CR recovered from cattle, humans and water buffalo, from 2003 to 2018, and whole genome sequencing (WGS) was performed in 95 of them. They were also assessed based on geographic origin, date of introduction, and phylogenetic associations in a worldwide and national context. Our results show circulation of five B. abortus lineages (I to V) in CR, phylogenetically related to isolates from the United States, United Kingdom, and South America. Lineage I was dominant and probably introduced at the end of the 19th century. Lineage II, represented by a single isolate from a water buffalo, clustered with a Colombian sample, and was likely introduced after 1845. Lineages III and IV were likely introduced during the early 2000s. Fourteen isolates from humans were found within the same lineage (lineage I) regardless of their geographic origin within the country. The main CR lineages, introduced more than 100 years ago, are widely spread throughout the country, in contrast to new introductions that seemed to be more geographically restricted. Following the brucellosis prevalence and the farming practices of several middle- and low-income countries, similar scenarios could be found in other regions worldwide.
Role of Clostridium perfringens toxins in necrotic enteritis in poultry
(Escuela de Medicina Veterinaria, 2016) Ramírez, M; Flores-Díaz, M; BARQUERO-CALVO, ELIAS; Alape-Girón, Alberto
Poultry products represent over 30% of animal protein consumption worldwide, and its demand is growing considerably. The current global annual production of poultry meat and eggs is more than 115 million tons and 70 million tons, respectively. Necrotic enteritis (NE) in poultry is a reemerging infectious disease caused by certain strains of Clostridium perfringens. This bacterium is found in limited quantities as a normal inhabitant of the birds’ gut; however, under certain circumstances, a pathogenic strain proliferates and secretes a variety of bacteriocins, mucins, and adhesins that favors bacteria colonization and establishment. Once bacterial population reaches a certain density, toxin production is triggered which induces mucosal damage. NE generates a dramatic reduction of production levels and a significant increase in mortality in flocks of broilers and laying hens, leading to annual economic losses for the poultry industry estimated to be over $6 billion. NE may manifest as an acute or chronic enterotoxemia. Acute infection is associated with higher rates of mortality and chronic infection, with loss of weight and productivity in sick animals. There is evidence that immunization with formalin-inactivated crude supernatants, native or modified toxins, or other proteins induces partial protection against NE. This review summarizes the findings concerning virulence factors associated with NE pathogenesis and the efforts oriented to develop rational strategies to prevent and control this disease
Salmonellosis detection and evidence of antibiotic resistance in an urban raccoon population in a highly populated area, Costa Rica
(WILEY, 2019-07-29) BALDI, MARIO; BARQUERO-CALVO, ELIAS; Hutter, Sabine; Walzer, Chris
Wild animals are involved in zoonotic disease transmission cycles. These are generally complex and poorly understood, especially among animals adapted to life in human ecosystems. Raccoons are reservoirs and effective carriers for infectious agents such as Salmonella throughout different environments and contribute to the transference of resistance genes. This study examined the presence of circulating Salmonella sp. in a population of raccoons in a tropical urban environment and evaluated resistance to antibiotics commonly used to treat salmonellosis. A total of 97 raccoons of different ages and sex were included in this study. 49% (38–60 CI) of the faecal samples were positive for Salmonella spp. The study identified 15 circulating serovars with the most prevalent being S. Hartford (7/15), S. Typhimurium (4/15) and S. Bovismorbificans (4/15). These serovars correspond to the serovars detected in humans with clinical symptoms in Costa Rica. 9.5% of the Salmonella strains recovered demonstrated ciprofloxacin resistance, and 7.1% showed resistance to nalidixic acid. This study provides evidence of multiple Salmonella serovars circulating in a population of urban raccoons in Costa Rica. Furthermore, the study confirms the existence of antimicrobial resistance to two antibiotics used to treat human salmonellosis. The findings emphasize the role of the raccoon as a reservoir of Salmonella in the Greater Metropolitan Area of Costa Rica (GAM) and stress the need for active monitoring of the presence and possible spread in antibiotic resistance due to this peri‐domestic carnivore.

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