Case Report: Acute Brucellosis Due to Brucella suis in a Brazilian Gold Miner Diagnosed in French Guiana.

A 29-year-old Brazilian illegal gold miner developed intermittent fever. Blood cultures were positive for Gram-negative coccobacilli and, after an initial misidentification by an automated identification system, the diagnosis of brucellosis caused by Brucella suis was confirmed. We hypothesize an association with domestic or wild swine exposure. The patient responded well to standard antibiotic therapy of brucellosis. We report the first case of human brucellosis on the Guiana Shield. This report underlines the importance of considering brucellosis in the presence of a fever of unknown origin, even in the Amazonian rainforest area, where several zoonotic diseases might be considered in the differential diagnosis of unexplained fever.

Phenotypic and molecular identification of Brucella suis biotype 1 in a pig from Brazil-case report.

Brucellosis is a zoonotic disease with a global impact. Brucella suis is one of the most pathogenic species to humans, requiring different measures for the control and/or eradication of the disease. The serological investigation for brucellosis was performed in pigs, horses, dogs, and cattle on a farm with a history of abortion in sows and necropsy of a boar with severe necrosuppurative orchitis. One sow, two cows, and two dogs reveled positive to Rose Bengal Test (RBT), although only the sow had a confirmatory outcome in 2-mercaptoethanol (2-ME). The 2-ME-positive sow was euthanized and microbiological culture of lymph nodes and liver followed by biochemical characterization allowed phenotypic characterization of Brucella suis biotype 1. PCR multiplex Bruce-ladder and Suis-ladder enabled molecular confirmation, respectively, of Brucella suis and biotype 1. The transmission aspects of B. suis to pigs and other domestic species, the combination of diagnostic procedures to diagnosis, as well as human health concerns of brucellosis are discussed.

Adhesive Functions or Pseudogenization of Type Va Autotransporters in Brucella Species.

Adhesion to host cells is a key step for successful infection of many bacterial pathogens and may define tropism to different host tissues. To do so, bacteria display adhesins on their surfaces. Brucella is an intracellular pathogen capable of proliferating in a wide variety of cell types. It has been described that BmaC, a large protein that belongs to the classical (type Va) autotransporter family, is required for efficient adhesion of Brucella suis strain 1330 to epithelial cells and fibronectin. Here we show that B. suis 1330 harbors two other type Va autotransporters (BmaA and BmaB), which, although much smaller, share significant sequence similarities with BmaC and contain the essential domains to mediate proper protein translocation to the bacterial surface. Gain and loss of function studies indicated that BmaA, BmaB, and BmaC contribute, to a greater or lesser degree, to adhesion of B. suis 1330 to different cells such as synovial fibroblasts, osteoblasts, trophoblasts, and polarized epithelial cells as well as to extracellular matrix components. It was previously shown that BmaC localizes to a single bacterial pole. Interestingly, we observed here that, similar to BmaC, the BmaB adhesin is localized mostly at a single cell pole, reinforcing the hypothesis that Brucella displays an adhesive pole. Although Brucella species have strikingly similar genomes, they clearly differ in their host preferences. Mainly, the differences identified between species appear to be at loci encoding surface proteins. A careful in silico analysis of the putative type Va autotransporter orthologues from several Brucella strains showed that the bmaB locus from Brucella abortus and both, the bmaA and bmaC loci from Brucella melitensis are pseudogenes in all strains analyzed. Results reported here evidence that all three autotransporters play a role in the adhesion properties of B. suis 1330. However, Brucella spp. exhibit extensive variations in the repertoire of functional adhesins of the classical autotransporter family that can be displayed on the bacterial surface, making them an interesting target for future studies on host preference and tropism.

Comparative proteomic analysis of outer membrane vesicles from Brucella suis, Brucella ovis, Brucella canis and Brucella neotomae.

Gram-negative bacteria release nanovesicles, called outer membrane vesicles (OMVs), from their outer membrane. Proteomics has been used to determine their composition. OMVs contain proteins able to elicit an immune response, so they have been proposed as a model to develop acellular vaccines. In this study, OMVs of Brucella suis, B. ovis, B. canis, and B. neotomae were purified and analyzed by SDS-PAGE, transmission electron microscopy and liquid chromatography coupled to mass spectrometry to determine the pan-proteome of these vesicles. In addition, antigenic proteins were detected by western blot with anti-Brucella sera. The in silico analysis of the pan-proteome revealed many homologous proteins, such as Omp16, Omp25, Omp31, SodC, Omp2a, and BhuA. Proteins contained in the vesicles from different Brucella species were detected by anti-Brucella sera. The occurrence of previously described immunogenic proteins derived from OMVs supports the use of these vesicles as candidates to be evaluated as an acellular brucellosis vaccine.

Brucella canis Group 2 isolated in Argentina.

The aim of this study was to estimate the diversity and prevalence of both groups of Brucella canis 1 and 2 with and without deletion respectively in different areas of Argentina. A total of 104 bacterial cultures were typed as B. canis strains using the classical biotyping method. Two PCR assays were performed to confirm that all isolates were B. canis and not Brucella suis. The differentiation between groups 1 and 2 was achieved using another PCR assay and the diversity of B. canis isolates was assessed with four MLVA_16 markers. All strains belonged to Group 2. Bruce 09 marker (MLVA_16 assay) showed the greatest diversity. Only Group 2 of B. canis was identified among the strains evaluated. The markers chosen from the MLVA_16 allowed us to detect genetic diversity among the strains of B. canis studied.

The BtaF Adhesin Is Necessary for Full Virulence During Respiratory Infection by Brucella suis and Is a Novel Immunogen for Nasal Vaccination Against Brucella Infection.

Brucella enters their hosts mostly through mucosae from where it spreads systemically. Adhesion to extracellular matrix (ECM) components or to host cells is important for the infectious process, and is mediated by several adhesins, including the BtaF trimeric autotransporter. Although Th1 responses and gamma interferon (IFN-γ) are important for protection, antibodies able to block adhesions might also contribute to prevent Brucella infection. We evaluated the importance of BtaF for respiratory Brucella infection, and characterized the immune response and protection from mucosal challenge induced by nasal vaccination with recombinant BtaF. While lung CFU numbers did not differ at day 1 p.i. between mice intratracheally inoculated with B. suis M1330 (wild type) and those receiving a ΔbtaF mutant, they were reduced in the latter group at 7 and 30 days p.i. For vaccination studies the BtaF passenger domain was engineered and expressed as a soluble trimeric protein. Mice were immunized by the nasal route with BtaF or saline (control group) plus the mucosal adjuvant c-di-AMP. Specific anti-BtaF antibodies (IgG and IgA) were increased in serum, including a mixed IgG2a/IgG1 response. In vitro, these antibodies reduced bacterial adhesion to A549 alveolar epithelial cells. Specific IgA antibodies were also increased in several mucosae. Spleen cells from BtaF immunized mice significantly increased their IL-2, IL-5, IL-17, and IFN-γ secretion upon antigen stimulation. In cervical draining lymph nodes, antigen-experienced CD4+ T cells were maintained mainly as central memory cells. A BtaF-specific delayed-type hypersensitivity response was detected in BtaF immunized mice. Lung cells from the latter produced high levels of IFN-γ upon antigen stimulation. Although nasal immunization with BtaF did not protect mice against B. suis respiratory challenge, it conferred significant protection from intragastric challenge; the splenic load of B. suis was reduced by 3.28 log CFU in immunized mice. This study shows that nasal vaccination with BtaF+c-di-AMP protects against intragastric challenge with B. suis by inducing local and systemic antibody responses, central memory CD4+ T cells and strong Th1 responses. Therefore, although BtaF vaccination did not protect from B. suis respiratory infection, this adhesin constitutes a promising immunogen against mucosal B. suis infection.

MapB, the Brucella suis TamB homologue, is involved in cell envelope biogenesis, cell division and virulence.

Brucella species are Gram-negative, facultative intracellular pathogens responsible for a worldwide zoonosis. The envelope of Brucella exhibits unique characteristics that make these bacteria furtive pathogens and resistant to several host defence compounds. We have identified a Brucella suis gene (mapB) that appeared to be crucial for cell envelope integrity. Indeed, the typical resistance of Brucella to both lysozyme and the cationic lipopeptide polymyxin B was markedly reduced in a ∆mapB mutant. MapB turned out to represent a TamB orthologue. This last protein, together with TamA, a protein belonging to the Omp85 family, form a complex that has been proposed to participate in the translocation of autotransporter proteins across the outer membrane (OM). Accordingly, we observed that MapB is required for proper assembly of an autotransporter adhesin in the OM, as most of the autotransporter accumulated in the mutant cell periplasm. Both assessment of the relative amounts of other specific outer membrane proteins (OMPs) and a proteome approach indicated that the absence of MapB did not lead to an extensive alteration in OMP abundance, but to a reduction in the relative amounts of a protein subset, including proteins from the Omp25/31 family. Electron microscopy revealed that ∆mapB cells exhibit multiple anomalies in cell morphology, indicating that the absence of the TamB homologue in B. suis severely affects cell division. Finally, ∆mapB cells were impaired in macrophage infection and showed an attenuated virulence phenotype in the mouse model. Collectively, our results indicate that the role of B. suis TamB homologue is not restricted to participating in the translocation of autotransporters across the OM but that it is essential for OM stability and protein composition and that it is involved in cell envelope biogenesis, a process that is inherently coordinated with cell division.

New Features in the Lipid A Structure of Brucella suis and Brucella abortus Lipopolysaccharide.

Brucellaceae are Gram-negative bacteria that cause brucellosis, one of the most distributed worldwide zoonosis, transmitted to humans by contact with either infected animals or their products. The lipopolysaccharide exposed on the cell surface has been intensively studied and is considered a major virulence factor of Brucella. In the last years, structural studies allowed the determination of new structures in the core oligosaccharide and the O-antigen of this lipopolysaccharide. In this work, we have reinvestigated the lipid A structure isolated from B. suis and B. abortus lipopolysaccharides. A detailed study by MALDI-TOF mass spectrometry in the positive and negative ion modes of the lipid A moieties purified from both species was performed. Interestingly, a new feature was detected: the presence of a pyrophosphorylethanolamine residue substituting the backbone. LID-MS/MS analysis of some of the detected ions allowed assurance that the Lipid A structure composed by the diGlcN3N disaccharide, mainly hexa-acylated and penta-acylated, bearing one phosphate and one pyrophosphorylethanolamine residue. Graphical abstract ᅟ.

Detección serológica de Brucella suis, virus de influenza y virus de la enfermedad de Aujeszky en criaderos porcinos familiares de menos de 100 madres en Argentina / Serological detection of Brucella suis, influenza virus and Aujeszky's disease virus in backyard and small swine holders in Argentina

Los criaderos porcinos de menos de 100 madres representan más del 99% de los de todo el país; sin embargo, existen escasos reportes sobre su situación sanitaria y productiva. Se recabó información productiva y se tomaron muestras para detectar anticuerpos contra Brucella suis (Bs), virus de la enfermedad de Aujeszky (VA) y virus de influenza (VI) en 68 establecimientos de menos de 100 madres ubicados en la región norte, centro y sur del país. El 80% de los establecimientos fueron positivos al VI H1 pandémico 2009, el 11% al H3 clúster 2, mientras que el 11,7% presentó anticuerpos contra el VA y el 6% contra Bs. Ninguno de los productores conocía los factores de riesgo para la transmisión de enfermedades del cerdo al humano. El 47% compra sus reproductores a pares o en ferias. En lo que respecta a normas de bioseguridad, solo el 16% de los establecimientos tenía cerco perimetral y el 37% de las granjas contaba con asesoramiento veterinario. Los resultados de este estudio demuestran que la caracterización productiva y el relevamiento sanitario son de suma importancia para mejorar la productividad y reducir el riesgo de transmisión de enfermedades. El conocimiento de la situación sanitaria y de los factores de riesgo es necesario para conseguir un mejor control y la erradicación de enfermedades en sistemas de baja tecnificación. Se deberían llevar a cabo estudios más representativos a nivel país para detectar los agentes circulantes y, sobre la base de esta información, implementar medidas de prevención y control.

Farmers raising less than 100 sows represent more than 99% of swine producers in Argentina, although little is known about their sanitary status and productive characteristics in the country. Sanitary and productive information was obtained. Furthermore, samples for serological studies were taken to detect antibodies against Brucella suis (Bs), Aujeszky's disease virus (AV) and influenza virus (IV) in 68 backyard and small producers with less than 100 sows located in the north, central and south regions of Argentina. Antibodies against H1 pandemic were detected in 80% of the farms while 11%, 11.7% and 6.0% of the producers were positive to influenza H3 cluster 2, AV and Bs, respectively. None of the producers was aware of the risk factors concerning the transmission of diseases from pigs to humans. A percentage of 47% of them buy pigs for breeding from other farmers and markets. With regard to biosecurity measures, only 16% of the farms had perimeter fences. The results of this study demonstrate that productive characterization and disease surveys are important to improve productivity and to reduce the risk of disease transmission among animals and humans. The study of sanitary status and risk factors is necessary for better control and eradication of diseases in backyard or small producers. More representative studies at country level should be carried out to detect the pathogensthat circulate and, with this knowledge, to implement prevention and control measures.

[Serological detection of Brucella suis, influenza virus and Aujeszky's disease virus in backyard and small swine holders in Argentina]. / Detección serológica de Brucella suis, virus de influenza y virus de la enfermedad de Aujeszky en criaderos porcinos familiares de menos de 100 madres en Argentina.

Farmers raising less than 100 sows represent more than 99% of swine producers in Argentina, although little is known about their sanitary status and productive characteristics in the country. Sanitary and productive information was obtained. Furthermore, samples for serological studies were taken to detect antibodies against Brucella suis (Bs), Aujeszky's disease virus (AV) and influenza virus (IV) in 68 backyard and small producers with less than 100 sows located in the north, central and south regions of Argentina. Antibodies against H1 pandemic were detected in 80% of the farms while 11%, 11.7% and 6.0% of the producers were positive to influenza H3 cluster 2, AV and Bs, respectively. None of the producers was aware of the risk factors concerning the transmission of diseases from pigs to humans. A percentage of 47% of them buy pigs for breeding from other farmers and markets. With regard to biosecurity measures, only 16% of the farms had perimeter fences. The results of this study demonstrate that productive characterization and disease surveys are important to improve productivity and to reduce the risk of disease transmission among animals and humans. The study of sanitary status and risk factors is necessary for better control and eradication of diseases in backyard or small producers. More representative studies at country level should be carried out to detect the pathogensthat circulate and, with this knowledge, to implement prevention and control measures.

High Incidence of Respiratory Involvement in a Cluster of Brucella suis-Infected Workers from a Pork Processing Plant in Argentina.

Epidemiological and clinical aspects of Brucella suis infection in 17 workers from a pork processing plant in Argentina occurring between January 2014 and July 2015 are presented. All patients reported working 9 h daily without adequate personal protection garment. Blood cultures were positive for Brucella spp. in 14 of the 17 patients (82.3%). All isolates were identified as B. suis biovar 1. Although fever, sweats, asthenia, myalgia and hepatic involvement were the most frequent clinical manifestations, an unusually high incidence of respiratory involvement was found. From 13 patients in which chest radiography was performed, four (30%) had radiological abnormalities, including lobar pneumonia in two cases (one with pleural effusion) and interstitial involvement in other two. The high frequency of respiratory involvement in our series makes necessary to consider brucellosis in the differential diagnosis of respiratory diseases in pork processing plant employees.

Brucella suis bacteremia misidentified as Ochrobactrum anthropi by the VITEK 2 system.

Ochrobactrum and Brucella are genetically related genera of the family Brucellaceae, sharing 98.8% rRNA similarity. Because of their phenotypic similarity, Ochrobactrum can be miscoded as Brucella by automated identification systems. The misidentification on blood cultures (BCs) of B. suis as O. anthropi by the VITEK 2 system is herein described. A 67-year-old male with a prosthetic mitral valve and fever was admitted with bacteremia due to a Gram-negative coccobacillus identified as O. anthropi by VITEK 2. The patient's fever persisted along with positive blood cultures despite specific antimicrobial treatment. Due to this adverse outcome, the patient was interrogated again and admitted having domestic swine. Serological tests were positive for acute brucellosis. Polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) of BC strains identified B. suis biovar 1. Timely identification of Brucella is essential for providing proper treatment to the patient and for advising safe handling of laboratory cultures in biological safety cabinets to prevent laboratory-acquired infection. Countries where brucellosis is endemic must be aware of this possibility.

Inhibition of ß-carbonic anhydrases from Brucella suis with C-cinnamoyl glycosides incorporating the phenol moiety.

A small series of C-glycosides containing the phenol moiety was tested for the inhibition of the ß-class carbonic anhydrases (ßCAs, EC 4.2.1.1) from Brucella suis. Many compounds showed activities in the micromolar or submicromolar range and excellent selectivity for pathogen CAs over human isozymes. Glycosides incorporating the 3-hydroxyphenyl moiety showed the best inhibition profile, and therefore this functionality represents lead for the development of novel anti-infectives with a new mechanism of action.

C-glycosides incorporating the 6-methoxy-2-naphthyl moiety are selective inhibitors of fungal and bacterial carbonic anhydrases.

A small series of C-glycosides containing the methoxyaryl moieties was tested for the inhibition of the ß-class carbonic anhydrases (CAs, EC 4.2.1.1) from Cryptococcus neoformans and Brucella suis. Many compounds showed activities in the micromolar or submicromolar range and excellent selectivity for pathogen CAs over human isozymes. The deprotected glycosides incorporating the 6-methoxy-2-naphthyl moiety showed the best inhibition profile and therefore represent leads for the development of novel anti-infectives with a new mechanism of action.

Prevalência e fatores de risco para brucelose suína em Mossoró-RN / Prevalence and risk factors for brucellosis in pigs in Mossoró-RN

A presente pesquisa teve como objetivo determinar a prevalência da brucelose e seus fatores de risco no rebanho suíno de Mossoró/RN. Compreendeu um estudo epidemiológico transversal e de abordagem quantitativa, no qual foram coletadas 412 amostras sanguíneas de suínos provenientes dos principais produtores do município e realizada inspeção das criações com entrevistas aos produtores. Anticorpos anti-Brucella spp. foram detectados pelo teste do antígeno acidificado tamponado (AAT) e confirmados pela reação de fixação de complemento (RFC). A prevalência da brucelose nos suínos foi de 27,0 por cento no teste de AAT e 17,5 por cento na RFC. Em 55 por cento das propriedades pesquisadas havia pelo menos um animal positivo, e a prevalência nestas variou de 6,7 por cento a 80,0 por cento. Os fatores de risco que estavam influenciando a ocorrência da doença foram: a presença de ratos nas criações, o contato com bovinos e a faixa etária jovem dos animais. Os resultados do estudo permitiram concluir que o agente etiológico da brucelose estava circulando em suínos do município de Mossoró-RN, com elevada prevalência no rebanho e nas propriedades, evidenciando o risco de transmissão desta zoonose para o homem.(AU)

The study aimed to determine the prevalence of brucellosis and its risk factors in the pig herd of Mossoró-RN. Comprised a cross-sectional quantitative approach and epidemiological study, where 412 blood samples of pigs from major producers in the municipality were collected and inspection of herds with interviews with producers were conducted. Antibodies to Brucella spp. were detected by the rose Bengal test (RBT) and confirmed by the complement fixation test (CFT). The prevalence of brucellosis in pigs was 27.0 percent in the RBT and 17.5 percent in the CFT. In 55 percent of the surveyed properties there was at least one positive animal, and these prevalence ranged from 6.7 percent to 80.0 percent. Risk factors that were influencing the occurrence of the disease were the presence of rats in the farms, contact with cattle and the young age of the animals. The study results showed that the causative agent of brucellosis was circulating in pigs in the municipality of Mossoró-RN, with high prevalence in the herd and on the properties, indicating the risk of transmission of this zoonosis to humans.(AU)

Prevalência e fatores de risco para brucelose suína em Mossoró-RN / Prevalence and risk factors for brucellosis in pigs in Mossoró-RN

A presente pesquisa teve como objetivo determinar a prevalência da brucelose e seus fatores de risco no rebanho suíno de Mossoró/RN. Compreendeu um estudo epidemiológico transversal e de abordagem quantitativa, no qual foram coletadas 412 amostras sanguíneas de suínos provenientes dos principais produtores do município e realizada inspeção das criações com entrevistas aos produtores. Anticorpos anti-Brucella spp. foram detectados pelo teste do antígeno acidificado tamponado (AAT) e confirmados pela reação de fixação de complemento (RFC). A prevalência da brucelose nos suínos foi de 27,0 por cento no teste de AAT e 17,5 por cento na RFC. Em 55 por cento das propriedades pesquisadas havia pelo menos um animal positivo, e a prevalência nestas variou de 6,7 por cento a 80,0 por cento. Os fatores de risco que estavam influenciando a ocorrência da doença foram: a presença de ratos nas criações, o contato com bovinos e a faixa etária jovem dos animais. Os resultados do estudo permitiram concluir que o agente etiológico da brucelose estava circulando em suínos do município de Mossoró-RN, com elevada prevalência no rebanho e nas propriedades, evidenciando o risco de transmissão desta zoonose para o homem.

The study aimed to determine the prevalence of brucellosis and its risk factors in the pig herd of Mossoró-RN. Comprised a cross-sectional quantitative approach and epidemiological study, where 412 blood samples of pigs from major producers in the municipality were collected and inspection of herds with interviews with producers were conducted. Antibodies to Brucella spp. were detected by the rose Bengal test (RBT) and confirmed by the complement fixation test (CFT). The prevalence of brucellosis in pigs was 27.0 percent in the RBT and 17.5 percent in the CFT. In 55 percent of the surveyed properties there was at least one positive animal, and these prevalence ranged from 6.7 percent to 80.0 percent. Risk factors that were influencing the occurrence of the disease were the presence of rats in the farms, contact with cattle and the young age of the animals. The study results showed that the causative agent of brucellosis was circulating in pigs in the municipality of Mossoró-RN, with high prevalence in the herd and on the properties, indicating the risk of transmission of this zoonosis to humans.

Brucella suis in armadillos (Chaetophractus villosus) from La Pampa, Argentina.

Brucellosis is a zoonotic disease transmitted from an animal reservoir to humans. Both, wildlife and domestic animals, contribute to the spreading of these zoonosis. The surveillance of the animal health status is strictly regulated for domestic animals, whereas disease monitoring in wildlife does not exist. The aim of the present study was to provide data on the prevalence of anti-Brucella antibodies in Chaetophractus villosus from a region of La Pampa, Argentina to assess public health risks. The C. villosus is endemic to South America, and in Argentina it represents a food resource for human consumption. A total of 150 sera of armadillos bleeding between 2007 and 2010 were tested using buffered plate antigen test (BPAT), serum agglutination test (SAT), 2-mercaptoethanol (2-ME) and complement fixation test (CFT), for the detection of anti-Brucella antibodies. Antibodies to Brucella sp. were found in 16% (24:150) of the armadillos tested using the BPAT test. All 24 positive samples were confirmed by the SAT, 2-ME and CFT tests. Strain isolation was attempted from liver and spleen samples of two animals with positive serology. Isolates were characterized by conventional biotyping and identification of specific DNA using polymerase chain reaction (PCR). A total of 2 isolates were recovered from spleen and liver. Both of them were identified as Brucella suis biovar 1. This preliminary study provides the first report on the seroprevalence of brucellosis and describes the first isolate of B. suis biovar 1 in C. villosus in Argentina.

The BtaF trimeric autotransporter of Brucella suis is involved in attachment to various surfaces, resistance to serum and virulence.

The adhesion of bacterial pathogens to host cells is an event that determines infection, and ultimately invasion and intracellular multiplication. Several evidences have recently shown that this rule is also truth for the intracellular pathogen Brucella. Brucella suis displays the unipolar BmaC and BtaE adhesins, which belong to the monomeric and trimeric autotransporter (TA) families, respectively. It was previously shown that these adhesins are involved in bacterial adhesion to host cells and components of the extracellular matrix (ECM). In this work we describe the role of a new member of the TA family of B. suis (named BtaF) in the adhesive properties of the bacterial surface. BtaF conferred the bacteria that carried it a promiscuous adhesiveness to various ECM components and the ability to attach to an abiotic surface. Furthermore, BtaF was found to participate in bacterial adhesion to epithelial cells and was required for full virulence in mice. Similar to BmaC and BtaE, the BtaF adhesin was expressed in a small subpopulation of bacteria, and in all cases, it was detected at the new pole generated after cell division. Interestingly, BtaF was also implicated in the resistance of B. suis to porcine serum. Our findings emphasize the impact of TAs in the Brucella lifecycle.

Human brucellosis at a pig slaughterhouse.

Seventeen workers in a pig slaughterhouse with signs and symptoms compatible with brucellosis were clinically examined at the outpatient service of different health institutions and studied by serological tests during the period 2005-2011. Eleven blood cultures were taken and six Brucella suis strains were isolated, three biovar 1 and three with atypical characteristics. In order to confirm that these cases had no common source, a variable number of tandem repeat (VNTR) analyses were performed on 5 of the 6 strains whose results showed substantial heterogeneity in the genotypes, thereby demonstrating that the immediate origin was not the same. Two hundred adult pigs admitted for slaughter at the plant were sampled by convenience and tested by buffered antigen plate test (BPAT), serum agglutination test (SAT) and 2-mercapto-ethanol test (MET). Seven of 62 males (11%) and 25/138 (18%) females tested positive. The study results contribute information on risk scenarios for packing plant workers and underscore the need to improve plant workers' education on appropriate containment measures and to actively screen animals for swine brucellosis.

BtaE, an adhesin that belongs to the trimeric autotransporter family, is required for full virulence and defines a specific adhesive pole of Brucella suis.

Brucella is responsible for brucellosis, one of the most common zoonoses worldwide that causes important economic losses in several countries. Increasing evidence indicates that adhesion of Brucella spp. to host cells is an important step to establish infection. We have previously shown that the BmaC unipolar monomeric autotransporter mediates the binding of Brucella suis to host cells through cell-associated fibronectin. Our genome analysis shows that the B. suis genome encodes several additional potential adhesins. In this work, we characterized a predicted trimeric autotransporter that we named BtaE. By expressing btaE in a nonadherent Escherichia coli strain and by phenotypic characterization of a B. suis ΔbtaE mutant, we showed that BtaE is involved in the binding of B. suis to hyaluronic acid. The B. suis ΔbtaE mutant exhibited a reduction in the adhesion to HeLa and A549 epithelial cells compared with the wild-type strain, and it was outcompeted by the wild-type strain in the binding to HeLa cells. The knockout btaE mutant showed an attenuated phenotype in the mouse model, indicating that BtaE is required for full virulence. BtaE was immunodetected on the bacterial surface at one cell pole. Using old and new pole markers, we observed that both the BmaC and BtaE adhesins are consistently associated with the new cell pole, suggesting that, in Brucella, the new pole is functionally differentiated for adhesion. This is consistent with the inherent polarization of this bacterium, and its role in the invasion process.