5 research outputs found

    Genetic and Phenotypic Characterization of the Etiological Agent of Canine Orchiepididymitis Smooth Brucella sp. BCCN84.3

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    Members of the genus Brucella cluster in two phylogenetic groups: classical and non-classical species. The former group is composed of Brucella species that cause disease in mammals, including humans. A Brucella species, labeled as Brucella sp. BCCN84.3, was isolated from the testes of a Saint Bernard dog suffering orchiepididymitis, in Costa Rica. Following standard microbiological methods, the bacterium was first defined as "Brucella melitensis biovar 2." Further molecular typing, identified the strain as an atypical "Brucella suis." Distinctive Brucella sp. BCCN84.3 markers, absent in other Brucella species and strains, were revealed by fatty acid methyl ester analysis, high resolution melting PCR and omp25 and omp2a/omp2b gene diversity. Analysis of multiple loci variable number of tandem repeats and whole genome sequencing demonstrated that this isolate was different from the currently described Brucella species. The smooth Brucella sp. BCCN84.3 clusters together with the classical Brucella Glade and displays all the genes required for virulence. Brucella sp. BCCN84.3 is a species nova taxonomical entity displaying pathogenicity; therefore, relevant for differential diagnoses in the context of brucellosis. Considering the debate on the Brucella species concept, there is a need to describe the extant taxonomical entities of these pathogens in order to understand the dispersion and evolution

    Global phylogenomic diversity of Brucella abortus: spread of a dominant lineage

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    Brucella abortus is a globally important zoonotic pathogen largely found in cattle hosts and is typically transmitted to humans through contaminated dairy products or contact with diseased animals. Despite the long, shared history of cattle and humans, little is known about how trade in cattle has spread this pathogen throughout the world. Whole genome sequencing provides unparalleled resolution to investigate the global evolutionary history of a bacterium such as B. abortus by providing phylogenetic resolution that has been unobtainable using other methods. We report on large-scale genome sequencing and analysis of B. abortus collected globally from cattle and 16 other hosts from 52 countries. We used single nucleotide polymorphisms (SNPs) to identify genetic variation in 1,074 B. abortus genomes and using maximum parsimony generated a phylogeny that identified four major clades. Two of these clades, clade A (median date 972 CE; 95% HPD, 781–1142 CE) and clade B (median date 150 BCE; 95% HPD, 515 BCE–164 CE), were exceptionally diverse for this species and are exclusively of African origin where provenance is known. The third clade, clade C (median date 949 CE; 95% HPD, 766–1102 CE), had most isolates coming from a broad swath of the Middle East, Europe, and Asia, also had relatively high diversity. Finally, the fourth major clade, clade D (median date 1467 CE; 95% HPD, 1367–1553 CE) comprises the large majority of genomes in a dominant but relatively monomorphic group that predominantly infects cattle in Europe and the Americas. These data are consistent with an African origin for B. abortus and a subsequent spread to the Middle East, Europe, and Asia, probably through the movement of infected cattle. We hypothesize that European arrival to the Americas starting in the 15th century introduced B. abortus from Western Europe through the introduction of a few common cattle breeds infected with strains from clade D. These data provide the foundation of a comprehensive global phylogeny of this important zoonotic pathogen that should be an important resource in human and veterinary epidemiology

    If You're Not Confused, You're Not Paying Attention: Ochrobactrum Is Not Brucella

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    Bacteria of the genus Brucella are facultative intracellular parasites that cause brucellosis, a severe animal and human disease. Recently, a group of taxonomists merged the brucellae with the primarily free-living, phylogenetically related Ochrobactrum spp. in the genus Brucella. This change, founded only on global genomic analysis and the fortuitous isolation of some opportunistic Ochrobactrum spp. from medically compromised patients, has been automatically included in culture collections and databases. We argue that clinical and environmental microbiologists should not accept this nomenclature, and we advise against its use because (i) it was presented without in-depth phylogenetic analyses and did not consider alternative taxonomic solutions; (ii) it was launched without the input of experts in brucellosis or Ochrobactrum; (iii) it applies a non-consensus genus concept that disregards taxonomically relevant differences in structure, physiology, population structure, core-pangenome assemblies, genome structure, genomic traits, clinical features, treatment, prevention, diagnosis, genus description rules, and, above all, pathogenicity; and (iv) placing these two bacterial groups in the same genus creates risks for veterinarians, medical doctors, clinical laboratories, health authorities, and legislators who deal with brucellosis, a disease that is particularly relevant in low- and middle-income countries. Based on all this information, we urge microbiologists, bacterial collections, genomic databases, journals, and public health boards to keep the Brucella and Ochrobactrum genera separate to avoid further bewilderment and harm.Las bacterias del género Brucella son parásitos intracelulares facultativos causantes de la brucelosis, una grave enfermedad animal y humana. Recientemente, un grupo de taxónomos fusionó las brucelas con las Ochrobactrum spp., principalmente de vida libre y filogenéticamente emparentadas, en el género Brucella. Este cambio, fundado únicamente en análisis genómicos globales y en el aislamiento fortuito de algunas Ochrobactrum spp. oportunistas de pacientes médicamente comprometidos, se ha incluido automáticamente en colecciones de cultivos y bases de datos. Sostenemos que los microbiólogos clínicos y ambientales no deberían aceptar esta nomenclatura, y desaconsejamos su uso porque (i) se presentó sin análisis filogenéticos en profundidad y no consideró soluciones taxonómicas alternativas; (ii) se lanzó sin la aportación de expertos en brucelosis u Ochrobactrum; (iii) aplica un concepto de género no consensuado que ignora las diferencias taxonómicamente relevantes en estructura, fisiología, estructura poblacional, ensamblajes del núcleo-pangenoma, estructura genómica, rasgos genómicos, características clínicas, tratamiento, prevención, diagnóstico, reglas de descripción del género y, sobre todo, patogenicidad; y (iv) colocar estos dos grupos bacterianos en el mismo género crea riesgos para veterinarios, médicos, laboratorios clínicos, autoridades sanitarias y legisladores que se ocupan de la brucelosis, una enfermedad especialmente relevante en países de renta baja y media. Basándonos en toda esta información, instamos a los microbiólogos, las colecciones bacterianas, las bases de datos genómicos, las revistas y los consejos de salud pública a mantener separados los géneros Brucella y Ochrobactrum para evitar más desconcierto y perjuicios.Universidad Nacional, Costa RicaEscuela de Medicina Veterinari
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