Novel IS711 chromosomal location useful for identification of marine mammal Brucella genotype ST27, which is associated with zoonotic infection

Novel Species of Brucella Causing Human Brucellosis, French Guiana

Human brucellosis is a zoonoses caused by bacteria of the genus Brucella. Infection results in subacute or chronic debilitating disease with nonspecific clinical manifestations and is often associated with consuming unpasteurized dairy products. We report 2 cases of brucellosis in male patients who were hospitalized in distinct towns of French Guiana, an overseas territory of France located on the northeastern shore of South America. Both men were citizens of Brazil working as clandestine goldminers in the deep Amazonian rainforest. Characterization of the 2 bacterial isolates revealed that they represent a potential new species of Brucella. Medical practitioners working in contact with wildlife in this region of the world should be aware of the existence of these pathogens and the potential for human infection.

Assays for Identification and Differentiation of Brucella Species: A Review

Brucellosis is one of the most important and widespread bacterial zoonoses worldwide. Cases are reported annually across the range of known infectious species of the genus Brucella. Globally, Brucella melitensis, primarily hosted by domestic sheep and goats, affects large proportions of livestock herds, and frequently spills over into humans. While some species, such as Brucella abortus, are well controlled in livestock in areas of North America, the Greater Yellowstone Ecosystem supports the species in native wild ungulates with occasional spillover to livestock. Elsewhere in North America, other Brucella species still infect domestic dogs and feral swine, with some associated human cases. Brucella spp. patterns vary across space globally with B. abortus and B. melitensis the most important for livestock control. A myriad of other species within the genus infect a wide range of marine mammals, wildlife, rodents, and even frogs. Infection in humans from these others varies with geography and bacterial species. Control in humans is primarily achieved through livestock vaccination and culling and requires accurate and rapid species confirmation; vaccination is Brucella spp.-specific and typically targets single livestock species for distribution. Traditional bacteriology methods are slow (some media can take up to 21 days for bacterial growth) and often lack the specificity of molecular techniques. Here, we summarize the molecular techniques for confirming and identifying specific Brucella species and provide recommendations for selecting the appropriate methods based on need, sensitivity, and laboratory capabilities/technology. As vaccination/culling approaches are costly and logistically challenging, proper diagnostics and species identification are critical tools for targeting surveillance and control.

Brucella ceti sequence type 23, 26, and 27 infections in North American cetaceans

Brucella ceti infection is associated with a variety of disease outcomes in cetaceans globally. Multiple genotypes of B. ceti have been identified. This retrospective aimed to determine if specific lesions were associated with different B. ceti DNA sequence types (STs). Characterization of ST was performed on 163 samples from 88 free-ranging cetaceans, including common bottlenose dolphin Tursiops truncatus (T.t.; n = 73), common short-beaked dolphin Delphinus delphis (D.d.; n = 7), striped dolphin Stenella coeruleoalba (n = 3), Pacific white-sided dolphin Lagenorhynchus obliquidens (n = 2), sperm whale Physeter macrocephalus (n = 2), and harbour porpoise Phocoena phocoena (n = 1), that stranded along the coast of the US mainland and Hawaii. ST was determined using a previously described insertion sequence 711 quantitative PCR. Concordance with 9-locus multi-locus sequence typing was assessed in a subset of samples (n = 18). ST 26 was most commonly identified in adult dolphins along the US east coast with non-suppurative meningoencephalitis (p = 0.009). Animals infected with ST 27 were predominately perinates that were aborted or died shortly after birth with evidence of in utero pneumonia (p = 0.035). Reproductive tract inflammation and meningoencephalitis were also observed in adult T.t. and D.d. with ST 27, though low sample size limited interpretation. ST 23 infections can cause disease in cetacean families other than porpoises (Phocoenidae), including neurobrucellosis in D.d. In total, 11 animals were potentially infected with multiple STs. These data indicate differences in pathogenesis among B. ceti STs in free-ranging cetaceans, and infection with multiple STs is possible.

Brucella Genomics: Macro and Micro Evolution

Brucella organisms are responsible for one of the most widespread bacterial zoonoses, named brucellosis. The disease affects several species of animals, including humans. One of the most intriguing aspects of the brucellae is that the various species show a ~97% similarity at the genome level. Still, the distinct Brucella species display different host preferences, zoonotic risk, and virulence. After 133 years of research, there are many aspects of the Brucella biology that remain poorly understood, such as host adaptation and virulence mechanisms. A strategy to understand these characteristics focuses on the relationship between the genomic diversity and host preference of the various Brucella species. Pseudogenization, genome reduction, single nucleotide polymorphism variation, number of tandem repeats, and mobile genetic elements are unveiled markers for host adaptation and virulence. Understanding the mechanisms of genome variability in the Brucella genus is relevant to comprehend the emergence of pathogens.

Taxonomic Organization of the Family Brucellaceae Based on a Phylogenomic Approach

Deciphering the evolutionary history of pathogenic bacteria and their near neighbors may help to understand the genetic or ecological bases which led to their pathogenic behavior. The Brucellaceae family comprises zoonotic pathogenic species belonging to the genus Brucella as well as the environmental genus Ochrobactrum for which some species are considered as opportunistic pathogens. Here, we used a phylogenomic approach including a set of 145 Brucellaceae genomes representative of the family diversity and more than 40 genomes of the order Rhizobiales to infer the taxonomic relationships between the family’s species. Our results clarified some unresolved phylogenetic ambiguities, conducting to the exclusion of Mycoplana spp. out of the family Brucellaceae and the positioning of all Brucella spp. as a single genomic species within the current Ochrobactrum species diversity. Additional analyses also revealed that Ochrobactrum spp. separate into two clades, one comprising mostly environmental species while the other one includes the species considered as pathogens (Brucella spp.) or opportunistic pathogens (mainly O. anthropi, O. intermedium, and O. pseudintermedium). Finally, we show that O. intermedium is undergoing a beginning of genome reduction suggestive of an ongoing ecological niche specialization, and that some lineages of O. intermedium and O. anthropi may shift toward an adaption to the human host.

Neurobrucellosis in a common bottlenose dolphin (Tursiops truncatus) stranded in the Canary Islands

Background

Brucella spp. isolation is increasingly reported in cetaceans, although associated pathologies, including lesions of the musculoskeletal and nervous systems, are less frequently described. Concerning the nervous system, Brucella sp. infection causing meningitis, meningoencephalitis or meningoencephalomyelitis have been extensively reported in striped dolphins (Stenella coeruleoalba), and less frequently in other cetacean species.

Case presentation

A juvenile female common bottlenose dolphin (Tursiops truncatus) was found stranded alive in Lanzarote (Canary Islands, Spain) in 2005, but died shortly after. On physical examination, the dolphin showed a moderate body condition and was classified as code 2 (fresh dead) at the time of necropsy. The main gross findings were severe multiorgan parasitism, thickened and congested leptomeninges, and (sero)fibrino-suppurative and proliferative arthritis of the shoulder joint. Histopathological examination revealed the distinct features of a sub-acute systemic disease associated with Cetacean Morbillivirus (CeMV) infection. However, brain lesions diverged from those reported in systemic CeMV infection. This led to suspect that there was a coinfecting pathogen, based on the characteristics of the inflammatory response and the lesion distribution pattern in the central nervous system. Brucella sp. was detected in the brain tissue by PCR and Brucella antigen was demonstrated by immunohistochemistry in the brain and shoulder joint lesions.

Conclusions

The zoonotic potential of marine mammal strains of Brucella has been demonstrated both in natural and laboratory conditions. In this study, PCR detected Brucella sp. in the brain of a common bottlenose dolphin stranded in the Canary Islands; the dolphin was also co-infected with CeMV. This is the first detection of Brucella sp. infection in a stranded cetacean in this archipelago. Therefore, we stress the importance of taking adequate measures during the handling of these species to prevent the transmissions of the infection to humans.

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

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 clade 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.

Application of real-time quantitative PCR assays for detecting marine Brucella spp. in fish

Brucella ceti and Brucella pinnipedialis have been documented as occurring in marine mammals, and B. ceti has been identified in 3 naturally acquired human cases. Seroconversion and infection patterns in Pacific Northwest harbor seals ( Phoca vitulina richardii) and North Atlantic hooded seals ( Cystophora cristata) indicate post-weaning exposure through prey consumption or lungworm infection, suggesting fish and possibly invertebrates play an epizootiologic role in marine Brucella transmission and possible foodborne risk to humans. We determined if real-time quantitative PCR (qPCR) assays can detect marine Brucella DNA in fish DNA. Insertion sequence (IS) 711 gene and sequence type (ST)27 primer-probe sets were used to detect Brucella associated with marine mammals and human zoonotic infections, respectively. First, DNA extracts from paired-species fish (containing 2 species) samples were tested and determined to be Brucella DNA negative using both IS 711 and ST27 primer-probe sets. A representative paired-species fish DNA sample was spiked with decreasing concentrations of B. pinnipedialis DNA to verify Brucella detection by the IS 711 primer-probe within fish DNA. A standard curve, developed using isolated DNA from B. pinnipedialis, determined the limit of detection. Finally, the IS 711 primer-probe was used to test Atlantic cod ( Gadus morhua) DNA extracts experimentally infected with the B. pinnipedialis hooded seal strain. In culture-positive cod tissue, the IS 711 limit of detection was ~1 genome copy of Brucella. Agreement between culture and PCR results for the 9 positive and 9 negative cod tissues was 100%. Although a larger sample set is required for validation, our study shows that qPCR can detect marine Brucella in fish.

Whole-Genome Sequence of the First Sequence Type 27 Brucella ceti Strain Isolated from European Waters

Brucella spp. that cause marine brucellosis are becoming more important, as the disease appears to be more widespread than originally thought. Here, we report a whole and annotated genome sequence of Brucella ceti CRO350, a sequence type 27 strain isolated from a bottlenose dolphin carcass found in the Croatian part of the northern Adriatic Sea.

Brucellosis in Endangered Hector's Dolphins (Cephalorhynchus hectori)

Brucella spp infections of marine mammals are often asymptomatic but have been associated with reproductive losses and deaths. Zoonotic infections originating from marine isolates have also been described. Hector's dolphins (Cephalorhynchus hectori) are an endangered species with a declining population, and the role of infectious disease in population dynamics is not fully understood. In this study, 27 Hector's dolphins found dead around the New Zealand coastline between November 2006 and October 2010 were evaluated for lesions previously associated with cetacean brucellosis. Tissues were examined using histological, immunohistochemical, and molecular (polymerase chain reaction [PCR]) techniques. Seven of 27 dolphins (26%) had at least 1 tissue that was positive on PCR for Brucella spp. Lesions consistent with brucellosis were present in 10 of 27 (37%) dolphins, but in 8 of these dolphins Brucella infection could not be demonstrated in lesional tissues. Two dolphins (7%) were diagnosed with active brucellosis: 1 female with placentitis and metritis, and 1 stillborn male fetus. Brucella identified in these 2 dolphins had genetic similarity (99%) to Brucella pinnipedialis. The omp2a gene amplicon from the uterus of the female had 100% homology with ST27 genotype isolates from a human in New Zealand and a bottlenose dolphin of Pacific origin. The remaining 5 PCR-positive dolphins were assessed as having asymptomatic or latent infection. While most Brucella infections identified in this study appeared to be subclinical, the finding of 2 dolphins with reproductive disease due to Brucella infection suggests that this disease has the potential to affect reproductive success in this species.

Brucella spp. of amphibians comprise genomically diverse motile strains competent for replication in macrophages and survival in mammalian hosts

Twenty-one small Gram-negative motile coccobacilli were isolated from 15 systemically diseased African bullfrogs (Pyxicephalus edulis), and were initially identified as Ochrobactrum anthropi by standard microbiological identification systems. Phylogenetic reconstructions using combined molecular analyses and comparative whole genome analysis of the most diverse of the bullfrog strains verified affiliation with the genus Brucella and placed the isolates in a cluster containing B. inopinata and the other non-classical Brucella species but also revealed significant genetic differences within the group. Four representative but molecularly and phenotypically diverse strains were used for in vitro and in vivo infection experiments. All readily multiplied in macrophage-like murine J774-cells, and their overall intramacrophagic growth rate was comparable to that of B. inopinata BO1 and slightly higher than that of B. microti CCM 4915. In the BALB/c murine model of infection these strains replicated in both spleen and liver, but were less efficient than B. suis 1330. Some strains survived in the mammalian host for up to 12 weeks. The heterogeneity of these novel strains hampers a single species description but their phenotypic and genetic features suggest that they represent an evolutionary link between a soil-associated ancestor and the mammalian host-adapted pathogenic Brucella species.

Evidence of Brucella strain ST27 in bottlenose dolphin (Tursiops truncatus) in Europe

Marine mammal brucellosis has been known for more than 20 years, but recent work suggests it is more widespread than originally thought. Brucella (B.) pinnipedialis has been isolated from pinnipeds, while B. ceti strains have been associated with cetaceans. Here we report a Brucella strain isolated from multiple lymph nodes of one bottlenose dolphin (Tursiops truncatus) during routine examination of dolphin carcasses found in the Croatian part of the northern Adriatic Sea during the summer of 2015. Classical bacteriological biotyping, PCR-based techniques (single, multiplex, PCR-RFLP) and 16S rRNA DNA sequencing were used to identify Brucella spp. Multiple-locus variable number tandem repeat analysis of 16 loci and multilocus sequence typing of 9 loci were used for genotyping and species determination. The combination of bacteriological, molecular and genotyping techniques identified our strain as ST27, previously identified as a human pathogen. This report provides, to our knowledge, the first evidence of ST27 in the Adriatic Sea in particular and in European waters in general. The zoonotic nature of the strain and its presence in the Adriatic, which is inhabited by bottlenose dolphins, suggest that the strain may pose a significant threat to human health.

Advancement of knowledge of Brucella over the past 50 years

Fifty years ago, bacteria in the genus Brucella were known to cause infertility and reproductive losses. At that time, the genus was considered to contain only 3 species: Brucella abortus, Brucella melitensis, and Brucella suis. Since the early 1960s, at least 7 new species have been identified as belonging to the Brucella genus (Brucella canis, Brucella ceti, Brucella inopinata, Brucella microti, Brucella neotomae, Brucella ovis, and Brucella pinnipedialis) with several additional new species under consideration for inclusion. Although molecular studies have found such high homology that some authors have proposed that all Brucella are actually 1 species, the epidemiologic and diagnostic benefits for separating the genus based on phenotypic characteristics are more compelling. Although pathogenic Brucella spp have preferred reservoir hosts, their ability to infect numerous mammalian hosts has been increasingly documented. The maintenance of infection in new reservoir hosts, such as wildlife, has become an issue for both public health and animal health regulatory personnel. Since the 1960s, new information on how Brucella enters host cells and modifies their intracellular environment has been gained. Although the pathogenesis and histologic lesions of B. abortus, B. melitensis, and B. suis in their preferred hosts have not changed, additional knowledge on the pathology of these brucellae in new hosts, or of new species of Brucella in their preferred hosts, has been obtained. To this day, brucellosis remains a significant human zoonosis that is emerging or reemerging in many parts of the world.

Brucella ceti and brucellosis in cetaceans

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.