Investigating genetic diversity of Brucella abortus and Brucella melitensis in Italy with MLVA-16

Molecular epidemiology of brucellosis in Asia: insights from genotyping analyses

Brucellosis infects humans and animals worldwide but is particularly prevalent in Asia. In many Asian countries, molecular diagnostic tools for accurate molecular diagnostics and molecular epidemiology are lacking. Nonetheless, some countries have conducted in-depth molecular epidemiological studies. The objective of this study was to reveal the genetic relationships, geographic origins, and distributions of Brucella strains across Asia for two primary species, B. abortus and B. melitensis. For this, we systematically searched genotyping data from published studies on the molecular epidemiology of Brucella species for both humans and livestock in Asia. We used data from multilocus sequence typing (MLST), multiple-locus variable-number tandem repeat analysis (MLVA), and whole genome sequencing analysis of Brucella strains. We also analyzed the MLVA genotypes of 129 B. abortus isolates and 242 B. melitensis isolates with known origins in Asia from an online MLVA database using MLVA-11 data in minimum spanning trees and MLVA-16 data in neighbor-joining trees. We found that the B. melitensis East Mediterranean lineage is predominant across the continent, with only a small number of samples from the Africa and Americas lineages, and none from the West Mediterranean lineage. The "abortus C" genotype was the most common group of B. abortus in Asia, with limited genetic variation for this species. Several studies also reported that Near Eastern countries frequently encounter human brucellosis cases of B. abortus from genotypes 42 and 43. Our study highlights the inconsistent collection of genetic data for Brucella species across Asia and a need for more extensive sampling in most countries. Finally, a consistent nomenclature is necessary to define various groupings of strains within a lineage (i.e., clade) so uniform terminology should denote particular genetic groups that are understood by all researchers.

Genomic analysis of Brucella isolates from animals and humans, Türkiye, 2010 to 2020

BackgroundBrucellosis is a bacterial zoonosis causing severe illness in humans and animals and leading to economic losses in the livestock production in Türkiye and other endemic countries.AimWe aimed at investigating genomic differences of Brucella isolates from animals and humans in Türkiye.MethodsWe used whole genome sequencing (WGS) to assess the genetic diversity of Brucella isolates from 41 provinces in Türkiye and compared with isolates from other countries. We applied allele-based typing and core genome single nucleotide polymorphism (cgSNP) determination.ResultsOf the 106 Turkish Brucella isolates included, 57 were B. abortus and 49 were B. melitensis. One B. melitensis and two B. abortus isolates were identified as vaccine strains. Most (n = 55) B. abortus isolates clustered in three major branches, with no spatial discernible pattern. Of the B. melitensis isolates, 48 were assigned to the Eastern Mediterranean lineage with no discernible patterns between host species, location and sampling date. The Turkish isolates clustered with isolates from neighbouring countries such as Greece and Syria, but some also with isolates from human patients in European countries, like Germany, Norway and Sweden, suggesting that the source may be travel-related.ConclusionSeveral B. melitensis and B. abortus lineages are circulating in Türkiye. To decrease the prevalence and prevent brucellosis in animals and humans, stricter control measures are needed, particularly in areas where humans and animals have close contact. Furthermore, illegal transportation of animals across borders should be more closely controlled and regulated.

Epidemiological Investigation of Animal Brucellosis in Domestic Ruminants in Greece from 2015 to 2022 and Genetic Characterization of Prevalent Strains

Brucellosis is one of the most important zoonotic diseases in Greece, causing a significant burden on both human and animal vitality as well as economic loss. The present study was conducted from 2015 to 2022 on 711,415 serum samples by determining the seroepidemiology of Brucellosis among livestock in 24 geographical areas in Greece using the Rose Bengal Test (RBT) and the complement fixation test (CFT) and further performing genetic analysis of Brucella spp. by species-specific real-time PCR and MLVA Brucella analysis. A total of 3086 serum samples from goats, sheep, and cattle showed positive results using the RBT and CFT, and only strongly positive samples (n = 800) were preserved in the Βlood Bank of the Veterinary Laboratory of Brucellosis. From these, 212 sera samples were randomly selected for molecular and genetic analysis. The results indicated that the incidence rate of Brucellosis is higher in cattle herds in comparison with other animal species. Overall, 48 samples tested positive by real-time PCR, of which forty-seven of them were B. abortus and one was B. melitensis. Genetic analysis of two B. abortus samples revealed a common pattern, indicating two Bruce04, two Bruce18, four Bruce07, two Bruce09, three Bruce16, and four Bruce30 for both samples, which, interestingly, were not identical with the known genotypes in the public MLVA Brucella database. Our findings substantiate that animal Brucellosis remains a health issue in Greece, with a stable but apparent incidence rate, and further investigation is needed to fully characterize the newly identified Brucella strains in Greece.

An Evaluation of the Lineage of Brucella Isolates in Turkey by a Whole-Genome Single-Nucleotide Polymorphism Analysis

Brucellosis is a disease caused by the Brucella (B.) species. It is a zoonotic disease that affects farm animals and causes economic losses in many countries worldwide. Brucella has the ability to persist in the environment and infect the host at low doses. Thus, it is more important to trace brucellosis outbreaks, identify their sources of infection, and interrupt their transmission. Some countries already have initial data, but most of these data are based on a Multiple-Locus Variable-Number Tandem-Repeat Analysis (MLVA), which is completely unsuitable for studying the Brucella genome. Since brucellosis is an endemic disease in Turkey, this study aimed to examine the genome of Turkish Brucella isolates collected between 2018 and 2020, except for one isolate, which was from 2012. A total of 28 strains of B. melitensis (n = 15) and B. abortus (n = 13) were analyzed using a core-genome single-nucleotide polymorphism (cgSNP) analysis. A potential connection between the Turkish isolates and entries from Sweden, Israel, Syria, Austria, and India for B. melitensis was detected. For B. abortus, there may be potential associations with entries from China. This explains the tight ties found between Brucella strains from neighboring countries and isolates from Turkey. Therefore, it is recommended that strict measures be taken and the possible effects of uncontrolled animal introduction are emphasized.

A 14th century CE Brucella melitensis genome and the recent expansion of the Western Mediterranean clade

Brucellosis is a disease caused by the bacterium Brucella and typically transmitted through contact with infected ruminants. It is one of the most common chronic zoonotic diseases and of particular interest to public health agencies. Despite its well-known transmission history and characteristic symptoms, we lack a more complete understanding of the evolutionary history of its best-known species-Brucella melitensis. To address this knowledge gap we fortuitously found, sequenced and assembled a high-quality ancient B. melitensis draft genome from the kidney stone of a 14th-century Italian friar. The ancient strain contained fewer core genes than modern B. melitensis isolates, carried a complete complement of virulence genes, and did not contain any indication of significant antimicrobial resistances. The ancient B. melitensis genome fell as a basal sister lineage to a subgroup of B. melitensis strains within the Western Mediterranean phylogenetic group, with a short branch length indicative of its earlier sampling time, along with a similar gene content. By calibrating the molecular clock we suggest that the speciation event between B. melitensis and B. abortus is contemporaneous with the estimated time frame for the domestication of both sheep and goats. These results confirm the existence of the Western Mediterranean clade as a separate group in the 14th CE and suggest that its divergence was due to human and ruminant co-migration.

Whole-genome sequencing for genetic diversity analysis of Iranian Brucella spp. isolated from humans and livestock

Brucellosis is one of the most common zoonoses in the Middle East. It is causing economic losses to the livestock industry and has a great public health concern. Little is known about the genetic diversity and distribution of brucellae in Iran. Therefore, forty Brucella spp. strains (B. abortus and B. melitensis) isolated from animals and humans were analyzed by whole genome sequencing (WGS) technology using single nucleotide polymorphism (SNP) analysis and core genome multilocus sequence typing (cgMLST). Brucella isolates were obtained from lymph nodes (cows and camels), milk (cows, camels and sheep), and aborted foetus samples (sheep and goats), as well as cerebrospinal fluid and blood of humans. The isolates were originating from thirteen provinces of Iran and isolated between 2015 and 2020. According to in-silico MLST, ST8 and ST2 were the most frequent sequence types in B. melitensis and B. abortus, respectively. Based on phylogeographic reconstruction using cgSNP analysis, the investigated Iranian B. melitensis strains belonged to the American and Mediterranean lineages of the B. melitensis phylogeny. Furthermore, cgSNP analysis revealed a similarity between Iranian B. abortus isolates and strains from Iraq and Egypt. Therefore, the origin of the Iranian strains can be suggested to be strains from neighboring and Middle East countries. Moreover, cgMLST analysis showed that the Iranian B. melitensis strains were closely relative to strains recovered from sheep and humans in Iraq, Afghanistan, Syria, Turkmenistan, and Pakistan. In the current panel of strains, cgMLST and cgSNP analysis provided an appropriate and accurate tool for effective traceback analyses for Brucella spp. from Iran. The results of cgSNP and cgMLST helped to understand the geographic distribution and interspecies transmission of Iranian strains and highlight the importance of specific brucellosis control measures in Iran with regard to the One-Health approach.

Evaluation of a Real-time PCR in Combination with a Cultivation Method for the Detection of Brucella Abortus in Organs of Infected Cattle in Southern Italy

Introduction

Brucellosis is a widespread zoonosis of great economic importance for livestock farming in many areas of the world. It is a highly infectious disease which is diagnosed using conventional serological and microbiological methods. The aim of this study was to assess the efficiency of a specific real-time PCR in combination with broth cultivation in detecting Brucella spp. in organs of infected cattle, in order to compare the sensitivity of the two approaches and the time needed in them until a correct diagnosis is made.

Material and Methods

We examined 67 organs collected from 10 cattle slaughtered following a brucellosis outbreak which occurred in February 2016 in southern Italy. The research was carried out by enrichment broth cultivations in combination with a real-time PCR every week for six weeks.

Results

Brucella strains were isolated by cultivation from 44 enrichment broths of organs. All isolates were later identified as Brucella abortus by real-time PCR. Using this method in combination with cultivation made it possible to identify the same percentage of infected animals faster than by cultivation alone. Moreover, the same diagnostic results were obtained, on average two weeks before they would have been using only cultivation. In almost all cases, Brucella was detected by real-time PCR after the first week of cultivation in pre-enrichment Brucella broth, while the bacterial growth was evident usually after 2 or 3 weeks.

Conclusion

Real-time PCR has allowed results to be obtained faster than in the classical microbiological method, reducing the response times to identify positive animals by half.

Identification and molecular characterization of Brucella abortus and Brucella melitensis isolated from milk in cattle in Azerbaijan

BACKGROUND

Azerbaijan currently ranks thirteenth in global incidence of human brucellosis, with an estimated annual incidence through 2000 at over 50 cases per million. Brucella melitensis has been isolated from patients and is thought to have been acquired through contact with small ruminants or as a foodborne infection. To reduce the burden of human brucellosis, the Azerbaijani government began in 2002, a nationwide vaccination control campaign in small ruminants. There is serological evidence of bovine brucellosis (presumably due to Brucella abortus) in Azerbaijan, but no prevalence estimates were available when this study started in March 2017. The aim of this study was to isolate and identify Brucella spp. from cow milk in the Ganja region, where brucellosis takes a heavy toll on humans and livestock.

RESULTS

Blood and milk samples were collected from cows (n = 1075) in early lactation (up to 90-days) in farms that had a history of previous positive serological results and abortions. Twenty-two out of 57 milk samples collected from seropositive cows, showed growth on Farrell's media, when incubated with 5% CO₂. Eight additional milk samples showed growth in the absence of CO₂. The classical biotyping classified them as Brucella abortus (22) and Brucella melitensis (8). RT-PCR confirmed that strains belonged to the genus Brucella. MLVA profiles were obtained for DNA extracted from two B. abortus and six B. melitensis strains. While the B. abortus genetic profile was described in the MLVA database, matching the profile of B. abortus strains isolated in East Europe, Central Asia and China, we found a new genotype for the B. melitensis strains isolated in Azerbaijan, clustering with strains belonging to the American clade, rarely identified in the region.

CONCLUSION

Despite the implementation of the vaccination program in small ruminants, our results suggest that spill-over events of B. melitensis from small ruminants to cattle have occurred. However, cattle are likely to be primarily infected with B. abortus, which warranted the implementation of a bovine brucellosis program. Such a program started in fall 2017. In the Ganja region, cattle should be considered as a potential source of B. abortus and B. melitensis for humans.

Tracking the Distribution of Brucella abortus in Egypt Based on Core Genome SNP Analysis and In Silico MLVA-16

Brucellosis, caused by the bacteria of the genus Brucella, is one of the most neglected common zoonotic diseases globally with a public health significance and a high economic loss among the livestock industry worldwide. Since little is known about the distribution of B. abortus in Egypt, a total of 46 B. abortus isolates recovered between 2012–2020, plus one animal isolate from 2006, were analyzed by examining the whole core genome single nucleotide polymorphism (cgSNP) in comparison to the in silico multilocus variable number of tandem repeat analysis (MLVA). Both cgSNP analysis and MLVA revealed three clusters and one isolate only was distantly related to the others. One cluster identified a rather widely distributed outbreak strain which is repeatedly occurring for at least 16 years with marginal deviations in cgSNP analysis. The other cluster of isolates represents a rather newly introduced outbreak strain. A separate cluster comprised RB51 vaccine related strains, isolated from aborted material. The comparison with MLVA data sets from public databases reveals one near relative from Argentina to the oldest outbreak strain and a related strain from Spain to a newly introduced outbreak strain in Egypt. The distantly related isolate matches with a strain from Portugal in the MLVA profile. Based on cgSNP analysis the oldest outbreak strain clusters with strains from the UK. Compared to the in silico analysis of MLVA, cgSNP analysis using WGS data provides a much higher resolution of genotypes and, when correlated to the associated epidemiological metadata, cgSNP analysis allows the differentiation of outbreaks by defining different outbreak strains. In this respect, MLVA data are error-prone and can lead to incorrect interpretations of outbreak events.

Seroprevalence trend of human brucellosis and MLVA genotyping characteristics of Brucella melitensis in Shaanxi Province, China, during 2008-2020

In this study, a total of 179,907 blood samples from populations with suspected Brucella spp. infections were collected between 2008 and 2020 and analyzed by the Rose Bengal plate test (RBPT) and serum agglutination test (SAT). Moreover, conventional biotyping, B. abortus-melitensis-ovis-suis polymerase chain reaction (AMOS-PCR), and multiple-locus variable-number tandem repeat analysis (MLVA) was applied to characterize the isolated strains. A total of 8103 (4.50%) samples were positive in RBPT, while 7705 (4.28%, 95% confidence interval (CI) 4.19-4.37) samples were positive in SAT. There was a significant difference in seroprevalence for human brucellosis over time, in different areas and different cities (districts) (χ² = 2 = 32.23, 1984.14, and 3749.51, p < .05). The highest seropositivity (8.22% (4, 965/60393; 95% CI 8.00-8.44) was observed in Yulin City, which borders Inner Mongolia, Ningxia, and Gansu Province, China, regions that have a high incidence of human brucellosis. Moreover, 174 Brucella strains were obtained, including nine with B. melitensis bv. 1, 145 with B. melitensis bv. 3, and 20 with B. melitensis variants. After random selection, 132 B. melitensis were further genotyped using MLVA-16. The 132 strains were sorted into 100 MLVA-16 genotypes (GTs) (GT 1-100), 81 of which were single GTs represented by singular independent strains. The remaining 19 shared GTs involved 51 strains, and each GT included two to seven isolates from the Shaan northern and Guanzhong areas. These data indicated that although sporadic cases were a dominant epidemic characteristic of human brucellosis in this province, more than 38.6% (51/132) outbreaks were also found in the Shaan northern area and Guanzhong areas. The 47 shared MLVA-16 GTs were observed in strains (n = 71) from this study and strains (n = 337) from 19 other provinces of China. These data suggest that strains from the northern provinces are a potential source of human brucellosis cases in Shaanxi Province. It is urgent to strengthen the surveillance and control of the trade and transfer of infected sheep among regions.

Genetic identification of the causative agent of Brucellosis

The development of animal husbandry suffers various kinds of losses due to the spread of infectious diseases among animals, in particular Brucellosis. A challenge faced by Brucella researchers has been the accurate identification of new isolates within the genus while preserving sufficient, and not excessive, biosafety and biosecurity requirements. The availability of discriminatory molecular typing tools to inform and assist conventional epidemiological approaches would be invaluable in controlling these infections, but efforts have been hampered by the genetic homogeneity of the genus. In this work, for better identification of infection, for control and monitor the source of outbreaks in prosperous areas was carried out identification of Brucella spp. strains which circulating in the Kostanay region. For this was used using multilocus analysis of a variable number of tandem repeats sequenced by 16 s – PNK on a genetic analyzer (sequencer). According to the results of a study of cattle, cultures of microorganisms were infected: No. 4, 5, 7, 8. Comparison of the obtained results with similar results of domestic and foreign works by A. Shevtsov, G. Borrello, P. Le Fleche, G. Garofolo suggest that the genotyping of local strains has an importance in the molecular epizootology of the Republic of Kazakhstan.

Trans-species transmission of Brucellae among ruminants hampering brucellosis control efforts in Egypt

AIMS

This study aimed to identify the genotypic fingerprinting of Brucella melitensis biovar 3 isolates from ruminants in Kafr El-Sheikh, Egypt, to compare with other peers globally and to highlight the epidemiology and potential causes of brucellosis control failure.

METHODS AND RESULTS

A multilocus variable-number tandem-repeat analysis (MLVA 16) was carried out on 41 B. melitensis bv3 isolates, 31 from the preferential hosts (28 sheep and three goats) and 10 from atypical hosts (nine cattle and one buffalo), identified by bacteriological and molecular techniques. MLVA-16 analysis revealed 19 genotypes with nine as singletons. The most prevalent genotypes were M3_K.E (3,5,3,13,1,1,3,3,7,43,8,7,6,7,5,3), M13_K.E (3,5,3,13,1,1,3,3,7,43,8,5,8,7,7,3) and M5_K.E (3,5,3,13,1,1,3,3,7,43,8,4,8,7,11,3) circulating between different animal species. The B. melitensis isolation from aborted cows in farms that had never reared small ruminants indicates the likelihood of cow to cow B. melitensis transmission. Different genotypes of B. melitensis could be isolated from the same animal. The local geographic distribution of genotypes showed a very close genetic relatedness with genotypes reported outside the study area. Worldwide, our genotypes were mostly related to the Western Mediterranean lineage and less likely to the America's clonal lineage.

CONCLUSION

There is a high genetic similarity of B. melitensis bv3 genotypes among different ruminant species, and the same animal could be infected with different genotypes. There is a high probability of spreading of B. melitensis among atypical hosts in the absence of the original hosts. The genetic relatedness of B. melitensis bv3 genotypes in the study area with other different geographic areas highlighted the national and international ruminants movement role as a potential factor for maintaining B. melitensis infection.

SIGNIFICANCE AND IMPACT OF THE STUDY

Further investigations are required to understand the impact of the presence of more than one genotype of B. melitensis in the same animal on the efficacy of brucellosis control strategies.

Emerging diversity and ongoing expansion of the genus Brucella

Remarkable genetic diversity and breadth of host species has been uncovered in the Brucella genus over the past decade, fundamentally changing our concept of what it means to be a Brucella. From ocean fishes and marine mammals, to pond dwelling amphibians, forest foxes, desert rodents, and cave-dwelling bats, Brucella have revealed a variety of previously unknown niches. Classical microbiological techniques have been able to help us classify many of these new strains but at times have limited our ability to see the true relationships among or within species. The closest relatives of Brucella are soil bacteria and the adaptations of Brucella spp. to live intracellularly suggest that the genus has evolved to live in vertebrate hosts. Several recently discovered species appear to have phenotypes that are intermediate between soil bacteria and core Brucella, suggesting that they may represent ancestral traits that were subsequently lost in the traditional species. Remarkably, the broad relationships among Brucella species using a variety of sequence and fragment-based approaches have been upheld when using comparative genomics with whole genomes. Nonetheless, genomes are required for fine-scale resolution of many of the relationships and for understanding the evolutionary history of the genus. We expect that the coming decades will reveal many more hosts and previously unknown diversity in a wide range of environments.

Human brucellosis epidemiology in the pastoral area of Hulun Buir city, Inner Mongolia autonomous region, China, between 2003 and 2018

Human brucellosis represents a serious public health concern in Hulun Buir and requires a comprehensive epidemiologic analysis to define adapted control measures. The present study describes the case numbers, constituent ratios and incidence rate of human brucellosis. Conventional biotyping, that is abortus, melitensis, ovis and suis (AMOS)-PCR and multi-locus variable-number tandem repeat analysis (MLVA) were used to characterize the Brucella strains. Between 2003 and 2018, a total of 23,897 human brucellosis cases were reported, with an incidence rate of 56.03/100,000, which is 20 times higher than the country's average incidence. This incidence rate increased year after year, culminating in 2005 and decreased between 2011 and 2018. Because Hulun Buir relies on a nomadic livestock rearing system, brucellosis spreads easily among different animal species and humans. In Xin Barag Left Banner and Xin Barag Right Banner, the incidence rates were, respectively, 226.54/100,000 and 199.10/100,000, exceeding those observed in other areas. Most of the cases occurred in the 25- to 45-year-old group, accounting for 65.74% of the cases (15,709/23,897), and among farmers, accounting for 66.71% (15,942/23,897). The male to female incidence ratio was 2.67:1. The higher incidence in younger people and the large gender ratio reflected the unique traditional production and lifestyle of nomads. Most reported cases were observed from April to June, indicating that more than 40% of the cases were related to the delivery of domestic livestock. The biotyping showed that the 44 isolated strains were all B. melitensis, including 12 Brucella melitensis biovar (bv) 1 and 32 B. melitensis bv. 3. The strains displayed a genetic similarity of 80%-100%. Our hypothesis is that human brucellosis outbreak in this region may be originating from a limited source of infection, so further investigation is necessary. The epidemic situation of human brucellosis in Hulun Buir is extremely serious, strengthened surveillance and control in animals' brucellosis should be priority.

Determination of investigation of the link between human and animal Brucella isolates in Iran using multiple-locus variable number tandem repeat method comprising 16 loci (MLVA-16)

Background

Epidemiological studies are important tools to assess the diversity of Brucella isolates and to estimate their epidemiological relationship among isolates from different geographical origins. In this study the MLVA16 (multiple-locus variable number tandem repeat analysis based on 16 loci) was employed to investigate the diversity of Brucella spp. Isolated from humans and animals for epidemiological purposes and to determine the most common Brucella genotypes in Iran.

Methods

We designed a molecular-based study to evaluate the potential reservoirs of human brucellosis. After isolation and identification of 54 Brucella spp human and animal specimens from three regions of Iran, bacterial genomic DNA was extracted MLVA with three panel was used for the genotyping of isolates. The size of PCR products were analyzed and converted to repeat unit numbers using a published allele numbering system and data set was imported into Bionumerics.

Results

Three isolates (5.55%) were identified as Brucella abortus and 51 (94.44%) as Brucella melitensis. Two isolates of Brucella abortus were from humans and one from an animal. Thirty-four Brucella melitensis isolates were from humans and 17 from animals. Using MLVA16-genotyping, 54 isolates with genetic similarity coefficient of 80% were divided into 46 genotypes and 22 genotypes were represented by a single isolate, while 4, 2, 1 and 2 genotypes were represented by 2, 3, 4 and 7 isolates, respectively. The most prevalent genotype was represented by 14 isolates. There were two other frequent genotypes each represented by seven isolates, among which only one was restricted to a geographic region. Discriminatory power for each locus was determined in this study and panel 2B shows the high discretionary power [Bruce04 (0.837), Bruce30 (0.806), Bruce 09 (0.787), Bruce 07 (0.772), Bruce16 (0.766)].

Conclusion

MLVA16 analysis of 54 Brucella isolates showed high level polymorphism in their genotypes. Only two genotypes, each observed in seven isolates, were related to one another and only one of these genotypes were found in to two separate regions.

Molecular investigation of infection sources and transmission chains of brucellosis in Zhejiang, China

In the present study, a total of 7793 samples from 5 different types of hosts were collected and tested, with a seroprevalence of 2.4% (184/7793). Although the seroprevalence of human and animal brucellosis is relatively low, numbers of human brucellosis cases reported have increased continuously from 2004 to 2018. A total of 118 Brucella strains containing 4 biotypes were obtained, including Brucella melitensis bv.1 (n = 8) and bv.3 (n = 106), Brucella abortus bv.3 (n = 3) and bv.7 (n = 1). Twenty-one shared MLVA-16 genotypes, each composed of 2 to 19 strains obtained from different hosts, suggest the occurrence of a brucellosis outbreak epidemic with multiple source points and laboratory infection events. Moreover, 30 shared MLVA-16 genotypes were observed among 59.6% (68/114) B. melitensis isolates from Zhejiang and strains from other 21 different provinces, especially northern provinces, China. The analysis highlighted the imported nature of the strains from all over the northern provinces with a dominant part from the developed areas of animal husbandry. These data revealed a potential transmission pattern of brucellosis in this region, due to introduced infected sheep leading to a brucellosis outbreak epidemic, and eventually causing multiple laboratory infection events. It is urgent to strengthen the inspection and quarantine of the introduced animals.

Molecular epidemiology of Brucella abortus strains from cattle in Inner Mongolia, China

Although the prevalence of brucellosis in Inner Mongolia Autonomous Region currently remains high, data available on the epidemiological of circulating Brucella abortus strains were limited. A total of 75 isolates obtained from cattle, sheep, and humans were analysed using both the classical method and multiple locus variable-number tandem repeat analysis (MLVA). There are at least three B. abortus biovars (1, 3 and 6) in this region, and B. abortus biovar 3 is the predominant one. Ten known MLVA-11 genotypes were identified, of which five genotypes (72, 75, 78, 82 and 210) were shared among strains from this study and others previously collected in two to seven different nations, suggesting that this population has multiple geographic origins. An MLVA-16 assay sorted the 75 B. abortus strains into two groups (I and II), 5 clusters (A-E) and 44 genotypes (GT1-44), with 26 unique genotypes represented by single isolates, indicating that these B. abortus brucellosis cases were not directly epidemiologically related. The remaining 18 shared genotypes (among a total of 47 isolates) were represented by two to eight isolates, suggesting that there were epidemiologically related pathogens from each shared genotype among the cases. Importantly, the cluster B1 branch including 22 cluster isolates with identical or similar genotypes confirmed the occurrence of a concentrated outbreak epidemic in the eastern region during 1988-1995. This work will contribute to better understanding of B. abortus brucellosis epidemiology in Inner Mongolia.

First identification of a Brucella abortus biovar 4 strain from yak in Tibet, China

Brucellosis is one of the major zoonotic diseases in the world. In China, understanding on its causative agent Brucella is still limited. Recently, we isolated a Brucella strain XZ19-1 from yak in Lhasa, Tibet. Phenotypical characterization proved that it belongs to B. abortus biovar 4, a biotype that has never been reported in China. MLVA-16 genotyping revealed a novel profile (4-5-3-12-2-2-3-3-8-32-8-5-4-3-3-3) in this strain, while MLST sequence typing demonstrated that it belongs to ST 71. Furthermore, the whole genome of XZ19-1 strain was sequenced. Subsequent phylogenetic analysis demonstrated that XZ19-1was genetically more closely related to B. abortus strains originated from European countries rather than to those collected from China previously. Isolation and identification of XZ19-1 strain may thus indicate a unique Brucella lineage existing in Qing-Tibet plateau. These findings will help to improve the diagnosis and epidemiological studies of brucellosis in animals and human in this part of China.

MLVA fingerprinting of Brucella melitensis circulating among livestock and cases of sporadic human illness in Egypt

Brucella melitensis is a serious public health threat, with human infection exhibiting acute febrile illness and chronic health problems. The present study investigated the genetic diversity and epidemiological links of the important zoonotic bacterium B. melitensis in Egypt using multilocus variable-number tandem repeat analysis (MLVA-16) including eight minisatellite (panel 1) and eight microsatellite (panel 2, subdivided into 2A and 2B) markers. A total of 118 isolates were identified as B. melitensis biovar 3 by classical biotyping and Bruce-ladder assay. Although B. melitensis is primarily associated with infection in sheep and goats, most of B. melitensis isolates in this study were obtained from secondary hosts (cattle, buffaloes, humans and a camel) suggesting cross-species adaptation of B. melitensis to large ruminants in Egypt. The MLVA-16 scheme competently discriminated 70 genotypes, with 51 genotypes represented by single isolates, and the remaining 19 genotypes were shared among 67 isolates, suggesting both sporadic and epidemiologically related characteristics of B. melitensis infection. Matching of local genotypes with representatives of global genotypes revealed that the majority of Egyptian isolates analysed had a West Mediterranean descendance. As this study represents the first comprehensive genotyping and genetic analysis of B. melitensis from different sources in Egypt, the information generated from this study will augment knowledge about the main epidemiological links associated with this bacterium and will allow a better understanding of the current epidemiological situation of brucellosis in Egypt. Ultimately, this will help to adopt effective brucellosis intervention strategies in Egypt and other developing nations.

Molecular characterization of Brucella ovis in Argentina

Brucellosis in rams is caused by Brucella ovis or Brucella melitensis and it is considered one of the most important infectious diseases of males in sheep-raising countries. Molecular characterization of Brucella spp. achieved by multi-locus variable number of tandem repeats analysis (MLVA) is a powerful tool to genotype Brucella spp. However, data regarding B. ovis genotyping is scarce. Thus, the aim of this study was to characterize the molecular diversity of B. ovis field-strains in Argentina. A total of 115 isolates of B. ovis from Argentina and Uruguay were genotyped using MLVA-16 and analyzed altogether with 14 publicly available B. ovis genotypes from Brazil. The Discriminatory Power (D) was 0.996 for MLVA-16 and 0.0998 for MLVA-8 and MLVA-11. Analysis of MLVA-16 revealed 100 different genotypes, all of them novel, including 90 unique ones. There was no correlation between geographical distribution and genotype and results showed a higher diversity within provinces than between provinces. Clustering analysis of the strains from Argentina, Uruguay and Brazil revealed that the 129 isolates were grouped into two clades. Whole Genome Sequencing analysis of the 19 B. ovis genomes available in public databases, and including some of the Argentinian strains used in this study, revealed clustering of the Argentinian isolates and closer relationship with B. ovis from New Zealand and Australia. This work adds new data to the poorly understood distribution map of genotypes regionally and worldwide for B. ovis and it constitutes the largest study of B. ovis molecular genotyping until now.

Genetic variation of Brucella isolates at strain level in Egypt

In this study, Multiple Locus Variable Number Tandem Repeat Analysis (MLVA‐16) was performed on 18 Brucella isolates identified bacteriologically and molecularly (AMOS‐PCR) as Brucella abortus (n = 6) and Brucella melitensis (n = 12). This was aimed to study the genetic association among some Egyptian Brucella genotypes isolated during the period from 2002 to 2013 along with the global genotypes database. MLVA‐16 analysis for B. melitensis and B. abortus strains illustrates a total of 11, and 3 genotypes with 10 and 1 singleton genotypes, respectively. B. melitensis strains displayed greater markers diversity by VNTRs analysis of the 16 loci than B. abortus and this was attributed mainly to the diverging in panel 2B markers. B. melitensis genotype M4_Fayoum_Giza (3,5,3,13,1,1,3,3,8,21,8,7,5,9,5,3) was the only predominated genotype circulating between two different governorates. The most common B. abortus genotype, GT A3_Dakahlia (4,5,4,12,2,2,3,3,6,21,8,4,4,3,4,4), was present in three identical isolates. In phylogeny, Egyptian B. abortus bv1 genotypes were closely related to East Asian strain (for the first time), Western Mediterranean and Americas clonal lineages. B. melitensis local genotypes exhibit a genetic relatedness mostly to Western Mediterranean clonal lineage and one strain of Eastern Mediterranean clonal lineage. In conclusion, the geographic location is not the only factor stands behind the high genetic similarity of the Egyptian Brucella genotypes. These low variations may be a result of a stepwise mutational event of the most variable loci from a very limited number of ancestors especially during the transmission through non‐preference hosts. The authors encourage the authorities in charge to establish pre‐movement testing to reduce the risk of brucellosis spread.

Persistence of Brucella abortus lineages revealed by genomic characterization and phylodynamic analysis

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.

Distribution of Brucella field strains isolated from livestock, wildlife populations, and humans in Italy from 2007 to 2015

Brucellosis is a major public health problem still prevalent as a neglected endemic zoonosis requiring proactive attention in many communities worldwide. The present study involved analysis of Brucella field strains submitted for typing to the Italian National Reference Laboratory for Brucellosis from 2007 to 2015. Strains were identified at the species and biovar levels by classic and molecular techniques according to the World Organisation for Animal Health Manual. In total, 5,784 strains were typed: 3,089 Brucella abortus (53.4%), 2,497 B. melitensis (43.2%), 10 B. ovis (0.2%), 181 B. suis (3.1%), and 7 B. ceti (0.1%). The 2,981 strains from cattle were typed as B. abortus biovars 1, 3, and 6 (90.1%) and B. melitensis biovar 3 (9.9%). The 318 strains from water buffalo were typed as B. abortus biovars 1, 3 (95.9%) and B. melitensis biovar 3 (4.1%). The 2,279 strains from sheep and goats were typed as B. abortus biovars 1 and 3 (4.3%); B. melitensis biovars 1, 3, (95.3%); and B. ovis (0.4%). The 173 strains from wild boar were typed as B. suis biovar 2 (98.3%) and B. melitensis biovar 3 (1.7%). The 11 strains from pigs were typed as B. suis biovar 2. The 13 strains from humans were typed as B. melitensis biovar 3. The two strains from horses were typed as B. abortus biovar 1, while the seven strains from dolphins were typed as B. ceti. This additional knowledge on the epidemiology of brucellosis in Italy may be useful to formulate policies and strategies for the control and eradication of the disease in animal populations. The animal species affected, biovars typed, geographical origins, and spatial distributions of isolates are herein analyzed and discussed.

Core Genome Multilocus Sequence Typing and Single Nucleotide Polymorphism Analysis in the Epidemiology of Brucella melitensis Infections

The use of whole-genome sequencing (WGS) using next-generation sequencing (NGS) technology has become a widely accepted method for microbiology laboratories in the application of molecular typing for outbreak tracing and genomic epidemiology. Several studies demonstrated the usefulness of WGS data analysis through single-nucleotide polymorphism (SNP) calling from a reference sequence analysis for Brucella melitensis, whereas gene-by-gene comparison through core-genome multilocus sequence typing (cgMLST) has not been explored so far. The current study developed an allele-based cgMLST method and compared its performance to that of the genome-wide SNP approach and the traditional multilocus variable-number tandem repeat analysis (MLVA) on a defined sample collection. The data set was comprised of 37 epidemiologically linked animal cases of brucellosis as well as 71 isolates with unknown epidemiological status, composed of human and animal samples collected in Italy. The cgMLST scheme generated in this study contained 2,704 targets of the B. melitensis 16M reference genome. We established the potential criteria necessary for inclusion of an isolate into a brucellosis outbreak cluster to be ≤6 loci in the cgMLST and ≤7 in WGS SNP analysis. Higher phylogenetic distance resolution was achieved with cgMLST and SNP analysis than with MLVA, particularly for strains belonging to the same lineage, thereby allowing diverse and unrelated genotypes to be identified with greater confidence. The application of a cgMLST scheme to the characterization of B. melitensis strains provided insights into the epidemiology of this pathogen, and it is a candidate to be a benchmark tool for outbreak investigations in human and animal brucellosis.

Rapid and safe one-step extraction method for the identification of Brucella strains at genus and species level by MALDI-TOF mass spectrometry

Brucellosis is essentially a disease of domesticated livestock; however, humans can also be infected via the consumption of contaminated meat or dairy products, underlying the need for rapid and accurate identification methods. Procedures for microbiological identification and typing of Brucella spp. are expensive, time-consuming, and must be conducted in biohazard containment facilities to minimize operator risk. The development of a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS)-based assay has reduced the processing time while maintaining performance standards. In this study, to improve the identification accuracy and suitability of the MALDI-TOF-based assay for routine diagnosis, we developed a new protein extraction protocol and generated a custom reference database containing Brucella strains representative of the most widespread species. The reference library was then challenged with blind-coded field samples isolated from infected animals. The results indicated that the database could be used to correctly identify 99.5% and 97% of Brucella strains at the genus and species level, respectively, indicating that the performance of the assay was not affected by the different culture conditions used for microbial isolation. Moreover, the inactivated samples were stored and shipped to reference laboratories with no ill effect on protein stability, thus confirming the reliability of our method for routine diagnosis. Finally, we evaluated the epidemiological value of the protocol by comparing the clustering analysis results of Brucella melitensis strains obtained via multiple locus variable-number tandem repeat analysis or MALDI-TOF MS. The results showed that the MALDI-TOF assay could not decipher the true phylogenetic tree, suggesting that the protein profile did not correspond with the genetic evolution of Brucella.

Typing and comparative genome analysis of Brucella melitensis isolated from Lebanon

Brucella melitensis is the main causative agent of the zoonotic disease brucellosis. This study aimed at typing and characterizing genetic variation in 33 Brucella isolates recovered from patients in Lebanon. Bruce-ladder multiplex PCR and PCR-RFLP of omp31, omp2a and omp2b were performed. Sixteen representative isolates were chosen for draft-genome sequencing and analyzed to determine variations in virulence, resistance, genomic islands, prophages and insertion sequences. Comparative whole-genome single nucleotide polymorphism analysis was also performed. The isolates were confirmed to be B. melitensis. Genome analysis revealed multiple virulence determinants and efflux pumps. Genome comparisons and single nucleotide polymorphisms divided the isolates based on geographical distribution but revealed high levels of similarity between the strains. Sequence divergence in B. melitensis was mainly due to lateral gene transfer of mobile elements. This is the first report of an in-depth genomic characterization of B. melitensis in Lebanon.

African Lineage Brucella melitensis Isolates from Omani Livestock

Brucellosis is a common livestock disease in the Middle East and North Africa, but remains poorly described in the region both genetically and epidemiologically. Traditionally found in goats and sheep, Brucella melitensis is increasingly recognized as infecting camels. Most studies of brucellosis in camels to date have focused on serological surveys, providing only limited understanding of the molecular epidemiology of circulating strains. We genotyped B. melitensis isolates from Omani camels using whole genome SNP assays and VNTRs to provide context for regional brucellosis cases. We identified a lineage of B. melitensis circulating in camels as well as in goats, sheep, and cattle in Oman. This lineage is genetically distinct from most genotypes from the Arabian Peninsula and from isolates from much of the rest of the Middle East. We then developed diagnostic assays that rapidly identify strains from this lineage. In analyses of genotypes from throughout the region, Omani isolates were genetically most closely related to strains from brucellosis cases in humans and livestock in North Africa. Our findings suggest an African origin for B. melitensis in Oman that has likely occurred through the trade of infected livestock. Moreover, African lineages of B. melitensis appear to be undersampled and consequently are underrepresented in genetic databases for Brucella. As we begin to more fully understand global genomic diversity of B. melitensis, finding and characterizing these unique but widespread lineages is essential. We predict that increased sampling of humans and livestock in Africa will reveal little known diversity in this important zoonotic pathogen.

Genotyping of Brucella melitensis and Brucella abortus strains in Kazakhstan using MLVA-15

Currently, although the prevalence of brucellosis in Kazakhstan remains high, there are limited data available on the genetic diversity of circulating Brucella strains. Here, MLVA was employed to genotype a panel of 102 Brucella isolates collected from eight Kazakh regions and neighboring countries (Russia, Kyrgyzstan) during the period 1935-2017. MLVA-11 analysis classified 64 B. abortus strains into genotypes 72, 82, 331, 71, 341 and 69, while one genotype was novel, having no correspondence within the MLVA international database. MLVA-11 analysis of 37 B. melitensis strains showed 100% identity with genotypes 116, 114 and 11. One B. suis strain was classified into genotype 33. Phylogeography based on MLVA-15 demonstrated that all B. abortus and B. melitensis strains belonged to "Abortus C" and "East Mediterranean" lineages, respectively. B. abortus strains from Kazakhstan and Russia resulted genetically related to Portuguese, Brazilian and US isolates, suggesting ancient spread of these lineages from Europe westwards to South America and eastwards to Turkey, Russia and Asia. Most of Kazakh B. melitensis isolates were related to strains circulating in China, likely due to long-term trading partnerships between the two countries. In fine-scale MLVA-15 analysis, 17 B. abortus and 12 B. melitensis genotypes were identified; among them 12 are novel. Interestingly, epidemiological information supporting molecular data were retrieved for two clusters within the B. abortus group, thus proving that MLVA is an appropriate tool for effective traceback analyses. Our findings suggest that molecular genotyping should be applied systematically to support control plans for eradication of brucellosis in Kazakhstan.

Multi-locus variable-number tandem repeat analysis of Chinese Brucella strains isolated from 1953 to 2013

BACKGROUND

Brucellosis was a common human and livestock disease caused by Brucella strains, the category B priority pathogens by the US Center for Disease Control (CDC). Identified as a priority disease in human and livestock populations, the increasing incidence in recent years in China needs urgent control measures for this disease but the molecular background important for monitoring the epidemiology of Brucella strains at the national level is still lacking.

METHODS

A total of 600 Brucella isolates collected during 60 years (from 1953 to 2013) in China were genotyped by multiple locus variable-number tandem repeat analysis (MLVA) and the variation degree of MLVA11 loci was calculated by the Hunter Gaston Diversity Index (HGDI) values. The charts and map were processed by Excel 2013, and cluster analysis and epidemiological distribution was performed using BioNumerics (version 5.1).

RESULTS

The 600 representative Brucella isolates fell into 104 genotypes with 58 singleton genotypes by the MLVA11 assay, including B. melitensis biovars 2 and 3 (five main genotypes), B. abortus biovars 1 and 3 (two main genotypes), B. suis biovars 1 and 3 (three main genotypes), and B. canis (two main genotypes) respectively. While most B. suis biovar 1 and biovar 3 were respectively found in northern provinces and southern provinces, B. melitensis and B. abortus strains were dominant in China. Canine Brucellosis was only found in animals without any human cases reported. Eight Brucellosis epidemic peaks emerged during the 60 years between 1953 and 2013: 1955 - 1959, 1962 - 1969, 1971 - 1975, 1977 - 1983, 1985 - 1989, 1992 - 1997, 2000 - 2008 and 2010 - 2013 in China.

CONCLUSIONS

Brucellosis has its unique molecular epidemiological patterns with specific spatial and temporal distribution according to MLVA.

TRIAL REGISTRATION

IDOP-D-16-00101.

Whole genome sequencing of Brucella melitensis isolated from 57 patients in Germany reveals high diversity in strains from Middle East

Brucellosis, a worldwide common bacterial zoonotic disease, has become quite rare in Northern and Western Europe. However, since 2014 a significant increase of imported infections caused by Brucella (B.) melitensis has been noticed in Germany. Patients predominantly originated from Middle East including Turkey and Syria. These circumstances afforded an opportunity to gain insights into the population structure of Brucella strains. Brucella-isolates from 57 patients were recovered between January 2014 and June 2016 with culture confirmed brucellosis by the National Consultant Laboratory for Brucella. Their whole genome sequences were generated using the Illumina MiSeq platform. A whole genome-based SNP typing assay was developed in order to resolve geographically attributed genetic clusters. Results were compared to MLVA typing results, the current gold-standard of Brucella typing. In addition, sequences were examined for possible genetic variation within target regions of molecular diagnostic assays. Phylogenetic analyses revealed spatial clustering and distinguished strains from different patients in either case, whereas multiple isolates from a single patient or technical replicates showed identical SNP and MLVA profiles. By including WGS data from the NCBI database, five major genotypes were identified. Notably, strains originating from Turkey showed a high diversity and grouped into seven subclusters of genotype II. MLVA analysis congruently clustered all isolates and predominantly matched the East Mediterranean genetic clade. This study confirms whole-genome based SNP-analysis as a powerful tool for accurate typing of B. melitensis. Furthermore it allows special allocation and therefore provides useful information on the geographic origin for trace-back analysis. However, the lack of reliable metadata in public databases often prevents a resolution below geographic regions or country levels and corresponding precise trace-back analysis. Once this obstacle is resolved, WGS-derived bacterial typing adds an important method to complement epidemiological surveys during outbreak investigations. This is the first report of a detailed genetic investigation of an extensive collection of B. melitensis strains isolated from human cases in Germany.

Brucellosis in a refugee who migrated from Syria to Germany and lessons learnt, 2016

A teenage woman migrating from Syria arrived in May 2015 in Germany. She gave birth to a healthy child in early 2016, but became febrile shortly after delivery. Blood cultures revealed Brucella melitensis. In retrospect, she reported contact with sheep in Syria and recurrent pain in the hip joints over about five months before diagnosis of brucellosis. We discuss consequences for adequate treatment of mother and child as well as for clinical and laboratory management.

Origins and global context of Brucella abortus in Italy

Background

Brucellosis is a common and chronic disease of cattle and other bovids that often causes reproductive disorders. Natural infection in cattle is caused by Brucella abortus and transmission typically occurs during abortions, calving, or nursing. Brucellosis is also a major zoonotic disease due to contamination of dairy products or contact with the tissues of infected animals. Brucellosis has been eradicated from most of the developed world in the last 40 years but persists in many regions—the disease remains prevalent in portions of Africa, the Middle East, Asia, and Central and South America, as well as in the Mediterranean basin. In Italy, B. abortus has persisted in southern regions in both cattle and water buffalo. Previous attempts at analyzing the phylogenetics of B. abortus in Italy have been challenging due to limited genetic variability and unresolved global population genetic structure of this pathogen.

Results

We conducted genome-wide phylogenetic analyses on 11 representative strains of B. abortus from Italy, and compared these sequences to a worldwide collection of publically available genomes. Italian isolates belong to three clades that are basal to the main and global B. abortus lineage. Using six SNP-based assays designed to identify substructure within the Italian clades, we surveyed a collection of 261 isolates and found that one clade predominates throughout endemic districts in the country, while the other two clades are more geographically restricted to portions of southern Italy.

Conclusions

Although related strains exist worldwide, B. abortus isolates from Italy are substantially different than those found in much of the rest of Europe and North America, and are more closely related to strains from the Middle East and Asia. Our assays targeting genetic substructure within Italy allowed us to identify the major lineages quickly and inexpensively, without having to generate whole genome sequences for a large isolate collection. These findings highlight the importance of genetic studies to assess the status and the history of pathogens.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-017-0939-0) contains supplementary material, which is available to authorized users.

Molecular epidemiology of Brucella abortus isolated from cattle in Brazil, 2009-2013

The aims of the present study were to genotype Brucella abortus strains isolated from cattle in Brazil between 2009 and 2013, and to analyze their distribution to support the Programa Nacional de Controle e Erradicação de Brucelose e Tuberculose (PNCEBT) (National Brucellosis and Tuberculosis Control and Eradication Program). One hundred forty B. abortus strains isolated from cattle in Brazil between 2009 and 2013 were genotyped using a set of 18 variable number of tandem repeats (VNTR) (MLVA16+HOOF-Print 3 and 4). The multiple locus VNTR analysis (MLVA) composed by eight markers (MLVA8) revealed eight different genotypes among B. abortus strains, including five previously described and three new ones. Analysis of the MLVA16 loci revealed fifty-eight distinct genotypes, from which three were identical, thirty-eight were considered very close, and seventeen were considered distant compared to those previously described and deposited in MLVAbank. Analysis of the HOOF-Prints 3 and 4 revealed the larger number of different alleles among all VNTR assessed, exhibiting maximum resolution when associated with MLVA16 markers. This study also provides insights on the genotypes of B. abortus circulating in Brazil, which certainly contribute for the better understanding of the epidemiology and control of bovine brucellosis in the country. Moreover, our data showed a high genetic diversity among the B. abortus strains isolated between 2009 and 2013, and a close relationship among these strains and Brazilian B. abortus deposited by MLVAbank.

MLVA Genotyping Characteristics of Human Brucella melitensis Isolated from Ulanqab of Inner Mongolia, China

Brucellosis is a serious public health problem in Ulanqab, which is a region located in the middle of the Inner Mongolia Autonomous Region adjacent to Shanxi and Hebei provinces. The disease is prevalent in both the latter provinces and Ulanqab with the highest prevalence of brucellosis occurring in Inner Mongolia. The MLVA-16 scheme is a genotyping tool for assessing genetic diversity and relationships among isolates. Moreover, this genotyping tool can also be applied to epidemiological trace-back investigations. This study reports the occurrence of at least two B. melitensis biovars (1 and 3) in Ulanqab, encompassing 22 and 94 isolates, respectively. B. melitensis biovar 3 was the predominant biovar in the area examined. Panel 1 (MLVA-8) identified three genotypes (42, 63, and 114), with genotype 42 (n = 101) representing 87% of the tested strains. MLVA-11 identified eight genotypes (116, 111, 297, 291, and 342-345) from 116 of the analyzed isolates. All of these isolates were identified as belonging to the East Mediterranean group. Genotype 116 (n = 94) was the predominant genotype and represented 81% of the isolates. The isolates pertaining to this genotype were distributed throughout most of Ulanqab and neighboring regions. The MLVA-16 scheme showed the presence of 69 genotypes, with 46 genotypes being represented by single isolates. This analysis revealed that Ulanqab brucellosis cases had epidemiologically unrelated and sporadic characteristics. The remaining 23 genotypes were shared (between a total of 70 isolates) with each genotype being represented by two to eight isolates. These data indicate that these cases were epidemiologically related. MLVA genotyping confirmed the occurrence of a multipoint outbreak epidemic and intrafamilial brucellosis. Extensive genotype-sharing events were observed among isolates from different regions of Ulanqab and from other provinces of China. These findings suggest either a lack of control of animal movement between different regions or the circulation of contaminated animal products in the market. Our study is the first comprehensive genotyping and genetic analysis of B. melitensis in Ulanqab. We believe that this study will help to improve the effectiveness of brucellosis control programs.

Epidemiology of Brucellosis and Genetic Diversity of Brucella abortus in Kazakhstan

Brucellosis is a major zoonotic infection in Kazakhstan. However, there is limited data on its incidence in humans and animals, and the genetic diversity of prevalent strains is virtually unstudied. Additionally, there is no detailed overview of Kazakhstan brucellosis control and eradication programs. Here, we analyzed brucellosis epidemiological data, and assessed the effectiveness of eradication strategies employed over the past 70 years to counteract this infection. We also conducted multiple loci variable-number tandem repeat analysis (MLVA) of Brucella abortus strains found in Kazakhstan. We analyzed official data on the incidence of animal brucellosis in Kazakhstan. The records span more than 70 years of anti-brucellosis campaigns, and contain a brief description of the applied control strategies, their effectiveness, and their impact on the incidence in humans. The MLVA-16 method was used to type 94 strains of B. abortus and serial passages of B. abortus 82, a strain used in vaccines. MLVA-8 and MLVA-11 analyses clustered strains into a total of four and seven genotypes, respectively; it is the first time that four of these genotypes have been described. MLVA-16 analysis divided strains into 28 distinct genotypes having genetic similarity coefficient that varies from 60 to100% and a Hunter & Gaston diversity index of 0.871. MST analysis reconstruction revealed clustering into "Kazakhstani-Chinese (Central Asian)", "European" and "American" lines. Detection of multiple genotypes in a single outbreak confirms that poorly controlled trade of livestock plays a crucial role in the spread of infection. Notably, the MLVA-16 profile of the B. abortus 82 strain was unique and did not change during 33 serial passages. MLVA genotyping may thus be useful for epidemiological monitoring of brucellosis, and for tracking the source(s) of infection. We suggest that countrywide application of MLVA genotyping would improve the control of brucellosis in Kazakhstan.

Cases of human brucellosis in Sweden linked to Middle East and Africa

BACKGROUND

Human brucellosis cases are still reported each year in Sweden despite eradication of the disease in animals. Epidemiological investigation has never been conducted to trace back the source of human infection in the country. The purpose of the study was to identify the source of infection for 16 human brucellosis cases that occurred in Sweden, during the period 2008-2012.

RESULTS

The isolates were identified as Brucella melitensis and MLVA-16 genotyping revealed 14 different genotypes of East Mediterranean and Africa lineages. We also reported one case of laboratory-acquired brucellosis (LAB) that was shown to be epidemiological linked to one of the cases in the current study.

CONCLUSIONS

Brucella melitensis was the only species diagnosed, confirming its highest zoonotic potential in the genus Brucella, and MLVA-16 results demonstrated that the cases of brucellosis in Sweden herein investigated, are imported and linked to travel in the Middle East and Africa. Due to its zoonotic concerns, any acute febrile illness linked to recent travel within those regions should be investigated for brucellosis and samples should be processed according to biosafety level 3 regulations.

Genome Sequences of 11 Brucella abortus Isolates from Persistently Infected Italian Regions

Bovine brucellosis, typically caused by Brucella abortus, has been eradicated from much of the developed world. However, the disease remains prevalent in southern Italy, persisting as a public and livestock health concern. We report here the whole-genome sequences of 11 isolates from cattle (Bos taurus) and water buffalo (Bubalus bubalis) that are representative of the current genetic diversity of B. abortus lineages circulating in Italy.

Molecular Epidemiology of Brucella abortus in Northern Ireland-1991 to 2012

Background

Brucellosis is the most common bacterial zoonoses worldwide. Bovine brucellosis caused by Brucella abortus has far reaching animal health and economic impacts at both the local and national levels. Alongside traditional veterinary epidemiology, the use of molecular typing has recently been applied to inform on bacterial population structure and identify epidemiologically-linked cases of infection. Multi-locus variable number tandem repeat VNTR analysis (MLVA) was used to investigate the molecular epidemiology of a well-characterised Brucella abortus epidemic in Northern Ireland involving 387 herds between 1991 and 2012.

Results

MLVA identified 98 unique B. abortus genotypes from disclosing isolates in the 387 herds involved in the epidemic. Clustering algorithms revealed the relatedness of many of these genotypes. Combined with epidemiological information on chronology of infection and geographic location, these genotype data helped to identify 7 clonal complexes which underpinned the outbreak over the defined period. Hyper-variability of some VNTR loci both within herds and individual animals led to detection of multiple genotypes associated with single outbreaks. However with dense sampling, these genotypes could still be associated with specific clonal complexes thereby permitting inference of epidemiological links. MLVA- based epidemiological monitoring data were congruent with an independent classical veterinary epidemiology study carried out in the same territory.

Conclusions

MLVA is a useful tool in ongoing disease surveillance of B. abortus outbreaks, especially when combined with accurate epidemiological information on disease tracings, geographical clustering of cases and chronology of infection.

MLVA as an Epidemiological Tool To Trace Back Brucella melitensis Biovar 1 Re-Emergence in Italy

Brucellosis is an important zoonosis caused by Brucella spp., still prevalent in most areas of the world. Brucellosis control in animals is the key to protect humans. The knowledge of Brucella spp. prevailing genotypes in a territory represents an important epidemiological tool to formulate policies and strategies for disease control and to trace back the introduction of new strains previously considered as exotic. In the last years, multiple-locus variable number tandem repeat analysis (MLVA) has been proposed as complementary to classical biotyping methods. MLVA may add important information to the classical epidemiological investigation techniques, to help in tracing back sources of infection in brucellosis outbreaks. Sardinia is an Italian region officially free from sheep and goats brucellosis since 1998. In 2011, Brucella melitensis biovar 1, a biotype not reported in Italy since 1995, was isolated in one flock in the region. The genotyping MLVA-16 showed that isolates belonged to a rare American lineage, confirming it was introduced from other countries. The strain was considered as probably originating from Spain, where this lineage is endemic. BrucellaMLVA-16 has been proved to be useful to analyse the epidemiological correlation of strains enabling to trace its geographic origin by comparing their previously reported genetic patterns.

Genetic diversity of Brucella abortus and Brucella melitensis in Kazakhstan using MLVA-16

Brucellosis is an endemic disease in Central Asia characterized by high infection rates in humans and animals. Currently, little is known about the genetic diversity of Brucella spp. circulating in the region, despite the high prevalence of brucellosis. This study aimed to analyze the genetic diversity of Brucella melitensis and Brucella abortus strains circulating in the Republic of Kazakhstan. We genotyped 128 B. melitensis and 124 B. abortus strains collected in regions with the highest prevalence of brucellosis. Genotyping was performed using multi-locus variable-number tandem-repeat analysis (MLVA). Analysis of a subset of 8 loci (MLVA-8) of 128 B. melitensis strains identified genotypes 42 (n=108), 43 (n=2), and 63 (n=19) related to the 'East Mediterranean' group. An MLVA-16 assay sorted 128 B. melitensis strains into 25 different genotypes. Excluding one variable locus, MLVA-15 of B. melitensis was distinct from strains originating in the Mediterranean region; however, 77% of them were identical to strains isolated in China. A minimum spanning tree for B. melitensis using MLVA-15 analysis clustered the local strains together with strains previously collected in China. MLVA-8 analysis of 124 B. abortus strains identified them as genotype 36, suggesting Eurasian distribution of this lineage. Complete MLVA-16 assay analysis clustered the strains into five genotypes, revealing little diversity of B. abortus when compared on the global scale. A minimum spanning tree for B. abortus obtained using MLVA-15 analysis clustered the 2 most prevalent genotypes (n=117) together with strains previously collected in China. Thus, MLVA analysis was used to characterize 252 strains of Brucella collected in Kazakhstan. The analysis revealed genetic homogeneity among the strains. Interestingly, identical MLVA-15 profiles were found in seemingly unrelated outbreaks in China, Turkey, and Kazakhstan. Further analysis is needed for better understanding of the epidemiology of brucellosis in Asia.

Multiple-locus variable-number tandem-repeat analysis (MLVA) genotyping of human Brucella isolates in Malaysia

Background

Brucellosis is one of the most common zoonotic diseases worldwide. It can cause acute febrile illness in human and is a major health problem. Studies in human brucellosis in Malaysia is limited and so far no genotyping studies has been done on Brucella isolates. The aim of the study was to determine the genetic diversity among Brucella species isolated from human brucellosis, obtained over a 6-year period (2009–2014).

Methods

In this study, the genotypic characteristics of 43 human Brucella melitensis isolates were analysed using multiple-locus variable-number tandem-repeat analysis (MLVA) which consisted of eight minisatellite loci (panel 1) and eight microsatellite loci; panels 2A (3 microsatellite loci) and panel 2B (5 microsatellite loci). Two human Brucella suis isolates were also investigated using the MLVA assay.

Results

Using panel 1 (MLVA8), two genotypes namely genotype 43 and 44 were obtained from the 43 B. melitensis isolates. Using the combination of panels 1 and 2A loci (MLVA11), two genotypes were obtained while using the complete panels 1, 2A and 2B, nine genotypes were obtained. The polymorphisms in using the complete panels (MLVA16) were observed in three loci from panel 2B, which showed a diversity index higher than 0.17. All B. melitensis isolates were closely related to the East Mediterranean group. For B. suis isolates, only genotype 6 and genotype 33 were obtained using panel 1 and MLVA11 respectively.

Conclusion

In conclusion, the results of the present study showed a low genetic diversity among B. melitensis and B. suis isolates from human patients. Based on the MLVA16 assay, B. melitensis belonging to the East Mediterranean group is responsible for the vast majority of Brucella infections in our Malaysian patients. To our knowledge, this is the first genotyping study of human Brucella isolates in Malaysia.

Genotyping of human Brucella melitensis biovar 3 isolated from Shanxi Province in China by MLVA16 and HOOF

Background

Brucellosis presents a significant economic burden for China because it causes reproductive failure in host species and chronic health problems in humans. These problems can involve multiple organs. Brucellosis is highly endemic in Shanxi Province China. Molecular typing would be very useful to epidemiological surveillance. The purpose of this study was to assess the diversity of Brucella melitensis strains for epidemiological surveillance. Historical monitoring data suggest that Brucella melitensis biovar 3 is the predominant strain associated with the epidemic of brucellosis in Shanxi Province.

Methods/Principal Findings

Multiple-locus variable-number repeat analysis (MLVA-16) and hypervariable octameric oligonucleotide fingerprinting (HOOF-print) were used to type a human-hosted Brucella melitensis population (81 strains). Sixty-two MLVA genotypes (discriminatory index: 0.99) were detected, and they had a genetic similarity coefficient ranging from 84.9% to 100%. Eighty strains of the population belonged to the eastern Mediterranean group with panel 1 genotypes 42 (79 strains) and 43 (1 strain). A new panel 1 genotype was found in this study. It was named 114 MLVAorsay genotype and it showed similarity to the two isolates from Guangdong in a previous study. Brucella melitensis is distributed throughout Shanxi Province, and like samples from Inner Mongolia, the eastern Mediterranean genotype 42 was the main epidemic strain (97%). The HOOF-printing showed a higher diversity than MLVA-16 with a genetic similarity coefficient ranging from 56.8% to 100%.

Conclusions

According to the MLVA-16 and HOOF-printing results, both methods could be used for the epidemiological surveillance of brucellosis. A new genotype was found in both Shanxi and Guangdong Provinces. In areas with brucellosis, the MLVA-16 scheme is very important for tracing cases back to their origins during outbreak investigations. It may facilitate the expansion and eradication of the disease.

Multiple-locus variable-number tandem repeat (VNTR) analysis (MLVA) using multiplex PCR and multicolor capillary electrophoresis: application to the genotyping of Brucella species

The multiple-locus variable-number tandem repeat (VNTR) analysis (MLVA) is a genetic typing method based on the evaluation of the number of repeated sequences in multiple selected loci of microbial DNA. Although several MLVA typing panels have been proposed for brucellae, the 16-loci panel is recognized as the standard genotyping method, also used for the Brucella international online database. This chapter describes a high-throughput MLVA-16 protocol using multiplex PCRs and multicolor capillary electrophoresis.

Human brucellosis in Maghreb: existence of a lineage related to socio-historical connections with Europe

Despite control/eradication programs, brucellosis, major worldwide zoonosis due to the Brucella genus, is endemic in Northern Africa and remains a major public health problem in the Maghreb region (Algeria/Morocco/Tunisia). Brucella melitensis biovar 3 is mostly involved in human infections and infects mainly small ruminants. Human and animal brucellosis occurrence in the Maghreb seems still underestimated and its epidemiological situation remains hazy. This study summarizes official data, regarding Brucella melitensis infections in Algeria, from 1989 to 2012, with the purpose to provide appropriate insights concerning the epidemiological situation of human and small ruminant brucellosis in Maghreb. Algeria and Europe are closely linked for historical and economical reasons. These historical connections raise the question of their possible impact on the genetic variability of Brucella strains circulating in the Maghreb. Other purpose of this study was to assess the genetic diversity among Maghreb B. melitensis biovar 3 strains, and to investigate their possible epidemiological relationship with European strains, especially with French strains. A total of 90 B. melitensis biovar 3 Maghreb strains isolated over a 25 year-period (1989-2014), mainly from humans, were analysed by MLVA-16. The obtained results were compared with genotypes of European B. melitensis biovar 3 strains. Molecular assays showed that Algerian strains were mainly distributed into two distinct clusters, one Algerian cluster related to European sub-cluster. These results led to suggest the existence of a lineage resulting from socio-historical connections between Algeria and Europe that might have evolved distinctly from the Maghreb autochthonous group. This study provides insights regarding the epidemiological situation of human brucellosis in the Maghreb and is the first molecular investigation regarding B. melitensis biovar 3 strains circulating in the Maghreb.

Retrospective and prospective perspectives on zoonotic brucellosis

Members of the genus Brucella are pathogenic bacteria exceedingly well adapted to their hosts. The bacterium is transmitted by direct contact within the same host species or accidentally to secondary hosts, such as humans. Human brucellosis is strongly linked to the management of domesticated animals and ingestion of their products. Since the domestication of ungulates and dogs in the Fertile Crescent and Asia in 12000 and 33000 ya, respectively, a steady supply of well adapted emergent Brucella pathogens causing zoonotic disease has been provided. Likewise, anthropogenic modification of wild life may have also impacted host susceptibility and Brucella selection. Domestication and human influence on wild life animals are not neutral phenomena. Consequently, Brucella organisms have followed their hosts’ fate and have been selected under conditions that favor high transmission rate. The “arm race” between Brucella and their preferred hosts has been driven by genetic adaptation of the bacterium confronted with the evolving immune defenses of the host. Management conditions, such as clustering, selection, culling, and vaccination of Brucella preferred hosts have profound influences in the outcome of brucellosis and in the selection of Brucella organisms. Countries that have controlled brucellosis systematically used reliable smooth live vaccines, consistent immunization protocols, adequate diagnostic tests, broad vaccination coverage and sustained removal of the infected animals. To ignore and misuse tools and strategies already available for the control of brucellosis may promote the emergence of new Brucella variants. The unrestricted use of low-efficacy vaccines may promote a “false sense of security” and works towards selection of Brucella with higher virulence and transmission potential.