Whole-Genome Sequencing of a Brucella melitensis Strain (BMWS93) Isolated from a Bank Clerk and Exhibiting Complete Resistance to Rifampin

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.

Seroprevalence and Molecular Characterization of Brucella abortus from the Himalayan Marmot in Qinghai, China

Objective

Brucellosis is a serious public health issue in Qinghai (QH), China. Surveying the seroprevalence and isolation of B. abortus strains from marmots is key to understanding the role of wildlife in the maintenance and spread of brucellosis.

Methods

In this study, a set of methods, including a serology survey, bacteriology, antibiotic susceptibility, molecular genotyping (MLST and MLVA), and genome sequencing, were employed to characterize the two B. abortus strains.

Results

The seroprevalence of brucellosis in marmots was 7.0% (80/1146) by serum tube agglutination test (SAT); one Brucella strain was recovered from these positive samples, and another Brucella strain from a human. Two strains were identified as B. abortus bv. 1 and were susceptible to all eight drugs examined. The distribution patterns of the accessory genes, virulence associated genes, and resistance genes of the two strains were consistent, and there was excellent collinearity between the two strains on chromosome I, but they had significant SVs in chromosome II, including inversions and translocations. MLST genotyping identified two B. abortus strains as ST2, and MLVA-16 analysis showed that the two strains clustered with strains from northern China. WGS-SNP phylogenetic analysis showed that the strains were genetically homogeneous with strains from the northern region, implying that strains from a common lineage were spread continuously in different regions and hosts.

Conclusion

Seroprevalence and molecular clues demonstrated frequent direct or indirect contact between sheep/goats, cattle, and marmots, implying that wildlife plays a vital role in the maintenance and spread of B. abortus in the Qinghai-Tibet Plateau.

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.

Determination of Virulence-Associated Genes and Antimicrobial Resistance Profiles in Brucella Isolates Recovered from Humans and Animals in Iran Using NGS Technology

Brucellosis is a common zoonotic disease in Iran. Antimicrobial-resistant (AMR) Brucella isolates have been reported from different developing countries, posing an imminent health hazard. The objective of this study was to evaluate AMR and virulence-associated factors in Brucella isolates recovered from humans and animals in different regions of Iran using classical phenotyping and next generation sequencing (NGS) technology. Our findings revealed that B. melitensis is the most common species in bovines, small ruminants and camels. B. abortus was isolated only from one human case. Probable intermediate or resistant phenotype patterns for rifampicin, trimethoprim-sulfamethoxazole, ampicillin-sulbactam and colistin were found. Whole genome sequencing (WGS) identified mprF, bepG, bepF, bepC, bepE, and bepD in all isolates but failed to determine other classical AMR genes. Forty-three genes associated with five virulence factors were identified in the genomes of all Brucella isolates, and no difference in the distribution of virulence-associated genes was found. Of them, 27 genes were associated with lipopolysaccharide (LPS), 12 genes were related to a type IV secretion system (virB1-B12), two were associated with the toll-interleukin-1 receptor (TIR) domain-containing proteins (btpA, btpB), one gene encoded the Rab2 interacting conserved protein A (ricA) and one was associated with the production of cyclic β-1,2 glucans (cgs). This is the first investigation reporting the molecular-based AMR and virulence factors in brucellae isolated from different animal hosts and humans in Iran. Iranian B. abortus and B. melitensis isolates are still in vitro susceptible to the majority of antibiotics used for the treatment of human brucellosis. WGS failed to determine classical AMR genes and no difference was found in the distribution of virulence-associated genes in all isolates. Still, the absence of classical AMR genes in genomes of resistant strains is puzzling, and investigation of phenotypic resistance mechanisms at the proteomic and transcriptomic levels is needed.

Molecular characterization and antimicrobial susceptibility testing of clinical and non-clinical Brucella melitensis and Brucella abortus isolates from Egypt

Brucellosis is a highly contagious and incapacitating disease of humans, livestock and wildlife species globally. Treatment of brucellosis in animals is not recommended, and in humans, combinations of antibiotics recommended by the World Health Organization are used. However, sporadic antimicrobial-resistant (AMR) isolates and relapse cases have been reported from different endemic regions. In the current study, molecular characterization and antibiotic susceptibility testing using the microdilution method for 35 B. abortus and B. melitensis strains isolated from humans, milk and animal were carried out. Additionally, Next-Generation-Sequencing (NGS) technology was applied to confirm Brucella at the species level and investigate AMR and pathogenicity-associated determinants. MALDI-TOF seemed to be a rapid and reliable tool for routine identification of brucellae to the genus level; however, DNA-based identification is indispensable for accurate species identification. Brucella abortus strains were isolated from two human cases and a sheep. Such infections are uncommon in Egypt. Egyptian Brucella strains are still in-vitro susceptible to doxycycline, tetracyclines, gentamicin, ciprofloxacin, levofloxacin, chloramphenicol, streptomycin, trimethoprim/sulfamethoxazole and tigecycline. Probable (no CLSI/EUCAST breakpoints have been defined yet) in-vitro resistance to rifampicin and azithromycin was observed. WGS failed to determine classical AMR genes, and no difference in the distribution of virulence-associated genes in all isolates was found. Isolates of human and non-human origins were still susceptible to the majority of antibiotics used for treatment in humans. The absence of classical AMR genes in genomes of "resistant" Brucella strains may reflect a lack of information in databases, or resistance might not be encoded by single resistance genes. The One Health approach is necessary for tackling brucellosis. Continuous susceptibility testing, updating of breakpoints, assessing mutations that lead to resistance are needed.

Whole Genome Sequence Analysis of Brucella melitensis Phylogeny and Virulence Factors

Brucellosis has a wide range of clinical severity in humans that remains poorly understood. Whole genome sequencing (WGS) analysis may be able to detect variation in virulence genes. We used Brucella melitensis sequences in the NCBI Sequence Read Archive (SRA) database to assemble 248 whole genomes, and additionally, assembled 27 B. melitensis genomes from samples of human patients in Southern Israel. We searched the 275 assembled genomes for the 43 B. melitensis virulence genes in the Virulence Factors of Pathogenic Bacteria Database (VFDB) and 10 other published putative virulence genes. We explored pan-genome variation across the genomes and in a pilot analysis, explored single nucleotide polymorphism (SNP) variation among the ten putative virulence genes. More than 99% of the genomes had sequences for all Brucella melitensis virulence genes included in the VFDB. The 10 other virulence genes of interest were present across all the genomes, but three of these genes had SNP variation associated with particular Brucella melitensis genotypes. SNP variation was also seen within the Israeli genomes obtained from a small geographic region. While the Brucella genome is highly conserved, this novel and large whole genome study of Brucella demonstrates the ability of whole genome and pan-genome analysis to screen multiple genomes and identify SNP variation in both known and novel virulence genes that could be associated with differential disease virulence. Further development of whole genome techniques and linkage with clinical metadata on disease outcomes could shed light on whether such variation in the Brucella genome plays a role in pathogenesis.

Whole-Genome Sequence of a Strain of Brucella melitensis Isolated from a Patient with Swelling of the Right Testicle in Inner Mongolia, China

This report describes the isolation, sequencing, and annotation of Ws20160810, which was isolated from a blood sample from a brucellosis patient suffering from swelling of the right testicle in the Inner Mongolia Autonomous Region, China. The genome size was 3,244,234 bp with a 57.23% GC content, 3,294 coding DNA sequences (CDSs), 55 tRNAs, 5 rRNAs (5S [n = 2], 16S [n = 1], and 23S [n = 2]), and 3 small RNAs (sRNAs).

This report describes the isolation, sequencing, and annotation of Ws20160810, which was isolated from a blood sample from a brucellosis patient suffering from swelling of the right testicle in the Inner Mongolia Autonomous Region, China. The genome size was 3,244,234 bp with a 57.23% GC content, 3,294 coding DNA sequences (CDSs), 55 tRNAs, 5 rRNAs (5S [n = 2], 16S [n = 1], and 23S [n = 2]), and 3 small RNAs (sRNAs).