Genotyping Brucella canis isolates using a highly discriminatory multilocus variable-number tandem-repeat analysis (MLVA) assay

Higher diversity of Brucella canis in Latin America, according to an MLVA_13 Bc analysis

Brucella canis is the main causative agent of canine brucellosis, which affects domestic and wild canids and leads to clinical signs and symptoms of the reproductive and locomotor systems. Owing to the scarce information on this pathogen, here we addressed the genetic diversity of the circulating strains of this species in Argentina by following an MVLA_13 Bc scheme. The analyzed sample set consisted of 101 strains of B. canis isolates collected between 2006 and 2020 from canines of the Autonomous City of Buenos Aires (CABA) and other regions of Argentina, as well as 235 isolates from North America. . The analysis yielded 336 variants (Hunter-Gaston Diversity Index, HGDI equal to 1.0) showing high diversity on a global scale. The analysis of the six most variable markers also reveled high diversity and allowed further analysis regarding variant relationships. Although the diversity obtained using both schemes (all or the 6 most variable markers) was higher for the Latin American than for the North American strains, we cannot discard that this was due to biases in the sampling methodology or to the different health policies employed in these regions regarding the management of infected individuals. Altogether, the Argentine circulating strains are genetically diverse, but with no apparent geographical association. The markers used in the MLVA_13 Bc are variable and highly useful for the evaluation of outbreaks. Furthermore, the reduced panel of 6 markers (MLVA_6 Bc) proposed in this study is convenient for the study of B. canis strain diversity.

MLVA typing of Brucella melitensis and B. abortus isolates of animal and human origin from India

Brucellosis is a widely prevalent zoonotic disease of major public health significance. A collection of Brucella melitensis and Brucella abortus field isolates of animal and human origin were subjected to MLVA-15 typing followed by phylogeography studies. The MLVA-15 analysis of B. melitensis (n = 65) field isolates resulted in 48 different profiles. The panel I marker bruce45 was found to be most conserved, while the rest of the panel I markers showed low to moderate length polymorphism. Among the panel II markers, bruce04, bruce16 and bruce30 showed a high discriminatory index. The MLVA-15 typing of 13 B. abortus field isolates revealed 13 different genotypes with panel II markers showing higher discriminatory ability vis-à-vis panel I. The minimum spanning tree analysis (MST) in comparison with isolates from the international database revealed that all B. melitensis and B. abortus isolates from this study belonged to the 'Eastern Mediterranean' and the 'abortus C' lineage, respectively. The MLVA-15 typing could differentiate field isolates of B. abortus and B. melitensis originating from different regions, reaffirming the technique's potential of high resolution and suitability for local epidemiological studies. The MLVA scheme also has the advantage of comparison of local isolates with a worldwide database, allowing for phylogeographical studies.

Transboundary Spread of Brucella canis through Import of Infected Dogs, the Netherlands, November 2016-December 2018

Brucella canis had not been isolated in the Netherlands until November 2016, when it was isolated from a dog imported from Romania. Including this case, 16 suspected cases were notified to the authorities during the following 25 months. Of these 16 dogs, 10 were seropositive; tracking investigations found another 8 seropositive littermates. All seropositive animals were rescue dogs imported from Eastern Europe. B. canis was cultured from urine, blood, and other specimens collected from the dogs. Genotyping of isolates revealed clustering by litter and country. Isolating B. canis in urine indicates that shedding should be considered when assessing the risk for zoonotic transmission. This case series proves introduction of B. canis into a country to which it is not endemic through import of infected dogs from B. canis-endemic areas, posing a threat to the naive autochthonous dog population and humans.

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.

Multilocus Variable-Number Tandem-Repeat Analysis for Geno-typing of Escherichia coli Strains Isolated from Hospital Wastewater, Tehran, Iran

Background:

Escherichia coli is one of the most frequent causes of many common bacterial infections. As a potential reservoir, hospital wastewater is considered for the dissemination of bacterial pathogens such as E. coli. Therefore, research on hospital waste’s bacteria by low-cost, rapid and easy molecular typing methods such as multilocus variable-number tandem-repeat analysis (MLVA) can be helpful for the study of epidemics.

Methods:

E. coli strains were isolated from hospital wastewater sources in Tehran, Iran, over a 24-month sampling period (Jun 2014- Jun 2016) and identified by standard bacteriological methods. The diversity of repeated sequences of seven variable-number tandem-repeat (VNTR) loci was studied by MLVA method base on polymerase chain reaction (PCR).

Results:

Overall, 80 E. coli isolates were discriminated into 51 different genotypes. Analysis of the MLVA profiles using a minimum spanning tree (MST) algorithm showed two clonal complexes with 71 isolates and only nine isolates were stayed out of clonal complexes in the form of a singleton. High genotypic diversity was seen among E. coli strains isolated from hospital wastewaters; however, a large number of isolates showed a close genetic relationship.

Conclusion:

MLVA showed to be a rapid, inexpensive and useful tool for the analysis of the phylogenetic relationships between E. coli strains under the study.

Prevalence and Genomic Characterization of Brucella canis Strains Isolated from Kennels, Household, and Stray Dogs in Chile

Canine brucellosis caused by Brucella canis is a zoonotic disease that causes reproductive alterations in dogs, such as infertility, abortion, and epididymitis. This pathogen is especially prevalent in South America, and due to the lack of official control programs and the growing trend of adopting dogs it constitutes a public health risk that must be addressed. The aim of this study was to determine the prevalence of B. canis infection in kennel, shelter, and household dogs and to characterize the genomic properties of circulating strains, including ure and virB operons and omp25/31 genes. Samples from 771 dogs were obtained, and the infection was detected by blood culture and/or serology in 7.0% of the animals. The complete ure and virB operons and the omp25/31 genes were detected. Interestingly, we found different single-nucleotide polymorphisms (SNPs) in some of the analyzed genes, which could mean a change in the fitness or virulence of these strains. This study provides further evidence about dogs as a source of B. canis strains that can infect people. This also highlights the need to implement official control programs, including the mandatory testing of dogs, especially stray dogs, before adoption.

MALDI-TOF MS and genomic analysis can make the difference in the clarification of canine brucellosis outbreaks

Brucellosis is one of the most common bacterial zoonoses worldwide affecting not only livestock and wildlife but also pets. Canine brucellosis is characterized by reproductive failure in dogs. Human Brucella canis infections are rarely reported but probably underestimated due to insufficient diagnostic surveillance. To improve diagnostics, we investigated dogs in a breeding kennel that showed clinical manifestations of brucellosis and revealed positive blood cultures. As an alternative to the time-consuming and hazardous classical identification procedures, a newly developed species-specific intact-cell matrix-assisted laser desorption/ionization–time of flight mass spectrometry analysis was applied, which allowed for rapid identification of B. canis and differentiation from closely related B. suis biovar 1. High-throughput sequencing and comparative genomics using single nucleotide polymorphism analysis clustered our isolates together with canine and human strains from various Central and South American countries in a distinct sub-lineage. Hence, molecular epidemiology clearly defined the outbreak cluster and demonstrated the endemic situation in South America. Our study illustrates that MALDI-TOF MS analysis using a validated in-house reference database facilitates rapid B. canis identification at species level. Additional whole genome sequencing provides more detailed outbreak information and leads to a deeper understanding of the epidemiology of canine brucellosis.

Investigation of the molecular epizootiological characteristics and tracking of the geographical origins of Brucella canis strains in China

Brucellosis is a global pandemic infectious zoonosis. Brucella canis is a rare source of human brucellosis in China, and its public health significance remains under debate. Moreover, data pertaining to the epizootiological characteristics and geographical origin of B. canis on a nationwide scale are limited, and the risk to public safety posed by B. canis infections is unknown. The MLVA (multilocus variable-number tandem repeat analysis) assay can be helpful to analyse epidemiological correlations among Brucella isolates and to track their geographic origins. To accomplish this task, MLVA-16 was used to analyse the epidemiological links of 63 isolates obtained from dogs and humans. Sixty-three B. canis strains were sorted into three large clusters (A, B and C) and 50 different genotypes (GT1-50), and 43 unique genotypes were represented by single isolates, suggesting that these strains had no obvious epidemiological links and that canine brucellosis is predominantly sporadic in China. The other seven shared genotypes (among a total of 20 isolates) were each represented by two to eight isolates, indicating that strains from each shared genotype were epidemiologically correlated. Five of the shared genotypes were from 16 strains obtained from Beijing, indicating that canine brucellosis in Beijing originates from multipoint outbreaks with multiple sources of infection. Based on comprehensive case analysis of clinical B. canis infection, we preliminarily suggest that human B. canis infections are associated with Mycoplasma pneumoniae infection that results in decreased patient immunity. B. canis may have limited epidemiological significance for the healthy population, but it remains a significant threat to the canine breeding industry and to humans who come into close contact with dogs. Based on MLVA-11 data, B. canis strains were clustered into 16 genotypes and divided into five evolutionary branches; these data confirm that this population covers an extensive geographic area and exhibits characteristics of the origin and evolution of co-existing introduced and locally native lineages. We believe this study will contribute to strengthening efforts to prevent and control canine brucellosis and to improve public understanding of the health risks posed by B. canis.

Investigation and characterization of Brucella canis infections in pet-quality dogs and associated human exposures during a 2007-2016 outbreak in Michigan

OBJECTIVE To estimate Brucella canis seropositivity rates for purebred dogs being bred by noncommercial breeders, describe epidemiological findings in infected commercial dog-production facilities, and characterize B canis infection in pet dogs and the risk to human health. DESIGN Retrospective descriptive study. SAMPLE 2,799 canine specimens submitted to the Michigan State University Veterinary Diagnostic Laboratory for B canis testing and records of B canis reports provided to the Michigan Department of Agriculture and Rural Development from 2007 through 2016. PROCEDURES Results of B canis laboratory tests and epidemiological findings for reported cases of B canis were reviewed and summarized. Federal and state public health officials were interviewed regarding human B canis infection. State veterinarians were interviewed regarding canine brucellosis reporting and control procedures. RESULTS Estimated B canis seropositivity was 0.4% among purebred Michigan dogs owned by noncommercial breeders. Infection was confirmed in dogs from 17 commercial dog-production facilities, 3 shelters, and 1 rescue agency. Estimated infection prevalence in production facilities ranged from 2 of 22 (9%) to 5 of 6 (83%). Transfer of infected dogs involved 22 Michigan counties and 11 states. Seven of 20 privately owned infected dogs had diskospondylitis; I also had uveitis. Fifty-three veterinary hospital or diagnostic laboratory personnel had inadvertent exposure to the pathogen. Brucella canis was isolated from 1 commercial production facility owner. CONCLUSIONS AND CLINICAL RELEVANCE B canis was uncommon in purebred dogs being bred by noncommercial breeders but endemic in Michigan commercial facilities producing dogs destined to become household pets. Infected pet dogs caused human B canis exposure, and several pet dogs had debilitating disease not associated with the reproductive system.

Molecular typing of Mycobacterium kansasii using pulsed-field gel electrophoresis and a newly designed variable-number tandem repeat analysis

Molecular epidemiological studies of Mycobacterium kansasii are hampered by the lack of highly-discriminatory genotyping modalities. The purpose of this study was to design a new, high-resolution fingerprinting method for M. kansasii. Complete genome sequence of the M. kansasii ATCC 12478 reference strain was searched for satellite-like repetitive DNA elements comprising tandem repeats. A total of 24 variable-number tandem repeat (VNTR) loci were identified with potential discriminatory capacity. Of these, 17 were used to study polymorphism among 67 M. kansasii strains representing six subtypes (I-VI). The results of VNTR typing were compared with those of pulsed-field gel electrophoresis (PFGE) with AsnI digestion. Six VNTRs i.e. (VNTR 1, 2, 8, 14, 20 and 23) allow to differentiate analyzed strains with the same discriminatory capacities as use of a 17-loci panel. VNTR typing and PFGE in conjunction revealed 45 distinct patterns, including 11 clusters with 33 isolates and 34 unique patterns. The Hunter-Gaston's discriminatory index was 0.95 and 0.66 for PFGE and VNTR typing respectively, and 0.97 for the two methods combined. In conclusion, this study delivers a new typing scheme, based on VNTR polymorphism, and recommends it as a first-line test prior to PFGE analysis in a two-step typing strategy for M. kansasii.