Molecular characterization of Burkholderia mallei strains isolated from horses in Brazil (2014-2017)

Clinical and Molecular Characterization of Human Burkholderia mallei Infection, Brazil

We report a case of Burkholderia mallei causing glanders in a 73-year-old patient from the Northeast Region of Brazil. The patient was hospitalized with severe pneumonia. PCR and genomic sequencing confirmed B. mallei in pleural drainage. Genotyping revealed a novel genotype, emphasizing the need for genetic surveillance in zoonotic infections.

First molecular characterization of Burkholderia mallei strains isolated from horses in Mongolia

Glanders, a highly contagious and often fatal disease affecting equids, is caused by Burkholderia mallei. Although sporadic cases of equine glanders have recently been documented in Mongolia, genome sequencing and molecular studies of the bacteria within this region are lacking. This study provided the first molecular characterization of B. mallei isolated from four native Mongolian horses from two different provinces in 2019 and 2022 by applying whole-genome sequencing with two SNP types (previously developed genotyping with 15 SNP markers that provide global coverage of the B. mallei population and the core genome coding SNP typing developed in this study). The Mongolian isolates were located within the L3B1 cluster, which was previously associated with the V-120 strain from Russia. Within the L3B1 cluster shared by neighboring countries, they were in a unique subbranch. In this study, specific SNP markers unique to the Mongolian strains were identified to track these strains using a high-resolution melting analysis (HRMA). This study revealed the unique phylogenetic background of Mongolian strains isolated from the eastern part of Mongolia. HRMA specific to the Mongolian subbranch may contribute to the molecular epidemiological monitoring of glanders in Mongolia and surrounding countries.

Spread analysis of glanders in the state of Piauí, northeastern Brazil

Brazil is strategic in controlling neglected zoonoses, such as glanders, in its territory. Among the Brazilian states, Piauí is a strategic state for the spread of the disease in the country. The present study aimed to evaluate the spatial and temporal distribution of official cases of glanders in Piauí between 2015 and 2022. The glanders cases were located in the municipalities of the north and central-north mesoregions, mainly in Campo Maior, Teresina and Altos. The highest incidence risk (IR) occurred in of Altos (IR = 257.9), Sussuapara (IR = 158.4), and Teresina (IR = 157.7). A primary cluster was formed with a relative risk of 14.88 between 2019 and 2022, encompassing 34 municipalities in the north and central-north regions. In Piauí, glanders is well localized, with the potential for spread across borders. This is the first study demonstrating the distribution of reported cases of glanders in the state of Piauí.

Glanders Diagnosis in an Asymptomatic Mare from Brazil: Insights from Serology, Microbiological Culture, Mass Spectrometry, and Genome Sequencing

This manuscript elucidates the occurrence of glanders in an asymptomatic mare from Brazil presenting positive Burkholderia mallei antibody titers. The diagnosis was established through a multi-pronged approach encompassing microbiological culture, mass spectrometry, and genome sequencing. The outbreak occurred in 2019 in Tatuí, São Paulo, Brazil, and the infected mare, despite displaying no clinical symptoms, had multiple miliary lesions in the liver, as well as intense catarrhal discharge in the trachea. Samples were collected from various organs and subjected to bacterial isolation, molecular detection, and identification. The strain was identified as B. mallei using PCR and confirmed by MALDI-TOF mass spectrometry. Whole-genome sequencing revealed a genome size of 5.51 Mb with a GC content of 65.8%, 5871 genes (including 4 rRNA and 53 tRNA genes), and 5583 coding DNA sequences (CDSs). Additionally, 227 predicted pseudogenes were detected. In silico analysis of different genomic loci that allow for differentiation with Burkholderia pseudomallei confirmed the identity of the isolate as B. mallei, in addition to the characteristic genome size. The BAC 86/19 strain was identified as lineage 3, sublineage 2, which includes other strains from Brazil, India, and Iran. The genome sequencing of this strain provides valuable information that can be used to better understand the pathogen and its epidemiology, as well as to develop diagnostic tools for glanders.

Molecular detection of Burkholderia mallei in different geographic regions of Brazil

Glanders is a contagious disease of equids caused by the Gram-negative bacterium Burkholderia mallei. In Brazil, the disease is considered to be reemerging and has been expanding, with records of equids with positive serology in most of the federative units. However, there are few reports describing the genotypic detection of the agent. This study demonstrated the detection of B. mallei by species-specific PCR directly from tissues or from bacterial cultures, followed by amplicon sequencing in equids (equines, mules, and asinines) with positive serology for glanders in all five geographic regions of Brazil. The molecular evidence of B. mallei infection in serologically positive equids in this study expands the possibility of strain isolation and the conduction of epidemiological characterizations based on molecular information. The microbiological detection of B. mallei in cultures from nasal and palate swabs, even in equids without clinical manifestations, raises the possibility of environmental elimination of the agent.

Current status of glanders in Brazil: recent advances and challenges

Glanders is an infectious disease that causes serious damage to the equine production chain in countries where it occurs endemically and poses a risk to public health. This study aimed to conduct an integrative review of the advances in the knowledge of glanders in Brazil over the last three decades since its re-emergence. Documentary research was conducted for the period between the years 2000 and 2022. SCOPUS and PUBMED databases were used to search for scientific articles, dissertations, and thesis, in addition to the Brazilian Digital Library of Thesis and Dissertations (BDTD). A total of 41 documents were retrieved, including 12 dissertations, five theses, and 24 scientific articles. The Federal Rural University of Pernambuco (UFRPE) group provided a noteworthy amount of material on this topic (25 documents, four theses, three dissertations, and 18 scientific articles). During this period, ten dissertations, one thesis, and six scientific articles published by other groups in other states of the Federation were also identified. It was concluded that there was a significant number of scientific publications with relevant data on the clinical, epidemiological, pathological, microbiological, serological, and molecular characteristics of glanders disease in Brazil. Additionally, training of human resources regarding this disease led to an increase in the nucleation of research groups, especially in the northeast region of Brazil. Despite significant advances, new research groups and specific funding are still needed for the development of more accurate diagnostic methods, immunizing production, training of veterinarians to recognize the disease, and more robust programs to control and eradicate the disease in Brazil.

Sequence-based detection and typing procedures for Burkholderia mallei: Assessment and prospects

Although glanders has been eradicated in most of the developed world, the disease still persists in various countries such as Brazil, India, Pakistan, Bangladesh, Nepal, Iran, Bahrain, UAE and Turkey. It is one of the notifiable diseases listed by the World Organization for Animal Health. Occurrence of glanders imposes restriction on equestrian events and restricts equine movement, thus causing economic losses to equine industry. The genetic diversity and global distribution of the causing agent, Burkholderia (B.) mallei, have not been assessed in detail and are complicated by the high clonality of this organism. Among the identification and typing methods, PCR-based methods for distinguishing B. mallei from its close relative B. pseudomallei as well as genotyping using tandem repeat regions (MLVA) are established. The advent and continuous advancement of the sequencing techniques and the reconstruction of closed genomes enable the development of genome guided epidemiological tools. For achieving a higher genomic resolution, genotyping methods based on whole genome sequencing data can be employed, like genome-wide single nucleotide polymorphisms. One of the limitations in obtaining complete genomic sequences for further molecular characterization of B. mallei is its high GC content. In this review, we aim to provide an overview of the widely used detection and typing methods for B. mallei and illustrate gaps that still require development. The genomic features of Burkholderia, their high homology and clonality will be first described from a comparative genomics perspective. Then, the commonly used molecular detection (PCR systems) and typing systems (e.g., multilocus sequence typing, variable number of tandem repeat analysis) will be presented and put in perspective with recently developed genomic methods. Also, the increasing availability of B. mallei genomic sequences and evolution of the sequencing methods offers exciting prospects for further refinement of B. mallei typing, that could overcome the difficulties presently encountered with this particular bacterium.