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

This research study conducted molecular characterization of Burkholderia mallei strains that were isolated from horses in Brazil between 2014 and 2017, to understand the diversity of the strains circulating in the country.

Objective of the Research

• The main purpose of this study was to gain more knowledge about the diversity of Burkholderia mallei strains circulating in Brazil. Burkholderia mallei is a bacterium that causes Glanders, an infectious disease that primarily affects horses.

Methodology

• The researchers obtained six Burkholderia mallei isolates from necropsies of glanderous horses between 2014 and 2017 in two different Brazilian states: Pernambuco and Alagoas.
• These isolates were then analyzed using a method known as polymerase chain reaction-high-resolution melting (PCR-HRM), a technique used for detecting mutations, polymorphisms, and epigenetic differences in double-stranded DNA.

Findings

• The analysis of the strains revealed that four of them (named 9902 RSC, BM_campo 1, BM_campo 3, and UFAL2) were part of the L3B2 branch, which also includes another Brazilian strain previously detected (16-2438_BM#8).
• Two other strains (BM_campo 2.1 and BM_campo 2.2) were found to belong to a different branch, L3B3sB3, which generally includes older isolates from Europe and the Middle East.
• Complete genomic sequencing of two strains (UFAL2 and BM_campo 2.1), belonging to different branches, validated the PCR-HRM typing results. This analysis also further elaborated the association between the strains, including the discovery of a novel genotype (L3B3Sb3Gp1SbGp1) not previously reported in contemporary strains.

Conclusions

• The study’s findings indicate multiple instances of glanders introduction in Brazil, potentially even linked with strains of European origin, possibly related to colonization or trade. This adds to existing knowledge of the spread and diversity of Burkholderia mallei strains, aiding future attempts to control and prevent the disease.