Molecular detection of Burkholderia mallei in different geographic regions of Brazil

Abstract

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.

Keywords: DNA sequencing; Glanders; Necropsy; PCR; Zoonosis.

Fig. 1

PCR amplification targeting IS407-fliP for Burkholderia mallei isolates from Brazil. All reactions shown in the figure are PCRs from microbiological cultures. Only one positive sample per animal was included. Arrow: 528 bp. Lane 1: 1 kb plus (Thermo Fisher, USA); lane 2: positive control: DNA from B. mallei (São Paulo) strain 86/19; lane 3: negative control; lane 4: Santa Catarina, equine, male, spleen; lane 5: Santa Catarina, equine, female, lung; lane 6: Bahia, equine, male, spleen; lane 7: Bahia, equine, male, lung; lane 8: Bahia, equine, female, tracheobronchial lymph node; lane 9: Bahia, equine, female, liver; lane 10: Bahia, equine, female, palate swab; lane 11: Rio Grande do Sul, equine, female, nasal swab; lane 12: Rio Grande do Sul, equine, male, mandibular lymph node; lane 13: Rio Grande do Sul, equine, male, ethmoidal concha abscess/piogranuloma; lane 14: Tocantins, mule, female, liver; lane 15: Mato Grosso, asinine, female, kidney; lane 16: Mato Grosso, equine, female; bladder; lane 17: Amazonas, equine, female, lung; lane 18: Piauí, equine, female, lymph node pool; lane 19: Sergipe, mule, female, liver; lane 20: Maranhão, equine, female, pulmonary lymph node