Vagococcus sp. a porcine pathogen: molecular and phenotypic characterization of strains isolated from diseased pigs in Brazil

Abstract

Introduction: Vagococcus spp. is known for its importance as a systemic and zoonotic bacterial pathogen even though it is not often reported in pigs. This is related to the pathogen misidentification due to the lack of usage of more discriminatory diagnostic techniques. Here we present the first report of Vagococcus lutrae in swine and the characterization of Vagococcus fluvialis and Vagococcus lutrae isolated from diseased animals.

Methodology: Between 2012 and 2017, 11 strains with morphological characteristics similar to Streptococcus spp. were isolated from pigs presenting different clinical signs. Bacterial identification was performed by matrix assisted laser desorption ionization time of flight (MALDI-TOF) mass spectrometry and confirmed by 16S rRNA sequencing and biochemical profile. Strains were further genotyped by single-enzyme amplified fragment length polymorphism (SE-AFLP). Broth microdilution was used to determine the minimal inhibitory concentration of the antimicrobials of veterinary interest.

Results: Ten strains were identified as V. fluvialis and one was identified as V. lutrae. The SE-AFLP analysis enabled the species differentiation with specific clustering of all V. fluvialis separately from the V. lutrae strain. Most strains presented growth in the maximum antibiotic concentration values tested for eight of the 10 analyzed antimicrobial classes.

Conclusions: The observed resistance pattern can represent a problem for veterinary and producers in the treatment of diseases associated Vagococcus spp. in swine production. Vagococcus species may also be a risk for pig industry workers. The data described here will be of great value in further understanding the behavior of this pathogen in animal production.

Keywords: Biochemical profile; MIC; SE-AFLP; Vagococcus fluvialis; Vagococcus lutrae.