Molecular characterization of Rhodococcus equi isolates of horse breeding farms from an endemic region in South of Brazil by multiplex PCR

Abstract

Rhodococcus equi is a gram-positive coco-bacillus and an intracellular opportunistic pathogen which causes pneumonia in foals. It is widely detected in environment and has been isolated from several sources, as soil, feces and gut from health and sick foals. The goal of this study was to characterize the epidemiological status (endemic, sporadic or no infection) of horse breeding farms from Bage County in South of Brazil, using a multiplex PCR. One hundred and eighteen R. equi isolates were identified by biochemical tests and submitted to a specie-specific and vapA multiplex PCR. These isolates were obtained from: three farms where the R. equi infection has been noticed, two farms where the disease has been not reported and one farm where the disease is frequent. All clinical isolates from horse breeding farms where the disease is endemic and/or sporadic were vapA-positive. None environmental isolates were vapA-positive. In three horse breeding farms with sporadic R. equi infection, 11.54% of the isolates from adult horse feces were vapA-positive. The multiplex PCR technique has proven to be effective for the molecular and epidemiological characterization of the R. equi isolates in horse breeding farms. An important finding in this study was the isolation of vapApositive R. equi from adult horse feces, which is an evidence for other routes of dissemination of this pathogen in the farms.

Characterization of Rhodococcus equi Isolates from Foals with Respiratory Problems using a Multiplex PCR for the vap Genes

“…Identification of the virulence plasmids associated with R. equi is of great importance in characterizing pathogenicity of disease in equines (Monego et al, 2009). The virulence is associated with the ability of the bacteria to prevent phagosome-lysosome fusion and replication within macrophages resisting clearance by organism defence (Kanaly et al, 1993;Krewer et al, 2008). Virulence factor is associated with presence of 85-90kb plasmid which encodes various virulence associated antigen (Byrne et al, 2001).…”

Identificação diferencial de Rhodococcus equi e Dietzia maris em bubalinos

“…A PCR multiplex, que utiliza iniciadores da região 16S, para identificação do gênero e espécie de R. equi e para os genes plasmideais de virulência (vapA e vapB), tem sido efetiva para a caracterização molecular e epidemiológica de isolados de R. equi em criações de equinos (Krewer et al, 2008). Para o gênero Dietzia, sem significado clínico marcante, os recursos moleculares são ainda escassos.…”

Rhodococcus equi: are phenotypic tests the best method for accurate identification?

“…(Pd et al 2012). The use of conventional methods with molecular technique such as polymerase chain reaction (using choE gene) is very important and necessary for accurate identification of R. equi (Pd et al 2012;Krewer et al 2008;Ladrón et al 2003). …”