Korean J Vet Res.  2019 Sep;59(3):141-149. 10.14405/kjvr.2019.59.3.141.

Pathologic characteristics for the Rhodococcus equi infection in foals in Jeju

• KMID: 2461011
• DOI: http://doi.org/10.14405/kjvr.2019.59.3.141

Abstract

From 1996 to 2014, 14 foals from nine farms in Jeju were diagnosed with a Rhodococcus equi infection. Clinically, most foals showed characteristic respiratory signs, including hyperthermia and dyspnea. The seasonal occurrence of R. equi infection in foals was higher in summer, such as June (eight foals; 57.1%) and July (four foals; 28.6%), than in the other seasons. The major cases of R. equi infections were observed among two-month-old (eight foals; 57.1%) and three-month-old (three foals; 21.4%) foals. Histopathologically, bronchopneumonia, abscess, and granulomatous pneumonia were the most prevalent lesions in the lungs of foals. Colonic ulcers and submucosal abscesses were found in a foal. Some foals showed granulomatous lymphadenitis and abscesses in the mesenteric and other lymph nodes. According to the polymerase chain reaction using 10 tissue samples of foals and nine R. equi isolates, the vapA gene was detected in 11/11 (100%) foals. Immunohistochemical staining using the anti-VapA monoclonal antibody was applied to detect the R. equi VapA antigen in the organs of foals. R. equi VapA antigens were demonstrated in most lungs and some mesenteric and hilar lymph nodes of 13 foals. Isolated virulent R. equi VapA bacteria showed high sensitivity to gentamicin, quinolones, rifampin, and vancomycin.

MeSH Terms

Abscess
Agriculture
Bacteria
Bronchopneumonia
Colon
Dyspnea
Fever
Gentamicins
Immunohistochemistry
Lung
Lymph Nodes
Lymphadenitis
Pneumonia
Polymerase Chain Reaction
Quinolones
Rhodococcus equi*
Rhodococcus*
Rifampin
Seasons
Ulcer
Vancomycin
Gentamicins
Quinolones
Rifampin
Vancomycin