Isolation of Rhodococcus equi from a mule with cutaneous wound

• Published in: Comparative clinical pathology 2015-05, Vol.24 (3), p.691-693
• Main Authors: Heidari Sureshjani, M., Atyabi, N., Tazikeh, A., Khanamani Falahatipour, S., Hashemian, M.
• Format: Article
• Language: English
• Subjects: Brief Communication; Hematology; Medicine; Medicine & Public Health; Oncology; Pathology
• ISSN: 1618-5641; 1618-565X
• DOI: 10.1007/s00580-014-2011-x

Rhodococcus equi is an encapsulated gram-positive, pleomorphic rod which exists in the soil and frequently is isolated from the feces of normal herbivores. It is the primary cause of pneumonia in foals. This organism has been isolated from various animals, but isolation from the wound is rarely reported. In May 2013, a 7-month-old Janet (female mule) was referred with some ulcers on the face below the zygomatic process in the right side in dimensions of 2 × 2 cm. Swab samples were taken from the ulcer for bacteriological cultures. The isolated bacteria grew on cysteine tellurite agar. The tests of catalase and nitrate reduction were positive, but urea hydrolysis was negative. The result of the Christie-Atkins-Munch-Petersen (CAMP) test was positive and “spade showel-shaped” hemolytic pattern was seen in blood agar. The bacteria were identified as R. equi . This organism was susceptible to gentamycin, azithromycin, and erythromycin. The presence of R. equi as a pathogen without pulmonary disease is important because it can cause wound contamination and leads to persistence of the organism in the environment. An exposure to soil contaminated with livestock manure seems to be the most probable mode of infection for this case.