Rhodococcus equi infection in a dairy goat from a herd in northeastern Italy

Abstract

A 3-year-old Chamois Colored dairy goat from a herd in Treviso province (Northeastern Italy) was examined for progressive weight loss and enlargement of cervical lymph nodes, which rapidly worsened to severe weakness and death within few days. Multiple nodular caseous pyogranulomas were found in Lymph nodes, lung, liver, and spleen. Numerous Gram-positive coccobacilli were filled the cytoplasm of macrophages and neutrophils. Aerobic bacterial cultures yielded pure cultures of Rhodococcus hoagii. 16S rDNA sequencing of the isolate revealed a 100% homology with Rhodococcus equi. The isolated strain resulted resistant trimethoprim/sulfamethoxazole and susceptible to tetracycline utilizing Mic values for horses (not available for goat species). Other infections including Mycobacterium spp., small ruminant lentivirus (SLRV) and pestiviruses, considered to be predisposing factors of systemic pyogranulomatous infections, were excluded. In recent years, several reports have described Rhodococcus equi infections in ruminants worldwide, especially after the recognition of the ruminant-pathogenic factor VapN. Rhodococcus equi might represent an unrecognized pathogen in goats that should be considered in the differential diagnosis of caprine pseudotuberculosis and tuberculosis, also in view of its zoonotic potential.