Multilocus sequence analysis (MLSA) of Nocardia cyriacigeorgica strain which caused severe bovine mastitis

Abstract

Abstract Available data on the clinical significance of Nocardia cyriacigeorgica in veterinary medicine are scarce and usually concern individual reports of local or systemic pyogranulomatous lesions in domestic animals. In this study, we report a case of severe bovine mastitis caused by N. cyriacigeorgica, non-responsive to antimicrobial therapy, on a smallholder farm in Bosnia and Herzegovina. At physical examination, the udder was hard, with enlarged hind quarters and teats, and reduced milk production with no gross changes to the secretion were documented. After causative agent isolation and suspected actinobacteria, further identification was impossible using routine microbiological methods. Antimicrobial susceptibility testing was performed using the disk diffusion method according to published recommendations. The sample was further examined using MALDI-TOF MS with inconclusive results. Additionally, the 16S rRNA sequence analysis, verified by multilocus sequence analysis (MLSA) using gyrB, 16S rRNA, secA1, and hsp65 sequences, confirmed the N. cyriacigeorgica species. To the best of our knowledge, this is the first report on N. cyriacigeorgica isolation from a clinical case of bovine mastitis in European dairy farms and the first MLSA methodology approach to discriminate a Nocardia spp. strain isolated from animals. Most lactating cows in Bosnia and Herzegovina are held in traditional farming conditions which may serve as a predisposing factor for nocardial mastitis. More studies are required to analyze the possible aspects leading to the occurrence of mastitis caused by Nocardia spp. and the overall importance of these bacteria in the pathogenesis of infections in domestic animals.