Outbreak of Nocardia neocaledoniensis mastitis in a Italian dairy herd [short communication]

Nocardia spp. are an uncommon cause of mastitis, and outbreaks have typically been reported in dairy farms with poor hygienic and management conditions. The outbreak described herein involved a dairy farm with 43 lactating cows that, after a long period with low bulk milk somatic cell counts (<180,000 cells/mL), experienced an increasing incidence of clinical mastitis with bulk milk somatic cell counts greater than 300,000 cells/mL. Fifteen mastitic quarters milk samples from 9 dairy cows were found to be infected by a member of the genus Nocardia, as identified on the basis of se-lected phenotypic and chemotaxonomic characteristics. The isolates were confirmed as Nocardia neocaledo-niensis by 16S rDNA gene sequencing. Average quarter milk somatic cell count for infected udders was 863,057 cells/mL, significantly greater than the average value in noninfected quarters (189,710 cells/mL).