Identification of Streptococcus agalactiae in western Cuba cattle milk affected by mastitis

Abstract

Streptococcus agalactiae is one of the main agents causing mastitis in dairy cattle, with important implications for humans; whereby the diagnosis, control and prevention of this microorganism is fundamental to animal and human health as well for the economy. The objective of this work was to detect the presence of S. agalactiae in milk from cattle herds affected by mastitis. Five hundred and seventy-four samples of milk were collected from quarters affected with mastitis (840 production cattle of Siboney de Cuba, Holstein and Jersey breeds of 14 dairy farms in western Cuba). Bacteriological diagnosis was performed in all samples. DNA and PCR were extracted with primers that amplified a segment of the 16S-23S rRNA intergenic region, from colonies with morphological characteristics and biochemical tests indicative of S. agalactiae. The 43.45 % of animals showed symptoms of clinical or subclinical mastitis. In 57 samples (9.97 %), colonies characteristic of S. agalactiae were isolated, and 43 (75.43 %) were positive by PCR. Of the latter, 26 (60.46 %) corresponded to quarters with three crossings, 14 (32.55 %) to two crossings and 3 (6.97 %) to clinical rooms. S. agalactiae was isolated in eight dairy farms and the most affected breeds were Holstein and Siboney de Cuba. Strains of S. agalactiae were isolated and identified in mastitis-affected cows, indicating the need for programs to control mastitis caused by S. agalactiae to mitigate the effects caused by this microorganism on human-animal-environment interfaces.