Molecular analysis of Staphylococcus aureus isolated from infected dairy goats

Abstract

Staphylococcus aureus is the leading cause of mastitis in dairy goats and is globally recognized as a significant
mastitis-causing pathogen in dairy animals. Previous studies have established it as the causative agent of various
human disorders, including food poisoning and Staphylococcal enterotoxins. Furthermore, poor sanitary conditions suit
infection by this bacterium. This study determined the occurrence of S. aureus in infected dairy goats by molecular
analysis. A hundred raw milk samples were collected from two infected dairy goat breeds (Beetal = 71; Teddy = 29)
and cultured on blood agar media. The strain identified as S. aureus by morphological method (Gram staining),
biochemical tests (catalase and coagulase) and further identified through molecular method using the 16SrRNA gene.
Overall, 58 (Beetal = 45; Teddy = 13) out of 100 raw milk samples (58%) were found to be positive for S. aureus. Further,
ten samples of fresh milk positive for other microbial species including S. hominis, S. capitis and S. lentus were isolated.
The 16SrRNA gene was sequenced of fifteen S. aureus isolates representing various geographical regions. Phylogenetic
analysis was performed based on the 16SrRNA gene. In conclusion, S. aureus was more prevalent in the raw milk
samples of the infected goats and acted as an etiologic agent of mastitis in the dairy goats. Hence, more measures that
are hygienic should be implemented to improve milk quality and to prevent S. aureus contamination.