Rapid isolation and identification of pathogens is a major goal of diagnostic microbiology. In order to isolate and identify Staphylococcus aureus, a number of authors have used a variety of selective and/or differential
culture media. However, to date, there are no reports comparing the efficacy of selective and differential
culture media for S. aureus isolation from
bovine mastitis cases using the
16S rRNA (rrs) gene sequence as a gold standard test. In the present study, we evaluated the efficacy of four selective and/or differential
culture media for the isolation of S. aureus from milk samples collected from cows suffering from
bovine mastitis. Four hundred and forty isolates were obtained using
salt-
mannitol agar (SMA, Bioxon), Staphylococcus-110
agar (S110, Bioxon), CHROMAgar Staph aureus (CSA, BD-BBL) and sheep's blood
agar (SBA, BD-BBL). All bacterial isolates were identified by their typical colony morphology in the respective media, by secondary tests (for
coagulase and β-
haemolysis) and by partial
16S rRNA (rrs) gene sequencing as a gold standard test. Sensitivity, positive predictive and negative predictive values were higher for SMA (86.96, 52.63 and 95.95%, respectively) compared with S110 (70.00, 23.73 and 90.91%, respectively), CSA (69.23, 28.13 and 95.74%, respectively) and SBA (68.75, 37.93 and 89.58%, respectively) while specificity values were similar for all media. Data indicated that the use of
culture media for S. aureus isolation combined with determination of
coagulase activity and
haemolysis as secondary tests improved accuracy of the identification and was in accordance with rrs gene sequence-analysis compared with the use of the
culture media alone.