Comparison of PCR and bacterial culture methods for diagnosis of dairy cattle's subclinical mastitis caused byStaphylococcus aureus

To compare PCR and bacterial culture methods for diagnosis of subclinical mastitiscaused by Staphylococcus aureus, 100 milk samples from cattle with subclinical mastitis and 20samples from healthy cattle were collected and tested. The samples were cultured on selectiveblood agar and bacteria were identified by standard methods. DNA extracted from samples wassubjected to PCR reaction with species specific primers and PCR products were analyzed byagarose gel electrophoresis. Based on the PCR results the prevalence of subclinical mastitis dueto S. aureus was 25%. In the bacteriological culture of single milk sampling, S. aureus wasisolated from the same samples being positive in PCR. A correlation of 100% was found betweenPCR and single milk sampling culture method by Mc Nemar test. All of the CMT negativesamples were also negative in culture and PCR methods. The results of this study indicate thatthe PCR reaction is sensitive and specific for diagnosis of S. aureus in subclinical mastitis andcan detect this pathogen in milk samples at species level in few hours.

Keywords:

Staphylococcus aureus , mastitis , bacterial culture , PCR