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Abstract: To compare PCR and bacterial culture methods for diagnosis of subclinical mastitis caused by Staphylococcus aureus, 100 milk samples from cattle with subclinical mastitis and 20 samples from healthy cattle were collected and tested. The samples were cultured on selective blood agar and bacteria were identified by standard methods. DNA extracted from samples was subjected to PCR reaction with species specific primers and PCR products were analyzed by agarose gel electrophoresis. Based on the PCR results the prevalence of subclinical mastitis due to S. aureus was 25%. In the bacteriological culture of single milk sampling, S. aureus was isolated from the same samples being positive in PCR. A correlation of 100% was found between PCR and single milk sampling culture method by Mc Nemar test. All of the CMT negative samples were also negative in culture and PCR methods. The results of this study indicate that the PCR reaction is sensitive and specific for diagnosis of S. aureus in subclinical mastitis and can detect this pathogen in milk samples at species level in few hours.
Key words: Staphylococcus aureus, mastitis, bacterial culture, PCR