Journal of Pure and Applied MicrobiologyVol. 8 No. 6

Identification of Methicillin Resistant Staphylococcus aureus in Raw Cow Milk through Amplification of mecA

Vimjam Swarupa1, Annamaraju Rupa Sundari2, Uppu Venkateswara Prasad1, Sthanikam Yeswanth1, Osuru Hari Prasad1 and Potukuchi Venkata Gurunadha Krishna Sarma1*

1Department of Biotechnology, Sri Venkateswara Institute of Medical Sciences; Tirupati - 517507, India. 2Department of Veterinary public Health, Sri Venkateswara Veterinary University, Tirupati - 517507, India.

Received on 29 August 2014 and accepted on 15 October 2014

 

ABSTRACT

Conventional detection of Staphylococcus aureus in farm animals has a greater importance as they are not only reservoirs of drug resistant S. aureus but also there is a possible chance of transmission between hosts. Thus in the current study 30 milk samples from dairy herds and milk venders of different places were examined. On the basis of black shiny colonies with clear zone on Baird parker plate, Gram staining followed by catalase and coagulase tests; 12of 30 samples (40%) were morphologically identified as S. aureus. Further growth in aureusAlertTM screening kit and amplification of 1.5kb 16S rRNA confirms screened isolates were S. aureus. The antibiotic susceptibility profile showed all the 12 isolates were resistant to Ampicillin and Pencillin where as 3 isolates (25%) LMV3, LMV4 and LMV5 exhibited additional resistance to Oxacillin with MIC of 14 ? 1.5 to 16 ? 0.75?g/ml indicating methicillin resistance. Colour change in aureusAlertTMR/S confirmation kit and presence of mecA gene (304 bp PCR product) on the chromosome of 3 oxacillin resistance isolates confirms them genetically as methicillin resistant S. aureus (MRSA) strains. Therefore results of the present study corroborate the gold standard methods for detecting MRSA in the raw milk.

Keywords : Staphylococcus aureus, 16S rRNA, mecA, aureusAlertTM, MRSA, raw milk.