they have spesific jet black (tellurite to tellirium) colonies with a halo due to their lecitinase activity on Baird Parker agar. Sometimes you can encounter larger atypical black colonies of S. aureus without the halo. pick those specific colonies and do coagulase (rabbit plasm with edta) and thermonuclease assays (with dna agar) (if both is to be positive then %95 S. aureus)..u can additionally use latex agglutinations with specificity around % 97.. plus u can confirm by 16s rRna specific primers..

You can grow the suspected bacterium on Mannitol Salt Agar (MSA) and look out for golden-like sheen colonies. In the third word where PCR is quite expensive and laborious to carry out, you may wish to confirm the colonies by emulsifying a bit of the growth on 2% hydrogen peroxide. Observe for bubbling and frothing (catalase test) which is peculiar to Staphylococcus. To distinguish between the species, pick a bit of the growth from the MSA and grow (incubate at 37 degree centrigrade) in rabbit citrated plasma and observe for coagulation of the plasma (coagulase test). This is positive for Staphylococcus aureus

You can grow the suspected bacterium on Mannitol Salt Agar (MSA) and look out for golden-like sheen colonies. In the third word where PCR is quite expensive and laborious to carry out, you may wish to confirm the colonies by emulsifying a bit of the growth on 2% hydrogen peroxide. Observe for bubbling and frothing (catalase test) which is peculiar to Staphylococcus. To distinguish between the species, pick a bit of the growth from the MSA and grow (incubate at 37 degree centrigrade) in rabbit citrated plasma and observe for coagulation of the plasma (coagulase test). This is positive for Staphylococcus aureus

thank you very much for the valuable information. I just wanted to know how do we isolate and confirm. your responses made it vivid.

@ Y. Emre Gencay: thank you, actually i am confirming it by 16s RNA but i wanted to isolate and confirm by biochemical assay prior to it.

@Mehvish : Thank you very much..!!

@Duro Damisa: Thank you very much..!!!

i will be pleased if some one could provide me any substantial proof or any research article on bio chemical assay of S.aureus....

Y dont you refer Bergey's manual of bacteriology for biochemical tests

@Mehvish:

thank you...!! as mentioned i am doing 16 s RNA for conformation. i needed the information for biochemical analysis only for preliminary analysis as mentioned by you...!!

@ Viraj Gala:

really... I hope it would help me out...!! thank you for the valuable information. i will search for that book

yes, i like to agree with Ms. Viraj Gala, Bergey's Manual of Determinative Bacteriology would be a good reference if you have several unknown isolates and is working towards differentiating several unknowns through biochemical tests. I have used it myself to correctly identify Proteus vulgaris phenotypically.

If you are working towards a more systematic/classification approach, then Bergey's Manual of Systematic Bacteriology is also good choice.

Best Regards!

Kris Alvarez

Euro-Med Laboratories

Hey Thanks Mehvish & Kris!! And All the best Sudheer! :)

thank you very much for the invaluable information.

simply identifection S. aureus via chromogenic agar preapering from oxoid company /UK or strip antibiodies S. aureus and the culture antigen when the reaction is positive

what about specific identification of S.aureus with PCR? which gen is the most specific for PCR, Nuc gene? protein A gene, Coagulase factor gene? of any other? I would appreciate if any one suggest the best one.

Thanks in advance

Try 16S rRNA..You should be able to find primers from articles..

Simple and a basic biochemical screening test could be useful I guess. Streak your suspected cocci on the Mannitol Salt Agar. If the media turns yellow, it is S. aureus, if it remains red, then it is S. epidermidis probably! We use this test in our lab to ensure the culture is still uncontaminated! Hope this helps ;)