Hi Sumaira

For your question ,after you standerized the MRSA suspension, dilute it to the required dilution.

500,000-fold dilution

This would have to be done in stages.

For example, start with a 100-fold dilution (10 µl into 1 ml, for example).

Then dilute the 100-fold dilution by another 100-fold, which brings it to 10,000-fold.

Then dilute the 10,000-fold dilution by 50-fold to get to 500,000-fold.

thank you so much seniors for your valuable answers.it helps alot.