We have not had any difficulty growing Staphylococcus aureus on MH agar.  You may want to check whether there is a contaminant in the MH agar source, or double check to make sure the temperature is not too high.  Instead of 37 degrees C you might try 35 as Sa does like it a little cooler.

Staph aureus sometimes does grow a little slower and 48 hours might be an appropriate time to check for growth.  Also, Staph aureus is often a yellow (or golden/aureus) color instead of white (Staph epidermidis is white).

Thank you for your answer! We grow Staph aureus on Nutrient Agar first, no problem. Later we grow it in Nutrient Broth, no problem. Then we grow it on Mueller Hinton Agar from Nutrient Broth, there was no white colonies grow as I have seen in Nutrient Agar. All clear... Maybe the temperature is high.. I have grown it for 48 hours but it still clear. Thanks again for your answer

Check the growth subculturing on blood agar.

If growth is good on blood agar, do the lawn culture (spread) on mueller hinton agar (MHA) directly for susceptibility.  I have never come across the problem you have faced for S. aureus.

We had not faced any trouble in growing S. aureus on MH broth. hence it should grow on MH agar. increase incubation time may give you results.

it is recommended for Srep. agalactiae to add 5% calf serum to grow on MH broth, the same may be for agar.

Dear Ayu...

We are also not facing  any difficulty growing Staphylococcus aureus on MH agar.  You may want to check whether there is a contaminant in the MH agar source, or double check to make sure the temperature is not too high.  Instead of 37 degrees C you might try 35 as Sa does like it a little cooler.

Sometimes s.aureus will grow slowly so incubate your plate for 48hrs then check it. 

I have successfully grown S.aureus on Mueller Hinton Agar and the form of colonies differ with the one on Nutrient Agar. The only problem is, the colonies are more faint haze on MHA than NA. Thank you for all of answers.

You might want to consider getting a new bottle of the Mueller Hinton Agar and see if a fresh bottle grows the Sa better.  In other words, it is possible your MH Agar may be bad because of age, heat while it was being shipped, moisture damage......  Try a fresh supply to see if that helps.

Hi,

Sometimes S aureus require longer incubation time means it grow slowly, you can check it after 48 hours rather than 24 hours. Secondly, you should use fresh media to check difference from older one.

Dear Auy,

No problem strains of S aureus can produce different colonies on different media. It is not necessary either a strain produce similar colony on MHA and NA.

Dear Ayu,

                          At what temperature did you incubate ?

S. aureus SHOULD grow on MHA. Verify your stock is viable by using a larger inoculum and allowing a longer incubation period @ 37C, as previously suggested.

Do make sure your incubator is set at the correct temperature, AND that the internal temperature is actually correct.  Sometimes incubators can run warmer than set, or be warmer toward the top, or if overfilled can have differences in different areas.

Hello Anuradha,

It is 37 Celcius

Then you should check viability of the test strain, temperature of the incubator by thermometer  .

Was it an ATCC strain ? or a clinical strain?

Hope you have QC checked the particular batch of MHA plates and hope they are OK. One possibility is viability of organisms in inoculum. Was the inoculum prepared from culture material on an old plate or was it a fresh log phase culture? Have you looked at a smear of the inoculm to see if bacteria are there in adequate nos and match the morphology of S. aureus ? How was the plating done - using an inoculation loop or L rod or any other device If you had flamed the loop or L rod and then used it too soon before it could cool down, then that could have impacted the viability of few microliters of the inoculum seeded on the plate. Besides, as others have pointed out issues with temperature  is a  possibility especially when it is at a range above 39C. 

Best Wishes

Girish

s.aurous absolutely should grow on muller hinton agar. Maybe it is better that you have some positive and negative control for checking the conditions of growth.Sometimes it happens that the medium you have bought has a problem,so you should do quality control with standard species for your MHA medium before and also for you incubator and so on. It is recommended that have cultur of your bacteria on some other medium like blood agar and emb agar for khnowing that they are live. Moreover you can use of some other bacteria or another s.aureous for finding and solving the problem.

 Dear Ayu

May kindly monitor the environmental factor (Temprature) of an incubator and assure the viability of your culure (S. aureus). S. aureus growth occur well on Muller Hinton Agar. At present, we have monitored the culture sensitivity of S. hemolyticus Co aggulase negative.

you are therefore suggested to monitor the media and use fresh culture as well.

Thanks for all answers. I will try to grow them on new MHA from another supplier, I think it is because of the medium i have bought got damaged, otherwise, I will grow them on MHA with blood. 

Dear colleague,

I had the same problem but with coagulase negative staphylococci. Since there was repeated failure of the organism to grow on Muller Hinton agar although it was strong catalase positive and appeared as gram positive cocci arranged in groups and triads, tetrads...etc, I wanted to be sure and I identified the isolate using the Vitek2C and it was a Staphylococcus hominis. 

I thought that the problem might be in the Muller Hinton agar because it was from a different supplier or it might be because the organism is slow grower. 

I will have to compared the susceptibility using two different Muller Hinton agar plates from different suppliers before concluding that it was a slow grower.

Dear all

Once I found the same problem with S.aureus, which did not grow on Muller Hinton agar at 37 degree celsius. Later I tried sensitivity on Blood agar plate provided microaerophilic condition in a candle jar and got sensitivity result.