Re: ERROR ON RESULTS FOR BLOOD AGAR, DNASE, AND MANNITOL SALT AGAR

Dear Sara,

Staphylococcus epidermidis is a member of the bacterial genus Staphylococcus, consisting of Gram-positive cocci arranged in clusters. It is catalase-positive and coagulase-negative and occurs frequently on the skin of humans and animals and in mucous membranes. It is a facultative anaerobe that grows by aerobic respiration or by fermentation. It is sensitive to the antibiotic Novobiocin; a feature that distinguishes it from the other common coagulase negative organism S. saprophyticus.

I do not know how are you conducting your tests. Sometimes, these tests give false positive or false negative results and in that case you need to repeat the tests.

Also, this may be a case of contamination, as S. epidermis is present on our skin and in mucous membranes. Due to contamination, S. epidermidis is probably the most common species found in laboratory tests.

I suggest that you repeat the tests, this time taking great care to avoid any contamination.

Best of luck,

Shashank