Excerpt. Staphylococcus epidermidis is a coagulase-negative, gram-positive cocci bacteria that form clusters. It is also a catalase-positive and facultative anaerobe. They are the most common coagulase-negative Staphylococcus species that live on the human skin.

Biochemical Test and Identification of Staphylococcus epidermidis

Coagulase testing is the single most reliable method for identifying Staphylococcus aureus [9]. Coagulase production can be detected using either the slide coagulase test (SCT) or the tube coagulase test (TCT).

Identification. The normal practice of detecting S. epidermidis is by using appearance of colonies on selective media, bacterial morphology by light microscopy, catalase and slide coagulase testing. Zobell agar is useful for the isolation of Staphylococcus epidermidis from marine organisms.

Most strains of S. epidermidis make acetoin, phosphatase and reduce nitrate. With oxygen, all strains can produce acid when exposed to glucose, fructose, maltose, sucrose, and glycerol and 70%-90% with galactose, mannose, and lactose.

Abstract. Urease is a virulence factor for the Gram-positive urinary tract pathogen Staphylococcus saprophyticus.

aureus isolates, 17 (85%) were found as positive for coagulase, catalase, methylene red, Voges-proskauer and hemolysis tests and negative for oxidase and indole tests.

epidermidis, another species of pathogenic CoNS, by testing for susceptibility to the antibiotic novobiocin. S. saprophyticus is novobiocin-resistant, whereas S. epidermidis is novobiocin-sensitive.

aureus is often hemolytic on blood agar; S. epidermidis is non hemolytic. Staphylococci are facultative anaerobes that grow by aerobic respiration or by fermentation that yields principally lactic acid. The bacteria are catalase-positive and oxidase-negative.

In the methyl red test (MR test), the test bacteria is grown in a broth medium containing glucose. If the bacteria has the ability to utilise glucose with production of a stable acid, the colour of the methyl red changes from yellow to red, when added into the broth culture.

epidermidis is confirmed; trehalose positive, mannitol negative, S. caprae is suspected; trehalose negative, mannitol positive, S. capitis subsp….TABLE 1.

multiplex PCR
aureus and Staph. epidermidis. Accordingly, a multiplex PCR was developed and we found that a single gene encoding the adhesin fibrinogen binding protein could be used to identify and differentiate the two species. Consequently, a multiplex reaction combining a triplex PCR for Staph.

The lab instructor suggested that the Mannitol Salt Agar gave a false positive and that other tests should be ran. Methyl Red was the next biochemical test to be done, which the result was positive for glucose fermentation and mixed acids. The Urea test was the final test.

The tests ran on the Gram-positive unknown ( Staphylococcus epidermidis) were as followed: Mannitol Salt Agar, Methyl Red, Catalase, and Urea. The observations after the incubation on the Mannitol Salt Agar concluded that the bacterium ferments mannitol.

Observe for any changes in the color. (8, 9, 10) The Methyl Red Test is positive if the culture medium turns red after adding methyl red.

Incubate at 35 to 37 degree Celsius for 24 hours or up to four days. Add five drops or at least 1 ml of methyl red indicator solution to the test tube. Re-incubate the remaining broth for at least 24 hours and add at least three drops of methyl red indicator.