Difference Between Staphylococcus Epidermidis and Staphylococcus Saprophyticus

The main difference between Staphylococcus epidermidis and Staphylococcus saprophyticus is that Staphylococcus epidermidis is sensitive to novobiocin whereas Staphylococcus saprophyticus is resistant to novobiocin. In addition, S. epidermidis forms bright-white, creamy colonies while S. saprophyticus forms white-yellow colonies on both blood agar and nutrient agar.

S. epidermidis and S. saprophyticus are non-hemolytic and coagulase-negative bacterial species. S. epidermidis causes hospital-acquired infections while S. saprophyticus causes community-acquired urinary tract infections.

Key Areas Covered

1. What is Staphylococcus Epidermidis
     – Definition, Facts, Infections
2. What is Staphylococcus Saprophyticus
     – Definition, Facts, Infections
3. What are the Similarities Between Staphylococcus Epidermidis and Staphylococcus Saprophyticus
     – Outline of Common Features
4. What is the Difference Between Staphylococcus Epidermidis and Staphylococcus Saprophyticus
     – Comparison of Key Differences

Key Terms

Normal Flora, Novobiocin, Staphylococcus, Staphylococcus epidermidis, Staphylococcus saprophyticus

What is Staphylococcus Epidermidis

Staphylococcus epidermidis is a bacterial species that belongs to the genus Staphylococcus. It is part of the skin flora and is also found in the mucous membranes. Generally, S. epidermidis is not pathogenic. But, it becomes an opportunistic pathogen in patients with compromised immune systems. Therefore, the S. epidermidis infections are hospital-acquired. It infects patients with catheters or other surgical implants. Also, it forms biofilms that grow on these devices. After overnight incubation, S. epidermidis forms white, raised, cohesive colonies that are about 1–2 mm in diameter.

Figure 1: S. epidermidis Colonies on Tryptic Soy Agar

S. epidermidis does not produce gelatinase enzyme required by the hydrolysis of gelatin. Therefore, it is sensitive to novobiocin. This makes the novobiocin test critical in the differentiation between S. epidermidis and S. saprophyticus, which is novobiocin-resistant.

What is Staphylococcus Saprophyticus

Staphylococcus saprophyticus is another species of the Staphylococcus genus. Since S. saprophyticus belongs to the normal flora of the female genital tract and perineum, it often causes urinary tract infections (UTIs) in females. Generally, 10-20% UTIs occur due to S. saprophyticus. Also, it is the second commonest cause of community-acquired UTIs. The risk of the infection increases by sexual activities. As patients infected by S. saprophyticus always have symptomatic cystitis,  this infection is called honeymoon cystitis.

Figure 2: S. saphrophyticus on Mueller-Hinton Agar Exhibiting Resistance to Novobiocin

Similarities Between Staphylococcus Epidermidis and Staphylococcus Saprophyticus

• S. epidermidis and S. saprophyticus are two types of Staphylococcus species that belong to the normal flora of animals.
• Both are saprotrophs or commensals.
• They are gram-positive bacteria arranged in clusters.
• Both are facultative anaerobes that use either aerobic or anaerobic fermentation.
• They are Catalase-positive, coagulase-negative, and non-hemolytic.
• They form opaque, smooth, raised, entire colonies.
• Both cause infections.

Difference Between Staphylococcus Epidermidis and Staphylococcus Saprophyticus

Definition

Staphylococcus epidermidis is a gram-positive bacterium, which is a part of the skin flora whereas, Staphylococcus saprophyticus is a bacterium in the Staphylococcus genus that cause urinary tract infections.

Colony Color

The colonies of Staphylococcus epidermidis are bright-white and creamy and that of Staphylococcus saprophyticus are white-yellow and glossy.

Novobiocin Test

Staphylococcus epidermidis is sensitive to novobiocin and the zone size is greater or equal to 16 mm whereas, Staphylococcus saprophyticus is resistant to novobiocin and the zone size is less than 12 mm.

Habitat

Skin flora is the habitat of Staphylococcus epidermidis while that of Staphylococcus saprophyticus is the normal flora of the female genital tract and perineum.

Pathogenicity

Staphylococcus epidermidis is the opportunistic pathogen and less pathogenic. Staphylococcus saprophyticus is pathogenic.

Infections

Staphylococcus epidermidis is a hospital-acquired infection while Staphylococcus saprophyticus causes community-acquired urinary tract infections.

Conclusion

Staphylococcus epidermidis is a bacterium of Staphylococcus genus, which is sensitive to novobiocin. But, Staphylococcus saprophyticus, which is in the same genus, is resistant to novobiocin. Both species are coagulase-negative. Also, they are non-hemolytic. The main difference between Staphylococcus epidermidis and Staphylococcus saprophyticus is the sensitivity to the novobiocin test.

Reference:

1. “Staphylococcus Epidermidis.” Chlamydia Trachomatis, Available Here
2. Ehlers, Sarah. “Staphylococcus Saprophyticus.” Advances in Pediatrics., U.S. National Library of Medicine, 26 Jan. 2018, Available Here

Image Courtesy:

1. “Staphylococcus epidermidis colonies on Tryptic Soy Agar” By HansN. – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Ssaphrophyticus-Novobiocin” By Deminorwood – Own work (CC BY-SA 4.0) via Commons Wikimedia