Staphylococcus Epidermidis

About the Microbe

Staphylococcus epidermidis is usually not pathogenic and is normally present on human skin and is part of our natural microflora. However, it can become pathogenic if it breaks through the skin barrier, which can happen in hospitals. S. epidermidis infections can spread through the body if they enter the bloodstream, so it is important to prevent these infections. Using proper aseptic techniques such as washing hands, changing gloves often, and sterilizing equipment when treating patients in a hospital can help prevent these bacteria from entering the body and causing an infection (1). S. epidermidis is important to us because although it is part of our skin’s natural microflora, it is very important to take precautions in a hospital setting to prevent this bacterium from entering the bloodstream and causing an infection in patients (1).

The first discovery of Staphylococcus epidermidis was by Friedrich Julius Rosenbach in 1884 (3). He was able to distinguish this bacterium from S. aureus because they form different colored colonies. S. epidermidis was initially named S. albus due to its white color that distinguished it from the gold S. aureus, but the name was changed eventually because it is commonly found on human skin (4).

Taxonomy

Domain: Bacteria

Phylum: Firmicutes

Class: Bacilli

Order: Bacillales

Family: Staphylococcaceae

Genus: Staphylococcus

Species: Staphylococcus epidermidis (5)

Growing the Microbe

Staphylococcus epidermidis is a BSL level 1 microbe. This microbe should be grown in nutrient agar or nutrient broth in aerobic conditions.
The propagation procedure was provided on the product sheet from AATC. When the product arrives, first open the vial of S. epidermidis by following the enclosed instructions. Using a Pasteur or 1.0 mL pipette, withdraw 0.5 to 1.0 mL from one tube of nutrient broth, labeled #3 broth. Use this broth to rehydrate the pellet, then transfer the contents of the vial back into the broth tube using aseptic techniques. Mix the tube thoroughly. This suspension can be used to inoculate the sample on a #3 nutrient agar slant and/or plate. The tubes and plate should be incubated for 24 hours at 37°C (6).

Visualizing the Microbe

Figure 1: This is a gram stain of Staphylococcus epidermidis (7). By looking at this figure, we can see that this bacterium is gram positive due to the purple color indicative of a thick peptidoglycan layer in the cell wall. The morphology of the cells is coccus and they are present primarily in clusters.

Figure 2: This is an image of a biofilm of Staphylococcus epidermidis under a scanning electron microscope (8). There was no chemical preparation done to this biofilm and the sample was air dried.

Figure 3: This figure depicts the growth of a Staphylococcus epidermidis biofilm visualized under a confocal laser scanning microscope (9). A live/dead stain was used in which green areas indicate live bacteria and red areas indicate dead bacteria.

Diagnostic Tests

Blood Agar

There is no transparent zone in the media around the colonies, so S. epidermidis is gamma-hemolytic (10).

MacConkey Agar

S. epidermidis will not grow on MacConkey Agar because it is gram positive. This is an image of S. aureus showing no growth on MacConkey agar, but the results for this test are the same for both species (11).

Mannitol Salt Agar

Since S. epidermidis is salt tolerant (6.5% NaCl) but mannitol negative, it will grow on the plate but the color of the media will not change and the colonies will be colorless. This is a comparison of S. epidermidis (pink) with S. aureus, which turns the media yellow because it is mannitol positive (12).

DNAse Test

S. epidermidis is DNase negative, so there will not be a colorless zone in the media present around the colonies (right). This image compares it to S. aureus, which is DNase positive and has a colorless zone (left) (13).

Gram Stain

S. epidermidis is gram positive, so it stains purple due to the thick peptidoglycan layer in its cell wall. It is also a coccus bacterium that grows mainly in clusters, which can be seen in the gram stain (14).

Phenol Red Broth

S. epidermis ferments glucose but would not produce gas, so the phenol red broth would be yellow but there would not be a bubble in the tube (15).

SIM Motility Test

S. epidermidis is not motile, so it would have a negative motility test and the media would be less turbid with a line of growth down the middle of the tube (16).

Catalase Test

S. epidermidis is catalase positive, so it would produce bubbles during the catalase test (17).

Oxidase Test

S. epidermidis is oxidase negative so it would remain colorless or possibly a very light shade of pink/purple during the oxidase test (18).

Molecular Diagnostics

Primers:

- Forward primer: 16S3 up
  - Sequence: ATGCAAGTCGAGCGAAC (19)
  - Melting temperature: 47.1 °C (20)
  - GC content: 53% (20)
- Reverse Primer: 16S3 down
  - Sequence: TGTCTCAGTTCCAGTGTGGC(19)
  - Melting temperature: 53.8 °C (20)
  - GC content: 55% (20)

16S partial sequence in FASTA format (21):
>NC_004461, from 1599222 to 1599503 (282 bp); Staphylococcus epidermidis ATCC_12228 TGTCTCAGTTCCAGTGTGGCCGATCACCCTCTCAGGTCGGCTACGCATCGTTGCCT TGGTAAGCCGTTACCTTACCAACTAGCTAATGCGGCGCGGATCCATCTATAAGTGAC AGCAAAACCGTCTTTCACTATTGAACCATGCGGTTCAATATATTATCCGGTATTAGCTC CGGTTTCCCGAAGTTATCCCAGTCTTATAGGTAGGTTATCCACGTGTTACTCACCCGT CCGCCGCTAACGTCAGAGGAGCAAGCTCCTCATCTGTTCGCTCGACTTGCAT

16S full sequence in FASTA format (22):
>Staphylococcus epidermidis, NBRC100911T, 16S rDNA, CC00765101, AB681292 GATGAACGCTGGCGGCGTGCCTAATACATGCAAGTCGAGCGAACAGACGAGGAGC TTGCTCCTCTGACGTTAGCGGCGGACGGGTGAGTAACACGTGGATAACCTACCTATA AGACTGGGATAACTTCGGGAAACCGGAGCTAATACCGGATAATATATTGAACCGCAT GGTTCAATAGTGAAAGACGGTTTTGCTGTCACTTATAGATGGATCCGCGCCGCATTA GCTAGTTGGTAAGGTAACGGCTTACCAAGGCAACGATGCGTAGCCGACCTGAGAGG GTGATCGGCCACACTGGAACTGAGACACGGTCCAGACTCCTACGGGAGGCAGCAG TAGGGAATCTTCCGCAATGGGCGAAAGCCTGACGGAGCAACGCCGCGTGAGTGAT GAAGGTCTTCGGATCGTAAAACTCTGTTATTAGGGAAGAACAAATGTGTAAGTAACTA TGCACGTCTTGACGGTACCTAATCAGAAAGCCACGGCTAACTACGTGCCAGCAGCC GCGGTAATACGTAGGTGGCAAGCGTTATCCGGAATTATTGGGCGTAAAGCGCGCGTA GGCGGTTTTTTAAGTCTGATGTGAAAGCCCACGGCTCAACCGTGGAGGGTCATTGG AAACTGGAAAACTTGAGTGCAGAAGAGGAAAGTGGAATTCCATGTGTAGCGGTGAA ATGCGCAGAGATATGGAGGAACACCAGTGGCGAAGGCGACTTTCTGGTCTGTAACT GACGCTGATGTGCGAAAGCGTGGGGATCAAACAGGATTAGATACCCTGGTAGTCCA CGCCGTAAACGATGAGTGCTAAGTGTTAGGGGGTTTCCGCCCCTTAGTGCTGCAGC TAACGCATTAAGCACTCCGCCTGGGGAGTACGACCGCAAGGTTGAAACTCAAAGGA ATTGACGGGGACCCGCACAAGCGGTGGAGCATGTGGTTTAATTCGAAGCAACGCGA AGAACCTTACCAAATCTTGACATCCTCTGACCCCTCTAGAGATAGAGTTTTCCCCTTC GGGGGACAGAGTGACAGGTGGTGCATGGTTGTCGTCAGCTCGTGTCGTGAGATGT TGGGTTAAGTCCCGCAACGAGCGCAACCCTTAAGCTTAGTTGCCATCATTAAGTTGG GCACTCTAAGTTGACTGCCGGTGACAAACCGGAGGAAGGTGGGGATGACGTCAAAT CATCATGCCCCTTATGATTTGGGCTACACACGTGCTACAATGGACAATACAAAGGGN AGCGAAACCGCGAGGTCAAGCAAATCCCATAAAGTTGTTCTCAGTTCGGATTGTAGT CTGCAACTCGACTATATGAAGCTGGAATCGCTAGTAATCGTAGATCAGCATGCTACGG TGAATACGTTCCCGGGTCTTGTACACACCGCCCGTCACACCACGAGAGTTTGTAAC ACCCGAAGCCGGTGGAGTAACCATTTGGAGCTAGCCGTCGAAGGTGGGACAAATGATTGGGGTGAAG

Disease and Treatment

Staphylococcus epidermidis only becomes infectious when it breaches the skin barrier and enters the bloodstream, and these infections can then spread throughout the body (1). It is especially dangerous if patients who are already immunocompromised develop a S. epidermidis infection (2). S. epidermidis has the ability to form biofilms, which can help it cling to surfaces in a hospital such as catheters or IVs and cause an infection in the patient (1). Methicillin can be used to treat some S. epidermidis infections, but some strains of this bacterium are methicillin resistant. Methicillin-resistant S. epidermidis infections are typically treated with vancomycin and either rifampin or gentamicin, or possibly all three of these drugs combined. It is also important to remove any medical devices still in the patient that may be covered in biofilms (2).

References

Otto M. 2009. Staphylococcus epidermidis — the “accidental” pathogen. Nature Reviews Microbiology 7:555–567.
https://www.nature.com/articles/nrmicro2182#:~:text=Staphylococcus%20epidermidis%20is%20a%20common,indwelling%20medical%20device%2Dassociated%20infections.
Blum RA, Rodvold KA. 1987. Recognition and importance of Staphylococcus epidermidis infections. Clin Pharm 6:464–475.
https://pubmed.ncbi.nlm.nih.gov/3319361/#:~:text=Virtually%20all%20Staph.,epidermidis %20infections.
Rosenbach, F.J. 1884. Microorganisms in the Wound Infections Diseases of Man. J.F. Bergmann, Wiesbaden, 18.
Licitra, Giancarlo. 2013. Etymologia: Staphylococcus. Emerging Infect Dis. vol. 19, no. 9, p. 1553. doi:10.3201/eid1909.ET1909.
Taxonomy browser (Staphylococcus epidermidis). https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=1282
Staphylococcus Epidermidis (Winslow and Winslow) Evans ATCC ® 1222. https://www.atcc.org/products/all/12228.aspx#culturemethod. Accessed 23 Sept. 2020.
Uribe-Alvarez C., Chiquete-Félix N., Contreras-Zentella M., Guerrero-Castillo S., Peña A., Uribe-Carvajal S. 2015. Staphylococcus epidermidis: metabolic adaptation and biofilm formation in response to different oxygen concentrations. FEMS Pathogens and Disease.
Hrubanova K., Krzyzanek V., Nebesarova J., Ruzicka F., Pilat Z., Samek O. 2018. Monitoring Candida parapsilosis and Staphylococcus epidermidis Biofilms by a Combination of Scanning Electron Microscopy and Raman Spectroscopy. Sensors 18:4089.
Cerca N, Gomes F, Pereira S, Teixeira P, Oliveira R. 2012. Confocal laser scanning microscopy analysis of S. epidermidis biofilms exposed to farnesol, vancomycin and rifampicin. BMC Res Notes 5:244.
Staphylococcus epidermidis under microscope: microscopy of Gram-positive cocci, morphology and microscopic appearance of Staphylococcus epidermidis, S.epidermidis gram stain and colony morphology on agar, clinical significance. https://www.microbiologyinpictures.com/bacteriainphotos/bacteria%20under%20microscope/staphylococcus%20epidermidis%20microscopy.html
Aryal S. 2015. MacConkey Agar- Composition, Principle, Uses, Preparation and Colony Morphology. Microbiology Info.com. https://microbiologyinfo.com/macconkey-agar-composition-principle-uses-preparation-and-colony-morphology/
Staphylococcus aureus and Staphylococcus epidermidis on Mannitol Salt Agar. Mannitol salt agar composition. Positive and negative result on mannitol salt agar. http://www.bacteriainphotos.com/Mannitol_Salt_Agar.html
2019. Deoxyribonuclease (DNase) Test - Procedure, Uses and Interpretation. Microbiology Info.com. https://microbiologyinfo.com/deoxyribonuclease-dnase-test/
Uribe-Alvarez C, Chiquete N, Contreras M, Guerrero-Castillo S, Peña A, Uribe-Carvajal S. 2015. Staphylococcus epidermidis : Metabolic adaptation and biofilm formation in response to different Oxygen Concentrations. Pathogens and Disease 74:ftv111. https://www.researchgate.net/figure/Characterization-of-S-epidermidis-ATCC-12228-A-Gram-stain-was-performed-using-a-kit_fig1_284791317
Tankeshwar A. 2016. Carbohydrate Fermentation Test: Uses, Principle, Procedure and Results. Learn Microbiology Online. https://microbeonline.com/carbohydrate-fermentation-test-uses-principle-procedure-results/
2019. Motility Test - Principle, Procedure, Uses and Interpretation. Microbiology Info.com. https://microbiologyinfo.com/motility-test/
Tankeshwar A. 2013. Catalase test: Principle, Procedure, Results and Applications. Learn Microbiology Online. https://microbeonline.com/catalase-test-principle-uses-procedure-results/
2015. Oxidase Test- Principle, Uses, Procedure, Types, Result Interpretation... Microbiology Info.com. https://microbiologyinfo.com/oxidase-test-principle-uses-procedure-types-result-interpretation-examples-and-limitations/
Skow Á, Mangold KA, Tajuddin M, Huntington A, Fritz B, Thomson RB, Kaul KL. 2005. Species-Level Identification of Staphylococcal Isolates by Real-Time PCR and Melt Curve Analysis. Journal of Clinical Microbiology 43:2876–2880. https://jcm.asm.org/content/43/6/2876
OligoCalc: Oligonucleotide Properties Calculator.
http://biotools.nubic.northwestern.edu/OligoCalc.html
In silico PCR amplification. http://insilico.ehu.es/PCR/
NCBI Blast:NC_004461 Staphylococcus epidermidis ATCC_12228. https://blast.ncbi.nlm.nih.gov/Blast.cgi#alnHdr_631252759

About the Researcher

Hi! My name is Gabriella Chehaitli and I'm from Daytona Beach, Florida. I'm a third year Microbiology and Chemistry major on the pre-med track at the University of Florida. Some things I enjoy are traveling and rock climbing.

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