Staphylococcus and Streptococcus are the two most common pathogenic gram-positive cocci of medical importance. They share some important properties.
Common characteristics shared by these gram-positive cocci are:
- Nonmotile,
- Non-sporing,
- Facultative anaerobes
Some of the major differences between Staphylococcus and Streptococcus are summarized in the table below.
| Characteristic | Staphylococcus | Streptococcus |
| Shape | Gram-positive cocci in clusters (grape-like) because cell division occurs in various directions on multiple axes. Gram-positive cocci in pairs, tetrads, and short chains are also seen. | Streptococci are either Gram-positive cocci in pairs (S. pneumoniae) or short chains (S. pyogenes). This is because the cell division occurs on a single axis. |
| Catalase Test (Most Important test to differentiate Staph from Strep) | Staphylococci are catalase-positive (presence of catalase enzyme) | Streptococci are catalase negative |
| Growth Requirement | Staphylococci are not fastidious (does not need enriched media) | Streptococci are fastidious (need enriched media); so they cant grow in nutrient agar and need blood agar for growth. |
| Hemolysis | Staphylococci give no hemolysis or beta hemolysis. | Species of Streptococci are able to show any types of hemolysis (alpha or beta or gamma hemolysis). Hemolysis is a helpful tool to differentiate species of Streptococcus |
| Common habitat | Staphylococci are commensal of skin and anterior nares | Streptococci are found mainly in the mouth and respiratory tract as a commensal |
| Common diseases | Staphylococci mostly cause wound infections. Other diseases caused by this organism are osteomyelitis, acute endocarditis, septic arthritis, surgical site infection, interstitial pneumonia, etc. | Pathogenic species of streptococci cause pneumonia, meningitis, sore throat, wound infection, necrotizing fasciitis, scarlet fever, rheumatic fever, acute post-streptococcal glomerulonephritis |
| Most pathogenic species | Staphylococcus aureus Staphyloccus saprophyticus (in females for causing UTI) | Streptoccus pneumoniae Streptoccus pyogenes Streptococcus agalactiae |
| Useful diagnostic tests | Catalase test Coagulase test Novobiocin sensitivity test | Catalase test Bacitracin sensitivity test (S. pyogenes) Optochin sensitivity test (S. pneumoniae) Bile solubility test (S. pneumoniae) CAMP test (S. agalactiae) |
References
- Causey W. A. (1979). Staphylococcal and streptococcal infections of the skin. Primary care, 6(1), 127–139.
- Kherabi, Y., Zeller, V., Kerroumi, Y., Meyssonnier, V., Heym, B., Lidove, O., & Marmor, S. (2022). Streptococcal and Staphylococcus aureus prosthetic joint infections: are they really different?. BMC infectious diseases, 22(1), 555. https://doi.org/10.1186/s12879-022-07532-x
- Moreillon, P., Que, Y. A., & Bayer, A. S. (2002). Pathogenesis of streptococcal and staphylococcal endocarditis. Infectious disease clinics of North America, 16(2), 297–318. https://doi.org/10.1016/s0891-5520(01)00009-5
- Madigan Michael T, Bender, Kelly S, Buckley, Daniel H, Sattley, W. Matthew, & Stahl, David A. (2018). Brock Biology of Microorganisms (15th Edition). Pearson.
