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) |
this good but i want to ask you this question in the butt of a TSI gas production is evidenced by want?
Thanks so much it was a great short and very good overview exactly what I was searching
Test result of a wound culture:
MANY STREPTOCOCCI, ALPHA HEMOLYTIC
MANY STAPHYLOCOCCUS SPECIES, NOT AUREUS
What does this mean? I got this on a Friday and the Dr is out until Monday. Thank you.
Hello Eric, Streptococcus genus contains both beta-hemolytic and alpha hemolytic species. S. pyogenes and S.agalactiae are beta-hemolytic but S.pneumoniae and viridans streptococci (common name for various Streptococci species that gives alpha hemolysis) are alpha hemolytic. In Staphylococci, S.aureus is the pathogenic one but S. epidermidis, S. saprophyticus are mostly commensal (normal flora) and occasionally be pathogenic. So common phrase Coagulase Negative Staphylococci (CONS) is used for them; (S. aureus is coagulase positive).