Staphylococcus vs Streptococcus- 20 Major Differences
Staphylococcus and Streptococcus are two genera of bacteria that belong to the phylum Firmicutes, which are characterized by having a thick layer of peptidoglycan in their cell wall. They are also Gram-positive, meaning that they retain the purple dye when stained with Gram stain, a technique used to classify bacteria based on their cell wall structure.
Staphylococcus and Streptococcus are both pathogenic cocci, which are spherical or oval-shaped bacteria that can cause various infections in humans and animals. They are among the most common causes of bacterial diseases worldwide, affecting different parts of the body such as the skin, respiratory tract, urinary tract, blood, and nervous system.
Staphylococcus and Streptococcus are both non-motile, non-sporing, and facultative anaerobes. This means that they do not have flagella or other structures for movement, they do not form endospores or dormant forms that can resist harsh conditions, and they can grow in the presence or absence of oxygen. However, there are some differences in their metabolic and biochemical characteristics that affect their growth and pathogenicity.
- Non-motile: Both Staphylococcus and Streptococcus lack flagella or other structures to move. However, some species of Staphylococcus can exhibit a type of movement called spreading or sliding motility on solid media. This is due to the production of extracellular polysaccharides or surfactants that reduce the surface tension and allow the bacteria to glide over the surface. Streptococcus does not show this type of movement.
- Non-sporing: Both Staphylococcus and Streptococcus do not form endospores to survive harsh conditions. Endospores are highly resistant structures that some bacteria produce when they encounter unfavorable environmental factors such as nutrient depletion, temperature extremes, or desiccation. Endospores can remain dormant for long periods of time and germinate when conditions become favorable again. Staphylococcus and Streptococcus do not have this ability and are more susceptible to physical and chemical agents that can damage their cell walls or membranes.
- Facultative anaerobes: Both Staphylococcus and Streptococcus can grow in the presence or absence of oxygen. However, they have different preferences and abilities to use oxygen as an electron acceptor in their metabolism. Staphylococcus is more tolerant to oxygen and can use it as a terminal electron acceptor in aerobic respiration. It can also use nitrate as an alternative electron acceptor in anaerobic respiration. Streptococcus is more sensitive to oxygen and cannot use it as a terminal electron acceptor in aerobic respiration. It relies on fermentation as its main metabolic pathway in both aerobic and anaerobic conditions. Fermentation produces organic acids such as lactic acid, which lower the pH of the environment and inhibit the growth of other bacteria.
These differences in their characteristics as non-motile, non-sporing, and facultative anaerobes influence their growth patterns, colony morphology, hemolytic activity, and virulence factors. They also help to differentiate them from other Gram-positive cocci such as Enterococcus and Micrococcus.
Staphylococcus and Streptococcus are both Gram-positive cocci that can cause various infections in humans and animals. However, they have some distinctive features that can help differentiate them based on their morphology, physiology, biochemistry, and pathogenicity. Some of the major differences are:
- Arrangement: Staphylococcus forms grape-like clusters due to its multiple axes of cellular division, while Streptococcus forms chains of round cells due to its single axis of division.
- Catalase Test: Staphylococcus is catalase-positive, meaning it can produce an enzyme that converts hydrogen peroxide to water and oxygen gas. This causes bubbles to form when hydrogen peroxide is added to a staphylococcal culture. Streptococcus is catalase-negative, meaning it lacks this enzyme and does not produce bubbles.
- Enriched Media: Staphylococcus does not need enriched media to grow, as it is not fastidious and can use a variety of substrates for energy. Streptococcus needs enriched media, such as blood agar or chocolate agar, to grow, as it is fastidious and requires certain nutrients and growth factors.
- Habitat: Staphylococcus is commonly found on the skin and mucous membranes of humans and animals, where it can form part of the normal flora or cause opportunistic infections. Streptococcus is mainly found in the respiratory tract of humans and animals, where it can cause respiratory infections or spread to other sites.
- Hemolysis: Staphylococcus can cause either no hemolysis (gamma-hemolysis) or complete hemolysis (beta-hemolysis) of red blood cells on blood agar plates. Streptococcus can cause either partial hemolysis (alpha-hemolysis), complete hemolysis (beta-hemolysis), or no hemolysis (gamma-hemolysis) of red blood cells on blood agar plates.
- Species Number: There are about 40 staphylococcal species identified so far, of which Staphylococcus aureus is the most pathogenic and clinically significant. There are about 50 streptococcal species identified so far, of which Streptococcus pyogenes and Streptococcus pneumoniae are the most pathogenic and clinically significant.
- Pathogenesis: Staphylococcus can cause a wide range of infections, such as food poisoning, bacterial conjunctivitis, skin diseases, community-acquired meningitis, surgical site infection, wound infection, impetigo, cellulitis, and toxic shock syndrome. Streptococcus can also cause a variety of infections, such as strep throat, scarlet fever, impetigo, toxic shock syndrome, cellulitis and necrotizing fasciitis (flesh-eating disease), sinusitis, blood infections, pneumonia and meningitis in newborns.
- Species Differentiation: Staphylococcus species can be differentiated by various tests and characteristics, such as coagulase test, novobiocin sensitivity test, biochemical tests, etc. Streptococcus species can be differentiated by various tests and characteristics, such as type of hemolysis, cell wall carbohydrate group (A, B, C, etc), bile solubility test, CAMP test, optochin sensitivity test, etc.
These are some of the major differences between Staphylococcus and Streptococcus that can help in their identification and diagnosis.
One of the most important tests to differentiate between Staphylococcus and Streptococcus is the catalase test. Catalase is an enzyme that breaks down hydrogen peroxide into water and oxygen. Staphylococcus species produce catalase, while Streptococcus species do not. Therefore, when a bacterial culture is mixed with hydrogen peroxide, bubbles of oxygen are produced if the bacteria are Staphylococcus, but not if they are Streptococcus.
The catalase test can be performed in two ways: on a slide or in a tube. In the slide method, a small amount of bacterial culture is smeared on a glass slide and a drop of hydrogen peroxide is added. In the tube method, a few drops of hydrogen peroxide are added to a tube containing bacterial culture. In both cases, the presence or absence of bubbles indicates a positive or negative result, respectively.
Another test that can be used to further differentiate between Staphylococcus species is the coagulase test. Coagulase is an enzyme that causes blood plasma to clot by converting fibrinogen to fibrin. Staphylococcus aureus, the most pathogenic species of Staphylococcus, produces coagulase, while other Staphylococcus species do not. Therefore, when a bacterial culture is mixed with plasma, clotting occurs if the bacteria are Staphylococcus aureus, but not if they are other Staphylococcus species.
The coagulase test can also be performed in two ways: using free coagulase or bound coagulase. Free coagulase is secreted by the bacteria into the medium and reacts with plasma directly. Bound coagulase is attached to the bacterial cell wall and reacts with plasma only after adding an antiserum that binds to it. In both cases, the presence or absence of clotting indicates a positive or negative result, respectively.
The catalase test and the coagulase test are simple and rapid methods to distinguish between Staphylococcus and Streptococcus, as well as between different Staphylococcus species. They are useful for the diagnosis and treatment of infections caused by these bacteria.
- Staphylococcus and Streptococcus are both Gram-positive cocci that cause various infections in humans and animals.
- Staphylococcus are catalase-positive and coagulase-positive or negative, while Streptococcus are catalase-negative and coagulase-negative.
- Staphylococcus are arranged in clusters, while Streptococcus are arranged in chains or pairs.
- Staphylococcus are more resistant to antibiotics and disinfectants than Streptococcus, due to their production of beta-lactamases and biofilms.
- Staphylococcus can grow in high salt concentrations, while Streptococcus cannot.
- Staphylococcus can ferment mannitol, while Streptococcus cannot.
- Staphylococcus are divided into two main groups: Staphylococcus aureus and coagulase-negative staphylococci (CNS). Streptococcus are divided into several groups based on their cell wall carbohydrate antigens (A, B, C, etc.), hemolytic patterns (alpha, beta, gamma), and biochemical properties (pyogenic, viridans, enterococci, etc.).
- Staphylococcus aureus is the most virulent and pathogenic species of Staphylococcus, causing skin infections, abscesses, food poisoning, toxic shock syndrome, endocarditis, osteomyelitis, pneumonia, and septicemia. CNS are mainly opportunistic pathogens that cause infections in immunocompromised hosts or in association with medical devices or prosthetic implants.
- Streptococcus pyogenes (group A streptococci) is the most important species of Streptococcus, causing pharyngitis, tonsillitis, scarlet fever, rheumatic fever, impetigo, cellulitis, necrotizing fasciitis, and toxic shock-like syndrome. Other streptococci can cause dental caries, endocarditis, meningitis, pneumonia, septicemia, and urinary tract infections.
- Both Staphylococcus and Streptococcus can be isolated and identified by culture methods using selective and differential media. They can also be detected by rapid antigen tests or molecular methods such as PCR or MALDI-TOF.
- The treatment of staphylococcal and streptococcal infections depends on the type and severity of the infection, the susceptibility of the bacteria to antibiotics, and the presence of any underlying conditions or complications. Penicillins are the drugs of choice for most streptococcal infections, but some strains may be resistant due to beta-lactamases or altered penicillin-binding proteins. Methicillin-resistant Staphylococcus aureus (MRSA) is a major problem in hospitals and community settings, requiring alternative antibiotics such as vancomycin or linezolid. The prevention of staphylococcal and streptococcal infections involves good hygiene practices, wound care, infection control measures, vaccination (for some streptococcal diseases), and prophylaxis (for rheumatic fever or endocarditis).
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