What does Alpha hemolysis indicate?

What does Alpha hemolysis indicate?

Alpha hemolysis is a greenish discoloration that surrounds a bacterial colony growing on the agar. This type of hemolysis represents a partial decomposition of the hemoglobin of the red blood cells.

What does alpha hemolysis mean?

Alpha hemolysis (α) is the reduction of the red blood cell hemoglobin to methemoglobin in the medium surrounding the colony. This causes a green or brown discoloration in the medium.

What does alpha hemolysis cause?


Other synonymous terms are incomplete hemolysis and partial hemolysis. Alpha hemolysis is caused by hydrogen peroxide produced by the bacterium, oxidizing hemoglobin producing the green oxidized derivative methemoglobin.

What does gamma hemolysis indicate?

Gamma hemolysis is the third type of hemolysis reaction. It refers to the non-destruction of red blood cells. This is due to the absence of hemolysin. Organisms do not produce hemolysin enzymes that are essential for the breakdown of red blood cells.

What is the difference between beta and alpha hemolysis?

The main difference between alpha and beta hemolysis is that alpha hemolysis is involved in partial hemolysis associated with the reduction of hemoglobin in red blood cells whereas beta hemolysis is involved in the complete hemolysis of red blood cells that surround the colony.

Microbiology: Hemolysis/Blood Agar

What is the difference between alpha and beta hemolysis on red blood cells 2 on blood agar plates?

In alpha hemolysis, red blood cells break down completely. In beta hemolysis, red blood cells break down partially. Alpha Hemolysis indicates the production of clear zones around the bacterial colonies on blood agar plates. Beta Hemolysis indicates greenish colour around the bacterial growth in blood agar plates.

Is alpha hemolysis pathogenic?

Alpha hemolytic Streptococcus viridans (AHSV) was found to be the predominant pathogen in neonatal septicemia from 1979 to 1981 at a 1,000-bed voluntary hospital with 5,000 deliveries per year.

What are alpha hemolytic Streptococcus?

29 Viridans streptococci are fierce competitors in the colonization of the mucosal surface of the mouth, producing bacteriocidins that have bactericidal activity against other organisms, killing more virulent species of streptococci and staphylococci.

What type of hemolysis is Staphylococcus aureus?

Staphylococcus aureus is a common pathogen causing both hospital and community-acquired infections. Hemolysin is one of the important virulence factors for S. aureus and causes the typical β-hemolytic phenotype which is called complete hemolytic phenotype as well.

What are the three types of hemolysis and explain each?

Hemolysis Patterns
  • Beta-hemolysis is complete hemolysis. It is characterized by a clear (transparent) zone surrounding the colonies. …
  • Partial hemolysis is termed alpha-hemolysis. Colonies typically are surrounded by a green, opaque zone. …
  • If no hemolysis occurs, this is termed gamma-hemolysis.

Why does alpha hemolysis turn green?

This is referred to as α-hemolysis (alpha hemolysis). The greenish color is caused by the presence of biliverdin, which is a by-product of the breakdown of hemoglobin. If the organism does not produce hemolysins and does not break down the blood cells, no clearing will occur.

What does hemolysis present mean?

Hemolysis refers to the destruction of red blood cells (RBCs). Typically, RBCs can live for up to 120 days before the body naturally destroys them. However, certain conditions and medications may cause them to break down quicker than usual. RBCs, or erythrocytes, are one of the main components of blood.

What type of hemolysis is Streptococcus pneumoniae?

Streptococcus pneumoniae and other streptococci produce a greenish halo on blood agar plates referred to as alpha-hemolysis.

What causes alpha hemolytic Streptococcus?

Predisposing factors in older children include endocarditis and trauma, surgery or anomaly involving the central nervous system. Dental infections, including dental caries, abscesses, and periodontal disease, often are due to viridans streptococci, most commonly S.

What lab tests does hemolysis affect?

Certain lab tests can be affected and the reported results will be inaccurate. It falsely decreases values such as RBC’s, HCT, and aPTT. It can also falsely elevate potassium, ammonia, magnesium, phosphorus, AST, ALT, LDH and PT.

What type of hemolysis does the bacteria infecting patient a cause?

What type of hemolysis does the bacteria infecting Patient A cause? With what are they probably infected? The type of hemolysins infecting patient A causes beta hemolysis. Patient A has streptococcus pyogenes due to the identical inoculation results from the blood agar plate.

Can Staphylococcus be alpha hemolysis?

At present, the hemolysins of staphylococci are classified in four different types including alpha (α), beta (β), gamma (γ) and delta (δ) (Aarestrup et al., 1999 ▶).

Are Staphylococcus alpha hemolytic?

Staphylococcus species are either beta hemolytic or gamma (not hemolytic). Staph aureus produces alpha toxin which typically causes wide zones of beta (complete) hemolysis.

Is E coli alpha or beta hemolytic?

E coli is a gram-negative bacillus that grows well on commonly used media. It is lactose-fermenting and beta-hemolytic on blood agar.

How will you identify an alpha-hemolytic streptococci?

Optochin sensitivity allows for the presumptive identification of alpha-hemolytic streptococci as S. pneumoniae, although some pneumococcal strains are optochin-resistant. Other alpha-hemolytic streptococcal species are optochin-resistant.

Is alpha-hemolytic strep contaminant?

Alpha-hemolytic streptococci are often included in the definition of contamination for comparing institutional rates, although it is known that they almost as often constitute true pathogens (23).

Is Streptococcus pneumoniae alpha hemolytic?

Streptococcus pneumoniae and other streptococci produce a greenish halo on blood agar plates referred to as alpha-hemolysis. This phenotype is utilized by clinical microbiology laboratories to report culture findings of alpha-hemolytic streptococci, including S.

What causes hemolysis?

One cause of hemolysis is the action of hemolysins, toxins that are produced by certain pathogenic bacteria or fungi. Another cause is intense physical exercise. Hemolysins damage the red blood cell’s cytoplasmic membrane, causing lysis and eventually cell death.

Why does beta hemolysis occur?

Beta-hemolytic Streptococci

Beta hemolysis is caused by two hemolysins O and S; the former is inactive in the presence of oxygen. Thus, stabbing of the plate increases the intensity of the hemolysis reaction. S is an oxygen-stable cytotoxin.

Is Streptococcus pyogenes alpha hemolytic?

Streptococcus pyogenes are nearly always beta-hemolytic whereas closely related Groups B and C streptococci usually appear as beta hemolytic colonies, but different strains can vary in their hemolytic activity. S.