Is Streptococcus pneumoniae alpha-hemolytic?

Historically, Streptococcus pneumoniae and other streptococci of the viridians group are classified as alpha-hemolytic bacteria on the basis of a greenish halo that surrounds colonies when grown aerobically on blood agar plates (1, 2).

Is Strep pneumoniae beta hemolytic?

Streptococcus pneumoniae, or pneumococcus, is a Gram-positive, spherical bacteria, alpha-hemolytic (under aerobic conditions) or beta-hemolytic (under anaerobic conditions), aerotolerant anaerobic member of the genus Streptococcus. They are usually found in pairs (diplococci) and do not form spores and are non motile.

Which streptococci are alpha hemolytic?

Streptococcus pneumoniae and a group of oral streptococci (Streptococcus viridans or viridans streptococci) display alpha-hemolysis.

What type of hemolysis does Streptococcus pneumoniae have?

pneumoniae appear as small, grey, moist (sometimes mucoidal), colonies and characteristically produce a zone of alpha-hemolysis (green) (Figure 1). The alpha-hemolytic property differentiates this organism from many species, but not from the commensal alpha-hemolytic (viridans) streptococci.

Is group A strep alpha or beta hemolytic?

Diseases Caused by Streptococci. The most significant streptococcal pathogen is S. pyogenes, which is beta-hemolytic and in Lancefield group A and is thus denoted as group A beta-hemolytic streptococci (GABHS).

Alpha Hemolysis and Identification of Streptococcus pneumoniae

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.

What organisms are alpha hemolytic?

Alpha-hemolytic Streptococcus species “Viridans group” streptococci, including species such as the Streptococcus mutans, mitis, and salivarius groups display alpha hemolysis.

What is alpha hemolysis?

Medical Definition of alpha hemolysis

: a greenish discoloration and partial hemolysis of the red blood cells immediately surrounding colonies of some streptococci on blood agar plates — compare beta hemolysis.

What is alpha and beta 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.

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 is the difference between Streptococcus pneumoniae and Streptococcus pyogenes?

Unlike certain other organisms, such as Streptococcus pyogenes, which produces a variety of tissue-damaging substances, S. pneumoniae produces few toxins and largely causes disease via replication in host tissues and generation of an intense inflammatory response (16).

Is Staphylococcus aureus alpha or beta hemolytic?

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 bacteria are beta hemolytic?

The bacteria most likely to cause strep throat and bacterial sore throats in general are called Group A beta-hemolytic Streptococcus pyogenes (GABHS). This test is a highly reliable way to diagnose strep throat because it has a sensitivity of 90% to 95%.

What is non hemolytic Streptococcus?

Nonhemolytic streptococci (NHS) cause serious infections, such as endocarditis and septicemia. Many conventional phenotypic methods are insufficient for the identification of bacteria in this group to the species level.

What type of hemolysis does Streptococcus pyogenes display?

pyogenes is a gram-positive, β-hemolytic streptococcus that is catalase negative. More than 150 different strains have been identified based on different M-protein types. It is a group A streptococcus based on its carbohydrate structure, according to Lancefield typing of β-hemolytic strains.

What bacteria are gamma hemolytic?

Gamma-hemolysis

Enterococcus faecalis (formerly called "Group D Strep"), Staphylococcus saprophyticus, and Staphylococcus epidermidis display gamma hemolysis.

What Lancefield group is Streptococcus pneumoniae?

Lancefield groups

Some streptococci, for example S. pneumoniae, have not been assigned to a group because their antigen extracts fail to react with group antisera. With the exception of S. pneumoniae all the equine streptococci belong to Lancefield group C.

How can you tell if hemolysis is alpha or beta?

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.

What are the types of streptococcal hemolysis describe?

They are divided into three groups by the type of hemolysis on blood agar: β-hemolytic (clear, complete lysis of red cells), α hemolytic (incomplete, green hemolysis), and γ hemolytic (no hemolysis).

Why is it important to distinguish Streptococcus pneumoniae from other streptococci?

Reliable distinction of Streptococcus pneumoniae and viridans group streptococci is important because of the different pathogenic properties of these organisms.

Can staph be alpha hemolytic?

Staph aureus produces alpha toxin which typically causes wide zones of beta (complete) hemolysis.

Is Strep Bovis alpha hemolytic?

It is a member of the Lancefield group D streptococci. Most strains are gamma-hemolytic (non-hemolytic), but some also display alpha-hemolytic activity on sheep blood agar plates. Strep bovis is a non-enterococci.

Is Streptococcus agalactiae alpha hemolytic?

agalactiae; Group C—beta-hemolytic; Group D—Enterococcus; and, Group F—alpha-hemolytic, S. viridans. These account for approximately 1% of adult pneumonias, and most are due to Group A, beta-hemolytic streptococcus.