5.2: Streptococcus Flashcards
Streptococcus is a Gram-___1___, round bacterium that tends to ___2___ structures.
- positive
- link to other bacteria in chain-like
True or False: Streptococcus is a Gram-negative round bacterium.
FALSE. Streptococcus is a Gram-positive round bacterium.
Strep is ___1___, meaning it cannot breakdown peroxides, and is often cultured on ___2___.
- catalase negative
- blood agar plates (BAP)
Strep is catalase negative, meaning it cannot breakdown what?
peroxides
True or False: Since there are numerous subtypes of Streptococcus, culturing on BAP is perhaps the quickest way to identify and classify a potential Streptococcus microbe based on its hemolytic properties.
True.
Describe Alpha-hemolysis.
Alpha-hemolysis presents as a greenish-brown discoloration surrounding the bacterial colony, the result of the partial decomposition of hemoglobin found within blood cells.
Alpha-hemolysis is characteristic of what strain of Streptococcus?
Alpha hemolysis is characteristic of Streptococcus pneumonia, so it can be used as a diagnostic feature in the identification of the bacterial strain.
Describe Beta-hemolysis.
Beta-hemolysis is classified as the capacity of a microbe to completely lyse red blood cells. The resulting lysis presents as a distinct zone of clearing around the growing colony.
Beta-Hemolysis is characteristic of what strain of Streptococcus?
Beta-hemolysis is characteristic of Streptococcus pyogenes and some strains of Staphylococcus aureus.
Describe Gamma-Hemolysis.
Gamma-hemolysis designates the absence or lack of hemolytic activity, and the resulting colonies are often white/tan in color growing on the red background color of the unaffected blood agar plate.
Gamma-Hemolysis is characteristic of what strain of Streptococcus?
Gamma hemolysis is a characteristic of Enterococcus faecalis.
______ Streptococcus can be divided into antigenic groups known as Lancefield groupings.
Beta-hemolytic
Beta-hemolytic Streptococcus can be divided into antigenic groups known as ______.
Lancefield groupings
While all bacteria within this system, Lancefield groupings, are ___1___ and ___2___, the distinction lies in the carbohydrate composition of bacterial antigens located in the ___3___.
- catalase-negative
- coagulase-negative
- cell wall
Streptococcus pyogenes, which belongs to Group___1___, is the causative agent behind more than ___2___ of human streptococcal infections resulting in ___3___, ___4___, or ___5___.
- A
- 90 percent
- pharyngitis
- scarlet fever
- rheumatic fever
Describe Streptococcal pharyngitis (strep throat).
Streptococcal pharyngitis (strep throat) is a Group A disease characterized by fever, enlargement of lymph nodes in the neck, and a reddening within the lining of the throat surface tissue causing soreness and discomfort.
Strep throat can also lead to additional complications within what areas?
Strep throat can also lead to additional complications within the ear, lung, or sinus cavities.
If left untreated, strep throat can progress to ______.
rheumatic fever
Rheumatic fever occurs in approximately ___1___ percent of untreated cases of Streptococcal ___2___, presenting approximately ___3___ weeks post-infection.
- 3
- pharyngitis
- 2 to 3
What are the symptoms of Rheumatic fever and what is the most dangerous one? Also which organ does it target?
Rheumatic fever presents with:
1. An inflammation of the joints
2. Involuntary jerking movements
3. The development of pea-sized nodules beneath the skin
4. Reddened areas with raised edges over the surface of the skin.
The most serious development is the damage to heart valves as the bacteria targets this organ.
What is being shown in the picture?
Streptococcus. (A) Staining of a step + sample, notice the characteristic formation of chains of cocci. (B) Patient presents with swelling within the throat and red patches at the site of inflammation, which are associated with soreness and discomfort.
