Which Streptococcus species does not have a Lancefield antigen?
Rebecca Lancefield, a prominent American microbiologist, introduced Lancefield grouping. (Note: viridans streptococci and Streptococcus pneumoniae have no group-specific antigen).
What does Lancefield grouping indicate?
Lancefield grouping is a serological method for classifying streptococci into one of 20 groups (designated by a letter) based on the presence of polysaccharide and teichoic acid antigens in the bacterial cell wall (Lancefield 1933).
What is Lancefield serotype grouping?
Lancefield grouping is a system of classification that classifies catalase-negative Gram-positive cocci based on the carbohydrate composition of bacterial antigens found on their cell walls.
What type of Streptococcus belongs to Lancefield group A?
TABLE 1.
| Species | Lancefield group | Origin |
|---|---|---|
| S. pyogenes | A | Human |
| S. agalactiae | B | Human, bovine |
| S. dysgalactiae | ||
| subsp. dysgalactiaeb | C | Animals |
What is Lancefield precipitation test?
a ring precipitation test for identification and classification of streptococci. Group-specific antibody reacts in vitro with group-specific polysaccharide to produce a ring of precipitation where the two reagents react at the interface.
What does PYR positive mean?
A positive PYR tests allows for the presumptive identification of group A streptococci (Streptococcus pyogenes) and group D Enterococci.
What causes strep F?
Strep throat is an infection of the throat and tonsils caused by a bacteria called group A streptococcus , also known as Streptococcus pyogenes. This bacteria lives in the nose and throat. You can get the infection from someone who is sick with strep A bacteria or is a carrier of it.
Which Streptococcus usually causes dental caries?
Streptococcus mutans, which causes dental caries, splits the sucrose in food and uses one of the sugars to build its capsule, which sticks tightly to the tooth.
What strep is PYR positive?
PYR (Pyrrolidonyl Aminopeptidase) Test is used for the detection of pyrolidonyl arylamidase (also called pyrrolidonyl aminopeptidase) activity in Streptococcus pyogenes (group A strep), Enterococcus spp., some coagulase-negative staphylococci, and some Enterobacteriaceae.