Exam 2: Streptococcus Flashcards
What is the result of streptococcus in a gram stain? Catalase test?
Positive
Negative
What does most streptococcus require to grow?
Blood or serum
When does streptococcus not grow?
When shed into the environment
What is used when streptococcus is classified by the Lancefield’s serological groups?
Cell wall antigens
Serological agglutination
What does antigenic specificity, used in Lancefield’s serological groups, reside in?
Polysaccharides attached to teichoic acid layer of cell wall, so called “C” substance (for carbohydrate)
What are the virulence factors for streptococcus?
Capsules: hyaluronic acid is non-immunogenic and non-antigenic, act as an adhesin and are antiphagocytic
M proteins, lipoteichoic acid, and other cell wall proteins with fimbriae cause adherence and are antiphagocitic
What group species is S. pyogenes?
Only group A species
What kind of pathogen is S. pyogenes?
Mostly human
What is the major virulence factor of S. pyogenes?
Over 60 different M proteins
Why are there no vaccines available for S. pyogenes?
Immunity is type-specific and there are so many M proteins that it is difficult to develop a vaccine
What group species is S. agalactiae?
Only group B species
What is used in late pregnancy?
Group B strep test
What species is related to CAMP factor?
S. agalactiae
What does CAMP factor cause?
Complete lysis of cow or sheep RBC in the presence of S. aureus beta hemolysin producing arrowhead appearance of enhanced hemolysis
What kind of pathogen is S. agalactiae?
Obligatory intramammary
Where does S. agalactiae live as an obligatory intramammary pathogen?
Milk duct
What is S. agalactiae a common cause of?
Contagious bovine mastitis
How is S. agalactiae spread?
Could not live outside of host, but easily spread by milking equipment or suckling calves
What is S. agalactiae sensitive to?
Penicillin
Where is S. dysgalactiae considered to be normal flora?
Mouth, vagina, and skin other than udder
Where does S. dysgalactiae survive well?
In environment
Can S. dysgalactiae be totally eliminated?
No
What is the most common cause of mastitis?
S. dysgalactiae
What is S. zooepidermicus subsp. zooepidermicus common normal flora in?
Many animals
Skin and upper respiratory track of horse
What is S. zooepidermicus subsp. equi the etiological agent of?
Strangels, a regional or generalized suppurative lymphadenitis
How is S. zooepidemicus subsp. equi differentiated from S. zooepidermicus subsp. zooepidermicus with morphology and biochemically?
Morphology: large mucoid colonies may run together, wide zone of clear hemolysis
Biochemically: S. equi does not ferment lactose or sorbitol
What are the virulence factors for S. zooepidermicus subsp. zooepidermicus?
M protein and capsule
What is a source of streptococcus?
Aerosol transmission
What is the exposure of streptococcus?
Inhalation, ingestion, contact, insects
What diseases can occur with or because of streptococcus?
Bastard strangles
Gutteral pouch empyema
Purpura hemorrhagica
What kind of immunity is there for streptococcus?
Mainly humoral
Is a vaccine available for strangles?
Yes
What is the treatment for something caused by streptococcus?
Drain abscess
Antimicrobial therapy (controversial)
Procaine penicillin G is the antibiotic of choice
Describe S. pneumoniae
Primates and humans only
No specific “C” substance or “M” protein
What does S. iniae occur in?
Many species of fish as a systemic disease
Where is S. mutans found?
Plaque and dental caries in humans
