Lesson 2b: Streptococcus species

Question 1

Streptococcus Species

Answer 1

• gram positive cocci
• catalase negative, facultative anaerobes, non-motile
• fastidious acquiring enriched media, colonies are small usually hemolytic and translucent
• pathogenic strains have thick capsules, and produce mucoid colonies
• usual habitat: commensals on the mucosae of the upper respiratory tract and lower urogenital tract

Question 2

occurs as slightly pear-shaped cocci in pairs

Answer 2

Streptococcus pneumoniae

Question 3

is an anaerobic gram-positive coccus, which is aetiologically implicated in bovine “summer mastitis” in association with Arcanobacterium pyogenes and S. dysgalactiae

Answer 3

Peptoniphilus indolicus

Question 4

Laboratory differentiation of Streptococcus species

Answer 4

hemolysis, Lancefield grouping, and biochemical testing

Question 5

Types of haemolysis on sheep or ox blood agar;

Answer 5

Beta-haemolysis, Alpha-haemolysis, Gamma-haemolysis

Question 6

is complete haemolysis indicated by clear zones around colonies

Answer 6

Beta-haemolysis

Question 7

is partial or incomplete haemolysis indicated by greenish or hazy zones around colonies

Answer 7

Alpha-haemolysis

Question 8

denotes no observable changes in the blood agar around colonies

Answer 8

Gamma-haemolysis

Question 9

non-pyogenic, is a major pathogen of pigs, causing septicemia, meningitis and pneumonia among other conditions

Answer 9

Streptococcus suis

Question 10

are generally more pathogenic than those producing alpha-haemolysis

Answer 10

Beta-haemolytic streptococci

Question 11

which are major virulence factors of S. pyogenes, S. pneumonia and most strains of S. equi, are anti-phagocytic that protects them from phagocytes

Answer 11

Polysaccharide capsules

Question 12

a febrile disease involving the upper respiratory tract with abscessation of regional lymph nodes

Answer 12

Strangles

Question 13

Asymptomatic carrier pigs harbour S. suis in tonsillar tissue

Answer 13

Streptococcus suis infections

Question 14

which is often fatal, is characterized by fever, tremors, incoordination, opisthotonos and convulsions

Answer 14

meningitis

Question 15

Streptococcus agalactiae, S. dysgalactiae and S. uberis are the principal pathogens involved in this disease

Answer 15

Bovine streptococcal mastitis

Question 16

Virulence factors include enzymes and exotoxins such as?

Answer 16

streptolysins, hyaluronidase, DNase, NADase, streptokinase, proteases