Streptococcus Agalactiae

Question 1

1) classification

Answer 1

Streptococcus agalactiae

Part of normal vaginal flora or lower GI tract

Question 2

2) morphology

Answer 2

• gram positive cocci

- in pairs or chains

Question 3

3) physiology

Answer 3

• aerobic (can be facultatively anaerobic)

Question 4

4) antigenic structure

Answer 4

• B antigen
• capsular polysaccharide (type specific)
• C protein (surface protein)

Question 5

5) virulence factor

Answer 5

• hemolysin
• neuraminidase
• hyaluronidase
• DNAase
• Protease

Question 6

6) disease

Answer 6

Early onset neonatal disease:

• mainly bacteremia
• occur within first week
• obstetric complications or premature births

Late onset neonatal diseases

• mainly meningitis
• commonly lead to permanent neurological disorders

Question 7

7) microbiological diagnosis

Answer 7

Culture:

Small colonies large beta hemolytic zone

Specific tests:

• catalase: negative
• Bacitracin: resistant
• CAMP test: positive

Direct antigen detection tests:
Direct latex agglutination tests are useful in immediate diagnosis of meningitis

Question 8

8) treatment and prevention

Answer 8

• penicillin G
• combine with aminoglycosides for severe infection
• less susceptible to penicillin G than S.pyogenes
• for penicillin allergic patient, vancomycin is given

Antimicrobial susceptibility tests: disk diffusion susceptibility testing should be done routinely on isolated from significant infections