This document summarizes key information about Group B and Group D streptococci. It discusses their classification, pathogenicity, laboratory identification tests like hemolytic patterns on blood agar, CAMP test, bacitracin sensitivity test, and characteristics that differentiate streptococcal species. Information provided includes diseases caused by Streptococcus agalactiae (Group B strep), Enterococcus faecalis, and the differences between enterococci and non-enterococcal Group D streptococci.

1. Group B
and Group D
Streptococci

2. Streptococcus
• Gram + Ve cocci
• Arranged in chains/pairs
• Important human pathogens: pyogenic
infection
• Tendency to spread
• Acute rheumatic fever; Glomerulonephritis

3. Classification
O2 requirement
Aerobes & facultative anaerobes Obligate anaerobes
Peptostreptococci
Hemolysis
α β γ
(Viridans gp) (Hemolytic) (Enterococcus)
Lancefield grouping
& Griffith typing
(Serological)

4. Beta hemolysis
Alpha hemolysis No hemolysis

5. Hemolysis Patterns of Streptococci

6. Group B streptococcus
(Streptococcus agalctiae)
– Important pathogen of cattle &
produce bovine mastitis
– Commensal of female genital tract
– Septic abortion & pueperal sepsis
– Neonatal septicemia & meningitis in
west

7. Differentiation between -hemolytic streptococci
CAMP test
Bacitracin
sensitivity
Hemolysis
Negative
Susceptible

S. Pyogenes
(Gp A)
Positive
Resistant

S. Agalactiae
( Gp B)
Inulin
Fermentation
Bile
solubility
Optochin
sensitivity
Hemolysis
Not ferment
Soluble
Sensitive
(≥ 14 mm)

S. pneumoniae
Ferment
Insoluble
Resistant
(≤13 mm)

Viridans strep
Differentiation between -hemolytic streptococci

8. Streptococcus agalctiae
• Gram-positive diplococcus
• Produces a narrow zone of -hemolysis on
blood agar
• Most strains are bacitracin resistant
• Positive CAMP test

9. Streptococcus agalctiae (cont-)
• Serologic Strains
– Type Ia, Ib, Ic, II, III, IV, V, VI, VII, and VIII
– Early onset disease can be due to any strain & can
be fatal
– Late onset disease is due to Type III in >90% of
cases

10. Epidemiology
• Colonizes ~20% of pregnant women
– Usually asymptomatic but can have UTIs,
chorioamnionitis, or endometritis
• 40-70% of infants born to colonized mothers are
colonized
• Nearly 50% of sexual partners of colonized women
are colonized 0.2-3.7/1000 live births
– Rates are diminishing with prophylaxis
• 0.5-2% of newborn infants born to colonized mothers
• Gets colonized.

11. Maternal Risk Factors
• Preterm labour < 37 weeks
• Preterm prom at 37 weeks
• Fever during labor
• Previous delivery of sibling with invasive gbs
disease
• Multiple births
11

12. GBS COLONIZATION
• IN MOTHER
• LOWER GENITAL TRACT
• ANORECTUM
• URINARY TRACT
• IN NEONATES
• EXTERNAL EAR (IN FIRST 24 H )
• ANTERIOR NARES, THROAT
• ANORECTUM
• UMBILICUS
12

13. Risk Factors for Colonization
• Heavily colonized mothers
• Mothers younger than 20
• African Americans
• Lower socioeconomic groups
• PROM
• Prolonged labor
• Maternal Chorioamnionitis
• Previous delivery with GBS disease

14. Early Onset v. Late Onset
• Occurs within the 1st
week of life (usually
<72 hours)
• Attack rate more in low
birth weight
• Accounts for 20%
• Cases appearing up to 6
months of age
• Cases after 1 month of
age occur primarily in
premature and
immunodeficient infants

15. Early Onset v. Late Onset
• Vertical transmission
• Ascending infection
(duration of ROM 
incidence of infection)
• During passage through
a colonized birth canal
• Maternal transmission
• Nonmaternal sites:
– Nursery
– Personnel
– Community
• Pathophysiology due to
weakened host defense

16. Early Onset v. Late Onset
• Pneumonia with
bacteremia
• Pulmonary HTN
Meningitis
• Bacteremia without a
focus (55%)
• Meningitis (35%)
• Osteomyelitis and
arthritis

17. Laboratory Findings
• Isolation and identification from normally
sterile sites
– CSF
– Gastric or tracheal aspirates
– Skin or mucous membranes

18. CAMP test
• Principle:
– Group B streptococci produce extracellular protein (CAMP factor)
– CAMP act synergistically with staph. -lysin to cause lysis of RBCs
• Procedure:
– Single streak of Streptococcus to be tested and a Staph. aureus are made
perpendicular to each other
– 3-5 mm distance was left between two streaks
– After incubation, a positive result appear as an arrowhead shaped zone of
complete hemolysis
– S. agalactiae is CAMP test positive while non gp B streptococci are
negative

19. Hemolysis on Blood agar
-hemolysis
-hemolysis
-hemolysis

20. CAMP test

21. CAMP test
Staph. aureus
Gp B
Streptococcus
Gp A
Streptococcus

22. GBS MENINGITIS
• MORTALITY RATE 50 - 75 %
• 21 % OF SURVIVORS HAVE MAJOR
PERMANENT NEUROLOGIC SEQUELAE
– MENTAL RETARDATION (USUALLY PROFOUND)
– SPASTIC QUADRIPLEGIA
– CORTICAL BLINDNESS
– DEAFNESS
– UNCONTROLLED SEIZURES
– HYDROCEPHALUS
– HYPOTHALAMIC DYSFUNCTION
22

23. GBS MENINGITIS
• 20 % OF SURVIVORS HAVE MILD TO
MODERATE NEUROLOGIC SEQUELAE
• BORDERLINE MENTAL RETARDATION
• LANGUAGE DELAY
• UNILATERAL HEARING LOSS
23

24. GBS BACTEREMIA WITHOUT FOCUS
• LATE ONSET DISEASE
• UNCOMPLICATED PERINATAL COURSE
• NON-SPECIFIC SIGNS IN FIRST FEW WEEKS OF
LIFE
– FEVER
– POOR FEEDING
– IRRITABILITY
– RINORRHEA
• “R/O SEPSIS” WORKUP
24

25. PREVENTION OF GBS INFECTION
• CHEMOPROPHYLAXIS
• IMMUNOPROPHYLAXIS
25

26. Bacitracin sensitivity
• Principle:
– Bacitracin test is used for presumptive
identification of group A
– To distinguish between S. pyogenes
(susceptible to B) & non group A such as S.
agalactiae (Resistant to B)
– Bacitracin will inhibit the growth of gp A Strep.
pyogenes giving zone of inhibition around the
disk
• Procedure:
– Inoculate BAP with heavy suspension of tested
organism
– Bacitracin disk (0.04 U) is applied to inoculated
BAP
– After incubation, any zone of inhibition around
the disk is considered as susceptible

27. Differentiation between -hemolytic streptococci
CAMP test
Bacitracin
sensitivity
Hemolysis
Negative
Susceptible

S. pyogenes
Positive
Resistant

S. agalactiae
Inulin
Fermentation
Bile
solubility
Optochin
sensitivity
Hemolysis
ferment
Soluble
Sensitive
(≥ 14 mm)

S. pneumoniae
Not-fermented
Insoluble
Resistant
(≤13 mm)

Viridans strep
Differentiation between -hemolytic streptococci

28. Enterococcus: Microbiological
Properties
• Gram-positive cocci (round to oval-shaped,
occasionally elongated)
• Catalase negative
• Growth on 5% sheep blood agar with optimal
growth for occasional strains in the presence
of 5-10% CO2
• -hemolysis (E. faecium) and no hemolysis or
narrow zone of  hemolysis (E. faecalis)
• Most strains are bacitracin resistant

29. Enterococcus
1. They are relatively heat resistant & can withstand heat
at 60°C for 30 minutes (heat test or heat resistant test)
2. Their abiliy to grow in the presence of 6.5% sodium
chloride.
3.Their abiliy to grow at 45°C and at pH 9.6
4. They are PYR test positive.
5. They are resistant to SXT (Trimethoprim &
sulphamethoxazole).
On MacConkey’s medium they grow as tiny deep pink
colonies.
On Gram staining, enterococci appears oval cocci in short
chains.

30. Enterococcus ( Cont-)
• The identification of the species is based on
biochemical reactions. E. faecalis is the most
commonly isolated enterococcus from human
sources.
• Other enterococci are E. faecium & E. durans
E. faecalis can be identified by fermentation of
mannitol, sucrose, aesculin & sorbitol, and by
producing black colonies when grown on tellurite
blood agar.
-Sub acute bacterial endocarditis
-Septicaemia, biliary tract infection
-peritonitis

31. Enterococcus (Cont-)
Strains resistant to Penicillin & other antibiotics
occur frequently.
-Vancomycin is the primary alternative drug
-Vancomycin resistant strains has also been
isolated.
-Resistance is most common in E. faecium, but
Vancomycin resistant strains of E. faecalis also
occurs.

33. Streptococcus: Types of Infectious
Disease
• Streptococcus pyogenes is one of the
most virulent bacterial pathogens, and
causes acute pharyngitis, impetigo,
cellulitis, necrotizing fasciitis and
myositis (flesh-eating bacteria),
pneumonia, bacteremia, and
streptococcal toxic shock syndrome

34. Enterococcus: Types of Infectious Disease
• High-level vancomycin resistance results from vanA gene
coding for abnormal peptidoglycan precursors having
terminal D-alanyl-D-lactate (normal = D-alanyl-D-alanine)
with decreased vancomycin binding affinity and diminshed
inhibition by vancomycin of cell wall peptidoglycan synthesis
for VRE strains (VRE=vancomycin-resistant enterococci)
• Associated with resistance to high concentrations of
vancomycin (vancomycin minimal inhibitory concentrations
> 256-µg/ml) and treatment failure in VRE infection
• Prevalent with Enterococcus faecium, unusual for
Enterococcus faecalis

35. Species Identification of Group II
Enterococcus (Facklam’s Scheme)1
MAN SOR ARG ARA PIG
E. faecalis + – + – –
E. faecium + – + + –
E. casseliflavus2 + – + + +
E. gallinarum2 + – + + –
1MAN=mannitol, SOR=sorbose, ARG=argininie,
ARA=arabinose, PIG=yellow pigment
2Motile (E. faecalis and E. faecium non-motile)

36. Bile-Esculin Hydrolysis Test
Positive in Gp D streptococci &enterococci
• The bile-esculin hydrolysis test
measures the ability of an isolate to
hydrolyze the -glycoside bond of
esculin with production of esculetin and
glucose in the presence of 40% bile.
Free esculetin reacts with the iron salt
ferric citrate to form a brown to black
precipitate.

38. Test Enterococcus Group ‘D’
streptocoocus
1. Growth in
the presnce of
6.5% NaCl
+ -
2. PYR test + -
3. Sensitivity
to SXT
R S
4. Ability to
grow at 45°C
+ _
Differences between enterococcus & Group D streptococcus

39. Some characteristic features of
different groups of streptococci
Lancefiel
d group
Species or common
name
Diagnostic test Diseases caused
A Str. Pyogenes Bacitracin sensitive, PYR
positive, resistant to SXT
Upper respiratory tract
infections, skin
infections, Ac
Rheumatic fever, Ac
glomerulonephritis
B Str. agalactiae CAMP test positive, hippurate
hydrolysis positive, resistant to
SXT
Neonatal septicaemia &
meningitis
C Str. equisimilis Ribose fermented, trehalose
fermented
Pharyngitis,
endocarditis
D (i) Enterococcus sp. ( E.
faecalis & other
enterococci)
Heat test positive, growth in
the presence of 6.5% NaCl, PYR
negative, Sensitive to SXT
Urinary tract infections,
woun infections
(ii)
Non-enterococcal
No growth in 6.5%, PYR
negative, Sensitive to SXT
Genitourinary infections
Not
typed
Viridans streptococci( Str.
Salivarius, Str. Mutans &
Optochin resitant, species
differentiation on biochemical
Endocarditis, dental
caries