prof . dr. ihsan edan alsaimary department of microbiology - college of medicine - university of basrah - basrah -IRAQ ihsanalsaimary@gmail.com 00964 7801410838

1. 1
STREPTOCOCCI
LEC . 8
Prepared by
DR. IHSAN EDAN ALSAIMARY
Professor
(Med.Microbiol & Immunol)

2. QUESTIONS SHOULD BE ANSWER THROUGH
LECTURE
-How can classify the streptococci ??
-WHAT ARE DISEASES THAT CAUSING? AND
HOW?
-WHO CAN DIAGNOSE IN LABORATORY?
-WHO CAN DIFFERENTIATE FROM CLOSLEY
RELATED SPECIES?
2

3. 3
Identification of Gram-positive cocci
None

4. 4
• Streptococci
– facultative anaerobe
– Gram-positive
– chains or pairs
– catalase negative
(staphylococci are catalase positive)

5. 5
• Streptococci
• Lancefield grouping(classification)
•18 subgroups of beta hemolytic streptococci
*one or more species per group
*According to surface antigens
*( C- SUBSTANCES)(polysaccharides)
* dimer of N-acetylglucosamine and rhamnose.
Beta hemolysis Alpha hemolysis Gamma hemolysis

6. 6
A- Streptococcus pyogenes GAS ( Group A, beta Hemolytic Streptococci).
B- Streptococcus agalactiae:GBS ( Group B, beta Hemolytic Streptococci).
C- Groups C and G.
D- Enterococcus fecalis(E. faecium, E durans): Group D.
E- Streptococcus bovis: Nonenterococcal group D
streptococci.
F- Streptococcus anginosis.
G- Group N Streptococci.
H- Groups E,F,G, H and K-U Streptococci.
I- Streptococcus pneumoniae.
J- Viridans Strepococci: (S. mitis, S. mutans, S. salivaris, S.
sanguis).
K- Nutritionally Variant Streptococci.
L- Peptostreptococcus (Many Species).
Classification of Streptococci of Medical Importance

7. 7
VIRULENCE FACTORS
Capsule: hyaluronic acid , antiphagocytosis.
Group-specific cell wall antigens (Lancefield groups A-V)
Specificity is determined by a dimer of N-acetylglucosamine
and rhamnose.
T protein: type-specific; function unknown.
M- proteins: binds IgM, IgG and a2-macroglobulin; interfere with
phagocytosis.
Lipoteichoic acid: binds to epithelial cells.
F protein: a major adhesin of S. pyogenes, binding with fibronectin.

8. 8
Enzymes and toxins
Streptokinase (fibrinolysin)
Can lyse blood clots and may be responsible for the rapid spread
of the organism.
Used (IV injection) for treatment of pulmonary emboli, coronary
artery thrombosis and venous thrombosis.
Streptodornase (DNases A to D)
Decreases viscosity of DNA suspension.
A mixture of this and streptokinase is used in removal of pus and
necrotic tissue.
Hyaluronidase (spreading factor):
Destroys connective tissue and aids in spreading infecting bacteria.
C5a peptidase
Prevents streptococci from C5a-mediated activation of phagocytes,
and is important for survival of S. pyogenes in tissue and blood.

9. 9
Hemolysins
Streptolysin O: O2-labile;
ASO (antistreptolysin O) for rheumatic fever
Streptolysin S: O2-stable. not antigenic.

10. • Streptococcus pyogenes
• Acute Suppurative Diseases
• 1. Pharyngitis
• 2. Impetigo (superficial skin infection)
• 3. Cellulitis (purulent inflammation of subcutaneous tissues)
• 3. Necrotizing Fasciitis
• 4. Erysipelas
• 5. Puerperal sepsis (uterine infection)
• 6. Surgical wound infections
• 7. Otitis media
• 8. Scarlet Fever (rare)
• 9. Toxic shock-like syndrome (TSLS
• Group B Streptococci (Strept.agalactiae)
Meningitis and pneumonia in neonates)
Non-suppurative
SEQUELAE:
•Acute Rheumatic Fever
•Acute Glomerular
Nephritis

11. 11
Laboratory Diagnosis
Smears: useful for soft tissue infections or pyoderma, but not
for respiratory infections.
Antigen detection tests: commercial kits for rapid detection of
group A streptococcal antigen from throat swabs.
Detection of group A streptococci by molecular methods:
PCR assay for pharyngeal specimens.
Culture: Specimens are cultured on blood agar plates in air.
10% CO2 although speeds hemolysis,
Identification: serological and biochemical tests.
Antibody detection
ASO titration for infections ( rheumatic fever & osteomylitis) .
Anti-DNase B and antihyaluronidase titration for skin infections.
Antistreptokinase; anti-M type-specific antibodies.

12. 12
CAMP test
Christie R, Atkins NE, and Munch-Peterson E. 1944. A note on a lytic phenomenon
shown by group B streptococci. Aust. J. Exp. Biol. Med. Sci. 22:197-200
DIFFERENTIATION BETWEEN STRPT. PYOGENES AND STREPT. AGALACTIAE
STREPT.
AGALACTIAE
STRPT. PYOGENES
STAPH.AUREUS

13. 13
Most streptococci are normal flora of the human body.
Source of S. pyogenes and S. agalactiae is a person harboring
these organisms (carrier).
Control:
1. Prompt eradication of streptococci from early infections.
2. Prophylactic antibiotic treatment for rheumatic fever
patients.
3. Eradication of S. pyogenes from carriers.
4. Dust control, ventilation, air filtration, UV irradiation and
aerosol mists are of doubtful efficacy.
5. Intrapartum penicillin to mother at risk of giving birth to an
infant with invasive group B disease.
Prevention and Control

14. 14
Viridans streptococci
• diverse species
• oral microbiota
• dental caries , tooth decay, endocarditis
• Alpha- hemolytic
• non-groupable.
• Includes
• Strept. mutans , Strept.mitis ,
Strept . Salivarius , Strept.
sangius

15. 15
Strep. pneumoniae
Morphology and Physiology
Gram-positive lancet-shaped diplococci for
typical organisms.
a-hemolytic (pneumolysin is similar to streptolysin O).
Growth is enhanced by 5-10% CO2.
Capsular polysaccharide: phosphocholine, 90 types.
*Quellung reaction (capsuel swelling) +ve
- Bile solubility positive
- optochin sensitivity +ve

16. 16
Pathogenesis and Immunity
Strep. pneumoniae
Pneumococci produce disease through
their ability to multiply in the tissues
(invasiveness).
virulence factors:
Capsule; cell wall polysaccharide,
phosphocholine,
pneumolysin,
IgA protease, etc.

17. 17
Strpt. pneumoniae
Laboratory diagnosis
Examination of sputum
Stained smears of sputum: a rapid diagnosis.
Quellung test with multivalent anticapsular antibodies.
Culture
Specimen: sputum, aspirates from sinus or middle ear, CSF.
cultured on blood agar plate in 5-10% CO2.
Identification: bile solubility, optochin sensitivity, etc.
biochemical, serologic or molecular diagnostic tests
Antigen detection: detect pneumococcal C polysaccharide
(teichoic acid; type-specific) in urine or CSF.

18. 18
Group D streptococcus
• Intestine flora
• Growth on bile esculin agar
– black precipitate
– PYRase test +ve (l-pyrroglutamyl-prptide hydrolase)
– resistant to optochin and bile tests
– Enterococcus faecalis
– Ent.faecium
– (Intraabdominal abscesses, urinary tract
infections, bacteremia, endocarditis)
– distantly related to other streptococci
– Resistant to 6.5% NaCl, 0.1% methyl blue and grow in bile-esculin agar.
More resistant to antibiotics than the streptococci.

19. 19
One of the leading causes of nosocomial infections.
Urinary tract (UTI), peritoneum (peritonitis) and heart tissue
in hospitalized patients with prolonged broad-spectrum
antibiotic treatment.
Intra-abdominal abscess and wound infections: generally
polymicrobial.
Many strains are completely resistant to all conventional
antibiotics. Vancomycin-resistant strains have been isolated
(first reported in England and France in 1987).
Enterococci can be differentiated by simple biochemical tests
(e.g., resistant to optochin and bile, hydrolyze PYR, etc.)
Enterococci
Clinical Diseases
Laboratory Diagnosis