Streptococcus species, Classification, Structure, Morphology, Biochemical Characteristics, diseases and infection caused by Streptococcus species,Diagnosis and treatment of Streptococcus species,

1.  For non-invasive infections a Rapid Strep Test (RST) can be carried out. This
involves a doctor taking a throat or nose swab that is analysed for group A
Streptococcus.
 An RST is one of the most common tests for this type of infection.
 For suspected invasive infections a blood test may be taken.
 Most infections are treated with antibiotics:
 superficial skin infections can be treated with topical antibiotic ointments
 other infections can be treated with oral or intravenous antibiotics depending on
the severity of the infection.
 Where the infection has caused a lot of skin damage, for example in cases of
necrotising fasciitis, damaged tissue may be removed surgically.

2.  streptococcus agalactiae usually lives harmlessly inside the digestive system
and female genitals.
 It can be transmitted sexually or from mother to baby during birth.
 Group B β-haemolytic Streptococcus tend to only affect new born babies as
the bacteria can be passed onto the baby from the mother through the
amniotic fluid (protective fluid that surrounds the foetus in the womb
 Due to being continually exposed to it through our lifetimes most people
quickly develop a natural immunity to Group B β-haemolytic Streptococcus.

3. Symptoms of group B β-haemolytic streptococcal infection in a newborn baby include:
 being floppy and unresponsive
 poor feeding
 unusually high or low body temperature
 unusually fast or slow heart rate

4.  If left untreated, group B β-haemolytic streptococcal infections can also lead to
much more serious conditions such as meningitis and pneumonia
 Factors increasing risk of group B β-haemolytic streptococcal infection in new-
born babies include:
 premature birth
 being part of a multiple birth
 having a mother with a history of group B streptococcal infection.

5.  These infections are diagnosed by a blood, urine or cerebral spinal fluid sample to
identify the bacteria?.
 A culture of fluid from the vagina or rectum can also determine if a woman is
infected.
 The infection is treated with antibiotics, often directly into the bloodstream
(intravenously).
 Treatment of these infections may require a hospital stay.

6.  Healthcare professionals take measures during labour and after birth to prevent
new-borns becoming infected with Streptococcus.

 If a baby is known to be at risk of Streptococcus infection, antibiotic injections are
given to the mother during labour or to the baby shortly after birth.

7. Species Host Disease
S. pyogenes human pharyngitis, cellulitis
S. agalactiae human, cattle neonatal meningitis and sepsis
S. dysgalactiae human, animals
endocarditis, bacteremia, pneumonia, meningitis, respiratory
infections
S. bovis human, animals biliary or urinary tract infections, endocarditis
S. anginosus human, animals
subcutaneous/organ abscesses, meningitis, respiratory
infections
S. sanguinis human endocarditis, dental caries
S. suis swine meningitis
S. mitis human endocarditis
S. mutans human dental caries
S. pneumoniae human pneumonia

8.  Specimens:
 Smears:
 Culture:
 Serological Tests of Streptococci:

9.  They are grown on Blood agar medium.
 Incubation in 10% CO2 often speeds haemolysis.
 Blood cultures in cases of suspected endocarditis may turn positive after a week or
longer as alpha haemolytic streptococci and enterococci may grow slowly.

10.  Several commercial kits are available for rapid detection of group A streptococci antigen
from throat swab.
 ELISA and agglutination tests can demonstrate the presence of antigen.
 These tests can be completed in 1-4 hours after the specimen is obtained.
 They are more sensitive and specific when compared to culture test.
 In respiratory disease, a rise in titre of antibodies can be estimated by ASO title which is
most widely used.
 In skin infection, anti-hyaluronidase test is useful.
 The streptozyme test is passive slide haemagglutination test
 The streptozyme uses erythrocytes sensitized with a crude preparation of extracellular
antigen of streptococci.
 It is a sensitive specific screening test for skin or throat infection.

11.  They are sensitive to penicillin, erythromycin.
 Penicillin G – drug of choice
 Penicillin G 1.2 M units IM every 3-4 weeks or daily oral penicillin or oral
sulfonamide
 Antimicrobial drugs have no effect on glomerulonephritis and rheumatic fever.

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