Pneumococcus, or Streptococcus pneumoniae, is a Gram-positive bacterium that can cause pneumonia. It appears in pairs under the microscope (diplococci) and each pair is enclosed in a polysaccharide capsule. It grows best at 37°C in an atmosphere containing carbon dioxide. On blood agar plates it forms alpha-hemolytic colonies. The capsule protects it from phagocytes and allows it to attach to cells in the nasopharynx before migrating to the lungs. This can cause lobar pneumonia in adults and bronchopneumonia in children. Diagnosis involves finding the bacteria in sputum or other samples through microscopy, culture, and serological tests. Treatment involves antibiotics like penicillin and

1. PNEUMOCOCCUS
RATHEESH R L

2. • Medically important species is
pneumococcus pneumonia

3. MORPHOLOGY
• They are Gram-positive (I mm diameter),
lanceolate shaped cocci arranged in pairs
(diplococci) with one end broad & another
pointed (flame shaped).
• They are capsulated (capsule enclosing each
pair) nun-motile & non-sporing

5. CULTURAL CHARACTERISTICS
• They are aerobic/ facultative anaerobic and
grow best at 37 degree C at pH 7.6.
• Growth occurs best in atmosphere of 10-20%
of carbon dioxide.

6. Serum & glucose broth
• After 24 hours, show uniform turbidity.
• Non-capsulated strains

7. Blood agar medium
• Colonies are raised, circular about 1 mm in
diameter surrounded by zone of alpha-
hemolysis but few strains also show beta-
hemolysis under anaerobic conditions under
refrigeration at 6°C.

8. PATHOGENLSIS
• The virulence of the organism is due to its capsule which
protects the organism from phagocytes.
• The organism gets attached to nasopharyngeal cells &
subsequently migrates through bronchial mucosa to
peribronchial lymphatics.
• Inflammatory reaction occurs in alveoli with an outpouring
of fibrinous edema fluid into alveoli, followed by red cells &
leucocytes leading to consolidation of portion of lung.

9. • The usual lesion in adults is segmental or lobar
in distribution (lobar pneumonia) but in
children & aged, there Is patchy involvement
of lung (bronchopneumonia).
• Microorganisms are found throughout the
exudates & bacteraemia is common.

10. • Pneumococcal meningitis:
Strep. pneumoniae are the second
most important cause of pyogenic meningitis
after N.meningitides.
It is most serious Pneumococcal
infection more common in children with 40-50%
mortality rate

11. LABORATORY DIAGNOSIS
• Hematological investigation:
1…..TLC: Shows increase in leucocytes
(> 15000/mm3>.
II…..DLC. Shows increase in
polymorphonuclear cells.

12. • Bacteriological investigation:
– Specimen: sputum, CSF, pleural fluid, peritoneal
fluid, pericardial fluid & pus discharges.

13. Microscopy
• Gram staining of the above specimen shows
flame shaped diplococci.
• India ink preparation shows capsule as a clear
halo.

14. Culture
• Specimen is inoculated on BAM & incubated
at 37 C for 24-48 hours in atmosphere of
5-10% CO 2.
• Colonies develop after 24 hours which appear
as flat, umbonate (depressed at centre)
showing alpha hemolysis (greenish
discoloration).

15. Biochemical tests
• Sugar fermentation test - Positive with acid
production only.
• Bile solubility test - Positive
• Catalase test - Negative
• Oxidase test - Negative

16. Serological tests
• Co-agglutination test (COA)
• Latex agglutination test (LA).
• Counter current immuno electrophoresis
(CCIE)

17. Animal pathogenicity test
• Mice are most susceptible to Pneumococcal
infection; therefore, this test provides rapid
diagnosis.
• Sputum from infected patient is emulsified
with saline & one ml of this suspension is
inoculated/injected intraperitoneally into 2
mice (test & control).

18. • The test mouse dies within 24 hours. The
heart blood and peritoneal fluid of the animal
shows diplococci within capsules under
microscope.

19. TREATMENT
• Antibiotics:
– Sulphonamides and penicillin are effective
medication