MICROORGANISM

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