Pneumococci

1. PNEUMOCOCCUS
(Strep.pneumoniae)

2. •They are Gram positive Doplococci seen as
commensals of upper respiratory tract
•They are imp pathogen of pneumonia & otitis
media in children
•They differ from Streptococci in their
•Morphology(diplococci)
•Bile solubility
•Optochin sensitivity
•Presence of a capsule

3. Morphology
•Gram positive ,small (0.1 diameter),
slightly elongated cocci arranged in pairs
•Each coccus has one end rounded &
other end pointed(flame
shaped,lanceolate shaped)
•They are capsulated & capsule encloses
each pair
•Capsule can be demonstrated as clear
halo in India Ink Preparation

5. Cultural characters
•They are aerobes & facultative anaerobes
•Opt temp-37(25-42)
•Opt pH -7.8 (6.5-8.3)
•Growth is enhanced by 5-10% Co2
•On blood agar
•Colonies are small ,dome shaped with an area of
greenish discolorisation(alpha haemolysis)
•On prolonged incubation the colonis become flat, with
raised edges & a central umbonation(due to autolysis)
•This will a show an appearance of concentric rings when
viewed from above
•This type of appearance is called Draughtman
appearance or Carom coin appearance

9. Biochemical reaction
•They ferment several sugars with acid
production only
•Fermentation of Inulin is imp in the
differentiation of Pneumococci from
Streptococci
•They are bile solubility test positive
•Catlase –negative
•Oxidase –negative

10. Inulin fermentation
Bile solubility test

11. Bile solubility test

12. Antigenic Structure
•1.capsular polysacheride
•it is also called Secific Soluble Substance(SSS)
since it is soluble in tissue ,diffuse in to culture
media & infective exudates
•Quellung/ Anti capsular rection(1902)
•Here , a suspension of Pneumococci is mixed on
a slide with a drop of specific anti serum
•In the presence of homologous anti serum ,the
capsule shows a swelling reation

13. Quellung Reaction

14. •2. M Protein
•3.Cell wall Carbohyrate(C-Substance)
•This as associated with the cell wall
•Against this ,an abnormal protein (Beta globulin) is
produced in the sera of patients that disappears during
convalescence
•It is also detected in sera of patients with some other
illness
•This is called C Reactive Proteins(CRP)
•This is an acute phase substance produced in
hepatocytes
•Its production is stimulated by bacterial infection
,malignancies & tissue destruction
•It can be detected by Latex Agglutination Test

15. Pathogenesis & clinical features
•It is one of the most common bacteria causing pneumonia
•1.Lobar pneumonia
•2.broncho pneumonia
Always secondary to viral infection
•3.meningitis
it is the most serous Pneumococcal infection
it is the 2
nd
most imp cause of pyogenic meningitis after
Meningococci
•Other infections
otitis media
sinusitis
empyema
peritonitis etc

16. Lab Diagnosis
Specimen
•Sputum,CSF ,Blood,Pleural exudate,Peritonial fluid etc
Methods
Direct microscopy
•Gram staining of specimens shows large number of Pus cell and
typical organism
Culture
•Shows typical colony morphology(Draughtman appearance & alpha
hemolysis etc)
Gram staining from the colony
Biochemical reactions

17. Quellung /anti capsular reactions
Serology for the ditection of capsular
polysacheride Ag by
Countrimmuno ectrohorosis ,laex aggutination etc
Animal pathogenesity test
By intra peritonial inoculation in to mice

18. treatment
•Penicillin
•Cephalosporin etc
Prophylaxis
A polyvalent polysaccharide vaccine is
available