This document provides an overview of Streptococcus pneumoniae (pneumococcus). It is a gram-positive lance-shaped diplococcus that is a normal inhabitant of the upper respiratory tract. It causes pneumonia and other respiratory infections. Key characteristics include being bile soluble, optochin sensitive, and having a polysaccharide capsule that allows for serotyping. It is treated with penicillin but antibiotics resistance is a concern. Vaccines can help prevent pneumococcal disease.

1. Dr . V S Vatkar
Asso Prof
Microbiology department
D Y Patil Mwdical college, Kolhapur

2. INTRODUCTION
 Gram +ve
 Lanceolate shaped diplococci
 Bile soluble
 Optochin sensitive
 Specific polysaccharide capsule
 Normal inhabitant of URT, mainly causes pneumonia
& otitis media in children
Sinusitis , bronchitis, meningitis etc
 First noticed by Pasteur in 1881

3. morphology
 Small, lanceolate
shaped (one end pointed
& other end flat)
 Arranged in pairs
 Capsulated : encloses
each pair, usually seen in
fresh sample, lost during
repeated subculture, well
demonstrated in India ink
preparation
 Non motile, non-sporing
 Easily stained with aniline
dyes, gram +ve

4. Gram Stain

5. Cultural characteristics
 Aerobes & facultative anaerobes
 Optimum temp : 37 0 C, pH : 7.8
 Growth improves in 5-10 % CO2
 Blood Agar: small dome shaped colonies with green
discoloration (α hemolysis) , further incubation
colonies become flat with raised edges & central
umbonation (Draughtsman or Carom Coin
Appearance)
 Some strains produce abundant capsular material :
large mucoid colonies are seen

6. Colonies on B A

7. Draughtsman or Carom Coin
Appearance

8.  Under anaerobic condition : on bl agar
shows β hemolysis due to O2 labile
hemolysin O.
 In Liquid media: such as Glucose broth
: uniform turbidity. Rapidly undergo
autolysis due to activity of intracellular
enzymes.
 Autolysis is enhanced by : bile salts,
Sodium lauryl sulphate
 Heat killed cultures do not undergo
autolysis

9. Biochemical reactions
 Ferment sugars : produce acid but no gas,
fermentation of Inulin : useful test to differentiate
them from streptococci
 Bile solubility test: few drops of 10% sodium
deoxycholate added in 1 ml of overnight broth
culture: culture clears due to lysis of cocci
(presence of amidase that cleavs the bond betn
alanine & muramic acid in peptidoglycan , it
activates bile salts & causes autolysis)
 Catalase & Oxidase negative

10. Resistance
 Easily destroyed by heat
 Sensitive to most of the antibiotics
 Optochin sensitive: useful to differentiate
pneumococci from streptococci

11. Antigenic structure
Capsule: important Ag: capsular
polysaccharides : it diffuses in cuture
media or infective exudates & tissues,
SPECIFIC SOLUBLE SUBSTANCE (SSS)
 Classification is based on capsular
polysaccharides, more than 90 serotypes:
mainly based on Agglutination,
Precipitation of SSS with specific serum:
detected by QUILLUG REACTION

12. *
* ** *
*
Inhibits the action of complement
Complement
receptor
Fc receptor
S. Pneumoniae capsule
Targets for
protective
antibody

13. QUILLUG REACTION
 Described by Neufeld (1902): suspension
of S pneumoniae is mixed on a glass slide
with a drop of specific antiserum & loopfull
of methylene blue solution
 Homologous antiserum capsule become
swollen
 Test can be directly done on sputum in Ac
pneumonia cases, CSF: in meningitis
cases

14. QUELLUNG
REACTION

15. Other Antigens
 ‘C’ carbohydrate Ag : abnormal
protein (β globulin) that precipitate
with somatic C Ag in ac cases. This is
known as CRP (C reactive protein)
test: passive agglutination by using
latex particles coated with anti CRP
antibodies
Toxins: pneumolysin: cytotoxic &
complement activating properties.
Immunogenic.

16. PATHOGENECITY
 Colonised in nasopharynx: causes
middle ear inf, paranasal sinusitis, direct
spared to resp tract
 80% lobar pneumonia & 60%
brochopneumonia, may cause
tracheobronchitis & empyma
 Lobar pneumonia: usually persons
immunity is lowered
 Bronchopneumonia: especially after viral
infection

18.  Chronic bronchitis : copious respiratory
secretions
 Meningitis : serious inf secondary to
pneumococcal inf like pneumonia, otitis
media, sinusitis etc
 Suppurative lesions in other parts of the
body: arthritis, peritonitis, keratitis,
dacrocystitis

19. Pathogenesis of pneumococci

21. EPIDEMIOLOGY
 Source of inf : human carriers, patients,
transmitted by droplet nuclei, droplets
 Host resistance lowered by resp viral inf,
pulmonary congestion, stress, malnutrition,
immunodeficiency, alcoholism
 Splenectomy, sickle cell anaemia

22. Laboratory diagnosis
 Specimen: sputum, CSF, blood, urine
 Microscopy: rusty sputum in ac cases, gram
stain: gram +ve diplococci
 Culture: on blood agar: incubated at 37 0 C
under 5-10% CO2. blood culture in Ac
condition
 Animal inoculation: mouse is used

23.  Antigen detection: demonstration of
SSS in CSF .
 Co-agglutination test: suspension
of killed Staph aureus are coated
with specific pneumococcal
antibodies bound to protein A of
Staph aureus cell wall
 When live or dead strept pnemoniae
in CSF is mixed with suspension of
Staph aureus visible co-agglutination
is seen

25. TREATMENT
 Penicillin is still first choice of drug , in
milder cases amoxicillin is used
 Erythromycin, tetracycline
 Third generation cephalosporins
 Vancomycin : reserve drug

26. vaccines

27. Difference between
Strepto pneumoniae Viridance
streptococci
Morphology Capsulated, lanceolate
shape,diplococci
Non-capsulated,
oval/rounded cells in
chains
Quellung
reaction
Positive Negative
Colonies on B A Initially dome shaped, later
‘draughtsman’ colonies
Dome shaped
Growth in liq
media
Uniform turbidity Granular turbidity
Bile solubility Positive Negative
Optochin
sensitivity
Positive Negative
Inulin
fermentation
Positive Negative

28. Other streptococci
a) group B streptococci
 Streptococcus agalactiae:
 A member of the normal flora of the female genital tract and
rectum. Up to about pregnant women carry it.
 Important in Neonatal infection:
a) Early Onset Diasease:
• deve within 24-48 hrs after birth
• Inf aquired in utero or during passage thr’ birth canal
• Associated with:
• Premature birth
• PROM
• High mortality rate
• Disease present as Respiratory distress syndrome or
septicemia or meningitis
a)Early-onset Disease:
severe disease develops within 24 – 48 hrs. after birth. Infection acquired either in-utero or
during passage through birth canal.

29. b) Late-onset Disease:
Often occurs in full term neonates without any
underlying disease. Infection occurs in the 2nd
week of birth. Prognosis better than early onset:
Mortality rate about 10%. Usually present as
meningitis.
Treatment:
 Penicillin /Ampicillin
 Sometimes may be combined with Gentamicin.

30. Gr B Streptococci
 identified by CAMP (Christie,
Atkins, Munch-Peterson) Test:
accentuated zone of hemolysis when
inoculated perpendicular to streak of
Staphylococcus aureus
Human pathogens ar capsulated

31. CAMP test

32. Group c streptococci
Streptococcus equisimilis:
 Predominantly animal pathogen
 Human inf : URTI, endocarditis, osteomyelitis,
brain absses pneumonia, purperial sepsis
 Resistance to penicillin, Gentimicin is drug of
choice
 Produce : streptolysin O, streptokinase, other
extracellular substances

33. Group f streptococci
Poorly grown on blood agar
Known as minute streptococci
Streptococcus MG : isolated from
primary atypical pneumonia, α
hemolytic
Demonstration of agglitinins to strep
MG diagnostic test for mycoplasma
(heterophilic Ag)

34. Group D Streptococci
 Has 2 main subgroups:
i) Entrococcal
ii) Non-Enterococcal
 Both are part of the normal intestinal flora.
1) Enterococci: can grow in the presence of
40% bile & 6.5% sodium chloride. They are generally
resistant to Penicillin, but sensitive to Ampicillin.

35. 2 Main Human Pathogens:
Enterococcus faecalis
Enterococcus faecium

36. 2) Non-enterococci:
• cannot grow in presence of 6.5%
NaCl
• main human pathogen Strep.bovis
• they cause UTI, endocartditis and
wound inf

37. -Haemolytic Streptococci
 Formarly called Streptococcus viridance
 Commensals of URT & mouth
 Produce α hemolysis on blood agar
 Spp : Strep. mitis , Strep mutance : dental
carries, Strep salivaris, Strep sanguis
 Usually non pathogenic, occasionally cause inf in
pre-existing cardiac lesions (bacterial
endocarditis)
 Strep sanguis: after tooth extraction or dental
procedures, prosthetic valves or congenital heart
ds: predisposing factors

39. Thank you