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Streptococcus pneumoniae
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
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
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
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
17.
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
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
24.
25. TREATMENT
Penicillin is still first choice of drug , in
milder cases amoxicillin is used
Erythromycin, tetracycline
Third generation cephalosporins
Vancomycin : reserve drug
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
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