The document provides information about Streptococcus pneumoniae (pneumococci) and Streptococcus viridans. It describes the typical morphology, culture characteristics, pathogenicity and laboratory identification of these two types of bacteria. S. pneumoniae is a leading cause of community-acquired pneumonia and other infections. It is distinguished from S. viridans by being optochin-sensitive, bile soluble and able to ferment inulin.

1. Sharq Elneil College
School of Medical Laboratory Sciences
Department of Microbiology
Medical Bacteriology course
Streptococcus pneumoniae
(Pneumococci)
Dr.Mahadi Hassan Mahmoud
mahadi2010sd@yahoo.com
Bsc, Msc, MIBMS Microbiology

2. The natural habitat
 pneumococci is provided by the
mucosa of the upper respiratory
tract.
About 40–70 % of healthy adults are
carriers. Pneumococcal infections .
Usually arise from this normal flora
(endogenous infections).

3. Morphology
 Gram-positive, oval to lancet-
shaped cocci (0.5 and 1.25
micrometers in diameter)
usually occur in pairs or short
chains
 surrounded by a thick capsule.

7. Culture &chaacteristics:
on blood agar,
 Alpha -hemolytic colonies
 Mucoid (smooth, shiny) appearance
Mutants without capsules produce
colonies with a rough surface (“R” form-
maintain integrity of nucleic acid target

8. streptococcus pneumoniae is a very
fragile bacterium
 contains within itself the enzymatic
ability to disrupt and to disintegrate the
cells. autolysin.
The physiological role of this autolysin is
to cause the culture to undergo a
characteristic autolysis that kills the entire
culture when grown to stationary phase.

9. Virtually all clinical isolates of
pneumococci harbor this autolysin and
undergo lysis usually beginning between
18-24 hours after initiation of growth under
optimal conditions.
 Autolysis is consistent with changes in
colony morphology.
Colonies initially appear with a plateau-
type morphology, then start to collapse in
the centers when autolysis begins.

10. Streptococcus pneumoniae is a
fermentative aerotolerant anaerobe
Unlike other streptococci, they do
not display an M protein.
 they hydrolyze inulin, and their
cell wall composition is characteristic
both in terms of their peptidoglycan
and their teichoic acid.

13. Antigenic Structure
 Classified in 90 different serovars
based on the fine chemical structure of
the capsule polysaccharides acting as
anti- gens.
 This capsule antigen can be
identified using specific antisera in a
reaction known as capsular swelling
test ( Quelling reaction

14. Antiphagocytic.
Prevents the desposition of
complement and subsequent
phagocytosis (opsonisation) in the
absence of type-specific
antibodies.
These serotypes are number and
subdivided on the basis of
morphological similarity.

15. It was believed that most disease
is caused by the 23 serotype, this is
not the case locally. It causes:
otitis media, sinusitis, mastoiditis
and pneumonia ,joint infections,
endocarditis and meningitis.

18. Pathology:
 Capsule protects the pathogens from
phagocytosis and is the most important
determinant of pneumococcal viru-lence.
Unencapsulated variants are not
capable of causing disease. Other
potential virulence factors include :
pneumolysin
IgA protease.
.

19. Predisposing factors include :
 primary cardiopulmonary diseases,
previous infections
(e.g., influenza)
 extirpation of the spleen or
complement system defects.

20. important pneumococcal infections:
 Lobar pneumonia consolidated mass, in
contrast to the spongy texture of normal lung
tissue.
Bronchopneumonia.
 Acute exacerbation of chronic
bronchitis
 Otitis media
Sinusitis

21. Meningitis
corneal ulcer.
 Severe pneumococcal infections
frequently involve sepsis

22. Laboratory diagnosis
specimens:
Collection of Spacimen
Direct Exam
Culture
Identificaion
Serology
Molecular characterization

23. Optochin sensitivity
Pneumococci are sensitive to optochin
(ethylhydrocupreine hydrochloride).
Method: Placing a disc (5 g) on a primary
sputum culture and culturing the plate aerobically
(not in CO2) can help to provide a rapid
Result : The zone of inhibition should be at
least10 mm. Most viridans streptococci and other
alphahaemolytic streptococci are resistant to
optochin. If the zone of inhibition is less than 10
mm (6 mm disc) the colonies should be tested for
bile solubility

25. *Bile solubility test
Method : a tube technique,
the results of which are easy to read.
Some workers, however, prefer to test
suspect alpha-haemolytic colonies directly
on a culture plate by touching a colony with
a loopful of 2% sodium deoxycholate
Incubation at 35–37 ºC for 30 minutes.
Result: examining for lysis (disappearance
of the colony, indicating S. pneumoniae).

26. Agglutination Test
Latex agglutination tests are widely used
methods for identification and typing
 The speed of the observed
agglutination reaction (positive
reactionwithin 10 s) is a great advantage.
 The same is true for the ease of
interpreting a reaction as positive
compared to that in the normal capsular
reaction test.

28. Treatments
 pencillins
high-frequency occurrence of strains
resistant to penicillin
 Cephalosporins
Cephalexin ceftriaxone
Macrolides

29.  Vancomycin
Erythromycin
 Cotrimoxazole ( trimethoprim
+sulphamexazole)

30. Antibiotic Resistant
 extreme genetic flexibility
enabling S. pneumoniae to
acquire antibiotic resistance
switch the capsular serotype is a
result of the unique pneumococcal
feature: natural competence for
genetic transformation.

31. Natural competence is a transient
physiological state enabling the
bacteria to acquire exogenous DNA.
 Competence is regulated by
quorum sensing system and thus
depends on cell density and many
other factors

32. pathogen reservoir.
Epidemiology and prophylaxis.
 Pneumococcal infections are endemic
and occur in all seasons, more frequently
in the elderly. Humans are the natural
pathogen reservoir
 The vaccine product Pneumovax is
available for immunization purposes.

33. jugate vaccine that is effective in children under two years
 purified capsule polysaccharides
(PPV )
seven-valent conjugate vaccine
a seven-valent con-
effective in children of less than 2
year (PCV)

35. Streptococcus Viridans
form part of the normal microbial
flora of the upper respiratory tract
(particularly oropharynx) and
gastrointestinal tract.
They may therefore be found with
S. pneumoniae in sputum (as
commensals)

36. Morphology
 Gram-positive cocci
usually occur in pairs or long chains

37. Culture:
on blood agar,
 Alpha -hemolytic colonies
the viridans group of streptococci can also
be nonhaemolytic and occasionally beta-
haemolytic.

38. A few species are pathogenic
.S. mutans,
S. sanguis,
S. mitior)
causing endocarditis, bacteraemia, and
dental caries.

39. S. anginosus group
(formerly S. milleri group)
 associated with deep
abscesses in various sites in the
body (abdomen, chest, brain)
often in association with other
bacteria.

40. Compare between Pnuemoccci
and Viridans strepococci
Optrichoin Bile Inulin
solubility Ferment
pneumoco Sensetive Posotive Ferment
cci
Viridans Resistant Negative Non
ferment

41. THANKYOU FOR ATTENTION