In this ppt student will know more abou bacteria that cause meningitis and the symptoms related to each type of bacteria

1. ‫الرحيم‬ ‫الرحمن‬ ‫هللا‬ ‫بسم‬
CNS
Problem 1
Bacterial Causes of meningitis

2. Bacterial Causes of meningitis
1. Neisseria meningitidis
2. Hemophilus influenza
3. E.coli
4. Streptococcus pneumonia
5. Streptococcus agalactiae

3. Neisseria meningitidis
Gram stain:
Gram negative diplococci, non-motile, non-sporing,
capsulated
Culture:
• facultative anaerobe
• It needs enriched media
• On chocolate agar: simple & translucent
• Grow also on Thayer-martin agar(lysed blood + VCN)

4. virulence factors
1. Capsular polysaccharides Antigens: N. meningitidis is divided into 13
serogroups.
2. Outer membrane protein in cell wall: It facilitates epithelial cells
invasion by N. meningitidis.
3. Lipopolysaccharides (endotoxin): in cell wall &responsible for toxicity
with infection
4. IgA protease enzyme: which splits & inactivates IgA.
5. Pili: for adherence to host cells.

5. • The organism present in nasopharynx of healthy carriers
• Source of infection: Case or carrier
• Mode of infection: Droplets.
• The organism reach the meninges through the blood, it crosses the BBB
Pathogenesis:

6. Symptoms
• fever
• petechial skin lesions (mild
haemorrhage under the skin).
• severe headache
• projectile vomiting
• rigidity of neck
• rash
• coma and death in severe cases .
This tends to occur in epidemic form.

7. Haemophilus influenza
 H. influenzae are Gram negative pale
staining coccobacilli , non-motile, non-
sporing,
 95% of them are non-capsulated(normal
flora in the upper respiratory tract)
 Some strains are capsulated (pathogenic)
 The capsule can be demonstrated by
capsular swelling reaction.

8. Quelling reaction

10. Haemophilus influenza
H. influenzae are fastidious organisms. Media for
their growth should contain X and V (NAD)
factor:
 X factor is a hemin . V factor is nicotinamide
adenine dinucleotide (NAD).
Bacteria require media containing X and V factor
that are essential for their growth.

11. Escherichia coli
1-Morphology:
Gram-negative bacilli, non-sporing and motile. Some strains are
capsulated.
2-Culture characters:
• It can grow on ordinary media.
● MacConkey's agar where they produce rose pink lactose
fermenting colonies.

12. Escherichia coli
Biochemical reaction:
1-They ferment glucose, lactose,
maltose, mannite, and sucrose
with the production of acid and
gas.
2-It is indole positive

13. Streptococcus
1.According to oxygen requirements for growth, Streptococci are classified into:
• ● Obligatory anaerobic Streptococci (peptostreptococci): are part of the normal flora of the mouth, upper respiratory
tract, bowel and female genital tract. They often participate in anaerobic infection in abdomen and pelvis e.g. puerperal
sepsis.
• ● facultative anaerobic Streptococci: are classified according to haemolytic reaction on blood agar into:
• Beta haemolytic Streptococci: That produce complete haemolysis i.e. colonies on blood agar are surrounded by a
clear zone of haemolysis e.g. Streptococcus pyogenes. Include large number of of Streptococci that are .
• Alpha haemolytic Streptococci: That cause incomplete lysis of erythrocytes with formation of greenish zone
around colonies e.g. Viridans streptococci.
• Non-haemolytic Streptococci.

14. Streptococcus aglactiae
Streptococcus agalactiae (also known as group B
streptococcus or GBS) is
gram-positive coccus (round bacterium) with a tendency to form chains .
It is a beta-hemolytic, catalase-negative, and facultative anaerobe
GBS is a harmless commensal bacterium being part of the
human microbiota colonizing the gastrointestinal and genitourinary tract of
up to 30% of healthy human adults (asymptomatic carriers). Nevertheless,
GBS can cause severe invasive infections.
Streptococcus agalactiae is surrounded by a bacterial capsule composed
of polysaccharides (exopolysacharide). The species is subclassified into
ten serotypes (Ia, Ib, II–IX) depending on the immunologic reactivity of their
polysaccharide capsule.
β-hemolytic colonies of Streptococcus agalactiae, blood
agar 18h at 36°C
Violet-stained gram-positive cocci and pink-stained gram-negative

15. Streptococcus aglactiae
group B streptococcus GBS neonatal infection typically originates in the lower reproductive tract of infected
mothers.
GBS infections in newborns are separated into two clinical syndromes,
early-onset disease (EOD)
and late-onset disease (LOD).
EOD manifests from 0 to 7 living days in the newborn, most of the cases of EOD being apparent within 24h of birth.
The most common clinical syndromes of EOD are sepsis without apparent focus, pneumonia, and less frequently
meningitis.
GBS LOD affects infants from 7 days to 3 months of age and is more likely to cause bacteremia or meningitis. LOD
can be acquired from the mother or from environmental sources.

16. Streptococcus pneumoniae
(Pneumococci)
1.Morphology:
Gram positive that are non motile, non sporing and capsulated. They are arranged in pairs, the capsule appears as an
unstained halo.
2-Culture characters:
• - S.pneumoniae cannot grow on ordinary media. It needs enriched media.
• - facultative anaerobe. Growth is enhanced by 5-10% Co2
• - Incubation temperature: 37°C.

17. • Culture media :
● Blood agar: colonies are small, at first dome shaped and later developed central plateau (due to natural autolysis) with
an elevated rim, giving the character of draughtsman appearance. They are surrounded by α haemolysis.
Streptococcus pneumoniae
(Pneumococci)

18. Antigenic structure:
The capsule is polysaccharide and has 90 immunologically distinct types. Types 1-8 are
responsible for 75% of pneumonia and pneumococcal bacteramia .It is essential for
virulence of the organism (resist phagocytosis).
Quelling reaction:
When Pneumococcus of certain antigenic type is mixed with specific anti- polysaccharide
serum of the same type or with polyvalent antiserum on a microscope slide, the capsule
swells markedly.
Streptococcus pneumoniae
(Pneumococci)

19. Diseases caused by pneumococci:
● Pneumococci cause most of bacterial pneumonia and its complications as otitis media,
sinusitis, empyema and bacteremia. Bronchitis, conjunctivitis and bacteremia that lead to
meningitis, peritonitis, septic arthritis and endocarditis.
Laboratory diagnosis:
1.Specimens according to lesions: pus, sputum, C.S.F. or blood culture.
2.Smear stained by Gram stain
3.halo (capsule), Quelling reaction.
4.Direct detection of pneumococcal antigen in body fluid as C.S.F. by latex
5.agglutination test.
6.Culture on blood agar. Colonies are identified by its morphology and α
7.heamolysis.
Streptococcus pneumoniae
(Pneumococci)

20. Prophylaxis:
•● Polyvalent conjugate vaccine prepared from 23 types of capsular protein polysaccharides .
Streptococcus pneumoniae
(Pneumococci)