Meningitis Bacterial Meningitis

1. NEISSERIAE
MENINGITIDIS
Dr. Uzma Mussarat

2. LEARNING OBJECTIVES
 Enlist the bacterial causes of meningitis
 Describe the morphological features,virulence
factors and diagnosis of following bacteria
 Neisseria meningitides
 Listeria monocytogenes
 Haemophilus influenzae
 Streptococcus agalactae
 streptococcus pneumonia

3. Meningitis
 Meningitis means inflammation but usually
implies serious infection of the meninges
 Microorganism reach the meninges either by
direct extension from the ears, nasopharynx,
cranial injury or congenital meningeal defect,
or by bloodstream spread.
 Non infectious causes of inflammation
include malignant cells, drugs and blood
following subarachnoid hemorrhage

4. Meningococcal Meningitis
Is inflammation of the meninges-
meningitis, caused by the bacteria
Nesseria meningitidis.
Neisseria meningitidis,Streptococcus
pneumoniae and Haemophilus
influenzae are the most common
agents of bacterial meningitis.

5. Meningococcal Meningitis
 Less common bacterial causes of Meningitis, such as
Staphylococci, enteric bacteria, group B streptococci
and Listeria, occur in sub-populations like the
immunocompromised, neonates, or head trauma
patients.
 Patients with Meningococcal Meningitis present with
sudden onset of fever, intense headache, nausea,
vomiting, stiff neck and, frequently, a petechial rash
with pink macules or, very rarely, vesicles. Delirium
and coma often appear.
 Case fatality rate is between 5% and 15%.

6. Pathology
 In acute bacterial meningitis, the pia arachnoid
is congested with polymorphs. A layer of pus
forms. This may organize to form adhesions,
causing cranial nerve palsies and hydrocephalus.
 In chronic infection (e.g. TB), the brain is
covered in a viscous grey green exudates with
numerous meningeal tubercles. Adhesions are
invariable. Cerebral edema occurs in any
bacterial meningitis.
 In viral meningitis there is a predominantly
lymphocytic inflammatory CSF reaction without
pus formation, polymorphs or adhesions, there is
little or no cerebral edema unless encephalitis
develops.

7. Neisseria
meningitides

8. General Characteristics of
Neisseria spp. Aerobic
 Gram-negative cocci often arranged in pairs
(diplococci) with adjacent sides flattened (like
coffe beans)
 Oxidase positive
 Most catalase positive
 Nonmotile
 Acid from oxidation of carbohydrates, not
from fermentation

9. Neisseria gonorrhoeae
Neisseria meningitidis
Important Human Pathogens
Other species normally colonize
mucosal surfaces of oropharynx and
nasopharynx and occasionally
anogenital mucosal membranes

10. Neisseria Associated Diseases
(ophthalmia
neonatorum)

11. Encapsulated small, gram-negative
diplococci
Second most common cause (behind S.
pneumoniae) of community-acquired
meningitis in previously healthy adults;
swift progression from good health to
life-threatening disease
Introductionof Neisseria meningitidis

12. Meningococcal meningitis

13.  Humans only natural hosts
 Person-to-person transmission by
aerosolization of respiratory tract
secretions in crowded conditions
 Close contact with infectious person
(e.g., family members, day care
centers, military barracks, prisons, and
other institutional settings)
Epidemiology of Meningococcal
Disease

14. Highest incidence in children
younger than 5 years and
particularly those younger than 1
year of age as passive maternal
antibody declines and as infants
immune system matures
Commonly colonize nasopharynx
of healthy individuals; highest oral
and nasopharyngeal carriage rates
in school-age children, young
adults and lower socioeconomic
groups

15. Occurrence
 Infections can occur through the year, but are more
common in late winter to early spring.
Mode of Transmission
 By direct contact- respiratory droplets from nose and throat
of infected people.
 Infection usually causes subclinical infection, severe
systemic infection is rare.
 Carrier prevalence can be as high as 25%.

16. Pathogenicity:
Pili-mediated, receptor-specific
colonization of nonciliated cells of
nasopharynx
Antiphagocytic polysaccharide capsule
allows systemic spread in absence of
specific immunity
Toxic effects mediated by
hyperproduction of lipooligosaccharide
 Serogroups A, B, C, Y, W135 account for
about 90% of all infections

17. Specific receptors (GD1 ganglioside) for bacterial
fimbriae on nonciliated columnar epithelial cells in
nasopharynx of host
Organisms are internalized into phagocytic
vacuoles, avoid intracellular killing in absence of
humoral immunity and complement system (patients
with late complement deficiencies are particularly at
risk)
Replicate intracellularly and migrate to subepithelial
space where excess membrane fragments are
released
athogenesis of Meningococcal
Disease

18. Hyperproduction of endotoxin (lipid A of
LOS) and blebbing into surrounding
environment (e.g., subepithelial spaces,
bloodstream) mediates most clinical
manifestations including diffuse vascular
damage (e.g., endothelial damage, vasculitis
(inflammation of vessel walls), thrombosis
(clotting), disseminated intravascular
coagulation (DIC)

19. Following dissemination of virulent
organisms from the nasopharynx:
 Meningitis
 Septicemia (meningococcemia) with or
without meningitis
 Meningoencephalitis
 Pneumonia
 Arthritis
 Urethritis
Diseases Associated with
Neisseria meningitidis

20. Meningitis Clinical findings
 Clinically: rapid deterioration of flu like illness
 Headache, neck stiffness, +ve kerning’s
sign, fever,
 Diagnosis: CSF + blood culture
 CSF: WBC , RBCs
 Gram stain: bacteria & cells

21. Neisseria meningitidis in
Cerebrospinal Fluid

22. Skin Lesions of Meningococcemia
NOTE:
Petechiae
have
coalesced
into
hemorrhagi
c bullae.

23. Neck rigidity

24. Haemorrhagic

25.  Large numbers (e.g., >107cells/ml) of
encapsulated, small, gram-negative
diplococci (flattened along adjoining
side) and polymorphonuclear
leukocytes (PMN’s) can be seen
microscopically in cerebrospinal fluid
(CSF)
Laboratory Characterization of
Neisseria meningitidis

26. Contd…
Transparent, non-pigmented
nonhemolytic colonies on
chocolate blood agar with
enhanced growth in moist
atmosphere with 5% CO2
Oxidase-positive
Acid production from glucose and
maltose but not from other sugars

27. Diagnosis
 Isolation of the organism
from CSF or blood.

28. 2. Streptococcus pneumoniae
 (G+,Lancet shaped diplococci
Alpha- haemolytic colonies on
blood agar
Quelling Test +ive
Optochin –sensitive
Bile solubility test +ive (bile
soluble)
Capsular polysaccharide Antigen
detection from CSF by Latex

29. Streptococcus pneumoniae
General characteristics
Inhabits the nasopharyngeal areas of healthy
individuals
Possess C substance
Virulence factors
Polysaccharide capsule
Clinical infections
pneumonia
meningitis
bacteremia

30. The quellung reaction
(swelling reaction) forms the
basis of serotyping and relies
On the swelling of the
capsule upon binding of
homologous antibody.
The test consists of mixing a
loopful of colony with equal
quantity of specific antiserum
and then examining
microscopically
for capsular swelling

31. Contd…
 Pneumoccus grow only in enriched media. (blood agar, glucose
broth)
 aerobes, facultative anaerobes
 optimal temperature – 37C (25-42C)
 optimal pH – 7.8 (6.5-8.3)
 increased growth in 5-10% CO2

32. Laboratory Diagnosis:
Streptococcus pneumoniae
Colony
morphology
Smooth,
glistening, wet-
looking, mucoid
a-Hemolytic
CO2enhances
growth

33. Laboratory Diagnosis:
Streptococcus pneumoniae
Identification
Catalase negative
Optochin-
susceptibility-test–
susceptible
Bile-solubility-test–
positive

34. Alpha & Beta Haemolysis

35. S. pneumoniae

36. Pus cells and S. pneumoniae
in sputum gram stain

37. Neutrophil & Red Cells

39. 3. Haemophilus influenzae
 Aerobic , Small, pleomorphic gram-negative coccobacilli
 Polysaccharide capsule
 Six different serotypes (a-f) of polysaccharide capsule(based on
the antigenicity of capsular polysacchrides)

40. Contd…
 95% of invasive disease caused
by type b
 The type b capsule is composed of polyribitol phosphates
 Unencapsulated and untypeable strains can cause sinusitis and otitis media
but are usually noninvasive
 Growth in culture requires heme (X factor) and/or nicotinamide adenine
dinucleotide (NAD) (V factor) for adequate energy production

41. H.INFLUENZAE IS THE LEADING
CAUSE OF MENINGITIS IN YOUNG
CHILDREN
Important cause of URTI(otitis
media,sinusitis and epiglottitis) and
sepsis in children
It causes pneumonia in adults particularly
in those having COPD (chronic
obstructive pulmonary disease)

42. LABORATORY DIAGNOSIS
Specimens:
 Oral swab: avoid contamination with oral secretions
 Sputum from LRT
 Direct needle aspiration
 Cerebrospinal fluid (CSF) and blood (>107 bacteria/ml)
Microscopy: both sensitive & specific; G(-)
bacilli in CSF in >80% cases before antibiotics
treatment

43. LABORATORY DIAGNOSIS
 Heated blood (chocolate) agar for isolation(to inactivate nonspecific inhibitors of
H.influenzae growth)
 Growth require heme (x factor) and nicotinamide adenine dinucleotide, NAD (v factor)

44. Contd..
Definitive identification can be
made by biochemical tests or the
capsular swelling “QUELLUNG
“reaction
Fluorescent-antibody staining of
the organism and
counterimmunoelectrophoresis or
latex agglutination tests detect
the capsular polysacchride.

45. Streptococcus agalactiae

46. Streptococcus agalactiae
 Gram +ive cocci in small chains
 Beta haemolytic colonies on blood agar
 Lance-field gouping ---group B (specific antiserum)
 Hippurate Hydrolysis test +ive
 CAMP – TEST +ive (Chtist,Atkin,Mouch,Peterson)
 Bacitracin Disk ----Negative

48. FIG. 6. CAMP-
positive Streptococcus
agalactiae (group B) inoculated
at right angles to the test
organism Staphylococcus aureus.
Note the arrow-shaped zones of
enhanced hemolysis.
FIG. 7. CAMP-negative Streptococcus
pyogenes (group A) inoculated at
right angles to the test organism
Staphylococcus aureus. Note the
absence of arrow-shaped zones of
enhanced hemolysis.)

49. Listeria Monocytogenes
 Gram +ive , motile rod. Coccobacillus , Non –
capsulated
 Motile at 18 – 20 C°, non motile at 37 C°
 Tumbling/ Rotating motility
 Grows at Refrigerating temp 2-8 C°also
 Can cross placenta
 Causes meningitis in new born and pregnant women

50. Listeria Monocytogenes

51. Laboratory Diagnosis
Gram staining----G+ive rods
Small grey coloured colonies
with narrow zone of beta
hemolysis on blood agar
Motile nature differentiate it
from corynaebacteria

52. THANKS