The document summarizes various pathogens that can cause meningitis and CNS infections, including mycobacteria, fungi, parasites, and viruses. It describes the characteristics of Mycobacterium tuberculosis, Treponema, Cryptococcus neoformans, and Naegleria fowleri. It also discusses laboratory findings for diagnosing various types of meningitis based on cell count, glucose, and protein levels in cerebrospinal fluid analysis. Microscopic examination and culture tests are outlined to identify different bacteria, fungi, parasites and viruses that may be the causative agents of meningitis and central nervous system infections.

3.  Enlist the other possible pathogens including
mycobacterium ,fungi and parasites causing
meningitis and CNS infections
 Describe the morphology ,virulence factor and
laboratory findings of the following
 Mycobaterium tuberculosis
 Treponema
 Cryptococcus neoformans
 Acanthamoeba,Naegleri fowleri

4.  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

5. Fungi
 Cryptococcus neoformans
 Candida albicans
 Aspergillus
 Histoplasma
 Blastomyces
 Coccidioides
Parasites
 Naegleria foweleri
 Trypanosoma species

6. Mycobacterium tuberculosis Infections

7.  AFB +ve by Zn staining
 Fluorescent staining Rhodamine & Auramine
 Non – chromogenic i.e. doesn't produce
pigment in light or darkness
 Slow growing
 Will not grow at 25C
 Niacin production test + (only Mycobacterium
tuberculosis)
 DNA – probe test

8. Eight Week Growth of Mycobacterium
tuberculosis on Lowenstein-Jensen Agar

9.  Can’t be gram stained
 can’t be grown on artificial culture media
 Direct microscopy of CSF – DGI (dark ground
illumination)
 Serological tests for syphilis
 Non specific
 Rapid plasma reagin ----RPR
 Floculation test ----VDRL
 Specific
 TPHA ---Hemagglutination assays
 FTA – AB --- T.pallidum reacts in immunofluorescence

10. Cryptococcus
Neoformans

11.  Encapsulated yeast
 4 serotypes
 A (C. neoformans v grubii)
 B and C ( C. gatti)
 D (C. neoformans v neoformans)
 All types can cause human disease
 Life cycle
 Asexual: yeast that reproduce by budding
 Human infections

12.  World wide
 C. neoformans associated with bird droppings
 C. gatti not associated with birds, associated with
eucalyptus trees
 Generally an infection of immunocompromised
but can cause clinical disease in healthy
persons
 Decreased Cell-mediated immunity
 AIDS – CD 4 usually < 100
 Prolonged corticosteroids
 Organ transplant

13.  Pulmonary
 Asymptomatic nodule
 Symptomatic: not distinguishable from other
causes
 History, PE, routine laboratory testing does not produce
features peculiarly suggestive of cryptococcal infection
 Diagnosis
 Staining of biopsy specimen
 Culture of sputum and/or blood
 Serum cryptococcal antigen (CRAG)
 All patients with pulmonary disease need a CSF
examination to r/o sub clinical meningitis

14. Silver Stain

15.  Cutaneous
 Disseminated disease
 Looks similar to molluscum contageosum
 Diagnosis:
 Unroofing a lesion and making a smear and culture
 Serum CRAG
 All patients with cutaneous disease need a CSF
examination to r/o sub clinical meningitis

17.  Cryptococcal Meningitis
 Typical
 Subacute onset of fever and headache
 Photophobia and/or meningeal signs in only 25%
 Less typical
 Seizures
 Confusion
 Progressive dementia
 Visual or hearing impairment
 FUO
 Diagnosis
 CSF
 Serum CRAG: > 99% sensitive in AIDS patients

18.  India ink – preparation (Pelikan black drawing
ink) oval or round cells, some showing
budding, irregular in size (2 – 10μm in
diameter). Surrounded by large unstained
capsule
 Wet film preparation – dark field microscopy
 Ag – detection from CSF

19. _ Naegleria fowleri is a free living brain-eating amoeba.
_ Typically found in warm fresh water (thermo tolerant
amoeba).
_ worldwide distribution.
_ It exists in trophozoite and cyst forms and in a transient
flagellate stage.
_ Naegleria fowleri is the causative agent of primary amebic
meningoencephalitis (PAM).
_ The period incubation is short, the symptoms are acute, and
death is almost certain and rapid.
_Naegleria fowleri invades the C.N.S. via penetration of the
olfactory mucosa and nasal tissues (nose).
_ Since Naegleria fowleri trophozoites and cysts are
susceptible to chlorine, swimming pools should be
adequately chlorinated.

20. When a victim swims or
sinks into freshwater.
- all victims have had a
history of swimming
in freshwater lakes or
ponds or swimming
pools a few days before
the onset of symptoms

22. • Structures of the amoeba form are : Trophozoit
and flagellate .
• The infective stage is trophozoit stage
• Method of transmission is by penetrate the
mucosal layer of olfactory tissue and nasal cavity
• Leads to Primary amebic meningoencephalitis
• Most symptoms involving fever , headache, stiff
neck and confusion.
• Diagnosis with X-ray , Occasionally, a C.T scan
may be ordered to rule out cerebral hematoma.
culture media of CSF and PCR .

23.  Primary amoebic meningo encephalitis
 Pus cells in CSF – no bact on gram staining
 Motile amoeba can be seen on microscopy –
(amoeboflagellate)
 CSF may contain eosinophils & red cells also

24. Diagnosis Cells
(Per μL)
Glucose
(mg/dL)
Protein
(mg/dL)
Opening
pressure
Normal 0-5 lymphocytes 45-85 15-45 70-
180mm
H2O
Purulent meningitis
(bacterial)
200-20,000 PMNs Low (<45) High (>50) ++++
Granulomatous meningitis
(Mycobacterial, fungal)
100-1000, mostly
lymphocytes
Low (<45) High (>50) +++
Aseptic meningitis, viral or
Meningoencephalitis
100-1000, mostly
lymphocytes
Normal Moderatel
y
High (>50)
Normal
to +
Spirochetal meningitis
(syphilis, leptospirosis)
25-2000, mostly
lymphocytes
Normal
or low
High (>50) +
Neighborhood reaction Variably increased Normal Normal or
high
Variable

25.  Bact. cell wall components (peptidoglycan &
LPS) – cascade of events involving
complements & cytokines
 TNF α and 1L – 1, inflammatory cascade
 Other chemokines, 1L – 6, 1L – 8, nitric oxide,
prostaglandin E2 (PGE2) – platelet activating
factor (PAF)

26.  Net result of above – blood brain barrier – more
permeable – increased intracranial pressure –
swelling of brain, toxic metabolic product of
bact. metabolism – added in CSF
 Purulent material accumulate at base of brain –
damage to cranial nerves (8th nerve – deafness),
obstruction to flow – (hydro cephalous) –
inflammation of brain & injury to small blood
vessels

27.  Capsule of organisms
 Polysaccharide of capsule interfere with
phagocytosis, and complement mediated killing
 Some capsule – non immunogenic, N. meningitidis
type B

28.  Pneumococcal toxin – Pneumolysins
 Lysis of eukaryotic cells
 Inhibit resp burst of phagocytes
 Inhibit chemotaxis & migration by these cells
 Inhibits mitogen proliferation B cells and antibody
production
 Activates production of TNF and 1L – 1 and
Complement

29.  Splenic function – decreased in sickle cells
disease
 Spleen
 Filters the capsulated organism
 Antibody producing organ especially opsonising
 Sequester bact. that are not well opsonised

30. Activate
Macrophage
Activate
complement
Activate tissue
factor
1L –
1
Fever
TNF
Fever &
Hypertensio
n
Nitrou
s
oxide
Hypotensio
n
C3a C5a
Hypotensio
n edema
Neutro
chemo-tax
Coagulation
cascade
DIC

36. Organism Age group Comment
Serogroup B
Streptococci
(streptococcus
agalactiae)
Neonates to age 3
months
As many as 25% of mothers have vaginal
carriage of serogroup B streptococci. Ampicillin
prophay laxis during labor of women at high
risk (prolonged rupture of membranes, fever,
etc) or of known carriers reduces the incidence of
infection in babies.
Escherichia coli Neonates Commonly have the K 1 antigen
Haemophilus
influenzae
Children 6 months
to 5 years
Widespread use of vaccine greatly reduces the
incidence of H influenzae meningitis in children
Neisseria
meningitides
Infants to 5 years
and young adults
Polysaccharide vaccine
Streptococcus
pneumoniae
All age groups;
highest incidence
in the elderly
Frequent cause of meningitis in AIDS patients
Cryptococcus
neoformans
AIDS patients Frequent cause of meningitis in AIDS patients

37.  Collection – aseptic measures
 Traumatic – 2 – 3 screw capped bottles
 Physical exam – color, turbidity, xantho –
chromia
 Biochemical exam
 Glucose, proteins
 Globulins

38.  Microscopy – cell count
 Type of cells
 Gram stain
 Leishmans
 AFB stain
 Wet film
 India ink staining

39.  Culture
 Blood agar - 37C
 Chocolate agar – 5% CO2
 Mac.Conkey’s agar if the patient is a neonate
for Escherichia coli / other GNR
 LJ medium
 Sabouraud’s agar – fungus

40.  Glucose in CSF
 Normal 45 – 85 mg/dl
 Acute Pyogenic meningitis – decrease or absent
 Tuberculous meningitis and fungal < 45 mg
 Aseptic meningitis (viral) – normal or meningo
encephalitis
 Spirochete – normal or low

41.  CSF proteins
 Normal 15 – 45 mg/dl – pandy’s test neg
positive
 Purulent meningitis increase > 50 mg / dl
 Granulomatous (tuberculous / fungal) – high >
50 mg/dl
 Aseptic meningitis – moderately high> 50
mg/dl
 Spirochetal– high > 50 mg/dl
 Neighbourhood reaction – normal or high

42.  Cell counts – cell / cmm or per μL
 Normal – 0 – 5 lymphocytes
 Purulent (bact) – 2000 – 20,000/cmm polys
 Granulomatous – 100 – 1000 mostly lymphos
TB, Fungal (cryptococcal)
 Aseptic – viral or meningo – encephalitis 100 –
1000 mostly lymphos
 Spirochetal 25 – 2000 mostly lymphos
 Neighbourhood reaction – variably increased

43. ISLAMIC INTERNATIONAL MEDICAL COLLEGE
RAILWAY HOSPITAL , RAWALPINDI
PATHOLOGY DEPARTMENT
Prof. Maj. Gen. (R) Muhammad
Muzaffar
M.B.B.S (PB)
F.R.C Path (London), F.C.P.S (Pak)
Name:_______________________________Age/Sex_______________________Date____________________
Ref.By________________________________Lab No_________________________________________(NE/E)
CSF. RE
Physical
Examination
Color
Turbidity
Xanthochromia
Coagulum
Biochemical
Examination
Glucose
Protein
Globulin increase or not
Bacteriology
Gram staining
Direct microscopy
Cytology, cell count