It discusses laboratory tests involved in diagnosing meningitis with more emphasis on details of each test and findings, esp useful for microbiologists and medical students.

2. Pyogenic
Tubercular
Aseptic
Pyogenic Bacteria
Eg. N. Meningitidis, S.
pneumoniae, H. Influenzae
Mycobacterium
Tuberculosis
Viral, Fungi and protozoa

3. Sample Collection
Transport
Initial Processing
Reporting
Examination

5. CSF – Lumbar Puncture
Blood – i.v.
Other samples :
 For viruses : Nasopharyngeal & Throat
swab, Feaces
 Cobweb appearance (Tubercular)

6. Lumbar Puncture

7. Contraindications
 Local skin infections
 Suspected spinal cord or i/c mass lesion
 bleeding diathesis
 Spinal column deformities
 Non-cooperation of patient

8. Stylet
Needle
Black – 22 G
Yellow – 20 G
Spinal Needle

9. STEP 1
PATIENT’S CONSENT IS TAKEN

10. STEP 2
PATIENT POSITIONING
Lateral lying position Sitting position

11. STEP 3
LANDMARKING PUNCTURE SITE
Line joining Post.
Sup. iliac crests
intersects Midline
at Spinous
process of L4

12. STEP 4
CLEANING SITE WITH ANTISEPTICS
First Iodinated
antiseptics
Then, Isopropyl
alcohol

13. STEP 5
LOCAL ANAESTHESIA
1% Lidocaine
without
Epinephrine

14. STEP 6
SPINAL NEEDLE INSERTION

16. STEP 7
CSF COLLECTION IN 3-4 TEST TUBES
TUBE 1
Glucose
Protein
TUBE 2
Gram stain
Culture
TUBE 3
Cell count
TUBE 4
For special
tests
(2-5 mL each)

17. STEP 8
REMOVAL OF NEEDLE AND
APPLYING BANDAID

19.  Immediately hand-delivered
 Never refrigerated (H.Inf may die)

21.  One Portion Centrifugated at 3000 rpm/5min
 Other portion left uncentrifuged
SUPERNATANT
DEPOSIT
UNCENTRIFUGED CENTRIFUGED
for Antigen detection,
Biochemical Analysis
for Direct Microscopy,
Culture
for Cell count

23. Cell Count
Biochemical Analysis
Direct Microscopy
Culture
Antigen Detection

24. Diagnosis Total Cells
(per mm3)
Predomina
nt cell
Proteins
(mg/dL)
Glucose
(mg/dL
CSF
Pressure
(mm Hg
Normal
CSF
0-5 Lymphocyte 15-45 40-80 70-180
Pyogenic
Meningitis
↑↑ed
(5-20,000)
Polymorph
(Neutrphl)
↑↑↑ed
(>100)
↓↓ed ↑ed
Tubercular
Meningitis
↑ed
(5-2,000)
Lymphocyte
↑↑ed
(>45)
↓ed ↑ed
Viral
Meningitis
↑ed
(5-2,000)
Lymphocyte
↑ed
(>45)
Normal ↑ed or
Normal

25. Direct Microscopy
 Using part of sediment
 Two types :
Dry Smear
Wet film

26. Direct Microscopy
Dry
Smear
Gram Stain

27. Direct Microscopy
Wet Films
Acanthamoeba Cryptococcus

28. Culture
CSF culture using sediment
 For Pyogenic Bacteria :
 Blood Agar
 Macconkey Agar
 Chocolate Agar
 Brain-Heart Infusion Broth
 For M. tuberculosis :
 Lowenstein-Jensen (LJ)
 Middlebrook media
 For fungi :
 Sabouraud dextrose agar (SDA)
Incubated at 37oC
for 48-72 hours
Incubated at 30oC
for 8 weeks
Incubated at 30oC
for 3 weeks

29. Culture
MacCconkey Agar (LF) Blood Agar (Str.
Pneumoniae)
Pink circular colonies Small, dome-shaped with greenish
discolouration (α-hemolysis)

30. Culture
Chocolate Agar
(H. Influenzae)
Brain-Heart Infusion Broth
(Fastidious bacteria)
Small opaque colonies

31. Culture
Lowenstein-Jensen
Medium
(Egg based)
Middle-brook Medium
(Agar based)
Dry, Rough, Tough,
buff coloured colonies
Granular colonies

32. Culture
SDA medium (Cryptococcus)
Smooth, Mucoid, Cream-
coloured colonies

33. Culture
Blood Culture
 Useful in meningitis due to :
 N. meningitidis
 H. influenzae
 Str. Pneumoniae
Special Culture/isolation techniques
 If Viral/Protozoal/Fungal meningitis is
suspected

34. Confirmatory Tests
For confirmation
 Microscopy and biochemical reactions
 Serological techniques
 Other confirmatory tests depending on the
organism

36. Rapid Diagnosis
 Supernatant fluid contains Antigen
 Detected Serologically
 Rapid Diagnostic Test for Meningitis
 Methods :
Latex Agglutination,
Counterimmunoelectrophoresis
(CIEP)

37. Rapid Diagnosis
Available for :
 N. meningitidis,
 Str. Pneumoniae,
 H. influenzae type b
 Group B streptococcus

38. Rapid Diagnosis
Latex Agglutination Test
Slide
AGGLUTINATION
occurs
Antigen
Polystrene
Latex
Particles
Antibody
coated
Supernatant

39. Rapid Diagnosis
Counter-immuno-electrophoresis
Antigen Antibodies
Supernatant
Slide
Agarose
layer
Wells cut
on surface
- +
Electric Current is applied
PRECIPITATION LINE forms

40. Relax !!!
Thank you…