Microbiology Test Flashcards
Purpose of microbiology test
identification of causative agent in Meningitis
Microorganisms must be recovered by growing it on the
appropriate culture medium
24 hrs
Bacterial meningitis
6 weeks
Tubercular meningitis
CSF centrifuged at
1500 rpm for 15 minutes
sediments is used for
Slides
Culture
Confirmatory rather than diagnostic procedure
CSF Culture
Detection of gram-positive, gram-negative bacteria
Gram stain
For mycobacterium
Acid Fast Stain
For Cryptococcus neoformans
India ink
For other causative agents of meningitis
Latex Agglutination Test
Bacterial Meningitis
Predominant cell :
Increase protein :
Glucose :
Lactate :
Neutrophil
Marked
Markedly decreased
>35 mg/dl
Viral Meningitis
Predominant cell :
Increase protein :
Glucose :
Lactate :
Lymphocyte
Moderate
Normal
Normal
Tubercular meningitis
Predominant cell :
Increase protein :
Glucose :
Lactate :
Lymphocyte, monocytes
Moderate to marked
Decreased
>25mg/dl
Fungal meningitis
Lymphocyte, monocyte, eosinophil
Moderate to mark
Normal to decrease
>25mg/dl
Routinely performed on CSF from all suspected cases of meningitis
Gram stain
Values lies in the detection of
bacterial and fungal organism
Highly concentrated specimen
Cytocentrifuge
results as gram-positive
acid-fast bacilli
Common causes of bacterial meningitis in infants
S. agalactiae
E. coli (K1 strain)
L. monocytogenes
Common causes of bacterial meningitis in adult
N. meningitides
H. influenza (Serotype B) S. pneumoniae
Common causes of bacterial meningitis in elderly
S. pneumoniae
N. meningitides
L. monocytogenes
[India Ink Preparation]
Cryptococcus neoformans
Fungal meningitis
[India Ink Preparation]
Cryptococcal meningitis
AIDS
[India Ink Preparation lab findings]
India ink
Thick encapsulated organism
[India Ink Preparation lab findings]
Gram stain
Starburst pattern
[India Ink Preparation lab findings]
Associated with
Increased eosinophil
Diagnosis of meningitis caused by Gram-negative bacteria
Limulus lysate test
Reacts with bacterial endotoxin of gram-negative bacteria
Limulus amebocyte
Limulus lysate test reagent
Horseshoe crab
Horseshoe crab came from
Limulus Polyphemus
Limulus lysate test positive result
Caogulation within 1hr of incubation at 37 deg C
Rapid tests
Latex agglutination
ELISA
Bacterial antigen test
Performed to detect the presence of Neurosyphilis
Serologic testing
Procedure recommended by the CDC to diagnose Neurosyphilis
VDRL
More sensitive than the VDRL
Prevent contamination with blood because the FTA-ABS remains positive in
the serum of treated cases of syphilis
FTA-ABS
