12. BACTEC TB-460 : rapid,specific,&rapid
culture method
Both respiratory & non respiratory specimens
13-14 days 200 viable bacilli
14-17 days 20 viable bacilli
13. Mycobacterial growth indicator tube
(MGIT)960
Art fluorescent technology
Rapidly 7-10 days
Based on O2 quenching of mycobacteria with
fluorescent dye
14. Uses specific Mycobacterial phages to detect
viable bacteria within 48 hrs
15. Serology helps in detecting either the
specific or non specific immune responses
of the host or the presence of the antigen in
the host
16. Specific Ig G &Ig M can be detected using
immunologic techniques against viruses
Various types include
precipitation
Agglutination widal test
Complement fixation
immunofluorescence
Elisa
Western blot
18. Tag Ab with fluorescein isothiocynate
Ab-virus complex or viral
antigens
microscopically by UV illumination
Detects viruses which are uncultivable
19. Ω Assays are available for rapid detection of
bacterial Ags in various body fluids
Ω Useful when prior antibiotic therapy has
been initiated and cultures are negative after
24 hrs of incubation
20. Detection of microbial
antigens/products
The following fluid/samples can be assayed
CSF: Latex agglutination & counter-current
immuno electrophoresis are used to
demonstrate the soluble polysaccharide Ag
of cryptococcus &….
21. Detection of microbial
antigens/products
Serum- Pl.falciparum/vivax are detected at
levels of 100-200 parasite/űl
Urine-strep.pneumonia legionella,
Stool :helicobacter pylori,clostridium
difficile,giardia
23. New developments
Answer for organisms with growth
characteristics
slow – mycobacteria
difficult – viruses,chlamydia
fastidious- mycoplasma
24. Highly sensitive – detects low pathogen no’s
as in meningitis
Used to monitor response to treatment
(viral load assays for hepatitis B,C&HIV)
25. Nucleic acid probes :
NA hybridization is powerful & widely used
technique
Used to detect and locate specific
DNA&RNA sequence in tissues or
chromosomes by making use of
radioactive/fluorescent labelled DNA/RNA
probes complementary to the required
sequence
26. Commercially available for the available for
identification of M.tuberculosis
complex,avium,intracellulaire,kansasi,
gordonae
28. Nucleic acid amplication
- Target amplification
PCR : An in vitro method for amplifying
specific DNA sequence
extremely minute amounts of NA
generates billions of exact copies
making genetic analysis a simple
process
29. Target DNA acts as template
nucleotides
primers&DNA polymerase
generates copies by alternate heating &
cooling for denturation, annealing, &extension
30. Nucleic acid amplication
- Target amplification
Real time PCR : rapid
a fluorescent signal is used for
real time monitoring of amplification
Transcription mediated amplification
Uses ribosomal rna as the target for reverse
transcriptase
31. Nucleic acid amplication
-signal
amplification
Increases the signal generated from
hybridized probe molecule
Probe amplification
End product is an amplified version of original
product includes LCR, cycling probe
technology
In LCR phenotypic change in the organism such
as virulence or drug resistance
32. Disadvantages of molecular
methods
Amplification can amplify even minute
quantities of contaminating DNA – false (+)
Do not differentiate dead from living
organisms
False(-) results may due to low copy no’s of
microorganisims at site of infection