molecularTB - MOLECULAR TOOLS IN DIAGNOSIS OF TUBERCULOSIS...

Info iconThis preview shows pages 1–15. Sign up to view the full content.

View Full Document Right Arrow Icon
MOLECULAR TOOLS IN DIAGNOSIS OF TUBERCULOSIS DM SEMINAR 08 Apr 05
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Scope • Rapid culture methods • Serological diagnosis • Nucleic acid based techniques • Mycobacteriophage based assays • Applications • Future directions
Background image of page 2
Introduction • Long generation time of the tubercle bacillus ~18- 24 hours • All microbiology reports are delayed ~4-6 weeks • Inadequate treatment encourages spread of drug resistant strains adding to disease burden in community • Molecular tools hold promise for future for early diagnosis and drug resistance testing
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Rapid culture methods • BACTEC system • Mycobact Growth Indicator Tube(MGIT) • MB/Bac T system • Septi-chek • ESP culture system • Microscopic observation of broth/slide cultures
Background image of page 4
BACTEC System • Radiometric method 14 C labelled palmitic acid added to liquid 7H12 medium • Detects MTB by metabolism rather than growth 14 CO 2 produced detected by specialized eqpt • Growth index(GI) measured • Results available in 7-14days (87-96%) Ramachandran et al, Ind J TB 2003
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
MGIT • Automated system • Capable of analyzing 960 specimen • Metabolism of MTB produces O 2 • Fluorescence of dye with oxygen measured • Results available in 7-14 days • Cost effective for high load microbio-labs
Background image of page 6
MB/Bac T system • Automated • Colorimetric detection of CO 2 • Slightly longer time (10-15 days) • Prone to contamination
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
ESP Myco system • Changes in gas pressure in a sealed culture broth bottle by gas production/consumption • Used in combination with solid medium not stand alone
Background image of page 8
Microscopic observation of broth culture • Rapid detection method • Relatively inexpensive •A s q u i c k • Equal sensitivity and specificity • Suitable for endemic countries with high disease burden
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Identification of isolates • Standard biochemical tests • Radiometric methods • Enzymatic/colorimetric method • Lipid analysis- HPLC • Mycobacteriophage based • DNA probes • Ribosomal RNA probes • Gene amplification – PCR/TMA/SDA
Background image of page 10
Serologic tests
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Serologic tests • Applied for variety of cases incl smear +ve pulmonary tuberculosis to smear & culture negative EPTB at inaccessible body sites. • ELISA based methods for the detection of mycobact antigen in body fluids • Most often for the diagnosis of neurological and pleural tuberculosis
Background image of page 12
Serologic tests • Positive test may perhaps “rule in” a diagnosis, but a negative test cannot “rule out” a diagnosis of tuberculosis • Used as supportive evidence along with conventional tests. • Some workers have advocated testing for a panel of antigens rather than single antigen.
Background image of page 13

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Limitations - Serologic tests • Affected by BCG vaccination, previous infection and environmental NTM exposure • Persistence of antibodies leads to difficulty in distinguishing between infection and disease • Low sensitivity in smear negative, HIV co-infection, and disease endemic countries
Background image of page 14
Image of page 15
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page1 / 73

molecularTB - MOLECULAR TOOLS IN DIAGNOSIS OF TUBERCULOSIS...

This preview shows document pages 1 - 15. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online