Your SlideShare is downloading. ×
  • Like
Diagnosis of Tuberculosis an Update
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×

Now you can save presentations on your phone or tablet

Available for both IPhone and Android

Text the download link to your phone

Standard text messaging rates apply

Diagnosis of Tuberculosis an Update

  • 1,251 views
Published

Diagnosis of Tuberculosis an Update

Diagnosis of Tuberculosis an Update

Published in Health & Medicine , Technology
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Be the first to comment
No Downloads

Views

Total Views
1,251
On SlideShare
0
From Embeds
0
Number of Embeds
0

Actions

Shares
Downloads
113
Comments
0
Likes
5

Embeds 0

No embeds

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
    No notes for slide

Transcript

  • 1. Diagnosis of Tuberculosis an update Dr.T.V.Rao MD Dr.T.V.Rao MD 1
  • 2. Testing for TB Infection • Tuberculosis (TB) is a disease that is spread through the air from one person to another. There are two kinds of tests that are used to determine if a person has been infected with TB bacteria: the tuberculin skin test and other direct and indirect Tests .Dr.T.V.Rao MD 2
  • 3. Diagnosis of TB Disease • People suspected of having TB disease should be referred for a medical evaluation, which will include Medical history, Physical examination, Test for TB infection (TB skin test or TB blood test), • Chest radiograph (X-ray), and • Appropriate laboratory tests Dr.T.V.Rao MD 3
  • 4. Who Should Get Tested for TB • TB tests are generally not needed for people with a low risk of infection with TB bacteria. • Certain people should be tested for TB bacteria because they are more likely to get TB disease, including: • People who have spent time with someone who has TB disease People with HIV infection or another medical problem that weakens the immune system • People who have symptoms of TB disease (fever, night sweats, cough, and weight loss)Dr.T.V.Rao MD 4
  • 5. Who Should Get Tested for TB • People who have spent time with someone who has TB disease • People with HIV infection or another medical problem that weakens the immune system • People who have symptoms of TB disease (fever, night sweats, cough, and weight loss) Dr.T.V.Rao MD 5
  • 6. Who Should Get Tested for TB • People from a country where TB disease is common (most countries in Latin America, the Caribbean, Africa, Asia, Eastern Europe, and Russia) • People who live or work somewhere in the United States where TB disease is more common (homeless shelters, prison or jails, or some nursing homes) • People who use illegal drugs Dr.T.V.Rao MD 6
  • 7. X ray of Chest a Commonly used Diagnostic tool • Acute pulmonary TB can be easily seen on an X-ray. However, the picture it presents is not specific and a normal chest X-ray cannot exclude extrapulmonary TB. Also, in countries where resources are more limited, there is often a lack of X-ray facilities.Dr.T.V.Rao MD 7
  • 8. Other tests • Other tests, such as a chest x-ray and a sample of sputum, are needed to see whether the person has TB disease.Dr.T.V.Rao MD 8
  • 9. Types of specimens: -Sputum. - BAL. -Pleural effusions - Urine - Stool -CSF -Aspiration ( gastric – cold abscess) - Blood in case of haematogenous TB Dr.T.V.Rao MD 9
  • 10. Laboratory Diagnosis 1- Sputum smears stained by Z-N stain Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB. Advantage: - cheap – rapid - Easy to perform - High predictive value > 90% - Specificity of 98% Disadvantages: - sputum ( need to contain 5000-10000 AFB/ ml.) - Young children, elderly & HIV infected persons may not produce cavities & sputum containing AFB.
  • 11. Sputum Collection • Sputum specimens are essential to confirm TB – Specimens should be from lung secretions, not saliva • Collect 3 specimens on 3 different days • Spontaneous morning sputum more desirable than induced specimens • Collect sputum before treatment is initiated 11
  • 12. Interpretation of sputum stained by Z N Stain (WHO ) More than 10 bacilli / field ------- +++ From 1 – 10 bacilli / field ------- ++ From 10 – 99 bacilli / 100 fields ----- + From 1 -9 bacilli/100 fields ------ write the no. No bacilli seen ---------- negative
  • 13. 2- Detecting AFB by fluorochrome stain using fluorescence microscopy: The smear may be stained by auramine-O dye. In this method the TB bacilli are stained yellow against dark background & easily visualized using florescent microscope. Advantages: - More sensitive - Rapid Disadvantages: - Hazards of dye toxicity - more expensive - must be confirmed by Z-N stain
  • 14. Acid Fast Bacilli under Fluorescent Microscope Dr.T.V.Rao MD 14
  • 15. Culture • Used to confirm diagnosis of TB • Culture all specimens, even if smear is negative • Initial drug isolate should be used to determine drug susceptibility 15
  • 16. Laboratory Diagnosis 1- Sputum smears stained by Z-N stain Three morning successive mucopurulent sputum samples are needed to diagnose pulmonary TB. Advantage: - cheap – rapid - Easy to perform - High predictive value > 90% - Specificity of 98% Disadvantages: - sputum ( need to contain 5000-10000 AFB/ ml.) - Young children, elderly & HIV infected persons may not produce cavities & sputum containing AFB. Dr.T.V.Rao MD 16
  • 17. 2- Detecting AFB by fluorochrome stain using fluorescence microscopy: The smear may be stained by aura mine-O dye. In this method the TB bacilli are stained yellow against dark background & easily visualized using florescent microscope. Advantages: - More sensitive - Rapid Disadvantages: - Hazards of dye toxicity - more expensive - must be confirmed by Z-N stain Dr.T.V.Rao MD 17
  • 18. Lowenstein–Jensen medium • When grown on LJ medium, M. tuberculosis appears as brown, granular colonies (sometimes called "buff, rough and tough"). The media must be incubated for a significant length of time, usually four weeks, due to the slow doubling time of M. tuberculosis Dr.T.V.Rao MD 18
  • 19. 3- Cultures on L J media Lowenstein –Jensen medium is an egg based media with addition of salts, 5 % glycerol, Malachite green. Advantages: - Specificity about 99 % - More sensitive (need lower no. of bacilli 10-100 / ml) - Can differentiate between TB complex & NTM using biochemical reactions - Sensitivity tests for antituberculous drugs ( St, INH, Rif., E) Disadvantages: Slowly growing ( up to 8 weeks ) Dr.T.V.Rao MD 19
  • 20. Recent Methods for Diagnosis I –BACTEC 460 ( rapid radiometric culture system ) specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 – labelled palmitic acid & PANTA antibiotic mixture. Growing mycobacteria utilize the acid, releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument. The daily increase in GI output is directly proportional to the rate & amount of growth in the medium.
  • 21. Mycobacteria Growth Indicator Tube (MGIT) Tube contains modified Middlebrook 7H9 broth base with OADC enrichment & PANTA antibiotic mixture. All types of clinical specimens, pulmonary as well as extra-pulmonary ( except blood) could be cultured on this type of media.
  • 22. The MGIT 960 System The MGIT 960 system is a non-radiometeric automated system that uses the MGIT media & sensors to detect the fluorescence. Advantages: -The system holds 960 plastic tubes which are continuously monitored. - Early detection as the machine monitoring & reading the tubes every hour.
  • 23. Detection and identification of mycobacteria directly from clinical samples • Genotypic Methods : • 􀂄 PCR • 􀂄 LAMP • 􀂄 TMA / NAA • 􀂄 Ligase chain reaction • 􀂄 Phenotypic Methods : • 􀂄 FAST Plaque TB Dr.T.V.Rao MD 23
  • 24. • Essentially PCR is a way to make millions of identical copies of a specific DNA sequence , which may be a gene, or a part of a gene, or simply a stretch of nucleotides with a known DNA sequence, the function of which may be unknown Polymerase Chain Reaction (PCR) Dr.T.V.Rao MD 24
  • 25. Polymerase Chain Reaction (PCR) & Gene probe Nucleic acid probes & nucleic acid amplification tests in which polymerase enzymes are used to amplify ( make many copies of specific DNA or RNA sequences extracted from mycobacterial cells. Advantages: - Rapid procedure - High sensitivity (1-10 ( 3 – 4 hours) bacilli / ml sputum)
  • 26. • Interferon-γ assays measure cell- mediated immunity by quantifying IFN-γ released from sensitized T cells in whole blood/PBMCs incubated with TB antigens. Quantiferon-GOLD Dr.T.V.Rao MD 26
  • 27. What Positive Skin Test ( Tuberculin Test means) • A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria. It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease Dr.T.V.Rao MD 27
  • 28. Tuberculin Test Interpretation: * A positive test indicates previous exposure and carriage of T.B. * A negative tuberculin test excludes infection in suspected persons * Tuberculin positive persons may develop reactivation type of T.B. * Tuberculin negative persons are at risk of gaining new infection * False positive reactions are mainly due to: - Infection with nontuberculous mycobacteria * Dr.T.V.Rao MD 28
  • 29. False negative reactions may be due to: -• False negative reactions may be due to: - Sever tuberculosis infection (Miliary T.B.) - Hodgkin’s disease • Corticosteroid therapy - Malnutrition - AIDS • Children below 5 years of age with no exposure history: • Positive test must be regarded suspicious Dr.T.V.Rao MD 29
  • 30. Tuberculin Test ( Mantoux Test ) • Test to be interpreted in relation to clinical evaluation. • Even the induration of 5 mm to be considered positive when tested on HIV patients. • Lacks specificity.
  • 31. Positive Test Means • This means the person’s body was infected with TB bacteria. Additional tests are needed to determine if the person has latent TB infection or TB disease. A health care worker will then provide treatment as needed. Dr.T.V.Rao MD 31
  • 32. Negative Test Means • This means the person’s body did not react to the test, and that latent TB infection or TB disease is not likely.Dr.T.V.Rao MD 32
  • 33. Tuberculin Testing - Limitations • False positive reactions are mainly due to: • - Infection with nontuberculous mycobacteria • * False negative reactions may be due to: • - Sever tuberculosis infection (Miliary T.B.) - Hodgkin’s disease • - Corticosteroid therapy - Malnutrition - AIDS • * Children below 5 years of age with no exposure history: • - Positive test must be regarded suspicious Dr.T.V.Rao MD 33
  • 34. Recent Methods for Diagnosis I – BACTEC 460 ( rapid radiometric culture system ) Specimens are cultured in a liquid medium (Middle brook7H9 broth base )containing C14 – labeled palmitic acid & PANTA antibiotic mixture. Growing mycobacteria utilize the acid, releasing radioactive CO2 which is measured as growth index (GI) in the BACTEC instrument. The daily increase in GI output is directly proportional to the rate & amount of growth in the medium. Dr.T.V.Rao MD 34
  • 35. TB blood tests • TB blood tests (also called interferon-gamma release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB. An IGRA measures how strong a person’s immune system reacts to TB bacteria by testing the person’s blood in a laboratory. • Two IGRAs are approved by the U.S. Food and Drug Administration (FDA) and are available in the United States Dr.T.V.Rao MD 35
  • 36. Positive IGRA • This means that the person has been infected with TB bacteria. Additional tests are needed to determine if the person has latent TB infection or TB disease. A health care worker will then provide treatment as needed. Dr.T.V.Rao MD 36
  • 37. Negative IGRA: • This means that the person’s blood did not react to the test and that latent TB infection or TB disease is not likely. Dr.T.V.Rao MD 37
  • 38. IGRAs are the preferred method of TB infection testing for the following: People who have received bacilli Chalmette–Guérin (BCG). BCG is a vaccine for TB disease. People who have a difficult time returning for a second appointment to look for a reaction to the TST. There is no problem with repeated IGRAs. Dr.T.V.Rao MD 38
  • 39. III Polymerase Chain Reaction (PCR) & Gene probe Nucleic acid probes & nucleic acid amplification tests in which polymerase enzymes are used to amplify ( make many copies of specific DNA or RNA sequences extracted from mycobacterial cells. Advantages: - Rapid procedure - High sensitivity (1-10 ( 3 – 4 hours) bacilli / ml sputum) Dr.T.V.Rao MD 39
  • 40. Molecular DR testing is particularly useful for • Patients suspected or at high risk of having drug-resistant TB,very ill patients for whom drug- susceptibility information might alter case management decisions, such as patients who do not get better while taking standard first-line therapy, Dr.T.V.Rao MD 40
  • 41. Detection of MDR Tuberculosis • Very ill patients for whom drug- susceptibility information might alter case management decisions, such as patients who do not get better while taking standard first-line therapy, Dr.T.V.Rao MD 41
  • 42. Detection of MDR Tuberculosis • outbreak or contact investigations when drug resistance is suspected in the source case or in some severely immunocompromised persons such as HIV-infected persons or those receiving dialysis in which knowledge of drug- susceptibility would be a significant benefit and affect preventive therapy decisions, Dr.T.V.Rao MD 42
  • 43. Tuberculosis and HIV infection • HIV association has become a threat to the developed countries too • HIV association will lead to rapid spread of tuberculosis Dr.T.V.Rao MD 43
  • 44. HIV Considerations • HIV is the strongest risk factor for progression to active disease • HIV kills CD4+ T Helper cells which normally inhibit M. tuberculosis • HIV interferes with PPD skin test • Protease inhibitors interfere with rifampin Dr.T.V.Rao MD 44
  • 45. Epidemiology • An ancient disease, called as white plague • 1/3 of the world population is infected • 2 billion infected • Each year 9 lakhs to 1 million are infected • Poor nations phase the burnt of the disease. • In developing world > 4o% of the population is effected • 15 million suffer the disease • 3 million are highly infective. Dr.T.V.Rao MD 45
  • 46. MDR tuberculosis • Multidrug resistant tuberculosis has become a global threat. • In 1993 WHO declared Tuberculosis a Global emergency • Animals shed the bacilli in Milk, human’s get infected after drinking the unsterilized Milk • Pasteurization has reduced the incidence of Bovine tuberculosis. Dr.T.V.Rao MD 46
  • 47. Why Tuberculosis continues to be Important • Someone in the world is newly infected with TB bacilli every second. • Overall, one-third of the world's population is currently infected with the TB bacillus. • 5-10% of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life. People with HIV and TB infection are much more likely to develop TB. Dr.T.V.Rao MD 47
  • 48. • Programme Created by Dr.T.V.Rao MD for Medical and Paramedical Students in Developing world • Email • doctortvrao@gmail.com Dr.T.V.Rao MD 48