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Diagnosis of TB.

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Presentation on theme: "Diagnosis of TB."— Presentation transcript:

1 Diagnosis of TB

2 Learning Objectives List the 4 principle components of a TB evaluation
Describe the criteria which differentiate PTB+ from PTB- Describe the 3 major indications for culture and DST

3 Common Sites of TB Disease
Lungs Pleura Central nervous system Lymphatic system Genitourinary systems Bones and joints Disseminated (miliary TB)

4 Systemic Symptoms of TB
Fever Chills Night sweats Appetite loss Weight loss Fatigue

5 Evaluation for TB HIV test Medical history Physical examination
Bacteriologic or histologic exam (Chest radiograph if indicated)

6 Medical History HIV status Symptoms of disease
History of TB exposure, infection, or disease Past TB treatment Demographic risk factors for TB Other medical conditions that increase risk for TB disease (e.g., diabetes)

7 Symptoms of Pulmonary TB
Productive, prolonged cough (duration of 2-3 weeks) Chest pain Hemoptysis (bloody sputum) Signs may vary based on HIV status

8 Specimen Collection Procedure
Obtain 3 sputum specimens for smear examination and culture Spot, first morning, spot Follow infection control precautions during specimen collection

9 Sputum Smear Examination
Specimens should be sent to the lab immediately to preserve the quality of the specimens Always aim for three specimens at each exam Always store at a cool temperature and away from sunlight to preserve the quality of specimens 3 respiratory specimens will detect 90% of smear-positive cases

10 AFB smear-microscopy Acid-fast bacilli (AFB) (shown in red) are tubercle bacilli

11 Acid fast smear showing TB bacilli

12 Smear-positive PTB vs. Smear-negative PTB-
PTB+ (Pulmonary TB smear-positive) One AFB-positive smear; i.e. any patient with at least one positive smear result (irrespective of quantity of AFBs seen on microscopy) Recommendations to improve the diagnosis of smear negative pulmonary and extrapulmonary TB among adults in HIV prevalent and resource constrained settings. Draft for discussion by Strategic and Technical Advisory Group of Stop TB Department of WHOJune 2006

13 Smear-positive PTB vs. Smear-negative PTB-
PTB- (smear-negative) Any pulmonary TB case that does not meet the definition of being smear-positive. This includes: 1. Patients with three negative smear results and radiological findings and doctor’s decision to treat for TB 2. Patients with negative smear results and a positive culture result for M. tuberculosis 3. Patients who are unable to produce sputum and with highly suspicious radiological and clinical findings and doctor's decision to treat for TB

14 Other Acid Fast Bacilli
Mycobacteria other than those comprising the M. tuberculosis complex are called Non-Tuberculous Mycobacteria (“NTM”) or Mycobacteria Other Than Tuberculosis (“MOTT”). These mycobacteria may cause pulmonary disease resembling TB. Increasingly, cases from these organisms are being reported in patients with weakened immune systems, especially due to HIV. It is important to note that infection with MOTT also may produce AFB-positive sputum smear results and positive Mantoux skin test readings mimicking M. tuberculosis. Culture can distinguish between M. tuberculosis and MOTT. Disease due to MOTT is usually unresponsive to first-line anti-TB drugs.

15 Chest Radiograph Diagnosis of PTB solely on basis of CXR not encouraged May have unusual appearance in HIV-positive persons CXR is helpful in HIV+, smear- negative patients Cannot confirm diagnosis of TB FROM WHO__ (Is this consistent with Manual) ? Although chest radiographic abnormalities are common in HIV-infected persons without TB, chest x-ray plays an important role in the diagnosis of TB among PLWHA. CXR presentations of TB in HIV patients are now well characterised and should no longer be considered ‘atypical’ for TB in HIV-prevalent settings. CXR plays a significant role in shortening the delay of diagnosis and should be done early in the course of investigation of a TB suspect. CXR can also be an important entry point to diagnosing non-TB chest diseases, which are common among PLWHA. However, the limitations that exist for its wider use such as unavailability at peripheral health facilities and difficulty of interpreting results, even by trained physicians need to be acknowledged and dealt with accordingly. Research is needed to identify innovative ways to enhance the ability of clinicians, including non-physicians, to interpret CXRs accurately, to assess the feasibility and added value of peer reviewing of CXRs and to evaluate novel imaging techniques that might replace conventional radiography. Arrow points to cavity in patient's right upper lobe.

16 Cultures Should be requested for ALL retreatment patients
Relapse Failure Return after default Culture is indicated for New and retreatment PTB cases still smear- positive at end of intensive phase Symptomatic contacts of known MDR cases Colonies of M. tuberculosis growing on media

17 Diagnosis in Children HIV test Patient history Contact to PTB+
Symptoms consistent with TB HIV test Clinical Exam TST Bacteriological confirmation Investigations for PTB and EPTB Guidance of National Tb Programmes for the Management of TB in Children WHO/HTM/TB/

18 Key Risk Factors in Children
Risk Factors For Children Include: Household contact with a newly diagnosed smear-positive case Age less than 5 years HIV infection Severe malnutrition.

19 Key Features of TB in Children
The presence of three or more of the following should strongly suggest a diagnosis of TB: Chronic symptoms suggestive of TB Physical signs highly of suggestive of TB A positive tuberculin skin test Chest X-ray suggestive of TB (The presentation in infants may be more acute, resembling acute severe pneumonia and should be suspected when there is a poor response to antibiotics. In such situations, there is often an identifiable source case, usually the mother.)

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