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Diagnosis Of TB

PULMONARY TBSymptomsDiagnostic tools

Advances in diagnosticsDiagnostic algorithmFlow chartGradingQuality assurance of smear microscopy

EXTRAPULMONARY TBTB lymphadenitis

PEDIATRIC TB

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Pulmonary TB

About 85% of all new TB cases in India arepulmonary TBResponsible for the spread of infection, therefore,epidemiologically important

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Pulmonary TB

Smear positive and smear negative patientsSmear positive

TB in a patient with at least 2 initial sputum smearspecimens positive for AFB, orTB in a patient with one sputum smear specimenpositive for AFB and radiographic abnormalitiesconsistent with pulmonary TB as determined by thetreating MO, orTB in a patient with one sputum smear specimenpositive for AFB and culture positive for M.tuberculosis

Source: Technical and Operational Guidelines for Tuberculosis Control. Oct 2005. P 16

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Pulmonary TB (contd.)

Smear negative TB in a patient with symptoms suggestive of TB

with at least 3 sputum smear specimens negativefor AFB, and radiographic abnormalities consistentwith pulmonary TB as determined by the treatingMO followed by a decision to treat the patient witha full course of anti-tuberculosis therapy, orDiagnosis based on positive culture but negative

AFB sputum smear examination

Source: Technical and Operational Guidelines for Tuberculosis Control. Oct 2005. P 16

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THINK TB!

Pat ients w i th TB f eel i l l and m ore than 80% seek m edicalcare*

Suspec t TB in al l pat ien ts p resen t ing w i th m ore than 3weeks cough

Other symptoms include

Weight loss, Tiredness, loss of appetite, fever with evening rise of

temperature

Chest pain, shortness of breath, loss of appetite, haemoptysis

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Diagnostic tools of pulmonary TB

Main tools for diagnosis are

sputum microscopy,

X-ray chest

sputum culture

Other tools

serological diagnosis-ELISA

amplification technologies

Rapid culture test

Demonstration of myco.TB in clinical samples

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Advantages of sputum microscopySimpleHighly specificLess expensive

More reliableCan be repeatedIndicates infectiousnessCan be used for diagnosis, monitoring progress

and defining cureFeasible even at peripheral health centers

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Limitations of smear microscopy fordiagnosis of TB

Labor intensiveReport of investigation takes more than onevisit.Requires quality control mechanismsNot highly sensitive

Research is ongoing to improve Sensitivity by:Centrifugation, sedimentation, concentration

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X-ray Chest as a primary diagnostictool

No chest X-ray pattern is absolutely typical of TB40% of patients diagnosed as having TB on the basisof x-ray alone do not have active TB10-15% of culture-positive TB patients not diagnosedby X-rayThere is a high Inter and Intra-reader variation in X-ray interpretation

Requires costly equipment and trained techniciansX Rays are highly sensitive but non-specific

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98%

70%

0

20

40

60

80

100

AFB Microscopy X-ray

Microscopy is more objectiveand reliable than X-ray

Inter-observeragreement

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50%

98%

0

20

40

60

80

100

AFB Microscopy X-ray

Microscopy is a more specifictest than X-ray for TB diagnosis

Specificity

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0

20

40

60

80

100

Diagnosed by X-ray alone

Actual cases

X-ray-based evaluation causesover-diagnosis of TB

Over-diagnosis

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Conventional sputum culture fordiagnosis of TB

AdvantagesMost reliablediagnostic methodHighly specificHighly sensitive - Candetect lower numbersof AFB (around 100organisms per ml)

LimitationsRequires speciallytrained staff andfacilitiesPracticable in only afew accreditedlaboratories in thecountryResults available aftera long interval (4-6weeks)

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RNTCPDiagnosticalgorithm

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81%

93% 100%

0%

50%

100%

First Second Third C u m u

l a t i v e

P o s

i t i v i t y

Three sputum smearsare optimal

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LABORATORYFORM FORSPUTUMEXAMINATION

AREVISED NATIONAL TUBERCULOSIS CONTROL PROGRAMMELaboratory Form for Sputum Examination

Name of Referring Health Facility: ____________________ Date: ___________Name of patient: _______________________________ Age: ____ Sex: M F Complete address: ________________________________________________

________________________________________________Type of suspect / disease: Pulmonary

Extra-pulmonary Site: ______________Reason for examination:

Diagnosis Repeat Examination for Diagnosis Follow-up of anti-TB treatment Patients TB No ____________

(Name and signature of referring person/ official)

If sputum samples are being transported:Specimen identification No.: __________ Date of sputum collection: __________Specimen Collectors name and signature ______________________________

RESULTS (To be completed in the laboratory of DMC)Name of DMC: ___________________________________________________Lab. Serial No.: __________________________________________________

Date ofexamination Specimen

Visual

appearance(M, B, S)*

Results

(Neg orPos)

Positive (grading)

3+ 2+ 1+ Scanty**

a

b

c

* M = Mucopurulent, B = Blood stained, S = Saliva** Write actual count of AFB seen in 100 oil immersion fields

Date: ______________ Examined by (signature): _____________________

The completed form (with results) should be sent to the referring PHI within one day of theexamination.

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Grading of Smears

If the slide has: Result Grading No. of fields to beexamined

More than 10 AFB per oil immersion field Pos 3+ 20 1-10 AFB per oil immersion field Pos 2+ 50

10-99 AFB per 100 oil immersion fields Pos 1+ 1001-9 AFB per 100 oil immersion fields Pos Scanty-B* 100No AFB in 100 oil immersion fields Neg 100

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Quality AssuranceRNTCP Lab network has three levels:

National Reference LaboratoriesNTI BangaloreTRC ChennaiLRS New Delhi

Intermediate Reference LaboratoriesState level

Network of Designated Microscopy Centers(>11,000)Includes microscopy centers in medical collegesOne DMC covers a population of about 1 lakhProvide quality assured acid-fast sputum smear microscopyservices

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Extra Pulmonary TB

RNTCP is a public health program with the main focuson pulmonary TB

Extra pulmonary TB constitutes

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RNTCP Classification ofExtra-pulmonary TB

Seriously ill Not seriously ill TB Meningitis

Disseminated TB

TB pericarditis

TB peritonitis, intestinal TB

Bilateral or extensive pleurisy Spinal TB with neurological

complications

Genito-urinary tract TB

Lymph node TB

Pleural effusion

(unilateral)

Bone (excluding spine)

Peripheral joint(s)

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TB lymphadenitis

Commonest form of EPTBIn HIV negative patients-

isolated cervical lymphadenopathy

HIV positive patients Multi focal involvementIntra-thoracic and intra-abdominal lymphadenopathy

Associated pulmonary disease common

Diagnostic algorithm for TB lymphadenitis

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Diagnostic algorithm for TB lymphadenitis

Lymph node enlargement of > 2 cm in one or more sites, with orwithout periadenitis, with or without evidence of TB elsewhere; orpresence of an abscess with or without discharging sinus

If lymph node enlargement persists, suspect TB lymphadenitis

Pus from discharging sinus / aspirate from lymph node using FineNeedle Aspiration Cytology (FNAC)Smear examination for AFB (using pus/aspirate) by Ziehl Neelsensmethod, Mantoux test for children < 14 years

Diagnosis confirmed if the pus / aspirate from FNACshows:1. ZN stain +ve for AFB, or2. Granulomatous changes (where facilities a vailable )

If FNAC results are inconclusive, excision biopsyis advisable for smear and histopathologicalexamination

Start Category IIItreatment

Prescribe a course of antibiotics for two weeks

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Screening of paediatric TB suspects

Bacteriological testing Sputum microscopy, if possibleGastric lavage if sputum not available

Mantoux testTuberculin testing(1TU PPD RT23 with Tween 80Positive if more than 10 mm induration in 48-72 hours

X-ray chest-see for Mediastinal/hilar lymphadenitisPleural effusionMiliary and fibrocaseous pictures

PCRVariable sensitivityNot recommended for routine use

SerologyNot useful in paediatric TB

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Diagnosis of Paediatric Tuberculosis

Diagnosis of TB in children is to be based ona combination of

clinical presentation,sputum examination, Chest X ray,

Mantoux testhistory of contact as described in thediagnostic algorithm

Algorithm 1: Diagnostic Algorithm For Pediatric Pulmonary TB

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g g g y

X-ray +Mantoux

Sputum PositiveTB (Anti TB Treatment)

If yes, examine 3 sputum smears

Is expectoration present?

If no, refer toPediatrician

Pulmonary TB Suspect Fever and / or cough 3 weeks Loss of wt/No wt gain History of contact with suspected

Or diagnosed case of active TB

Refer to Pediatrician

Negative

Antibiotics10-14 da s

1 Positive

X-Ray

Cough Persists

2 or 3 Positives

2 or 3 Positives 3 Negatives

Negative for TB

Suggestive of TB

Repeat 3 SputumExaminations

Sputum-Positive TB(Anti-TB Treatment)

Suggestive of TB

Negative for TB

Sputum-Negative TB