TB Diagnosis

8/2/2019 TB Diagnosis

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Diagnosis of Tuberculosis

Dr. John WatsonDr. John Watson

Leeds General InfirmaryLeeds General Infirmary


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Some definitions

uuPulmonary TBPulmonary TB -- active TB disease in the lungactive TB disease in the lung

uuExtra pulmonary TBExtra pulmonary TB -- disease anywhere elsedisease anywhere else

(including pleura, intra(including pleura, intra--thoracic nodes)thoracic nodes)uuLatent TB infection (LTBI)Latent TB infection (LTBI) -- some bacilli in thesome bacilli in the

body, not active diseasebody, not active disease


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Delays in TB Diagnosis

uuDelay from onset of symptoms to start ofDelay from onset of symptoms to start of

treatment median 68 daystreatment median 68 days

2003, Yorkshire and Humber Region2003, Yorkshire and Humber RegionuuTB DeathsTB Deathsdelay from onset of symptomsdelay from onset of symptoms

to diagnosis 116 daysto diagnosis 116 days

199219922002, Leeds2002, Leeds


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Consider the Possibility

uuBe aware of epidemiological risk factorsBe aware of epidemiological risk factors

Known TB contactKnown TB contact

Ethnic groupEthnic group Country of birthCountry of birth

HIVHIV

Other immune compromiseOther immune compromise

DeprivationDeprivation

uuRemember TB can affect anyoneRemember TB can affect anyone


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Take a history

uuHistory of risk factorsHistory of risk factors

uuConstitutional symptomsConstitutional symptoms

uuPulmonary symptomsPulmonary symptoms

uuOther organ symptomsOther organ symptoms

uuPrevious history of TB diagnosis / treatmentPrevious history of TB diagnosis / treatment


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Symptoms - constitutional

uuFeverFever

Persisting more than 2 weeksPersisting more than 2 weeks

uuChillsChillsuuNight SweatsNight Sweats

uuAnorexiaAnorexia

uuWeight lossWeight lossuuFatigueFatigue


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Symptoms - Pulmonary

uuCoughCough

uuSputumSputum

uu +/+/-- HaemoptysisHaemoptysis

uuMay also haveMay also have

Chest pain (Chest pain (pleuriticpleuritic))

BreathlessnessBreathlessness


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Symptoms -

extrapulmonary

Back painBack pain

ConvulsionsConvulsions

DysuriaDysuria

Abdominal painAbdominal pain Red eyeRed eye

Swollen footSwollen foot

DizzinessDizziness

Neck lumpsNeck lumps

Joint painJoint pain

ParaesthesiaeParaesthesiae

Altered bowel habitAltered bowel habit InfertilityInfertility

DysphagiaDysphagia

Skin ulcerSkin ulcer

uu Almost any chronic symptomAlmost any chronic symptomuuconsider TB especially if constitutional symptomsconsider TB especially if constitutional symptoms


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Symptoms

Latent TB Infection

NoneNone


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Symptoms - interpretation

uuSymptoms not specificSymptoms not specific

uuSymptoms not sensitiveSymptoms not sensitive

EgEg in a Los Angeles studyin a Los Angeles study CoughCough 72%72%

Cough > 2/52Cough > 2/52 48%48%

Pulmonary TB, cough > 2/52Pulmonary TB, cough > 2/52 52%52%

FeverFever 52%52%

Fever > 2/52Fever > 2/52 29%29%


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Examine the patient

uuPulmonaryPulmonary

Depends on site and extent of diseaseDepends on site and extent of disease

Chest examination often normal unless advancedChest examination often normal unless advanceddiseasedisease

uuExtraExtra--pulmonarypulmonary

Almost any sign, anywhereAlmost any sign, anywhere

uuLatent TB InfectionLatent TB Infection

NormalNormal


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Chest Xrayuu Abnormalities most common in upper lobes orAbnormalities most common in upper lobes or

apical segment of lower lobesapical segment of lower lobes

InfiltratesInfiltrates

NodulesNodules

ConsolidationConsolidation

CavitiesCavities

FibrosisFibrosis

uu Atypical inAtypical in immunosuppressedimmunosuppressed (including HIV)(including HIV)

uu Cannot confirm diagnosisCannot confirm diagnosis

uu Cannot distinguish active and old diseaseCannot distinguish active and old disease


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Infiltration withInfiltration with

cavity and volume losscavity and volume loss

in Leftin Left

upper lobeupper lobe


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Infiltrates in rightInfiltrates in right

upper lobeupper lobe


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Extensive bilateralExtensive bilateraldiseasedisease

40 year old40 year old

White, UK born,White, UK born,

Employed,Employed,HIV negativeHIV negative


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AfterAfter

completingcompletingtreatmenttreatment


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Right lower lobeRight lower lobe

consolidationconsolidation

Old changes leftOld changes leftapexapex


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Pleural effusionPleural effusion


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Differential diagnosis

uu Unilateral infiltrateUnilateral infiltrate

Pneumonia, carcinomaPneumonia, carcinoma

uu Bilateral infiltratesBilateral infiltrates

SarcoidSarcoid

uu Upper zone fibrosisUpper zone fibrosis

SarcoidSarcoid, Extrinsic allergic, Extrinsic allergic alveolitisalveolitis, ABPA, ABPA

uu Solitary cavitySolitary cavity

Carcinoma, Abscess, RheumatoidCarcinoma, Abscess, Rheumatoiduu Multiple cavitiesMultiple cavities

WegenerWegenerss granulomatosisgranulomatosis,, StaphStaph. Pneumonia, PMF. Pneumonia, PMF

uu HilarHilar// MediastinalMediastinal Lymph NodesLymph Nodes

SarcoidSarcoid, Lymphoma, Lymphoma


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Differential diagnosis

Some TB which wereSome TB which weremissedmissedoriginallyoriginallythought to be:thought to be:

uu LymphomaLymphoma

uu PneumoniaPneumonia

uu Bronchial CarcinomaBronchial Carcinoma

uu Ca colonCa colon

uu EmpyemaEmpyema

uu Right heart failureRight heart failure

uu OsteoarthritisOsteoarthritis

Some I thought wereSome I thought wereTB but were notTB but were notturned out to be:turned out to be:

uu LymphomaLymphoma

uu PneumoniaPneumonia

uu WegenersWegenersgranulomatosisgranulomatosis

uu SarcoidosisSarcoidosis

uu PCPPCP

uu MesotheliomaMesothelioma


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Sputum examination

uu Sputum smear +Sputum smear +veve::

So many bacilli in theSo many bacilli in thesputum you can see themsputum you can see themunder a microscopeunder a microscope

Most infectiousMost infectious

uu Sputum SmearSputum Smear--veve

not enough bugs in thenot enough bugs in thesputum to seesputum to see

need 3 morningneed 3 morningspecimens to be surespecimens to be sure

may still be culture +may still be culture +veve

infectiousness approxinfectiousness approx25% of smear +25% of smear +veve

AAFB (shown in red) are tubercle bacilli


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Culture

uu Gold standard forGold standard fordiagnosisdiagnosis

uu Results in 2Results in 2--3 weeks with3 weeks with

liquid medialiquid mediauu Enables sensitivity testingEnables sensitivity testing

uu Distinguishes nonDistinguishes nontuberculoustuberculous mycobacteriamycobacteria

uu Culture all specimensCulture all specimens Sputum, biopsy specimens,Sputum, biopsy specimens,

BAL, aspiratesBAL, aspirates

uu RememberRemember-- Formalin kills!Formalin kills!

Colonies ofM. tuberculosis

growing on solid media


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What, no sputum?

Culture something else!uuGastric aspiratesGastric aspirates

uuInduced sputumInduced sputum

NebulisedNebulised hypertonic salinehypertonic salineuuBronchoscopyBronchoscopy withwith lavagelavage

uuExtraExtra--pulmonarypulmonaryaspirate / biopsyaspirate / biopsy

Pleural biopsy more sensitive than pleural fluidPleural biopsy more sensitive than pleural fluid


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Endobronchial TB

uuBronchoscopicBronchoscopic

appearance ofappearance of

tuberculosistuberculosis

affecting loweraffecting lower

tracheatrachea

uuConfirmed onConfirmed on

histology andhistology andcultureculture


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Other diagnostic tests

uu HistologyHistology

caseatingcaseating granulomagranuloma (+/(+/-- AAFB)AAFB)

uu PCRPCR

M. tuberculosisM. tuberculosisDNADNA

Can be done on any specimenCan be done on any specimen

even after formalineven after formalin

Cannot distinguish viable from dead bacilliCannot distinguish viable from dead bacilli

Sensitivity about 80%Sensitivity about 80%

uu Tuberculin testTuberculin test

uu Assays of T cell production of Gamma InterferonAssays of T cell production of Gamma Interferon


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Tuberculin Skin Test

uuMantouxMantoux ororHeafHeaf

uuEvidence of exposure toEvidence of exposure to tuberculoustuberculousantigensantigens

TB diseaseTB disease

LTBILTBI

BCGBCG

NonNon tuberculoustuberculous mycobacteriamycobacteria

uuFalse negativeFalse negative

ImmunosuppressedImmunosuppressed

Overwhelming TB diseaseOverwhelming TB disease


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TB Diagnosis

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