TUBERCULOSISTUBERCULOSIS

ByBy

Fahad Al Majid, M.D., FRCPFahad Al Majid, M.D., FRCP

MICROBIOLOGYMICROBIOLOGY

Organism: Organism: – Mycobacterium tuberculosisMycobacterium tuberculosis– AerobicAerobic– Non-spore forming ,non-motileNon-spore forming ,non-motile– Rod..: 2—5 mm longRod..: 2—5 mm long– Resistant to disinfectantResistant to disinfectant– Once stained it resists decolorization with Once stained it resists decolorization with

acid and alcohol facultative intracellular acid and alcohol facultative intracellular organismorganism

Human is the main reservoir of M TBHuman is the main reservoir of M TB

EPIDEMIOLOGYEPIDEMIOLOGY

It is a world wide diseaseIt is a world wide disease Tb infects 1.7 billion with 3 million Tb infects 1.7 billion with 3 million

deaths/yrdeaths/yr UK: 1st half of 20UK: 1st half of 20thth century: a lot century: a lot

of death secondary to TB epidemicof death secondary to TB epidemic 90% of cases and 95% of death 90% of cases and 95% of death

occurred in developing countries.occurred in developing countries. No of cases in developed No of cases in developed

countries has declined because of: countries has declined because of: improved nutritionimproved nutrition

EPIDEMIOLOGYEPIDEMIOLOGY

Case finding and chemotherapyCase finding and chemotherapy Tuberculous infection: a state in Tuberculous infection: a state in

which the tubercle bacillus is which the tubercle bacillus is established in the body without established in the body without symptoms.symptoms.

Tuberculous disease: a state in Tuberculous disease: a state in which one or more organs of the which one or more organs of the body becomes diseased by the body becomes diseased by the disease.disease.

EPIDEMIOLOGYEPIDEMIOLOGY

What increase the spread of the What increase the spread of the disease: disease:

1) crowding living 1) crowding living

2) migration of people from 2) migration of people from endemic endemic area.area.

10% of infected people ---- active 10% of infected people ---- active diseasedisease

505 of active disease --- 505 of active disease --- contagiouscontagious

EPIDEMIOLOGYEPIDEMIOLOGY

What increase the risk of What increase the risk of developing disease after TB developing disease after TB infection ?infection ?– Infecting doseInfecting dose– Host factorsHost factors

age: under 5 yrs age: under 5 yrs debilitating illness and poor nutritiondebilitating illness and poor nutrition alcoholismalcoholism gastrectomygastrectomy diabetes mellitusdiabetes mellitus

EPIDEMIOLOGYEPIDEMIOLOGY

Mode of spreadMode of spread Inhalation of droplet nucleiInhalation of droplet nuclei

PATHOGENESISPATHOGENESIS

Droplet nuclie ---terminal air Droplet nuclie ---terminal air space ---space ---

Multiplication … initial focusMultiplication … initial focus– SubpleuralSubpleural– 75%single75%single

Migration through blood and Migration through blood and lymph node --- another focuslymph node --- another focus

Ingestion of the bacteria by the Ingestion of the bacteria by the macrophage --- slow multiplicationmacrophage --- slow multiplication

IMMUNOLOGICAL FEATUREIMMUNOLOGICAL FEATURE

TB require CMI for its controlTB require CMI for its control Ab response is rich but has no role Ab response is rich but has no role Multiplication proceeds for weeks Multiplication proceeds for weeks

both in:both in:– initial focusinitial focus– lymphohaematogenous metastatic focilymphohaematogenous metastatic foci

Until development of ... cell Until development of ... cell mediated immunitymediated immunity

CLINICAL FEATURESCLINICAL FEATURES

Pulmonary 80%Pulmonary 80% Extra pulmonary 20%Extra pulmonary 20% Pulmonary tuberculosisPulmonary tuberculosis Primary: the lung is the 1Primary: the lung is the 1stst organ organ

involved ... middle and lower lobe.involved ... middle and lower lobe. Health: asymptomatic Health: asymptomatic Heals spontaneouslyHeals spontaneously CXR normal.CXR normal.

CLINICAL FEATURESCLINICAL FEATURES

MalnutritionMalnutrition HIVHIV Severe casesSevere cases

– primary lesion progress to clinical primary lesion progress to clinical illnessillness

– cavitating pneumoniacavitating pneumonia– lymphatic spread and lobar collapse lymphatic spread and lobar collapse

due to LNdue to LN 40 haematohenous dissemination 40 haematohenous dissemination

kmkm

CLINICAL FEATURESCLINICAL FEATURES

In children In children Asymptomatic state my cause Asymptomatic state my cause

miliary tuberculosis and TB miliary tuberculosis and TB meningitis meningitis

Post primary (reactivation)Post primary (reactivation) Result from endogenous Result from endogenous

reactivation of layent infection reactivation of layent infection and manifest clinically : and manifest clinically : – fever and night sweatfever and night sweat– weight lossweight loss– cough… non-productive then cough… non-productive then

productiveproductive And may have haemoptysisAnd may have haemoptysis Signs: rales in chest examSigns: rales in chest exam

Extra pulmonary Extra pulmonary – lymph node lymph node – pleural pleural – bone and jointbone and joint– meningesmeninges– peritoniumjjperitoniumjj

Tuberculous lymphadenitis … 25 Tuberculous lymphadenitis … 25 %%

The commonestThe commonest Localized painless swellingLocalized painless swelling Common sites: cervical & Common sites: cervical &

supraclavicularsupraclavicular Early: glands are discreteEarly: glands are discrete Late: glands are matted -/+ sinusLate: glands are matted -/+ sinus Dx: fna 30% in biopsy for histo Dx: fna 30% in biopsy for histo

and cultureand culture

Pleural tbPleural tb Result form penetration by few Result form penetration by few

bacilli into the pleural space bacilli into the pleural space resulting into :resulting into :– pleural effusion and fever pleural effusion and fever – dx; aspirate --- exudate dx; aspirate --- exudate – afb rarely seen afb rarely seen – culture 30% positiveculture 30% positive– bx 80% granulomabx 80% granuloma

Skeletal tbwo Skeletal tbwo Source: Source:

– reactivation of haematogenous focusreactivation of haematogenous focus– spread from an adjacent ln spread from an adjacent ln

Common sites: spine --- hips --- Common sites: spine --- hips --- kneesknees

Spinal tb:Spinal tb: Dorsal site is the commonest site Dorsal site is the commonest site

Involve two vertebral bodies and Involve two vertebral bodies and destroy the disc in between.destroy the disc in between.

Advance disease Advance disease Collapse fracture of the bodies Collapse fracture of the bodies

------------ Kyphosis and gibbus deformityKyphosis and gibbus deformity Paravertebral abscessParavertebral abscess Dx: ct scan and mriDx: ct scan and mri Biopsy: histopathBiopsy: histopath

Tuberculous meningitis Tuberculous meningitis Most often: children and may affect Most often: children and may affect

adultadult Source: Source:

– blood spread blood spread – rupture of a sub-ependymal tuberclerupture of a sub-ependymal tubercle

Symptoms: Symptoms: – fever fever – headache headache – neck rigidity neck rigidity

Disease typically evolve in 2 wks. Disease typically evolve in 2 wks. Dx; CSF STUDYDx; CSF STUDY

TB AND AIDSTB AND AIDS

Person with active TB are more Person with active TB are more frequent to have HIV than general frequent to have HIV than general populationpopulation

Aids in HAITIANS: almost all children Aids in HAITIANS: almost all children are positive for PPD --- active TB in are positive for PPD --- active TB in

60%60% New York: 50% of active TB patients New York: 50% of active TB patients

are HIV+are HIV+

Africans: 60% of active TB Africans: 60% of active TB patients are HIV+patients are HIV+

TB can appear at any stage of HIV TB can appear at any stage of HIV infectioninfection

But presentation varies with the But presentation varies with the stage: stage:

Early:Early:– Typical pattern of upper lobe infiltrate -Typical pattern of upper lobe infiltrate -

+cavitation …+cavitation … Late: Late:

– diffuse infiltrate .. no cavitation .. LNdiffuse infiltrate .. no cavitation .. LN Sputum is less frequent to be + for Sputum is less frequent to be + for

AFB with HIV than without.AFB with HIV than without. Extra pulmonary is more common … Extra pulmonary is more common …

40%40%

Pulmonary TB and HIV --- Pulmonary TB and HIV --- diagnosis is difficultdiagnosis is difficult– sputum (-) in 40 %sputum (-) in 40 %– atypical cxratypical cxr– negative ppdnegative ppd

DIAGNOSISDIAGNOSIS

For any respiratory symptoms:For any respiratory symptoms: Do chest x-ray … if abnormal ---Do chest x-ray … if abnormal ---

– Sputum for :Sputum for : Zn stain Zn stain culture ..definite diagnosisculture ..definite diagnosis

– Use lowenstein-jansen mediaUse lowenstein-jansen media slow growth … 3 - 6 wksslow growth … 3 - 6 wks Bactic liquid media ...Bactic liquid media ...

DIAGNOSISDIAGNOSIS

PPD … intradermally …PPD … intradermally … 5 unit in o.1 ml 5 unit in o.1 ml 10 mm: 90 % infected10 mm: 90 % infected More than 15 mm: 100% infectedMore than 15 mm: 100% infected Bcg and positive ppdBcg and positive ppd Unless very recent: positive ppd Unless very recent: positive ppd

of more than 10mm should not be of more than 10mm should not be due to BCGdue to BCG

DIAGNOSISDIAGNOSIS

False negative resultFalse negative result 20 % of active disease20 % of active disease MalnutritionMalnutrition SarcoidSarcoid Viral infectionViral infection SteroidSteroid PPD: is of limited value because PPD: is of limited value because

of of Low sensitivity and specificityLow sensitivity and specificity

TREATMENTTREATMENT

Chemotherapy: cure Chemotherapy: cure Isonised Isonised RifampicinRifampicin PyrazinamidePyrazinamide EthambutolEthambutol

– rapidly reduce the number of viable rapidly reduce the number of viable organismorganism

– kill the bacillikill the bacilli– slow rate of induction of drug resistanceslow rate of induction of drug resistance

Drug failureDrug failure– none compliancenone compliance– in appropriate drugin appropriate drug– drug resistance drug resistance

INFECTION CONTROLINFECTION CONTROL

Active pulmonary tuberculosis:Active pulmonary tuberculosis:– Isolation of the patient Isolation of the patient – Isolation room should be negative Isolation room should be negative

pressurepressure– Patient remain until 3 negative Patient remain until 3 negative

smears and there is clinical smears and there is clinical improvementimprovement