tuberculosis by fahad al majid, m.d., frcp. microbiology organism: organism: –mycobacterium...
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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
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