Mycobacteria Bpt

8/14/2019 Mycobacteria Bpt

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MYCOBACTERIAMYCOBACTERIA

Dr. Sudheer KherDr. Sudheer Kher


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Classification ofClassification of

MycobacteriaMycobacteria1.1. Tubercle bacilliTubercle bacilli

a)a) Human MTBHuman MTB

b)b) Bovine M. bovisBovine M. bovis

3.3. Lepra bacilliLepra bacilli

a)a) Human M.Human M.

lepraeleprae

1.1. Atypical MycobacteriaAtypical Mycobacteria(Runyon Groups)(Runyon Groups)

a)a) PhotochromogensPhotochromogensb)b) ScotochromogensScotochromogens

c)c) NonphotochromogeNonphotochromogensns

d)d) Rapid growersRapid growers


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M. tuberculosisM. tuberculosis

major human diseasemajor human disease

healthy peoplehealthy people

problemsproblems

association with AIDSassociation with AIDS

multiple drug-resistancemultiple drug-resistanceChronic diseaseChronic disease

Prolonged treatmentProlonged treatment

TuberculosisTuberculosis

(TB, Consumption, Kochs Disease)(TB, Consumption, Kochs Disease)


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General characters of theGeneral characters of the

genusgenus Slender rodsSlender rods

Resist staining but once stained,Resist staining but once stained,

resist decolorization by dilute mineralresist decolorization by dilute mineral

acids; hence calledacids; hence called ACID FASTACID FAST

BACILLIBACILLI (AFB)(AFB)

Aerobic, Non-motile, Non-sporing,Aerobic, Non-motile, Non-sporing,

Non-capsulated.Non-capsulated.

Growth generally slowGrowth generally slow


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MycobacteriumMycobacterium

tuberculosistuberculosis One of the most serious infectiousOne of the most serious infectious

diseases in the developing worlddiseases in the developing world

One thirdOne thirdof worlds population infectedof worlds population infected

withwith M. tuberculosisM. tuberculosis Thirty millionThirty million people have active diseasepeople have active disease

Nine millionNine million new cases occurnew cases occur

Three millionThree million people die of the disease,people die of the disease,

each year.each year.


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Mycobacterium tuberculosisMycobacterium tuberculosis

(MTB)(MTB)

Morphology Morphology

Ziehl Neelsen stain Once stained byZiehl Neelsen stain Once stained by

Carbol fuchsin, resist decolorization byCarbol fuchsin, resist decolorization by

20% Sulphuric acide and absolute20% Sulphuric acide and absolutealcohol. Acid & Alcohol Fast (AFB)alcohol. Acid & Alcohol Fast (AFB)

Fluorescent dyes like Auramine O orFluorescent dyes like Auramine O or

Rhodamine also stain and theRhodamine also stain and thedecolorization is resisted.decolorization is resisted.


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MTB : Cultural charactersMTB : Cultural characters

Grow slowly. Generation timeGrow slowly. Generation time

14-15 hrs14-15 hrs

Colonies appear after 2Colonies appear after 2weeks or at 6-8 weeksweeks or at 6-8 weeks

MTB - Obligate aerobeMTB - Obligate aerobe


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enstein Jensen Medium

ective. Always in screw capped bottle. Bluish Green.ntains Egg protein Solidifying agent

Mineral salts Mg sulphate, Mg citrateAsparagineMalachite Green Selective agent

rilized by - Inspissation


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Mycobacterium tuberculosisMycobacterium tuberculosis

(MTB)(MTB) Morphology Morphology

Straight or slightlyStraight or slightly

curved rodscurved rods


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Modes of infection

1- Droplet infectionPerson to person by inhalation aerosolsMycobacterium tuberculosis (Pulmonary

tuberculosis)

2- Ingestion of milkInfected cattleMycobacterium bovis (Intestinal tuberculosis)

3- Contamination of abrasion Laboratory workers (Skin infection)

h i fP th i f


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Pathogenesis ofPathogenesis of

tuberculosistuberculosis

infects lunginfects lung

distributed within macrophagesdistributed within macrophages

facultative intracellular pathogenfacultative intracellular pathogen

inhibits phagosome-lysosome fusioninhibits phagosome-lysosome fusion

resists lysosomal enzymesresists lysosomal enzymes


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TuberculosisTuberculosis

Clinical picture :Clinical picture :

* Low grade fever* Low grade fever

* Weight loss* Weight loss* Night sweats* Night sweats

* Fatigue* Fatigue

* Cough & haemoptysis* Cough & haemoptysis


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Laboratory DiagnosisLaboratory Diagnosis

Demonstration of bacilliDemonstration of bacilli

Culture & isolation or AnimalCulture & isolation or Animal

inoculationinoculation

Demonstration of hypersensitivity toDemonstration of hypersensitivity to

tubercular proteintubercular protein

Serological tests limited valueSerological tests limited value


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SpecimenSpecimen** According to site of infection :According to site of infection :

- Sputum - Urine - Body- Sputum - Urine - Body

fluidsfluids

- Gastric lavage - Blood - Tissue- Gastric lavage - Blood - Tissue

biopsybiopsy

* S* Specimens need appropriate processingpecimens need appropriate processing

Liquefaction with N-acetyl-L-Liquefaction with N-acetyl-L-

cysteinecysteine

SputumSputum Decontamination with NaOHDecontamination with NaOH


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Pulmonary TB Pulmonary TB

Specimen Specimen Sputum Early morning, if scanty 24 hrs, threeSputum Early morning, if scanty 24 hrs, three

consecutive day samples. Laryngeal swabs or gastricconsecutive day samples. Laryngeal swabs or gastric

lavage in children.lavage in children.

Microscopy See at least 100 field / 10Microscopy See at least 100 field / 10

minutes.minutes. Grading Grading

1+ -> 3-9 bacilli in entire smear1+ -> 3-9 bacilli in entire smear 2+ -> 10 or more in entire smear2+ -> 10 or more in entire smear

3+ -> 10 or more bacilli seen in most oil3+ -> 10 or more bacilli seen in most oil

immersion fieldsimmersion fields


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Laboratory diagnosisLaboratory diagnosis

M. tuberculosisM. tuberculosis

Acid fast bacteria in sputumAcid fast bacteria in sputum

Culture on L J mediaCulture on L J media

Biochemical identificationBiochemical identification Antibiotic sensitivity testAntibiotic sensitivity test

Tuberculin testTuberculin test

PCRPCR


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Laboratory diagnosis -Laboratory diagnosis -

tuberculosistuberculosis skin testingskin testing

delayed hypersensitivitydelayed hypersensitivity

tuberculintuberculin

protein purifiedprotein purifiedderivative, PPDderivative, PPD

X-rayX-ray


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Tuberculin TestTuberculin Test (Mantoux(Mantouxtest)test)

Delayed hypersensitivityDelayed hypersensitivityskin test to assay:skin test to assay:

cell mediated immunitycell mediated immunityto tubercle bacilliusto tubercle bacillius

Material:Material: A purifiedA purified

protein derivative (PPD)protein derivative (PPD)

DoseDose :: 0.1 ml of (PPD)0.1 ml of (PPD)is injected intradermalis injected intradermal

Reading :Reading : Positive test isPositive test isdefined asdefined as

- Induration equal or- Induration equal orgreater than 10 mmgreater than 10 mm

- Develop 48-72 hours- Develop 48-72 hoursafter injectionafter injection


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Positive skin testPositive skin test

-tuberculosis-tuberculosis

indicates exposure toindicates exposure to

organismorganism

does not indicate activedoes not indicate activediseasedisease


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Extra -Pulmonary TB Extra -Pulmonary TB

Specimen Specimen CSF in suspected meningitisCSF in suspected meningitis

Pleural fluid & other exudatesPleural fluid & other exudates

2-3 days urine in renal TB2-3 days urine in renal TB

Biopsy material.Biopsy material.


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TreatmentTreatment

Chemoprophylaxis INH for one yearChemoprophylaxis INH for one year Domicilliary treatment preferredDomicilliary treatment preferred Drugs Drugs

RifampicinRifampicin

IsoniazideIsoniazide BactericidalBactericidal PyrazinamidePyrazinamide

StreptomycinStreptomycin

EthambutolEthambutol

EthionamideEthionamide

ThiacetazoneThiacetazone BacteriostaticBacteriostatic

Paraminosalicylic acidParaminosalicylic acid

CycloserineCycloserine


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TreatmentTreatment

Short term chemotherapy of sixShort term chemotherapy of six

months is sufficientmonths is sufficient

Problem area Development ofProblem area Development of

resistance by mutant selectionresistance by mutant selection

Solution Treatment by two to threeSolution Treatment by two to three

drug combination, adequate treatment.drug combination, adequate treatment.


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Immuno-prophylaxisImmuno-prophylaxis

Intradermal injection of liveIntradermal injection of live

attenuated vaccine Bacille Calmette-attenuated vaccine Bacille Calmette-

Guerin (BCG).Guerin (BCG).

The strain causes self limited lesionThe strain causes self limited lesion

and induces hypersensitivity &and induces hypersensitivity &

immunity.immunity.

Coverts tuberculin negative personCoverts tuberculin negative person

to positive reactor.to positive reactor.

Immunity lasts for 10-15 years.Immunity lasts for 10-15 years.

Immunity 60-80%Immunity 60-80%


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BCGBCG

Given at birth without tuberculinGiven at birth without tuberculin

testingtesting

Protects against TB, the disease runsProtects against TB, the disease runs

milder course in protected, preventsmilder course in protected, prevents

skeletal, meningeal & miliary forms.skeletal, meningeal & miliary forms.

Also found useful in leprosy,Also found useful in leprosy,

leukaemias and other malignanciesleukaemias and other malignancies

by non-specific stimulation of REby non-specific stimulation of RE

system.system.


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MycobacteriaMycobacteria

Mycobacterium lepraeMycobacterium leprae


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Classification of Atypical MycobacteriaClassification of Atypical Mycobacteria

Ridley Jopling Classification of LeprosyRidley Jopling Classification of Leprosy

Basis - ImmunologicalBasis - Immunological

RR-Reversal reaction; ENL-Erythema nodosum leprosum; PB-Paucibacillary, MB-M ltib ill

Mycobacteria Bpt

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