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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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Laboratory DiagnosisLaboratory Diagnosis
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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Laboratory DiagnosisLaboratory Diagnosis
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