Uploaded byDrBhavikapatel
PPTX, PDF534 views

tb pathogenesis and laboratory diagnosis .pptx

The document provides an in-depth overview of tuberculosis (TB), focusing on its classification, pathogenesis, clinical manifestations, and laboratory diagnosis. It emphasizes the role of Mycobacterium tuberculosis, transmission methods, immune responses, and the differences between primary and secondary TB. Additionally, it discusses the epidemiology and drug resistance challenges in TB treatment, while outlining diagnostic methodologies such as microscopy and nucleic acid amplification tests.

Embed presentation

Download to read offline
Tuberculosis Dr Bhavika patel MBBS,MD Microbiology,DIPC Assistant Professor Department of microbiology GMERS MC, Valsad.
Learning objectives At the end of the session, the students will be able to understand: ▰ Classification of mycobacteria. ▰ Antigenic structure, pathogenesis, clinical manifestations, lab diagnosis, treatment, drug resistance and prophylaxis of TB.
Tuberculosis(TB)
Mycobacteria Tuberculosis ► Non sporing, Non-capsulated. Weakly Gram Positive. ► Strongly Acid Fast (due to mycolic acid in cell wall). ► Lipid Rich Cell Wall (confers resistance to disinfectants, detergents, common antibiotics and traditional stains). ► Long Generation time. ► Humans are the only natural reservoir. ► Person to person transmission, by infectious aerosols/droplets.
Antigenic Structure ▰ 1. Cell wall (insoluble) antigens:  Peptidoglycan layer – maintains shape & rigidity  Arabinogalactan layer - survival of M.tuberculosis within macrophages  Mycolic acid layer - principal constituent, confers very low permeability, acid fastness and reduces the entry of most antibiotics  Outermost layer - lipids, glycolipids & mycosides
Antigenic Structure (Cont..) ▰ 1. Cell wall (insoluble) antigens (Cont..):  Proteins (e.g. porins, transport proteins) - found throughout various layers  Plasma membrane - helps in attachment to host cell and is also a target antigen used for diagnosis
Antigenic Structure (Cont..) ▰ 2. Cytoplasmic (soluble) antigens:  These include antigen 5, antigen 6, antigen 60  Used in serodiagnosis of tuberculosis.
Lin P et al. J Immunol 2010 Clearance Pulmonary TB Low grade TB “percolating “ Dormant infection Septic TB Miliary TB Extrapulmonary TB Spectrum of M. tuberculosis infection
Tuberculosis or TB (short for tubercle bacillus) ► Is a common and often deadly infectious disease caused by mycobacterium usually mycobacterium tuberculosis. ► M.tuberculosis complex includes: 1.M.tuberculosis 2. M.bovis 3.Other member: M.africanum, M. microti , M. caprae, M. pinnipedii, M. canetti , M. suricattae, M. orygis , M.mungi
Pathogenesis
Modes of infection 1.Droplet infection • Person to person by inhalation aerosols • Mycobacterium tuberculosis (Pulmonary tuberculosis) 2.Ingestion of milk • Infected cattle • Mycobacterium bovis (Intestinal tuberculosis) 3. Inoculation (in skin tuberculosis) 4.Transplacental route (rare route)
Pathogenesis - Risk Factors ▰ Sputum positive patients with Bacillary load at least 104 bacilli/mL ▰ Cavitary lesions in lung - more bacillary load ▰ Overcrowding in poorly ventilated rooms ▰ Low cell-mediated immunity – HIV ▰ Other comorbid conditions - Post-silicosis, postransplantation, hemodialysis, diabetes, IV drug abuse, smoking, etc. ▰ Age: Late adolescence and early adulthood ▰ Sex: women at 25–34 years, men in older ages
5.If the bacilli are successful in arresting phagolysosome fusion, then they happily replicate inside the macrophage. The macrophage eventually ruptures and releases its bacillary contents which infect other uninfected phagocytes and infection cycle continues. 4.Survival inside the macrophages due to bacterial cell wall LAM which impairs phagosomelysosome fusion by inhibiting an increase in intracellular Ca2+ and phosphatidylinositol 3-phosphate 3.Phagocytosis by macrophages (complement (C3b) mediated opsonization of bacilli) 2.Adhesion to macrophages Mycobacterial surface lipoarabinomannan (LAM) binds to complement receptors and mannose receptors present on the surface of macrophages. 1.Droplet nuclei containing tubercle bacilli from infectious patients are inhaled. EVIDENCE OF INFECTION WITH M TUBERCULOSIS Chest x-ray / positive skin test
Host Immune Response - Cell-mediated Immune Response ▰ Macrophages present the mycobacterial antigens to TH (T helper) cells - TH1and TH2 subsets. ▰ TH1 cells release - IL-2 and IFN-γ - activate monocytes and macrophages ▰ Activation of TH1 cells - development of two host responses:  1. A macrophage-activating response  2. Tissue-damaging response.
Host Immune Response - Cell-mediated Immune Response (Cont..) ▰ 1. A macrophage-activating response: ▰ IFN γ activates macrophages ▰ Tubercles: a favorable sign  Hard tubercles: initially hard - central zone containing activated macrophages (epithelioid and giant cells) and a peripheral zone of lymphocytes and fibroblasts.  Soft tubercles - central part undergoes caseous necrosis - Bacilli inhibited within this necrotic environment because of low oxygen tension and low pH - lesion heals and calcifies.
Host Immune Response - Cell-mediated Immune Response (Cont..) ▰ 2. Tissue-damaging response: ▰ Minority of cases, associated with risk factors -macrophage- activating response is weak & bacilli more virulent ▰ Mycobacterial growth inhibited only by an intensified delayed hypersensitivity reaction - lung tissue destruction
Host Immune Response - Cell-mediated Immune Response (Cont..) ▰ Spread of caseous necrosis 1. Direct draining into the airways - discharged with cough 2. Lymphatic spread - reseeding into same or opposite lung → disseminate to other organs. 3. Hematogenous spread to various organs
Host Immune Response - Cell-mediated Immune Response (Cont..) ▰ Humoral Immune Response: ▰ TH2 release - IL-4, IL-5 - activate B-cells - antibodies.  M. tuberculosis being obligate intracellular organism, humoral immunity plays a minor role  Anti-LAM antibodies play a role in preventing dissemination of tuberculosis in children.
Symptoms and Signs of Tuberculosis
Clinical Manifestations ▰ Tuberculosis (TB) is classified as:  Pulmonary TB and  Extrapulmonary TB
Comparison of primary and secondary pulmonary tuberculosis Features Primary PTB Post-primary (adult- type)/secondary PTB Results due to Initial exogenous infection with tubercle bacilli  Exogenous reinfection  Endogenous- reactivation of latent primary lesion Age group affected Children Adults Parts of lungs commonly affected Sub pleural lesion affecting, upper part of lower lobe and lower part of upper lobe Apical and posterior segments of the upper lobes (high oxygen tension) Lesions formed at the initial sites Fibrotic nodular lesions are formed (Ghon focus) Hematogenous seedling in the apex of lungs called Simon’s focus
Comparison of primary and secondary pulmonary tuberculosis (Cont..) Features Primary PTB Post-primary (adult-type)/secondary PTB Lymph node Ghon focus with associated hilar lymphadenopathy is common (called as primary complex) Lymph node involvement is unusual Clinical feature It may be asymptomatic or may present with fever, productive cough (with or without hemoptysis) and occasionally chest pain, night sweating, weight loss Lesions undergoing necrosis and tissue destruction, leading to cavity formation. Symptoms are similar, but more pronounced.
Extrapulmonary Tuberculosis (EPTB) ▰ Tuberculous lymphadenitis – MC form (35% of all EPTB)  Posterior cervical and supraclavicular lymph nodes - painless swelling in neck region without warmth or color change ▰ Pleural tuberculosis – (20%) - pleural effusion ▰ Tuberculosis of the upper airways - larynx, pharynx, and epiglottis
Extrapulmonary Tuberculosis (EPTB) (Cont..) ▰ Genitourinary tuberculosis: Renal tuberculosis  Genital tuberculosis – Females: fallopian tubes & endometrium - infertility. Males: epididymis ▰ Skeletal tuberculosis - Weight-bearing joints (spine, hips & knees)  Complications - collapse of vertebral bodies - kyphosis & paravertebral ‘cold’ abscess
Extrapulmonary Tuberculosis (EPTB) (Cont..) ▰ Tuberculosis of CNS – M/C in children, Tuberculous meningitis & tuberculoma are common forms ▰ Tuberculous pericarditis - direct extension from adjacent lymph nodes or following hematogenous spread
Extrapulmonary Tuberculosis (EPTB) (Cont..) ▰ Gastrointestinal tuberculosis - Terminal ileum and caecum  Due to swallowing of sputum with direct seeding, hematogenous spread, or ingestion of cow’s milk contaminated with M. bovis ▰ Tuberculous skin lesions:  Scrofuloderma – skin involvement by direct extension from underlying tuberculous lymphadenitis  Lupus vulgaris: Apple jelly nodules are formed over face
Extrapulmonary Tuberculosis (EPTB) (Cont..) ▰ Miliary or disseminated tuberculosis: Hematogenous spread - yellowish 1–2 mm size granulomatous lesions resembling millet seeds in various organs. ▰ Post-TB aspergillosis: Chronic pulmonary aspergillosis - due to colonization of Aspergillus fumigatus in the residual TB cavities
Epidemiology ▰ Quarter of the current world population is infected asymptomatically with M. tuberculosis, of which 5–10% develop the clinical disease. ▰ World: 10 million new cases of TB occurred in 2018. ▰ Deaths due to TB - 12 Lakh in HIV-negative and 2.5 Lakh in HIV- coinfected people in 2018.
Epidemiology (Cont..) ▰ WHO regions: South-East Asia (44%), followed by Africa (24%) and the Western Pacific (18%) ▰ Countries: Eight countries accounted for two-third of the total TB burden, with India having the largest share. ▰ India: In 2018 - 27 Lakh cases occurred India - highest burden from Uttar Pradesh
Epidemiology (Cont..) ▰ WHO regions: South-East Asia (44%), followed by Africa (24%) and the Western Pacific (18%) ▰ Countries: Eight countries accounted for two-third of the total TB burden, with India having the largest share.
Laboratory diagnosis of Tuberculosis
Laboratory diagnosis of Tuberculosis ● Specimen collection ⮚ In pulmonary TB: Sputum (2 specimens—spot and early morning), gastric aspirate (in children) ⮚ In EPTB: Specimens vary depending on the site involved
Extrapulmonary specimens Sterile site specimens collected aseptically Optimum specimens CSF, pericardial fluid, synovial fluid and ascitic fluid Suboptimal specimens (organism load is less) Pleural fluid (20–50 mL is collected and centrifuged) Blood (indicated only for disseminated TB and co- infected with HIV) Specimens containing normal flora Swabs Considered suboptimal specimen. The only recommended swabs are:  Laryngeal swabs: Collected early morning in empty stomach or  Swab from discharging sinus Urine Three early morning specimens collected (500 mL/ specimen, centrifuged) on different days as TB bacilli in urine are shed intermittently Stool For disseminated TB in HIV infected patients and infants
Extrapulmonary specimens (Cont..) Specimens containing normal flora Other respiratory specimens Bronchial secretions (2–5 mL) Bronchoalveolar lavage (20–50 mL) Transbronchial and other biopsies (collected in sterile normal saline) Gastric lavage Recommended for children (tend to swallow sputum), or ICU patients (aspiration) Early morning lavage should be collected and processed early (<4 hours)
PRESUMPTIVE TB PT
Integrated DR-TB diagnosis and treatment algorithm 40 Rifampicin resistance detected4 All TB patients All Presumptive TB1 or Key Population2 Non-responders Rifampicin resistance not detected4 DS-TB regimen NAAT3 FL-LPA 5 + SL-LPA 6 + LC DST7 – Z, Bdq8, Cfz8, Mfx, Lzd, Dlm8 • No additional resistance detected4 or • H resistance detected4 with KatG or InhA mutation (not both) & FQ resistance not detected4 • H resistance detected4 with both KatG and InhA mutation or • FQ resistance detected4 Shorter oral Bedaquiline-containing MDR/RR-TB regimen10 Longer oral M/XDR-TB regimen11 FL-LPA 5 Additional resistance or intolerance or non-availability of any drug in use or emergence of exclusion criteria or return after LTFU or failure H mono/poly DR-TB regimen Modify H mono/poly DR-TB regimen as per replacement table H resistance detected4 Non-responders Additional resistance or intolerance or non-availability of any drug in use or emergence of exclusion criteria or return after LTFU or failure Longer oral M/XDR-TB regimen, modified if needed as per replacement table Reflex testing for SL-LPA 6 + LC DST7 – Mfx, Z, Lzd, Cfz8 Other exclusion criteria9 for shorter regimen PRESE NT ABSE NT After completing PTE, check on Nikshay or with C&DST lab, if LPA results are available N O Y E S Y E S Stop DS- TB Regimen FIRST SPECIMEN TESTED AT NAAT SITE SECOND SPECIMEN TESTED AT C-DST LAB Y e s N o
Integrated DR-TB diagnosis and treatment algorithm 41 Rifampicin resistance detected4 All TB patients All Presumptive TB1 or Key Population2 Non-responders Rifampicin resistance not detected4 DS-TB regimen NAAT3 FL-LPA 5 + SL-LPA 6 + LC DST7 – Z, Bdq8, Cfz8, Mfx, Lzd, Dlm8 • No additional resistance detected4 or • H resistance detected4 with KatG or InhA mutation (not both) & FQ resistance not detected4 • H resistance detected4 with both KatG and InhA mutation or • FQ resistance detected4 Shorter oral Bedaquiline-containing MDR/RR-TB regimen10 Longer oral M/XDR-TB regimen11 FL-LPA 5 Additional resistance or intolerance or non-availability of any drug in use or emergence of exclusion criteria or return after LTFU or failure H mono/poly DR-TB regimen Modify H mono/poly DR-TB regimen as per replacement table H resistance detected4 Non-responders Additional resistance or intolerance or non-availability of any drug in use or emergence of exclusion criteria or return after LTFU or failure Longer oral M/XDR-TB regimen, modified if needed as per replacement table Reflex testing for SL-LPA 6 + LC DST7 – Mfx, Z, Lzd, Cfz8 Other exclusion criteria9 for shorter regimen PRESE NT ABSE NT After completing PTE, check on Nikshay or with C&DST lab, if LPA results are available N O Y E S Y E S Stop DS- TB Regimen FIRST SPECIMEN TESTED AT NAAT SITE SECOND SPECIMEN TESTED AT C- DST LAB Y e s N o
Laboratory Diagnosis A SMEAR MICROSCOPY 1- Sputum smears stained by Z-N stain Two morning successive mucopurulent sputum samples are needed to diagnoise pulmonary TB. Advantage: - cheap – rapid - Easy to perform Disadvantages: - sputum ( need to contain 5000-10000 AFB/ ml.) - Young children, elderly & HIV infected persons may not produce cavities & sputum containing AFB.
Limitation of Microscopy for Tuberculosis. ► Repeated sample examinations. load on technical staff. ► Training and dedication of Microscopist. ► The load of bacilli must be more than 10,000 / 1 ml of sputum. ► Low in sensitivity < 50 % ► Repeated requests for samples ► Not dependable in pediatric age group.
Grading If the slide has Result Grading No. of fields to be examined More than 10 AFB /oil immersion field pos 3+ 20 1-10 AFB/ oil immersion field pos 2+ 50 10-99 AFB/100 oil immersion field pos 1+ 100 1-9 AFB/100 oil immersion field pos Scanty* 100 No AFB in 100 oil immersion field neg 100 *record actual number of bacilli seen in 100 fields
2- Detecting AFB by fluorochrome stain using fluorescence microscopy: The smear may be stained by auramine-O dye. In this method the TB bacilli are stained yellow against dark background & easily visualized using florescent microscope. Advantages: - More sensitive - Rapid Disadvantages: - Hazards of dye toxicity - more expensive
Mycobacterium Tuberculosis Stained with Fluorescent Dye From Carl Zeiss microimaging GmbH (FluoLED) Yellow bacilli with green background.
B.CBNAAT/True NAT ► Fully automated Cartridge based Nucleic Acid Amplification Test working on the principal of PCR ► Generates digital report in 2 Hours (Test Turn around Time*) ► Sensitivity is similar to Culture and highly specific for M.TB Complex (For Sputum Samples) ► Advantage – Detects Rifampicin Resistance additionally ► Extrapulmonary Samples – Gastric Lavage, BAL, CSF, Pericardial Fluid, Synovial Fluid, Pleural Fluid N.B., Samples should not contain blood, Formalin should not be added
C.Mycobacterial Culture Reasons to request mycobacterial culture: • Patient previously on anti-TB treatment (Relapse, Defaulter) • Still smear-positive after intensive phase of treatment or after finishing treatment • Symptomatic and at high-risk of MDR-TB • To test fluids potentially infected with M. tuberculosis • Investigation of patients who develop active PTB during or after IPT. • TB in health workers
50 FLOW CHART CONTD. Screen by AFB smear & inoculate media (one liquid & one solid) Liquid Medium Solid Media MGIT BACTEC SEPTI-CHEK CMS Incubate At 37ºC For 6 wks Incubate At 37ºC For 6 wks Incubate inverting At 37ºC For 8 wks Incubate At 37ºC For 6 wks Fluoresc- -ence detected Growth Index >10 Colonies or turbidity Growth detected Confirm by AFB smear Reinoculate on Solid media L J L J with RNA LJ with Pyruvic acid Incubate At 37ºC For 8 wks If growth Confirm on AFB smear
Solid media ► Cultures incubated at 35°c in the dark in an atmosphere of 5% to 10% co2 and high humidity ► Cultures are examined weekly for growth ► Most isolates appear between 3 and 6 weeks a few isolates appear after 7 or 8 weeks ► After 8 wks of incubation negative cultures are reported
Eight Week Growth of Mycobacterium tuberculosis on Lowenstein-Jensen Agar
Commonly used liquid media systems to culture and detect the growth of mycobacterium ► BACTEC 460 ► Mycobacteria growth indicator tube (MGIT) ► BACTEC MGIT 960 ( continuous growth monitoring systems)
Liquid media ► Use of liquid media system reduces the turn- around time for isolation of acid-fast bacilli to approximately 10 days compared with 17 days or longer in conventional methods ► Once growth is detected in the liquid media , an acid fast stain is performed to confirm the presence of acid-fast bacilli
Laboratory diagnosis of Tuberculosis (Cont..) 55 ● Culture identification ⮚ Automated identification—by MALDI-TOF ⮚ MPT 64 antigen detection—by ICT ⮚ Different biochemical test – ex Nitrate reduction and niacin production are definitive for M.tb
DST (Drug Susceptibility Testing) 56 ● Phenotypic Methods ● Genotypic Methods
Methods for drug susceptibility testing Genotypic testing is much faster than phenotypic methods.
Choice of diagnostic technology DR diagnostic technology Choice NAAT/LPA First Liquid culture isolation and LPA DST Second Liquid culture isolation and liquid DST Third ⮚ Solid LJ media- of up to 84 days, ⮚ Liquid Culture (MGIT) up to 42 days, ⮚ LPA up to 72 hours ⮚ NAAT - 2 hours. Turn around time
Laboratory diagnosis of Tuberculosis (Cont..) ● Diagnosis of latent tuberculosis ⮚ Tuberculin skin test (e.g. Mantoux test) ⮚ Interferon gamma release assay (IGRA).
Laboratory diagnosis of Tuberculosis (Cont..) 60 ● Diagnosis of latent tuberculosis ⮚ Tuberculin skin test (e.g. Mantoux test) ⮚ Interferon gamma release assay (IGRA).
Mantoux Tuberculin Skin Test (TST) ► 0.1 ml of tuberculin purified protein derivative (- PPD) into inner surface of forearm intradermally. Read between 48-72 hrs. ► A positive tuberculin skin test result is supportive evidence in the diagnosis of TB in areas of low prevalence (or no vaccination); however, a negative tuberculin skin test result may occur in approximately one third of patients.
Cytokine Assays T- cell Interferon-Gamma Release Assay (IGRA) ►INF- y produced by T-lymphocytes, is capable of activating macrophages, increasing their bactericidal capacity against M tuberculosis and is involved in granuloma formation. ►Elevated concentrations of INF-y in TB is related to increased production at the disease site by effectors T cells. ►The sensitivity of an elevated level varies from 78 to 100% and specificity from 95 to 100%
❖ IGRA is useful in targeted strategy for latent TB infection(LTBI) detection in low TB incidence settings ❖ More specific than Tuberculin Skin Test ❖ Can’t distinguish active from treated TB or LTBI. ❖ False positive results in- Hematologic malignancies Empyema.
Methods for detection of IFN-y Two new blood tests 1. T-SPOT.TB [Oxford Immunec] – directly count the no of IFN-y secreting T cells. 2. QuantiFERON-TB Gold [Cellestis Limited] – measures the concentration of IFNy secretion. Both tests based on detection of IFN-y in blood have been found to be more accurate than the tuberculin skin test in the diagnosis of latent TB infection. Future research should focus on the potential efficacy of quantification of specifically activated lymphocytes in body fluid and blood using IFN-Y release assay in the diagnosis of TB.
Comparison between TST and IGRA test ► A positive test result by either of the two methods available is not by itself a reliable indicator that the person will progress to TB disease as the possibility of false positive results cannot be ruled out. ► Conversely, a negative test result does not rule out TBI, given the possibility of a false- negative test result among at-risk groups, such as young children or among those recently infected.
Progress in TB Diagnosis Past Present Koch discovered tubercle bacillus 133 yrs back No major discovery Except TB Genome, IS6110, BACTEC 460 (liquid media) TB diagnosed by symptoms - prehistoric Still the same practice in many High Bruden Countries (HBCs) Tuberculin test - > 100yrs Still Commonly used Egg based media –almost 100yrs Still most commonly used AFB Smear for diagnosis – 133 yrs back Still the major diagnostic tool in many countries Radiological Diagnosis Still Important (X-ray, CT Scan)
Global and National TB Programmes ▰ The End TB Strategy (WHO) ▰ Revised National Tuberculosis Control Programme (RNTCP) ▰ National Strategic Plan, India (2020–2025) – Nikshay and 99DOTS
Vaccine Prophylaxis Against Tuberculosis - Bacillus Calmette-Guérin Vaccine (BCG) ▰ BCG strain: In India, WHO recommended Danish 1331 strain of BCG is used. ▰ Reconstitution of BCG: Available in lyophilized form, should be reconstituted before administration. ▰ Administration of BCG: 0.1 mL (0.1 mg TU) of BCG vaccine - administered above the insertion of left deltoid by intradermal route
Vaccine Prophylaxis Against Tuberculosis - Bacillus Calmette-Guérin Vaccine (BCG) (Cont..) Protection: ▰ Efficacy: Variable efficacy of 0–80% ▰ Duration of immunity - 15–20 years ▰ Protection to infants and young children against the development of complications - tuberculous meningitis and disseminated tuberculosis.
Vaccine Prophylaxis Against Tuberculosis - Bacillus Calmette-Guérin Vaccine (BCG) (Cont..) Complications following BCG: ▰ Most common complications - ulceration at the vaccination site and regional lymphadenitis ▰ Rarely - keloid or lupus lesion, osteomyelitis, non-fatal meningitis, progressivetuberculosis and disseminated BCG infection (“BCGitis”).
Vaccine Prophylaxis Against Tuberculosis - Bacillus Calmette-Guérin Vaccine (BCG) (Cont..) Indications of BCG ▰ Direct BCG: BCG is directly given to the newborn soon after birth. ▰ Indirect BCG: BCG is given after performing tuberculin skin test.
Vaccine Prophylaxis Against Tuberculosis - Bacillus Calmette-Guérin Vaccine (BCG) (Cont..) Contraindications to BCG include: ▰ HIV-positive child ▰ Child born to AFB positive mother ▰ Child with low immunity ▰ Generalized eczema ▰ Pregnancy.
Chemoprophylaxis ▰ Treatment of selected high-risk tuberculin reactors (i.e. people with latent tuberculosis) aims at preventing active disease. ▰ Isoniazid or ethambutol for six months - tried. ▰ Chemoprophylaxis has several shortcomings such as— ▰ (1) it is expensive, (2) risk of developing tuberculosis is minimal in tuberculin reactors, and (3) side effects of the drugs.
Chemoprophylaxis (Cont..) ▰ INH preventive therapy (IPT) - restricted to limited indications:  Adults with HIV - unlikely to have active TB  Children with HIV - no TB symptoms and unlikely to have active TB  All children with HIV - successfully completed treatment for TB.
tb pathogenesis and laboratory diagnosis .pptx
tb pathogenesis and laboratory diagnosis .pptx

More Related Content

PPTX
Pathology of Tuberculosis, pathogenesis of Tuberculosis
byMithun Venugopal
 
PPT
Pulmonary Tuberculosis Presentation
byJack Frost
 
PPTX
Enteric fever
byPrbn Shah
 
PPTX
Tuberculosis
byMuhammad Saim
 
PPTX
Tuberculosis
byaachal jain
 
PPTX
VIROLOGY - POLIO
byMeenatchisundaram Subramani
 
PPTX
Tuberculosis & Leprosy
byimrana tanvir
 
PPTX
Malaria
byJNMC AMU, Aligarh, India
 
Pathology of Tuberculosis, pathogenesis of Tuberculosis
byMithun Venugopal
 
Pulmonary Tuberculosis Presentation
byJack Frost
 
Enteric fever
byPrbn Shah
 
Tuberculosis
byMuhammad Saim
 
Tuberculosis
byaachal jain
 
VIROLOGY - POLIO
byMeenatchisundaram Subramani
 
Tuberculosis & Leprosy
byimrana tanvir
 
Malaria
byJNMC AMU, Aligarh, India
 

What's hot

PPTX
Swine Flu
byKULDEEP VYAS
 
PPT
Pathogenesis of tuberculosis
byDr.Mohamed Zakaria Sayed-Ahmed
 
PPTX
Rabies ,microbiology
byLubnaSSubair
 
PPTX
Pathogenesis and management of viral hepatitis
bySai Siddharth M
 
PPTX
Tissue healing
byDr Chirag Ananth
 
PPTX
Gram positive bacteria
byMicrobiology
 
PPTX
Meningitis .. Microbiological Approach
byAhmed Essam
 
PPTX
Bacterial Capsules: Introduction, Examples and Functions
by4RTPCRAnand
 
PPTX
Japanese Encephalitis
byKULDEEP VYAS
 
PPTX
Bacterial anatomy
byReena Kulshrestha
 
PDF
4. Cholera.pdf
byJitendra Bhargav
 
PPTX
Gram Positive Cocci-Staphylococcus
byDr. Samira Fattah
 
PPTX
Viral hemorrhagic fevers.pptx
byAzad Haleem
 
PPTX
Rickettsiae
byShaan Ahmed
 
PPTX
Cysticercosis -types symptoms| management |prevention (medical notes)
bymartinshaji
 
PPT
HIV-AIDS- Classification, pathogenesis, diagnosis, management
byammarSiddiqui25
 
PPTX
Chickenpox
byDr. Saurabh Agrawal
 
PPTX
Pyogenic infection
bySayali Gujjewar
 
PPTX
MMR vaccination for women DR. SHARDA JAIN
byLifecare Centre
 
PPT
Mycobacterium tuberculosis
byMahmood Khaleel
 
Swine Flu
byKULDEEP VYAS
 
Pathogenesis of tuberculosis
byDr.Mohamed Zakaria Sayed-Ahmed
 
Rabies ,microbiology
byLubnaSSubair
 
Pathogenesis and management of viral hepatitis
bySai Siddharth M
 
Tissue healing
byDr Chirag Ananth
 
Gram positive bacteria
byMicrobiology
 
Meningitis .. Microbiological Approach
byAhmed Essam
 
Bacterial Capsules: Introduction, Examples and Functions
by4RTPCRAnand
 
Japanese Encephalitis
byKULDEEP VYAS
 
Bacterial anatomy
byReena Kulshrestha
 
4. Cholera.pdf
byJitendra Bhargav
 
Gram Positive Cocci-Staphylococcus
byDr. Samira Fattah
 
Viral hemorrhagic fevers.pptx
byAzad Haleem
 
Rickettsiae
byShaan Ahmed
 
Cysticercosis -types symptoms| management |prevention (medical notes)
bymartinshaji
 
HIV-AIDS- Classification, pathogenesis, diagnosis, management
byammarSiddiqui25
 
Chickenpox
byDr. Saurabh Agrawal
 
Pyogenic infection
bySayali Gujjewar
 
MMR vaccination for women DR. SHARDA JAIN
byLifecare Centre
 
Mycobacterium tuberculosis
byMahmood Khaleel
 

Similar to tb pathogenesis and laboratory diagnosis .pptx

PPTX
General Characteristics of Mycobacteria and Pathogenesis of TB.pptx
byAshwaniSood12
 
PPTX
Basics and Pathology of mycobacteria.pptx
byAshwaniSood12
 
PPTX
Pulmonary tuberculosis latest guidelines and treatment
bypugalrockzz1
 
PPTX
Tuberculosis
byD Venkatesh Kumar
 
PPTX
Mycobacterium tuberculosis diagnosis and treatment.pptx
byKawalyasteven
 
PPTX
19.TUBERCULOSIS 300L B. Pharm 2023 24.pptx
byZechariahNggita
 
PPTX
tuberculosis mycobacterium disease (3).pptx
byEmadOsman9
 
PPTX
TB SEMINAR.pptx
byMANJUSINGH948460
 
PPTX
Pulmonary Tuberculosis-Etiology, Path, Dx, Rc
byMarkendeyKhanna
 
PPT
mycobacteria and general properties .ppt
byYeliztanrverdi
 
PDF
TB infection mycobacterium tuberculosis.pdf
byAmmar Alhakimi
 
PPTX
Tuberculosis lecture by Prof. Bimalka - copy.pptx
byGayanukaMendis
 
PDF
Tuberculosis
byDr Shahnawaz Shah
 
PPTX
Tuberculosis presentation by Sohel Memon
byDr.Sohel Memon
 
PPTX
Tuberculosis
byDr. Lavita Hazarika
 
PPTX
Tuberculosis.pptx
byMkindi Mkindi
 
PPTX
Pathology: Tuberculosis - lectures-.pptx
byMihretKahsay
 
PDF
Mycobacterium Tuberculosis
byMohsin Javed
 
PPTX
TUBERCULOSIS pharmacology notes types cure
byAffrin Shaik
 
PPTX
Pathophysiology of tuberculosis
byDr. Koppala R.V.S. Chaitanya
 
General Characteristics of Mycobacteria and Pathogenesis of TB.pptx
byAshwaniSood12
 
Basics and Pathology of mycobacteria.pptx
byAshwaniSood12
 
Pulmonary tuberculosis latest guidelines and treatment
bypugalrockzz1
 
Tuberculosis
byD Venkatesh Kumar
 
Mycobacterium tuberculosis diagnosis and treatment.pptx
byKawalyasteven
 
19.TUBERCULOSIS 300L B. Pharm 2023 24.pptx
byZechariahNggita
 
tuberculosis mycobacterium disease (3).pptx
byEmadOsman9
 
TB SEMINAR.pptx
byMANJUSINGH948460
 
Pulmonary Tuberculosis-Etiology, Path, Dx, Rc
byMarkendeyKhanna
 
mycobacteria and general properties .ppt
byYeliztanrverdi
 
TB infection mycobacterium tuberculosis.pdf
byAmmar Alhakimi
 
Tuberculosis lecture by Prof. Bimalka - copy.pptx
byGayanukaMendis
 
Tuberculosis
byDr Shahnawaz Shah
 
Tuberculosis presentation by Sohel Memon
byDr.Sohel Memon
 
Tuberculosis
byDr. Lavita Hazarika
 
Tuberculosis.pptx
byMkindi Mkindi
 
Pathology: Tuberculosis - lectures-.pptx
byMihretKahsay
 
Mycobacterium Tuberculosis
byMohsin Javed
 
TUBERCULOSIS pharmacology notes types cure
byAffrin Shaik
 
Pathophysiology of tuberculosis
byDr. Koppala R.V.S. Chaitanya
 

More from DrBhavikapatel

PPTX
standard precaution drbhavika.pptx Skill Module 1.9 (Foundation Course): Demo...
byDrBhavikapatel
 
PPTX
AETCOME COMMUNICATION 2.1 DRBHAVIKA - Copy.pptx
byDrBhavikapatel
 
PPTX
SEXUALLY TRANSMITTED INFECTIONS part .pptx
byDrBhavikapatel
 
PPTX
Healthcare-associated Infections Part-1.pptx
byDrBhavikapatel
 
PPTX
chapter 47 - Infective syndromes of hepatobiliary system dr bhavika.pptx
byDrBhavikapatel
 
PPTX
chapter 11 - DRBHAVIKA Antibody(Immunity).pptx
byDrBhavikapatel
 
PPT
dr bhavika sample collection and transport.ppt
byDrBhavikapatel
 
PPTX
AETCOM 2 BENEFICENCE & ROLE OF PHYSICIAN - Copy.pptx
byDrBhavikapatel
 
PPTX
AETCOM DR BHAVIKA.pptx (Autonomy &Non-maleficence)
byDrBhavikapatel
 
PPTX
Parasitic Infections of Skin, Soft tissue and musculoskeletal system dr bhavi...
byDrBhavikapatel
 
PPTX
Intestinal Helminthic Infection: Intestinal CESTODE Infection dr bhavika.pptx
byDrBhavikapatel
 
PPTX
Gas gangrene dr bhavika(pathogenies,clinical features and lab diagnosis).pptx
byDrBhavikapatel
 
PPTX
Enteric fever pathogenesis, clinical features and lab diagnosis .pptx
byDrBhavikapatel
 
PPT
INTRODUCTION TO MICRO LAB, STAINING TECHNIQUES & MORPHOLOGY OF BACTERIA
byDrBhavikapatel
 
standard precaution drbhavika.pptx Skill Module 1.9 (Foundation Course): Demo...
byDrBhavikapatel
 
AETCOME COMMUNICATION 2.1 DRBHAVIKA - Copy.pptx
byDrBhavikapatel
 
SEXUALLY TRANSMITTED INFECTIONS part .pptx
byDrBhavikapatel
 
Healthcare-associated Infections Part-1.pptx
byDrBhavikapatel
 
chapter 47 - Infective syndromes of hepatobiliary system dr bhavika.pptx
byDrBhavikapatel
 
chapter 11 - DRBHAVIKA Antibody(Immunity).pptx
byDrBhavikapatel
 
dr bhavika sample collection and transport.ppt
byDrBhavikapatel
 
AETCOM 2 BENEFICENCE & ROLE OF PHYSICIAN - Copy.pptx
byDrBhavikapatel
 
AETCOM DR BHAVIKA.pptx (Autonomy &Non-maleficence)
byDrBhavikapatel
 
Parasitic Infections of Skin, Soft tissue and musculoskeletal system dr bhavi...
byDrBhavikapatel
 
Intestinal Helminthic Infection: Intestinal CESTODE Infection dr bhavika.pptx
byDrBhavikapatel
 
Gas gangrene dr bhavika(pathogenies,clinical features and lab diagnosis).pptx
byDrBhavikapatel
 
Enteric fever pathogenesis, clinical features and lab diagnosis .pptx
byDrBhavikapatel
 
INTRODUCTION TO MICRO LAB, STAINING TECHNIQUES & MORPHOLOGY OF BACTERIA
byDrBhavikapatel
 

Recently uploaded

PDF
Why Projects Fail – The Need to “Do the Right Project” and “Do the Project Ri...
byAssociation for Project Management
 
PPTX
MEMORY &FORGETTING. Shilpa Hotakar.Psychology pptx
bySHILPA HOTAKAR
 
PPTX
How to Manage Closest Location in Odoo 18 Inventory
byCeline George
 
PPTX
Complete Overview of Revamp in Odoo 18 Debug
byCeline George
 
PPTX
Lesson_1 Acceleration.pptx_Science 8-4th quarter
byAnnabelAlarcon
 
PDF
TỔNG HỢP 156 ĐỀ CHÍNH THỨC KỲ THI CHỌN HỌC SINH GIỎI TIẾNG ANH LỚP 12 CÁC TỈN...
byNguyen Thanh Tu Collection
 
PDF
APPSC APPSC Forest Draughtsman GS Question paper.pdf
byssuser9d8e4e
 
PPTX
Chapter 1: Introduction to Economics - Macroeconomics and Microeconomics.pptx
byFJ M
 
PDF
Bones by Sadu Kassam (play) story ppt pdf
byRonnieMaeBorres
 
PPTX
Chapter 1 - Introduction to Business Research.pptx
byFJ M
 
PPTX
GRADE 8 - QUARTER 4 TYPES AND PARTS OF LETTER.pptx
byvillariasjazminercai
 
PDF
West Hatch High School - GCSE French Specification
byWestHatch
 
PDF
APPSC APPSC AEE-AE GENERAL STUDIES QUESTION PAPER.pdf
byssuser9d8e4e
 
PDF
Unit Plan and Unit Test-pdf-Dr. Rajashekhar Shirvalkar, Principal, SMRS B.Ed ...
byRajashekhar Shirvalkar
 
PPTX
GRADE 8_WEEK 2_QUARTER 4_ENGLISH_MATATAG.pptx
byRoinelReyes1
 
PDF
Nursing care plan for Vomiting /B.Sc nsg
byDr. Sudhadevi Sadanandan
 
PPTX
ENGLISH-7-Quarter-4-Week-3 Matatag .pptx
byKimberlyJadeCuyos
 
PPTX
industrial arts grade 6 tle_q4_w3_melc.pptx
byadrianatillaga1
 
PPTX
West Hatch High School - GCSE Spanish Presentation
byWestHatch
 
PDF
Artificial Intelligence in Research and Academic Writing, Workshop on Researc...
byProf. Vinod Kumar Kanvaria
 
Why Projects Fail – The Need to “Do the Right Project” and “Do the Project Ri...
byAssociation for Project Management
 
MEMORY &FORGETTING. Shilpa Hotakar.Psychology pptx
bySHILPA HOTAKAR
 
How to Manage Closest Location in Odoo 18 Inventory
byCeline George
 
Complete Overview of Revamp in Odoo 18 Debug
byCeline George
 
Lesson_1 Acceleration.pptx_Science 8-4th quarter
byAnnabelAlarcon
 
TỔNG HỢP 156 ĐỀ CHÍNH THỨC KỲ THI CHỌN HỌC SINH GIỎI TIẾNG ANH LỚP 12 CÁC TỈN...
byNguyen Thanh Tu Collection
 
APPSC APPSC Forest Draughtsman GS Question paper.pdf
byssuser9d8e4e
 
Chapter 1: Introduction to Economics - Macroeconomics and Microeconomics.pptx
byFJ M
 
Bones by Sadu Kassam (play) story ppt pdf
byRonnieMaeBorres
 
Chapter 1 - Introduction to Business Research.pptx
byFJ M
 
GRADE 8 - QUARTER 4 TYPES AND PARTS OF LETTER.pptx
byvillariasjazminercai
 
West Hatch High School - GCSE French Specification
byWestHatch
 
APPSC APPSC AEE-AE GENERAL STUDIES QUESTION PAPER.pdf
byssuser9d8e4e
 
Unit Plan and Unit Test-pdf-Dr. Rajashekhar Shirvalkar, Principal, SMRS B.Ed ...
byRajashekhar Shirvalkar
 
GRADE 8_WEEK 2_QUARTER 4_ENGLISH_MATATAG.pptx
byRoinelReyes1
 
Nursing care plan for Vomiting /B.Sc nsg
byDr. Sudhadevi Sadanandan
 
ENGLISH-7-Quarter-4-Week-3 Matatag .pptx
byKimberlyJadeCuyos
 
industrial arts grade 6 tle_q4_w3_melc.pptx
byadrianatillaga1
 
West Hatch High School - GCSE Spanish Presentation
byWestHatch
 
Artificial Intelligence in Research and Academic Writing, Workshop on Researc...
byProf. Vinod Kumar Kanvaria
 

tb pathogenesis and laboratory diagnosis .pptx

  • 1.
    Tuberculosis Dr Bhavika patel MBBS,MDMicrobiology,DIPC Assistant Professor Department of microbiology GMERS MC, Valsad.
  • 2.
    Learning objectives At theend of the session, the students will be able to understand: ▰ Classification of mycobacteria. ▰ Antigenic structure, pathogenesis, clinical manifestations, lab diagnosis, treatment, drug resistance and prophylaxis of TB.
  • 4.
  • 6.
    Mycobacteria Tuberculosis ► Nonsporing, Non-capsulated. Weakly Gram Positive. ► Strongly Acid Fast (due to mycolic acid in cell wall). ► Lipid Rich Cell Wall (confers resistance to disinfectants, detergents, common antibiotics and traditional stains). ► Long Generation time. ► Humans are the only natural reservoir. ► Person to person transmission, by infectious aerosols/droplets.
  • 7.
    Antigenic Structure ▰ 1.Cell wall (insoluble) antigens:  Peptidoglycan layer – maintains shape & rigidity  Arabinogalactan layer - survival of M.tuberculosis within macrophages  Mycolic acid layer - principal constituent, confers very low permeability, acid fastness and reduces the entry of most antibiotics  Outermost layer - lipids, glycolipids & mycosides
  • 8.
    Antigenic Structure (Cont..) ▰1. Cell wall (insoluble) antigens (Cont..):  Proteins (e.g. porins, transport proteins) - found throughout various layers  Plasma membrane - helps in attachment to host cell and is also a target antigen used for diagnosis
  • 9.
    Antigenic Structure (Cont..) ▰2. Cytoplasmic (soluble) antigens:  These include antigen 5, antigen 6, antigen 60  Used in serodiagnosis of tuberculosis.
  • 10.
    Lin P etal. J Immunol 2010 Clearance Pulmonary TB Low grade TB “percolating “ Dormant infection Septic TB Miliary TB Extrapulmonary TB Spectrum of M. tuberculosis infection
  • 11.
    Tuberculosis or TB(short for tubercle bacillus) ► Is a common and often deadly infectious disease caused by mycobacterium usually mycobacterium tuberculosis. ► M.tuberculosis complex includes: 1.M.tuberculosis 2. M.bovis 3.Other member: M.africanum, M. microti , M. caprae, M. pinnipedii, M. canetti , M. suricattae, M. orygis , M.mungi
  • 12.
  • 13.
    Modes of infection 1.Dropletinfection • Person to person by inhalation aerosols • Mycobacterium tuberculosis (Pulmonary tuberculosis) 2.Ingestion of milk • Infected cattle • Mycobacterium bovis (Intestinal tuberculosis) 3. Inoculation (in skin tuberculosis) 4.Transplacental route (rare route)
  • 14.
    Pathogenesis - RiskFactors ▰ Sputum positive patients with Bacillary load at least 104 bacilli/mL ▰ Cavitary lesions in lung - more bacillary load ▰ Overcrowding in poorly ventilated rooms ▰ Low cell-mediated immunity – HIV ▰ Other comorbid conditions - Post-silicosis, postransplantation, hemodialysis, diabetes, IV drug abuse, smoking, etc. ▰ Age: Late adolescence and early adulthood ▰ Sex: women at 25–34 years, men in older ages
  • 15.
    5.If the bacilliare successful in arresting phagolysosome fusion, then they happily replicate inside the macrophage. The macrophage eventually ruptures and releases its bacillary contents which infect other uninfected phagocytes and infection cycle continues. 4.Survival inside the macrophages due to bacterial cell wall LAM which impairs phagosomelysosome fusion by inhibiting an increase in intracellular Ca2+ and phosphatidylinositol 3-phosphate 3.Phagocytosis by macrophages (complement (C3b) mediated opsonization of bacilli) 2.Adhesion to macrophages Mycobacterial surface lipoarabinomannan (LAM) binds to complement receptors and mannose receptors present on the surface of macrophages. 1.Droplet nuclei containing tubercle bacilli from infectious patients are inhaled. EVIDENCE OF INFECTION WITH M TUBERCULOSIS Chest x-ray / positive skin test
  • 16.
    Host Immune Response- Cell-mediated Immune Response ▰ Macrophages present the mycobacterial antigens to TH (T helper) cells - TH1and TH2 subsets. ▰ TH1 cells release - IL-2 and IFN-γ - activate monocytes and macrophages ▰ Activation of TH1 cells - development of two host responses:  1. A macrophage-activating response  2. Tissue-damaging response.
  • 17.
    Host Immune Response- Cell-mediated Immune Response (Cont..) ▰ 1. A macrophage-activating response: ▰ IFN γ activates macrophages ▰ Tubercles: a favorable sign  Hard tubercles: initially hard - central zone containing activated macrophages (epithelioid and giant cells) and a peripheral zone of lymphocytes and fibroblasts.  Soft tubercles - central part undergoes caseous necrosis - Bacilli inhibited within this necrotic environment because of low oxygen tension and low pH - lesion heals and calcifies.
  • 18.
    Host Immune Response- Cell-mediated Immune Response (Cont..) ▰ 2. Tissue-damaging response: ▰ Minority of cases, associated with risk factors -macrophage- activating response is weak & bacilli more virulent ▰ Mycobacterial growth inhibited only by an intensified delayed hypersensitivity reaction - lung tissue destruction
  • 19.
    Host Immune Response- Cell-mediated Immune Response (Cont..) ▰ Spread of caseous necrosis 1. Direct draining into the airways - discharged with cough 2. Lymphatic spread - reseeding into same or opposite lung → disseminate to other organs. 3. Hematogenous spread to various organs
  • 20.
    Host Immune Response- Cell-mediated Immune Response (Cont..) ▰ Humoral Immune Response: ▰ TH2 release - IL-4, IL-5 - activate B-cells - antibodies.  M. tuberculosis being obligate intracellular organism, humoral immunity plays a minor role  Anti-LAM antibodies play a role in preventing dissemination of tuberculosis in children.
  • 22.
    Symptoms and Signsof Tuberculosis
  • 23.
    Clinical Manifestations ▰ Tuberculosis(TB) is classified as:  Pulmonary TB and  Extrapulmonary TB
  • 24.
    Comparison of primaryand secondary pulmonary tuberculosis Features Primary PTB Post-primary (adult- type)/secondary PTB Results due to Initial exogenous infection with tubercle bacilli  Exogenous reinfection  Endogenous- reactivation of latent primary lesion Age group affected Children Adults Parts of lungs commonly affected Sub pleural lesion affecting, upper part of lower lobe and lower part of upper lobe Apical and posterior segments of the upper lobes (high oxygen tension) Lesions formed at the initial sites Fibrotic nodular lesions are formed (Ghon focus) Hematogenous seedling in the apex of lungs called Simon’s focus
  • 25.
    Comparison of primaryand secondary pulmonary tuberculosis (Cont..) Features Primary PTB Post-primary (adult-type)/secondary PTB Lymph node Ghon focus with associated hilar lymphadenopathy is common (called as primary complex) Lymph node involvement is unusual Clinical feature It may be asymptomatic or may present with fever, productive cough (with or without hemoptysis) and occasionally chest pain, night sweating, weight loss Lesions undergoing necrosis and tissue destruction, leading to cavity formation. Symptoms are similar, but more pronounced.
  • 26.
    Extrapulmonary Tuberculosis (EPTB) ▰Tuberculous lymphadenitis – MC form (35% of all EPTB)  Posterior cervical and supraclavicular lymph nodes - painless swelling in neck region without warmth or color change ▰ Pleural tuberculosis – (20%) - pleural effusion ▰ Tuberculosis of the upper airways - larynx, pharynx, and epiglottis
  • 27.
    Extrapulmonary Tuberculosis (EPTB) (Cont..) ▰Genitourinary tuberculosis: Renal tuberculosis  Genital tuberculosis – Females: fallopian tubes & endometrium - infertility. Males: epididymis ▰ Skeletal tuberculosis - Weight-bearing joints (spine, hips & knees)  Complications - collapse of vertebral bodies - kyphosis & paravertebral ‘cold’ abscess
  • 28.
    Extrapulmonary Tuberculosis (EPTB) (Cont..) ▰Tuberculosis of CNS – M/C in children, Tuberculous meningitis & tuberculoma are common forms ▰ Tuberculous pericarditis - direct extension from adjacent lymph nodes or following hematogenous spread
  • 29.
    Extrapulmonary Tuberculosis (EPTB) (Cont..) ▰Gastrointestinal tuberculosis - Terminal ileum and caecum  Due to swallowing of sputum with direct seeding, hematogenous spread, or ingestion of cow’s milk contaminated with M. bovis ▰ Tuberculous skin lesions:  Scrofuloderma – skin involvement by direct extension from underlying tuberculous lymphadenitis  Lupus vulgaris: Apple jelly nodules are formed over face
  • 30.
    Extrapulmonary Tuberculosis (EPTB) (Cont..) ▰Miliary or disseminated tuberculosis: Hematogenous spread - yellowish 1–2 mm size granulomatous lesions resembling millet seeds in various organs. ▰ Post-TB aspergillosis: Chronic pulmonary aspergillosis - due to colonization of Aspergillus fumigatus in the residual TB cavities
  • 31.
    Epidemiology ▰ Quarter ofthe current world population is infected asymptomatically with M. tuberculosis, of which 5–10% develop the clinical disease. ▰ World: 10 million new cases of TB occurred in 2018. ▰ Deaths due to TB - 12 Lakh in HIV-negative and 2.5 Lakh in HIV- coinfected people in 2018.
  • 32.
    Epidemiology (Cont..) ▰ WHOregions: South-East Asia (44%), followed by Africa (24%) and the Western Pacific (18%) ▰ Countries: Eight countries accounted for two-third of the total TB burden, with India having the largest share. ▰ India: In 2018 - 27 Lakh cases occurred India - highest burden from Uttar Pradesh
  • 33.
    Epidemiology (Cont..) ▰ WHOregions: South-East Asia (44%), followed by Africa (24%) and the Western Pacific (18%) ▰ Countries: Eight countries accounted for two-third of the total TB burden, with India having the largest share.
  • 34.
  • 35.
    Laboratory diagnosis ofTuberculosis ● Specimen collection ⮚ In pulmonary TB: Sputum (2 specimens—spot and early morning), gastric aspirate (in children) ⮚ In EPTB: Specimens vary depending on the site involved
  • 36.
    Extrapulmonary specimens Sterile sitespecimens collected aseptically Optimum specimens CSF, pericardial fluid, synovial fluid and ascitic fluid Suboptimal specimens (organism load is less) Pleural fluid (20–50 mL is collected and centrifuged) Blood (indicated only for disseminated TB and co- infected with HIV) Specimens containing normal flora Swabs Considered suboptimal specimen. The only recommended swabs are:  Laryngeal swabs: Collected early morning in empty stomach or  Swab from discharging sinus Urine Three early morning specimens collected (500 mL/ specimen, centrifuged) on different days as TB bacilli in urine are shed intermittently Stool For disseminated TB in HIV infected patients and infants
  • 37.
    Extrapulmonary specimens (Cont..) Specimens containingnormal flora Other respiratory specimens Bronchial secretions (2–5 mL) Bronchoalveolar lavage (20–50 mL) Transbronchial and other biopsies (collected in sterile normal saline) Gastric lavage Recommended for children (tend to swallow sputum), or ICU patients (aspiration) Early morning lavage should be collected and processed early (<4 hours)
  • 39.
  • 40.
    Integrated DR-TB diagnosis andtreatment algorithm 40 Rifampicin resistance detected4 All TB patients All Presumptive TB1 or Key Population2 Non-responders Rifampicin resistance not detected4 DS-TB regimen NAAT3 FL-LPA 5 + SL-LPA 6 + LC DST7 – Z, Bdq8, Cfz8, Mfx, Lzd, Dlm8 • No additional resistance detected4 or • H resistance detected4 with KatG or InhA mutation (not both) & FQ resistance not detected4 • H resistance detected4 with both KatG and InhA mutation or • FQ resistance detected4 Shorter oral Bedaquiline-containing MDR/RR-TB regimen10 Longer oral M/XDR-TB regimen11 FL-LPA 5 Additional resistance or intolerance or non-availability of any drug in use or emergence of exclusion criteria or return after LTFU or failure H mono/poly DR-TB regimen Modify H mono/poly DR-TB regimen as per replacement table H resistance detected4 Non-responders Additional resistance or intolerance or non-availability of any drug in use or emergence of exclusion criteria or return after LTFU or failure Longer oral M/XDR-TB regimen, modified if needed as per replacement table Reflex testing for SL-LPA 6 + LC DST7 – Mfx, Z, Lzd, Cfz8 Other exclusion criteria9 for shorter regimen PRESE NT ABSE NT After completing PTE, check on Nikshay or with C&DST lab, if LPA results are available N O Y E S Y E S Stop DS- TB Regimen FIRST SPECIMEN TESTED AT NAAT SITE SECOND SPECIMEN TESTED AT C-DST LAB Y e s N o
  • 41.
    Integrated DR-TB diagnosis andtreatment algorithm 41 Rifampicin resistance detected4 All TB patients All Presumptive TB1 or Key Population2 Non-responders Rifampicin resistance not detected4 DS-TB regimen NAAT3 FL-LPA 5 + SL-LPA 6 + LC DST7 – Z, Bdq8, Cfz8, Mfx, Lzd, Dlm8 • No additional resistance detected4 or • H resistance detected4 with KatG or InhA mutation (not both) & FQ resistance not detected4 • H resistance detected4 with both KatG and InhA mutation or • FQ resistance detected4 Shorter oral Bedaquiline-containing MDR/RR-TB regimen10 Longer oral M/XDR-TB regimen11 FL-LPA 5 Additional resistance or intolerance or non-availability of any drug in use or emergence of exclusion criteria or return after LTFU or failure H mono/poly DR-TB regimen Modify H mono/poly DR-TB regimen as per replacement table H resistance detected4 Non-responders Additional resistance or intolerance or non-availability of any drug in use or emergence of exclusion criteria or return after LTFU or failure Longer oral M/XDR-TB regimen, modified if needed as per replacement table Reflex testing for SL-LPA 6 + LC DST7 – Mfx, Z, Lzd, Cfz8 Other exclusion criteria9 for shorter regimen PRESE NT ABSE NT After completing PTE, check on Nikshay or with C&DST lab, if LPA results are available N O Y E S Y E S Stop DS- TB Regimen FIRST SPECIMEN TESTED AT NAAT SITE SECOND SPECIMEN TESTED AT C- DST LAB Y e s N o
  • 42.
    Laboratory Diagnosis A SMEARMICROSCOPY 1- Sputum smears stained by Z-N stain Two morning successive mucopurulent sputum samples are needed to diagnoise pulmonary TB. Advantage: - cheap – rapid - Easy to perform Disadvantages: - sputum ( need to contain 5000-10000 AFB/ ml.) - Young children, elderly & HIV infected persons may not produce cavities & sputum containing AFB.
  • 44.
    Limitation of Microscopyfor Tuberculosis. ► Repeated sample examinations. load on technical staff. ► Training and dedication of Microscopist. ► The load of bacilli must be more than 10,000 / 1 ml of sputum. ► Low in sensitivity < 50 % ► Repeated requests for samples ► Not dependable in pediatric age group.
  • 45.
    Grading If the slidehas Result Grading No. of fields to be examined More than 10 AFB /oil immersion field pos 3+ 20 1-10 AFB/ oil immersion field pos 2+ 50 10-99 AFB/100 oil immersion field pos 1+ 100 1-9 AFB/100 oil immersion field pos Scanty* 100 No AFB in 100 oil immersion field neg 100 *record actual number of bacilli seen in 100 fields
  • 46.
    2- Detecting AFBby fluorochrome stain using fluorescence microscopy: The smear may be stained by auramine-O dye. In this method the TB bacilli are stained yellow against dark background & easily visualized using florescent microscope. Advantages: - More sensitive - Rapid Disadvantages: - Hazards of dye toxicity - more expensive
  • 47.
    Mycobacterium Tuberculosis Stained withFluorescent Dye From Carl Zeiss microimaging GmbH (FluoLED) Yellow bacilli with green background.
  • 48.
    B.CBNAAT/True NAT ► Fullyautomated Cartridge based Nucleic Acid Amplification Test working on the principal of PCR ► Generates digital report in 2 Hours (Test Turn around Time*) ► Sensitivity is similar to Culture and highly specific for M.TB Complex (For Sputum Samples) ► Advantage – Detects Rifampicin Resistance additionally ► Extrapulmonary Samples – Gastric Lavage, BAL, CSF, Pericardial Fluid, Synovial Fluid, Pleural Fluid N.B., Samples should not contain blood, Formalin should not be added
  • 49.
    C.Mycobacterial Culture Reasons torequest mycobacterial culture: • Patient previously on anti-TB treatment (Relapse, Defaulter) • Still smear-positive after intensive phase of treatment or after finishing treatment • Symptomatic and at high-risk of MDR-TB • To test fluids potentially infected with M. tuberculosis • Investigation of patients who develop active PTB during or after IPT. • TB in health workers
  • 50.
    50 FLOW CHART CONTD. Screenby AFB smear & inoculate media (one liquid & one solid) Liquid Medium Solid Media MGIT BACTEC SEPTI-CHEK CMS Incubate At 37ºC For 6 wks Incubate At 37ºC For 6 wks Incubate inverting At 37ºC For 8 wks Incubate At 37ºC For 6 wks Fluoresc- -ence detected Growth Index >10 Colonies or turbidity Growth detected Confirm by AFB smear Reinoculate on Solid media L J L J with RNA LJ with Pyruvic acid Incubate At 37ºC For 8 wks If growth Confirm on AFB smear
  • 51.
    Solid media ► Culturesincubated at 35°c in the dark in an atmosphere of 5% to 10% co2 and high humidity ► Cultures are examined weekly for growth ► Most isolates appear between 3 and 6 weeks a few isolates appear after 7 or 8 weeks ► After 8 wks of incubation negative cultures are reported
  • 52.
    Eight Week Growthof Mycobacterium tuberculosis on Lowenstein-Jensen Agar
  • 53.
    Commonly used liquidmedia systems to culture and detect the growth of mycobacterium ► BACTEC 460 ► Mycobacteria growth indicator tube (MGIT) ► BACTEC MGIT 960 ( continuous growth monitoring systems)
  • 54.
    Liquid media ► Useof liquid media system reduces the turn- around time for isolation of acid-fast bacilli to approximately 10 days compared with 17 days or longer in conventional methods ► Once growth is detected in the liquid media , an acid fast stain is performed to confirm the presence of acid-fast bacilli
  • 55.
    Laboratory diagnosis ofTuberculosis (Cont..) 55 ● Culture identification ⮚ Automated identification—by MALDI-TOF ⮚ MPT 64 antigen detection—by ICT ⮚ Different biochemical test – ex Nitrate reduction and niacin production are definitive for M.tb
  • 56.
    DST (Drug SusceptibilityTesting) 56 ● Phenotypic Methods ● Genotypic Methods
  • 57.
    Methods for drugsusceptibility testing Genotypic testing is much faster than phenotypic methods.
  • 58.
    Choice of diagnostictechnology DR diagnostic technology Choice NAAT/LPA First Liquid culture isolation and LPA DST Second Liquid culture isolation and liquid DST Third ⮚ Solid LJ media- of up to 84 days, ⮚ Liquid Culture (MGIT) up to 42 days, ⮚ LPA up to 72 hours ⮚ NAAT - 2 hours. Turn around time
  • 59.
    Laboratory diagnosis ofTuberculosis (Cont..) ● Diagnosis of latent tuberculosis ⮚ Tuberculin skin test (e.g. Mantoux test) ⮚ Interferon gamma release assay (IGRA).
  • 60.
    Laboratory diagnosis ofTuberculosis (Cont..) 60 ● Diagnosis of latent tuberculosis ⮚ Tuberculin skin test (e.g. Mantoux test) ⮚ Interferon gamma release assay (IGRA).
  • 61.
    Mantoux Tuberculin SkinTest (TST) ► 0.1 ml of tuberculin purified protein derivative (- PPD) into inner surface of forearm intradermally. Read between 48-72 hrs. ► A positive tuberculin skin test result is supportive evidence in the diagnosis of TB in areas of low prevalence (or no vaccination); however, a negative tuberculin skin test result may occur in approximately one third of patients.
  • 63.
    Cytokine Assays T- cellInterferon-Gamma Release Assay (IGRA) ►INF- y produced by T-lymphocytes, is capable of activating macrophages, increasing their bactericidal capacity against M tuberculosis and is involved in granuloma formation. ►Elevated concentrations of INF-y in TB is related to increased production at the disease site by effectors T cells. ►The sensitivity of an elevated level varies from 78 to 100% and specificity from 95 to 100%
  • 64.
    ❖ IGRA isuseful in targeted strategy for latent TB infection(LTBI) detection in low TB incidence settings ❖ More specific than Tuberculin Skin Test ❖ Can’t distinguish active from treated TB or LTBI. ❖ False positive results in- Hematologic malignancies Empyema.
  • 65.
    Methods for detectionof IFN-y Two new blood tests 1. T-SPOT.TB [Oxford Immunec] – directly count the no of IFN-y secreting T cells. 2. QuantiFERON-TB Gold [Cellestis Limited] – measures the concentration of IFNy secretion. Both tests based on detection of IFN-y in blood have been found to be more accurate than the tuberculin skin test in the diagnosis of latent TB infection. Future research should focus on the potential efficacy of quantification of specifically activated lymphocytes in body fluid and blood using IFN-Y release assay in the diagnosis of TB.
  • 66.
    Comparison between TSTand IGRA test ► A positive test result by either of the two methods available is not by itself a reliable indicator that the person will progress to TB disease as the possibility of false positive results cannot be ruled out. ► Conversely, a negative test result does not rule out TBI, given the possibility of a false- negative test result among at-risk groups, such as young children or among those recently infected.
  • 68.
    Progress in TBDiagnosis Past Present Koch discovered tubercle bacillus 133 yrs back No major discovery Except TB Genome, IS6110, BACTEC 460 (liquid media) TB diagnosed by symptoms - prehistoric Still the same practice in many High Bruden Countries (HBCs) Tuberculin test - > 100yrs Still Commonly used Egg based media –almost 100yrs Still most commonly used AFB Smear for diagnosis – 133 yrs back Still the major diagnostic tool in many countries Radiological Diagnosis Still Important (X-ray, CT Scan)
  • 69.
    Global and NationalTB Programmes ▰ The End TB Strategy (WHO) ▰ Revised National Tuberculosis Control Programme (RNTCP) ▰ National Strategic Plan, India (2020–2025) – Nikshay and 99DOTS
  • 70.
    Vaccine Prophylaxis AgainstTuberculosis - Bacillus Calmette-Guérin Vaccine (BCG) ▰ BCG strain: In India, WHO recommended Danish 1331 strain of BCG is used. ▰ Reconstitution of BCG: Available in lyophilized form, should be reconstituted before administration. ▰ Administration of BCG: 0.1 mL (0.1 mg TU) of BCG vaccine - administered above the insertion of left deltoid by intradermal route
  • 71.
    Vaccine Prophylaxis AgainstTuberculosis - Bacillus Calmette-Guérin Vaccine (BCG) (Cont..) Protection: ▰ Efficacy: Variable efficacy of 0–80% ▰ Duration of immunity - 15–20 years ▰ Protection to infants and young children against the development of complications - tuberculous meningitis and disseminated tuberculosis.
  • 72.
    Vaccine Prophylaxis AgainstTuberculosis - Bacillus Calmette-Guérin Vaccine (BCG) (Cont..) Complications following BCG: ▰ Most common complications - ulceration at the vaccination site and regional lymphadenitis ▰ Rarely - keloid or lupus lesion, osteomyelitis, non-fatal meningitis, progressivetuberculosis and disseminated BCG infection (“BCGitis”).
  • 73.
    Vaccine Prophylaxis AgainstTuberculosis - Bacillus Calmette-Guérin Vaccine (BCG) (Cont..) Indications of BCG ▰ Direct BCG: BCG is directly given to the newborn soon after birth. ▰ Indirect BCG: BCG is given after performing tuberculin skin test.
  • 74.
    Vaccine Prophylaxis AgainstTuberculosis - Bacillus Calmette-Guérin Vaccine (BCG) (Cont..) Contraindications to BCG include: ▰ HIV-positive child ▰ Child born to AFB positive mother ▰ Child with low immunity ▰ Generalized eczema ▰ Pregnancy.
  • 75.
    Chemoprophylaxis ▰ Treatment ofselected high-risk tuberculin reactors (i.e. people with latent tuberculosis) aims at preventing active disease. ▰ Isoniazid or ethambutol for six months - tried. ▰ Chemoprophylaxis has several shortcomings such as— ▰ (1) it is expensive, (2) risk of developing tuberculosis is minimal in tuberculin reactors, and (3) side effects of the drugs.
  • 76.
    Chemoprophylaxis (Cont..) ▰ INHpreventive therapy (IPT) - restricted to limited indications:  Adults with HIV - unlikely to have active TB  Children with HIV - no TB symptoms and unlikely to have active TB  All children with HIV - successfully completed treatment for TB.