Presentation on theme: "Tuberculosis Definition: Infection and in some cases lung disease by Mycobacterium tuberculosis, a human pathogen. 9,582 TB cases reported in 2013 (steady."— Presentation transcript:
1 TuberculosisDefinition: Infection and in some cases lung disease by Mycobacterium tuberculosis, a human pathogen. 9,582 TB cases reported in 2013 (steady decline since 1953 (84,304 cases); all TB isolates are genotyped.Transmission: occurs by aerosol droplets that are inhaled.Disease: latently infected individuals harbor M. tuberculosis within granulomas without disease symptoms but can be identified by skin or blood tests; they may (15%) progress to active disease, typically granulomatous lung lesions that eventually produce cavernous lesions.Symptoms: cough, chest pain, bloody sputum, weakness, weight loss, chills, low grade fever, night sweatsRisk factors: latent TB, HIV infection, diabetes, alcohol or drug abuseDiagnosis: chest X-ray and skin test for screening; latent and active disease can be diagnosed with skin (Mantoux) and blood (IGRA) tests. Mtb detection and isolation in sputum to detect “open TB” and conduct antibiotic resistance testing.Treatment: latent TB= isoniazid (INH) for 9 months or INH & rifapentine (RPT, rifampicin (RIF) derivative) for 3 months; active TB=INH, RIF, ethambutol (EMB), pyrazinamide (PZA) for 2 months then INH & RIF for 4-7 months (continuation phase)
3 Pathogenesis of tuberculosis Infection is initiated by the inhalation of aerosol droplets that contain bacteria. The initial stages of infection are characterized by innate immune responses that involve the recruitment of inflammatory cells to the lung. Following bacterial dissemination to the draining lymph node, dendritic cell presentation of bacterial antigens leads to T cell priming and triggers an expansion of antigen-specific T cells, which are recruited to the lung. The recruitment of T cells, B cells, activated macrophages and other leukocytes leads to the establishment of granulomas, which can contain Mycobacterium tuberculosis. Most infected individuals will remain in a 'latent' state of infection, in which no clinical symptoms are present. A small percentage of these people will eventually progress and develop active disease, which can lead to the release of M. tuberculosis from granulomas that have eroded into the airways. When individuals with active tuberculosis (TB) cough, they can generate infectious droplets that transmit the infection.
4 Mycobacterium tuberculosis primary infection - the exudative response
7 Structure and cellular constituents of the tuberculous granuloma The tuberculous granuloma at its most basic is a compact, organized aggregate of epithelioid cells — macrophages that have undergone a specialized transformation to have tightly interdigitated cell membranes that link adjacent cells. Epithelioid cells can be highly phagocytic but in some cases do not contain bacteria at all. Granuloma macrophages can also fuse into multinucleated giant cells or differentiate into foam cells, which are characterized by lipid accumulation. Foam cells have been noted to be most frequently located at the rim of the necrotic centre of a mature tuberculous granuloma. The consequences of these changes are not well understood, but in general foam cells and multinucleated giant cells have been reported to contain only a few bacteria, if any. Bacteria are most commonly present in the central necrotic areas in which dead and dying macrophages can be seen. Many other cell types also populate the granuloma, such as neutrophils, dendritic cells, B and T cells, natural killer (NK) cells, fibroblasts and cells that secrete extracellular matrix components. Finally, the epithelial cells surrounding the granuloma (not shown) are now thought to participate in its formation also.
11 Tuberculin TestsDelayed Type Hypersensitivity develops 1 months after infectionCaused by cell mediated immunity and transferred by T lymphocytesPositive reaction documents Tb infection or vaccination with BCGDoes not reveal information on the state of Tb diseaseFalse negative reaction in anergic individuals: age, HIV infection, steroid therapy etc.Skin test: Mantoux tuberculin skin test (TST), intradermal injection of tuberculin (≥10 mm induration positive)Interferon-gamma release assays (IGRAs): QuantiFERON-TB Gold In-Tube Test (QFT-GIT) and T-SPOT are blood sample assays for INFγ production
13 RD1 (ESAT6)-mediated recruitment of macrophages to the tuberculous granuloma This figure shows the steps by which matrix metalloproteinase 9 (MMP9) can be induced in the epithelial cells surrounding a forming granuloma. The Mycobacterium tuberculosis protein ESAT6 can be released from infected macrophages through their apoptotic death (which it causes) and/or through its pore-forming activity. It then causes the transcriptional induction of Mmp9 in neighbouring epithelial cells; increased levels of MMP9 production in turn result in the enhanced chemotactic recruitment of uninfected macrophages to the granuloma, by as yet unknown mechanisms. Possible mechanisms include the activation of a macrophage-specific chemokine, and chemokine release from the extracellular matrix (ECM).
14 Proliferation and dissemination of mycobacteria through granuloma formation a | A macrophage infected with wild-type Mycobacterium tuberculosis recruits new macrophages and induces their rapid movement. Following the apoptosis of the infected cell, it is phagocytosed by the recruited cells. After more bacterial growth, these infected cells also die and are phagocytosed by additional recruited macrophages. Infected cells egress from the primary granuloma to initiate secondary granulomas. b | The same events are altered during infection with RD1-mutant M. tuberculosis. The intracellular growth of these mutant mycobacteria within an infected macrophage occurs in a similar manner to that of wild-type M. tuberculosis. However, the death of this macrophage is delayed compared with wild-type infection, and the recruited macrophages are fewer in number and lack the rapid movement observed during wild-type infection. The slower death of infected macrophages and the delayed phagocytosis of the dead cells combine to produce small, delayed granulomas with better containment of infection.
15 M. tuberculosis granuloma caseous necrosis & post primary TB
17 Sputum analysis for M. tuberculosis Mycoid colonies on Loewenstein-Jensen agar are formed after weeks!Ziehl-Neelsen stain for acid fast bacilli and microscopy [rapid (1 hour), not sensitive, reveals M. tuberculosis load in sputum]Sputum inoculation on selective media (Loewenstein-Jensen agar) to culture M. tuberculosis: slow (4-6 weeks), highly sensitive, yields Mtb for genotypic analysis and antibiotic susceptibility testingNucleic acid amplification test (NAAT) (a.k.a PCR): fast (within 24 hours), specific, sensitive but does not yield M. tb for genotyping and antibiotic susceptibility testingNAATAFB in sputumMycoid colonies on LJ agar
22 Tuberculosis vaccine: BCG Single intra-muscular injection of Bacillus Calmette Guerin (BCG), an attenuated Mycobacterium bovis strain, into peopleOnly tuberculin negative individuals (newborns!) can be vaccinated70% protection against severe tuberculosis (miliary Tb and Tb meningitis) in children over 5 yearsLimited effectiveness of BCG for preventing the most common forms of TB and in preventing TB in adultsBCG vaccination does not protect against infection, causes skin test conversion & has been abandoned in the United StatesAlthough new Tb vaccines and vaccine regimen have been tested in clinical trials, there are currently no advances!
23 Prediciting TB vaccine success Prediciting TB vaccine success? Production of IFN-γ by CD4+ T cells does not predict successa | The 'central dogma' of protective immunity to tuberculosis (TB) is that CD4+ T cells produce interferon-γ (IFNγ) (T helper 1 (TH1) cells), which synergizes with tumour necrosis factor (TNF; produced by the T cell or the macrophage), and together these activate macrophage antimicrobial activity that is capable of restricting the growth of Mycobacterium tuberculosis. Two pathways activated by IFNγ that are capable of killing M. tuberculosis are nitric oxide production and phagosome–lysosome fusion, which acidifies the bacterial phagosome. b | 'A revised view of T cell-mediated immunity' incorporates additional T cell subsets (CD4+ T cells, CD8+ T cells and unconventional T cells: γδ T cells, mucosal-associated invariant T (MAIT) cells and CD1-restricted T cells) and includes additional mechanisms by which T cells mediate killing of M. tuberculosis. These include additional cytokines (for example, granulocyte–macrophage colony-stimulating factor (GM-CSF)) and cytolysis of infected macrophages. The cytolytic mechanisms vary and can include cytotoxic granules, which can deliver antimicrobial peptides, such as granulysin, but can also deliver granzymes, which can trigger apoptotic cell death. Cytotoxic T lymphocyte (CTL) activity mediated by FAS ligand (FASL)–FAS or TNF can also lead to apoptosis. Apoptosis can have a beneficial effect on the outcome of infection, as infected apoptotic cells can be engulfed by bystander macrophages, which are capable of destroying the apoptotic cells, including any intracellular bacteria. Finally, several components of the innate response, including interleukin-1 (IL-1) and vitamins, can synergize with cytokines that are produced by T cells. c | 'Protective T cells and vaccination' focuses on the desired features of protective T cell responses. Rational vaccine design should aim to elicit protective T cells by optimizing their action on infected cells in several ways. Vaccine-elicited memory T cells must rapidly expand and generate secondary effector T cells that undergo sustained proliferation following activation. Whereas the functions of primary effector T cells are heterogeneously expressed, vaccination can lead to more homogenous expression of effector functions during the recall response. Such T cells, which are often identified as multifunctional T cells, may have a greater protective potential. Primed effector and memory T cells should efficiently traffic to sites of infection, but the kinetics of the response must be balanced with respect to T cell subsets and limit the potential for T cell exhaustion, excessive inflammatory pathology or an ineffective response that hinders T cell–target contact.
24 Socioeconomic impact on tuberculosis infection and mortality (a) England and (b) Netherlands a | Decline in tuberculosis (TB) mortality in England and Wales for the period 1900– b | TB incidence, reactivation and death rates (per 100,000) and the average annual risk of TB infection (per 10,000) in the Netherlands for the period 1901–1983.
25 Trends in TB incidence and case notifications WHO data for 1990-2010 by region The graphs show trends in case notification rates (new and relapse cases, all forms), estimated incidence rates, including HIV-positive tuberculosis (TB) and estimated incidence rates of HIV-positive TB cases in the WHO regions for the period 1990–2010. The shaded areas represent uncertainty bands. AFR, Africa Region; AMR, Region of the Americas; EMR, Eastern Mediterranean Region; EUR, European Region; SEA, South East Asia Region; WPR, Western Pacific Region.
26 TB-related mortality in HIV-infected individuals WHO data for and projected for by regionThe graphs show tuberculosis (TB)-related mortality, including deaths in HIV-infected individuals, for the period 1990–2010 and projected mortality for the period 2011–2015, for the WHO regions. The shaded areas represent uncertainty bands. Uncertainty is comparatively lower when the data come from vital registration records. AFR, Africa Region; AMR, Region of the Americas; EMR, Eastern Mediterranean Region; EUR, European Region; SEA, South East Asia Region; WPR, Western Pacific Region. The dashed line represents the Stop TB Partnership target of 50% reduction in the mortality rates by 2015 compared with 1990 levels.
27 TB-related mortality in HIV-infected individuals WHO data for and projected for by regionThe graphs show tuberculosis (TB)-related mortality, including deaths in HIV-infected individuals, for the period 1990–2010 and projected mortality for the period 2011–2015, for the WHO regions. The shaded areas represent uncertainty bands. Uncertainty is comparatively lower when the data come from vital registration records. AFR, Africa Region; AMR, Region of the Americas; EMR, Eastern Mediterranean Region; EUR, European Region; SEA, South East Asia Region; WPR, Western Pacific Region. The dashed line represents the Stop TB Partnership target of 50% reduction in the mortality rates by 2015 compared with 1990 levels.
28 The Lübeck Accident Genetic traits, still uncharacterized, determine susceptibility to Tb disease 251 healthy children were accidentally inoculated with fully virulent M. tuberculosis instead of BCGAll children were initially x-ray and skin test negative for infection or disease77 children developed fatal disease127 children developed primary complexes that healed47 children showed no sign of disease
29 Envelope architecture M. tuberculosisEnvelope architectureThree forms of mycolic acids are depicted. α-Mycolates are the most abundant form in M. tuberculosis (orange). It has 2 cyclopropane rings (triangles) in cis configuration. Oxygenated mycolates (keto- and methoxy-, shown in red) have one cyclopropane ring each that is in either cis ortrans configuration. They are covalently linked to the arabinogalactan layer, which is linked to the peptidoglycan layer. Other lipid complexes in the cell wall include acyl glycolipids (including TDM) and other complex free lipids (e.g., phthiocerol dimycocerosate) as well as sulfolipids. Lipoarabinomannan is shown linked to the plasma membrane via a phosphodiester bond. Rao et al. (1) found that the oxygenated mycolates of acmaA2M. tuberculosis mutant lack trans-cyclopropanated rings. Such a change could affect the mycolate layer of the cell envelope, which they claim causes a hyperinflammatory response in mice.
30 Antibiotics against Tb Schatz & Waksman isolate streptomycin; Domagk develops isoniazid (INH) Schatz (l) & Waksman (r)Standard therapy: isoniazid (INH) and rifampicin (RIF) for 9 months, pyrazinamide (PZA) and ethambutol (EMB) for 2 monthsFirst line oral drugs: isoniazid, rifampicin, rifapentine, pyrazinamide and ethambutolInjectable drugs: streptomycin, amikacin, kanamycin, capreomycinSecond line oral drugs: ofloxacin, ciprofloxacin, ethionamide, aminosalicylic acid, cycloserine, bedaquiline fumarateG. Domagk
31 Isoniazide (INH) Mode of activation and antibiotic action on FASII & comparison with Pyridomycin Pyridomycin, a natural product with potent antituberculosis activity (not licensed for clinical use), inhibits a major drug target, the InhA enoyl reductase, which is responsible for mycolic acid formation. InhA is also inhibited by isoniazid, which requires activation by KatG.
32 Pyrazinamide (PZN) blocks FAS-I and mycolic acid biosynthesis in M Pyrazinamide (PZN) blocks FAS-I and mycolic acid biosynthesis in M. tuberculosisPyrazinamide (PZN) blocks mycolic acid biosynthesis in M. tuberculosis. PZN is a prodrug and first activated by pyrazinamidase (PncA) to pyrazinoic acid, which then inhibits fatty acid synthase I (FAS-I), an enzyme responsible for the synthesis of short chain mycolic acids.
33 Ethambutol (EMB) inhibits arabinosyl-transferase (EmbB) and blocks arabinogalactan synthesis Ethambutol (EMB) inhibits arabinosyl-transferase (EmbB) and blocks arabinogalactan synthesis, which is essential for the formation of the mycolic acid layer.
34 MDR-Tb multi-drug resistant Mycobacterium tuberculosis Definition: M. tuberculosis isolates resistant to isoniazid and rifampin; may also be resistant to other Tb drugsCause: incomplete therapy (insufficient dose or non-compliance, HIV infectionEpidemiology: 95 cases of MDR-Tb in the United States reported to CDC in 2013Treatment: Strain isolation, antibiotic resistance characterization, genotyping. Therapy with up to 7 drugs (2nd line oral and injectable drugs), 50% cure ratesBedaquiline fumarate (Sirturo™): inhibits the proton pump of ATPase; only drug approved by FDA in 40 years for use as part of a combination therapy in adults with pulmonary multidrug-resistant tuberculosis (MDR TB) when effective treatment cannot otherwise be provided.
35 Antibiotic activation and resistance in MDR-Tb Case studies for INH and ETH (ethionamide), a second line oral antibiotic for the therapy of MDR-TbProposed mechanism of action of INH and ETH. INH and ETH are both prodrugs that are activated by the catalase-peroxidase KatG or the monooxygenase EthA, respectively. The activated forms react with NAD+ to form an INH-NAD or ETH-NAD adduct. These adducts inhibit the common target InhA, the NADH-dependent enoyl-ACP reductase of the fatty acid synthase type II system, resulting in mycolic acid biosynthesis inhibition and cell lysis. Resistance to INH or ETH is associated with recessive mutations in the genes encoding the activators of the drugs, katG and ethA, respectively, which prevent drug activation. Coresistance to INH and ETH is associated with dominant mutations in the gene encoding the common target of the drugs, inhA, which result in target amplification or target modification. A novel mechanism of coresistance to INH and ETH is by recessive mutations in ndh, which increase the NADH intracellular concentration and cause resistance by competitively inhibiting the binding of the INH-NAD or ETH-NAD adduct to InhA. This working model accounts for all known resistance phenotypes that have been transferred from drug-sensitive to drug-resistant strains to date.
36 XDR-Tb extensively-drug resistant Mycobacterium tuberculosis Definition: M. tuberculosis isolate that is resistant to isoniazid, rifampin, fluoroquinolones and at least one of three injectable second-line drugs (amikacin, kanamycin, or capreomycin)Epidemiology: 62 cases of XDR-Tb in the United States reported to CDC betweenDiagnosis: positive skin or blood test; culture isolation and resistance testing requires 6-16 weeksTreatment: US cure rates of 30-50%; therapy requires laboratory testing for all available antibioticsPrevention: HIV-infected travelers have the highest risk when visiting countries with XDR-Tb
37 TB Case Rates in U. S. -born vs TB Case Rates in U.S.-born vs. Foreign-born Persons, United States, 1993 – 2013*Cases per 100,000*Updated as of June 11, 2014.
38 Reported TB Cases by Origin and Race/Ethnicity,* United States, 2013 U.S.-bornForeign-born***All races are non-Hispanic. Persons reporting two or more races accounted for less than 1% of all cases.** American Indian or Alaska Native and Native Hawaiian or Other Pacific Islander accounted for less than 1% of foreign-born cases and are not shown.
39 Primary MDR TB, United States, 1993 – 2013* No. of CasesPercentage*Updated as of June 11, 2014.Note: Based on initial isolates from persons with no prior history of TB. MDR TB defined as resistance to at least isoniazid and rifampin.
40 XDR TB Case Count Defined on Initial DST* by Year, 1993 – 2013** Year of Diagnosis* Drug susceptibility test.** Updated as of June 11, 2014.Note: Extensively drug-resistant TB (XDR TB) is defined as resistance to isoniazid and rifampin, plus resistance to any fluoroquinolone and at least one of three injectable second-line anti-TB drugs.
41 Hansen’s disease (leprosy) Definition: long lasting infection with Mycobacterium leprae causing disfigurement due to loss of neurological tissue & function and traumaEpidemiology: globally about 2 million people are infected with M. leprae (S.-America, Africa, SE Asia); 213 cases in the US (2009). Armadillo & humans are the natural reservoirs.Transmission: prolonged contact with Hansen’s disease patients; 95% of the human population is resistant to M. lepraeSymptoms & signs: After 2-10 yr incubation, skin discoloration/growth, pain, numbness/loss of sensation, muscle weakness & paralysis, blindness, stuffy nose, nose bleeds, foot ulcerations.Diagnosis: skin biopsy and staining for AFB; M.l. can only be cultured in mouse foot pads or armadillos; no lab tests with sufficient sensitivity availableTreatment: 6 month-2 years multidrug therapy: dapsone (blocks dihydrofolic acid synthesis), rifampicin and clofazimine [blocks transcription and prevents the leprosy reaction: ENL (erythema nodosum leprosum)]
42 Leprosy spectrum and mechanisms of pathogenesisThe leprosy spectrum and possible mechanisms of tissue damage. Leprosy manifestations are classified along a clinical spectrum of tuberculoid (TT), borderline tuberculoid (BT), borderline borderline (BB), borderline lepromatous (BL), and lepromatous (LL) leprosy. Each pole is associated with a characteristic cell-mediated or humoral immune profile. The cell-mediated (Th1) response of the TT pole features the elimination or containment of the organism in granulomas, while the ineffective humoral response at the LL (Th2) pole allows the proliferation of mycobacteria within and around foamy macrophages. Reversal reactions reflect a sudden shift toward the Th1 pole from the BT, BB, or BL state and can lead to irreversible nerve damage (neuritis). Erythema nodosum leprosum (ENL) reactions occur in patients with BL or LL leprosy and reflect an increase in both cell-mediated and humoral responses to M. leprae. ENL is associated with the systemic release of TNF and IL-4, a brisk polymorphonuclear leukocyte (PMN) influx, and antigen-antibody (Ag/Ab) complex deposition. The mechanism of nerve damage is unclear but may involve immune injury due to the release of inflammatory cytokines or activity of cytotoxic T cells, ischemia due to edema within the perineural sheath, apoptosis, or demyelination (see discussion in the text).
43 Genes and products involved in the immune response to M. leprae Genes and gene products involved in the immune response to M. leprae. Molecular and cellular interactions known or postulated to play a role in the immune response to M. leprae are depicted, as are genes with evidence of an association with susceptibility to leprosy and/or leprosy immune reactions through candidate gene studies, linkage analyses, or genome-wide association studies. Laminin binding protein 21 (LBP21) and phenolic glycolipid 1 (PGL-1) in the M. leprae cell wall bind to the α2 chain of laminin-2 (LAMA2) and α-dystroglycan on the Schwann cell membrane. This permits entry and subsequent damage to the peripheral nerve. Abbreviations: C3, complement factor 3; CR1, complement receptor 1; DEFB1, beta defensin 1; IFNG, gamma interferon; IL10, interleukin-10; IL12B, interleukin-12 subunit p40; IL12RB2, interleukin-12 receptor beta 2; LTA4H, leukotriene A4 hydrolase; LTA, lymphotoxin-α; MHC II, major histocompatibility complex class II; MBL2, mannose binding lectin 2; MRC1, mannose receptor; NOD2, nucleotide oligomerization domain 2; RIP2, receptor-interacting kinase; SLC11A1, solute carrier family 11, member 1 (also known as NRAMP); TCR, T-cell receptor; Th1, T-cell helper type 1; Th2, T-cell helper type 2; TLR, Toll-like receptor; TNF, tumor necrosis factor.
47 Features and disease spectrum of leprosy TT-Tuberculoid L Features and disease spectrum of leprosy TT-Tuberculoid L.; BT-Borderline Tuberculoid L.; BB-Borderline Leprosy; BL-Borderline Lepromatous Leprosy; LL-Lepromatous Leprosy (LTT, Lymphocyte Transformation Test)
48 Phylogenetic tree for Actinobacteria based upon sequences for 35 conserved proteinsTb, Hansen’s diseaseDiphtheriaNocardiosisPhylogenetic tree for 98 actinobacterial species whose genomes have been sequenced, based upon concatenated sequences for 35 conserved proteins. Many genera for which sequence information is available from multiple species are represented by triangles in this tree. The sizes of the triangles reflect the number of species that have been sequenced, and more detailed trees for some of these groups are presented in other figures. The tree shown is based on neighbor-joining (NJ) analysis, and the numbers at the nodes represent the bootstrap scores of the nodes. Similar branching patterns for most of these groups can also be observed in a maximum likelihood tree. The asterisks mark the Frankiales species that branch in different positions in this tree.Actinomycosis
49 ActinomycosisDefinition: Slowly progressing deep tissue abscess lesions caused by mixed infections with anaerobic actinomyces following mucocutaneous trauma.Agents: A. israelii or five other spp. are commensals of the oropharynx and GI. Actinomyces enter deeper tissue and replicate as mixed infection (Actinobacillusactinomycetemcomitans, Bacteroides, Eikanella coorodens or Prevotella) to seed pururlent abscess lesions because they require anaerobiosis.Clinical disease: abscesses in mouth, lungs, GI/GU tracts are designated cervicofacial, abdominal, and thoracic actinomycosis.Pathology: sulfur granules and Gram-positive beads or hyphae like structures; culture isolation of Actinomyces requires anaerobiosis and daysTreatment: abscess drainage and penicillin GGram-positive A. israeliiSulfur granulesA. Israelii in abscess
50 Sulfur granules & actinomycosis Mineralized mass with calcium phosphate and radiatingfilamentous actimomycesPathognomonic when recovered from a typical lesionOther infections associated with granules: mycetoma, botryomycosis
52 NocardiosisDefinition: lung or systemic or cutaneous infection with aerobic Nocardia (N. brasiliensis, N. asteroides or 31 other spp), mostly (~70%) in immunocompromised individuals, that progresses slowly and is refractory to conventional antibiotic therapyTransmission: Nocardia are commensals of the human oropharynx and ubiquitous in soil; infection is initiated by trauma and immunossuppression; about 1,000 cases in the US per yearClinical disease: pneumonia - night sweats, fever, chest pain, cough, X-ray w/ pulmonary infiltrates; meningitis – headache, seizures, neurological deficits, CT scan to detect lesions; endoacarditis – w/ destruction of heart valves and disseminated lesions; skin lesions – resembling erysipelas or w/ osteitis as Madura foot/handDiagnosis: tissue biopsy or sample, Gram-positive or acid-fast bacilli; culture supports definitive diagnosis (hold for weeks)Treatment: 6 months trimethoprim/sulfamethoxazol; clinical success dictates whether other antibiotics may be used: amikacin, imipenem, meropenem, ceftriaxone, moxifloxacin, minocycline and others.