Lecture 10 Mycobacterium

Lecture 10 Mycobacterium - Overview: Gram­Pos Rods...

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Unformatted text preview: Overview: Gram­Pos Rods Overview: Gram­Pos Rods Gram+ Rod Spores Shape regular irregular + Clostridium - Acid Fast Listeria Branched Filaments CoryneNocardia Mycobacterium bacterium CMN-Group + - + Lecture 10 Lecture 10 Mycobacterium Classification Classification Family Genus Mycobacteriaceae Mycobacterium Species >85 including: M. tuberculosis M. leprae M. kansasii M. avium M. ulcerans General Characteristics General Characteristics slow growing (3­8weeks) Fastidious growth complex cell wall (lipid rich) Acid fast staining (unique) Weak gram positive Non spore forming Rod shape Acid Fast Test Acid Fast Test Acid fastness is based on physical property of cell to resist decolorization reaction by acids Ziehl­Neelsen stain Acid fast bacteria = RED Background= BLUE Auramine­Rhodamine stain Acid fast bacteria = GREEN Background= non fluorescent Morphology Morphology Acid Fast staining Takes 3 weeks to get colony General Characteristics General Characteristics Cell wall structure Mycolic Acid and Cord Factor Arabino­ galactan Cell Wall:Figure 29­1 Mycobacterial cell wall structure. The components include the (A) plasma membrane, (B) peptidoglycans, (C) arabinogalactan, (D) mannose­capped lipoarabinomannan, (E) plasma­associated and cell wall­associated proteins, (F) mycolic acids, and (G) glycolipid surface molecules associated with the mycolic acids. • – – • – – • • – Mycobacteria longest chain length strongly acid fast Mycolic acids Mycolic acids Nocardia/Rhodococcus intermediate chain length weakly acid fast Corynebacteria shortest chain length not acid fast History: M.tuberculosis History: Tuberculosis “The White Plague” “Mankind's Slow Stain” no drastic pandemic outbreaks “Consumption” subject die only after months­ years Arguably killed more humans than any other infectious disease 1815 England 1 of 4 death due to TB Presently still 2­3 million death annually Tuberculosis: Ancient Disease Most recent genomic analysis suggest that human Mtb strains have existed for at least 40,000 years TB: Ancient Disease TB: Ancient Disease Torso of 6-8 year or girl found in tomb build 1500-500 BC.Arrow indicates major connective tissue adhesions, suggesting chronic infection. Tissue positive for Mtb DNA. Tuberculosis Huge impact of disease on society during 16th­ 19th century Important genetic component to disease susceptibility Whole families got wiped out Until end of 19th century TB was considered by many to be hereditary disease 1882­R.Koch:”The Etiology of TB” 1882­R.Koch:”The Etiology of TB” Landmark paper: established “Koch’s Postulates” for Mycobacterium tuberculosis and TB Sets standard for medical microbiology research ­developed growth media, staining procedures Culture techniques Culture techniques Photo documentation Photo documentation Koch’s greatest failure Koch’s greatest failure •1890 10th international congress of medicine in Berlin >5000 participants Koch announces the cure for TB! •It is called Koch’s lymph or Tuberculin and is a glycerol extract of the bacterium •Is soon abandoned because it kills more people than it cures due to strong immune reaction •Tuberculin or modified prep. (PPD) is still used today as diagnostic tool for TB 1) Inject PPD (Purified Protein Derivate) 2) Wait two days 3) Measure diameter of skin erythema Diagnosis: Mantoux test Diagnosis: Mantoux test detects latent + active infections Problem: subjects vaccinated with BCG vaccine or infected with non­virulent mycobacteria may be test­positive (confirm via X­ray) After 120years still the most widely used diagnostic assay!! New Diagnostic Tool New Diagnostic Tool 1930s Diagnosis Diagnosis Chest X­Ray ­detects active infections In the 1880s, Dr. Edward Livingston Trudeau ushered in a new era in the history of TB in the USA Sanatorium: healthy air, good food and lots of rest Established the first lab in the US devoted to study Mtb TB­Public Health History TB­Public Health History TB­History Public Health The National Association for the Study and Prevention of Tuberculosis (NTA) was formed in 1904 to unify and expand the country's regional anti­ tuberculosis programs. Inspired by the identification of the tuberculosis bacteria in sputum, its mission included an aggressive campaign against public spitting. The amazing discovery that bacteria could survive in spit for an entire day even convinced many women to stop wearing their long, trailing dresses into town for fear they might pick up sputum and drag it into their homes. TB­History Public Health TB­History Public Health TB­Fundraisers TB­Fundraisers TB­Fundraisers TB­Fundraisers Glen Dale Hospital Glen Dale Hospital Prince George County 1934­1982 TB­Sanatorium ­by 1930s ~ 700 public and private sanatoriums in US ­public health officials had power to quarantine TB­patients against their will ­some public “sanatoriums” were more like prisons http://www.washingtonpost.com/wp­dyn/content/article/2006/12/06/AR2006120601206.html TOPIC: Public Health vs. Individual Freedoms TOPIC: TB and Public Health TB and Public Health Principles on the Limitation and Derogation of Provisions in the International Covenant on Civil and Political Rights holds: “Public health may be invoked as a ground for limiting certain rights in order to allow a state to take measures dealing witha serious threat to the health of the population or individual members of the population. These measures must be specifically aimed at preventing disease or injury or providing care for the sick and injured”. ­Principle applied in NYC outbreak of MDR­TB (1989­92) ­Andrew Speaker and other cases ­ Influenza outbreaks? The Vaccine (1921) The Vaccine (1921) Calmette and Guerin (Inst. Pasteur) passaged virulent M. bovis for 10 years to make it non­ virulent Bacillus Calmette Guerin (BCG) Used since 1920’s good efficiency to protect against pediatric TB Poor efficiency to protect adults from pulmonary TB The first drug: Streptomycin (1944) The first drug: Streptomycin (1944) Selman A. Waksman Nobel Lecture, December 12, 1952 The Lord hath created medicines out of the earth; and he that is wise will not abhor them. Ecclesiasticus, XXXVIII , 4 “The conquest of the Great White Plague, undreamt of less than 10 years ago, is now virtually within sight.” Why is Mtb­research important? Why is Mtb­research important? To develop more efficient drugs and vaccines against Mtb because…. 1891­Last effective diagnostic for latent TB 1921­ last vaccine for TB 1967­last new first line drug class for treatment of TB Leads to…. Inefficacy of current chemotherapy (6­9 months multi­drug treatment) Drug Resistant : MDR­TB & XDR­TB Inefficacy of BCG Vaccine (0% ­ 80%) efficacy in adults) Paucity of tools to treat/prevent TB Paucity of tools to treat/prevent TB EPIDEMIOLOGY EPIDEMIOLOGY GLOBAL BURDEN OF TB • • • 1/3 of the worlds population is latently infected with Mtb 8­10 million new cases of active disease each year ­ 15,000 TB/year cases in USA (50% immigrants) ­80% of cases in developing countries 2 million deaths each year= about one death every 15sec (98% in dev. Countries) WHO EPIDEMIOLOGY EPIDEMIOLOGY GLOBAL BURDEN OF TB • • • • Multi­drug resistant TB is present in >100 countries 5% of all new cases are MDR­TB XDR­TB is increasing (45 countries) HIV / TB co­infection (30­70% of HIV patients die of TB) WHO TB is increasing TB is increasing TB incidence rates TB incidence rates WHO 2002­2007 HIV prevalence in new TB cases HIV prevalence in new TB cases WHO 2002­2007 Any resistance among new cases Any resistance among new cases 1994­2008 WHO 2008 XDR­TB ( 45 countries) XDR­TB ( 45 countries) WHO 2008 Outbreak of XDR­TB in 2007 Outbreak of XDR­TB in 2007 53 XDR­Tb cases 52 died; median survival time 16 days!! 44 were HIV pos. Ethical dilemma: How to inhibit spread of TB? Forced quarantine? TB: Drug Resistance TB: Drug Resistance Current Drug Treatment (TB) Current Drug Treatment (TB) Current Drug Treatment (MDR­ TB) 18­24 month with 2nd line drugs 2 month with 4 first line drugs 4 month with rifampin and isoniazide alone With DOTS: 80­90% cure rate With DOTS: 50% cure rate Daily MDR­TB Drug Dose Daily MDR­TB Drug Dose Schluger et al. PLOS Medicine 2007 Multi drug resistant TB present in >100 countries and cases of XDR TB are increasing Legal and illegal immigration from countries with high incidences of TB Localized outbreak of MDR­TB in NYC cost about 1 billion dollar to contain New TB vaccine may make broad vaccination program cost effective even in developed countries. Tuberculosis: a poor men’s Tuberculosis: a poor men’s problem!? Yes, but… Aerosol Transmission Aerosol Transmission 10% active disease 90% control infection: Latent Tuberculosis! Mycobacterium tuberculosis Mycobacterium tuberculosis Mtb survives and replicates within macrophages Is able to persist in lungs of humans for decades Mtb has evolved to manipulate infected cells in many different ways Clinical Disease Clinical Disease Pulmonary tuberculosis ­slow onset of disease, weight loss, night sweats, cough ­sputum bloody or purulent (lung tissue destruction) ­increase weight loss, fever, “Consumption” Disseminated tuberculosis: ­rare, pediatric disease, can result in meningitis Classification Classification Family Genus Mycobacteriaceae Mycobacterium Species >85 including: M. tuberculosis M. leprae M. kansasii M. avium M. ulcerans Leprosy in the movies…. Leprosy in the movies…. Leprosy= Hansen’s disease Leprosy= Hansen’s disease Dr. G. Hansen discovered M. leprae Mycobacterium leprae Mycobacterium leprae Member of Mtb complex Cannot be cultured in vitro!!! Armadillo is only known host beside human causes a chronic intracellular disease in humans “Hansen’s disease” / Leprosy ­Initial subclinical replication of bacteria in macrophages, later spread to peripheral nerves and subsequent sensory impairment Washington Post , May 27th 2008 M. leprae skin rash M. leprae skin rash World distribution of Hansen’s World distribution of Hansen’s disease Epidemiology Epidemiology Endemic in 10 countries (India, Brazil, Nepal, Myanmar) ~700,000 new cases in 2002 world wide, ~ 250,000 reported in 2008 Spread by person­to­person contact, exact route unknown, not very infectious Strong genetic component to disease (only 5% of population is susceptible) Armadillo zoonotic reservoir? Hansen’s disease in USA Hansen’s disease in USA 166 new cases were reported in the U.S. in 2005 Most (100 or 60%) of these new cases were reported in California Louisiana Massachusetts New York Texas US Marine Hospital #66 US Marine Hospital #66 Carville Leprosy Sanatorium Louisiana Leper Home (1894) Triumph at Carville: A Tale of Leprosy in America (PBS) Laboratory diagnosis M. leprae M. leprae Acid­fast bacilli seen in smears of lesions Lepromin Test (similar to Mantoux test) but detects only tuberculoid leprosy PCR on tissue samples Treatment and Prevention M. leprae M. leprae MDT: Rifampin, Dapsone (antimetabolite; folic acid biosynthesis) and Clofazimine ( inhibits DNA replication) for 6 ­12 month BCG for immunization Classification Classification Family Genus Mycobacteriaceae Mycobacterium Species >85 including: M. tuberculosis M. leprae M. kansasii M. avium M. ulcerans Non tuberculous mycobacteria Non tuberculous mycobacteria (NTM) M.avium complex (MAC) M.avium/M. intracellulare M.paratuberculosis M.Kansasii Epidemiology Epidemiology Environmental sources, including natural waters Infection caused by inhalation or ingestion Major pathogen in immunocompromised subjects (Chemotherapy/ AIDS!!) ­30­50% of AIDS patients had MAC infections at time of death ­90% of mycobacterial infections in AIDS patients are either Mtb or MAC (Mtb more common in high endemic regions) Mycobacterium in showerheads Mycobacterium in showerheads PNAS 2009 Mycobacterium in showerheads Mycobacterium in showerheads PNAS 2009 Clinical Manifestations Clinical Manifestations M.avium/intracellulare and M.kansasii ­pulmonary infections in patients with pre­existing lung condition ­disseminating infections in immunodeficient patients (AIDS)(very high bacterial burden in tissues and blood) M.paratuberculosis ­causes inflammatory bowl disease in sheep/cattle (John’s Disease) ­suspected to cause similar disease in humans (Crohn’s disease ­extremely fastidious growth requirements and slow growth Diagnosis Diagnosis Same diagnostic tests as for Mtb Differential diagnosis Mtb/NTM and especially among NTMs is challenging (colony morphology/pigmentation) Use of specific nucleotide probes for hybridization and/or characterization via 16S rRNA amplification Diagnosis Diagnosis M.tuberculosis; Rough M.kansasii; Smooth, pigmented Treatment: NTM Treatment: NTM MAC ­drug­resistance! ­ Clarithromycin / Ethambutol/ Rifabutin (same mechanism as Rifampicin/Rifampin) 9month ­but success of treatment and tolerance of patient to treatment needs to be monitored M.kansasii ­INH/Rifampin/Ethambutol 9month ...
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This note was uploaded on 01/24/2011 for the course BSCI 424 taught by Professor Staff during the Fall '08 term at Maryland.

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