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Mycobacterium

Mycobacterium. aerobic, non- endospore -forming rods myco = “fungus-like”. Mycobacterium. distinctive cell wall: waxy, water-resistant layer resistant to stress: e.g. drying few antimicrobial drugs can enter the cell nutrients enter slowly = slow growth rate. Mycobacterium avium.

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Mycobacterium

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  1. Mycobacterium aerobic, non-endospore-forming rods myco = “fungus-like”

  2. Mycobacterium • distinctive cell wall: waxy, water-resistant layer • resistant to stress: e.g. drying • few antimicrobial drugs can enter the cell • nutrients enter slowly = slow growth rate

  3. Mycobacterium avium Readings question #1: What is MAC? Who is susceptible to this infection? What are the common symptoms? What organism is responsible? Where is it found? • What are its portals of entry?

  4. MAC • common bacteria • weakened immune system: “opportunistic” • blood infections, hepatitis, pneumonia • combination of antibiotics: • azithromycin (Zithromax) • clarithromycin (Biaxin) • 3 other drugs

  5. Mycobacterium tuberculosis • slender rod, obligate anaerobe • rods grow slowly and tend to grow in clumps • resistant to conventional staining

  6. Mode of Transmission • fine particles: 1-3 bacilli reach the lungs Readings question #2: Explain the process of M. tuberculosis attacking macrophages. When does the tubercle form? What happens when the macrophages die? Describe the process of liquefaction and its end result. What is cavitation?

  7. Ghon Complexes dormant disease: lesions calcify

  8. Miliary Tuberculosis • cardiovascular and lymphatic systems • defenses overwhelmed • weight loss, coughing (blood), general malaise

  9. Treatment • streptomycin • multiple drugs • chemotherapy for months • tubercle bacillus grows slowly • hidden by macrophages or other locations difficult to reach with antibiotics

  10. Diagnosis • Tuberculin Skin Test: purified protein derivitive • Mantoux Test: most accurate tuberculin test • Induration induration

  11. Tuberculosis Vaccines • BCG: live culture of Mycobacterium bovis • avirulent culture • available since the 1920’s • certain children at high risk • positive reaction to tuberculin skin tests • not effective for adolescents and adults

  12. Spirochetes “a genus of bacteria having a flexible cell wall but no flagella in the traditional sense. Movement occurs by contractions (undulating) of long filaments (endoflagella) that run the length of the cell.”

  13. Spirochetes • human oral cavity • Among first organisms described by van Leewenhoek in the 1600’s that he found in saliva and tooth scrapings. • 3 common genera: Borrelia Leptospira Treponema

  14. Leptospira interrogans • leptospirosis • domestic or wild • exceedingly fine spiral • obligate aerobe • animals shed bacteria in their urine • humans infected by contact with urine-contaminated water or soil, or animal tissue

  15. Leptospirosis

  16. Portal of Entry • minor abrasions • when ingested: mucosa of upper digestive system • incubation period of 1-2 weeks • acute symptoms subside • second episode of fever: Weil’s Disease • kidney failure is the most common COD

  17. Borrelia burgdorferi • tick-borne disease: seasonal occurrence lack of contagiousness unusual skin rash • bacterial pathogen: penicillin • 1983: spirochete identified as the cause • Lyme Disease most prevalent on Atlantic coast

  18. Tick Feeding Cycle • first and second feedings: larva and nymph • third feeding: adult

  19. Deer Tick

  20. Erythema Migrans • 75% of all cases • 15 cm and resembles “bull’s eye”

  21. Second Phase • heart: pacemaker • chronic neurological symptoms: facial paralysis, meningitis, encephalitis • arthritic symptoms • diagnosis: symptoms, geographic area • no laboratory test for Lyme’s disease • several antibiotics are effective

  22. Removing a Tick

  23. Treponema pallidum • gram-negative spirochete, thin and tightly coiled • Stains poorly • Greek: “twisted thread” “pale”

  24. Primary Stage of Syphilis • Readings question #3: What is the most notable sign for the primary stage of syphilis?

  25. Secondary Stage of Syphilis • Readings question #4: List 3 signs and symptoms that an individual may experience during the secondary stage of syphilis.

  26. Secondary Stage of Spyhilis mucous patches anal warts

  27. Tertiary Stage of Syphilis Readings question #5: During the tertiary stage of syphilis, what distinguishing sign occurs? • lesions may ulcerate and cause extensive tissue damage

  28. Congenital Syphilis • transmitted across the placenta • damage to mental development and other neurological symptoms • pregnancy during the primary or secondary stage is likely to produce a still birth

  29. Treatment for Syphlis • benzathine penicillin: effective in the body for 2 weeks • doxycycline for penicillin-sensitive people • Antibiotic therapy must be administered for a longer period of time due to the slow-growing spirochete.

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