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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 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? MAC • • • • common bacteria weakened immune system: “opportunistic” blood infections, hepatitis, pneumonia combination of antibiotics: – azithromycin (Zithromax) – clarithromycin (Biaxin) – 3 other drugs Mycobacterium tuberculosis • slender rod, obligate anaerobe • rods grow slowly and tend to grow in clumps • resistant to conventional staining 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? Ghon Complexes dormant disease: lesions calcify Miliary Tuberculosis • cardiovascular and lymphatic systems • defenses overwhelmed • weight loss, coughing (blood), general malaise Treatment • • • • • streptomycin multiple drugs chemotherapy for months tubercle bacillus grows slowly hidden by macrophages or other locations difficult to reach with antibiotics Diagnosis • Tuberculin Skin Test: purified protein derivitive • Mantoux Test: most accurate tuberculin test • Induration induration 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 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.” 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 Leptospira interrogans • • • • • • leptospirosis domestic or wild exceedingly fine spiral obligate aerobe animals shed bacteria in their urine humans infected by contact with urinecontaminated water or soil, or animal tissue Leptospirosis 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 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 Tick Feeding Cycle • first and second feedings: larva and nymph • third feeding: adult Deer Tick Erythema Migrans • 75% of all cases • 15 cm and resembles “bull’s eye” 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 Removing a Tick Treponema pallidum • gram-negative spirochete, thin and tightly coiled • Stains poorly • Greek: “twisted thread” “pale” Primary Stage of Syphilis • Readings question #3: What is the most notable sign for the primary stage of syphilis? Secondary Stage of Syphilis • Readings question #4: List 3 signs and symptoms that an individual may experience during the secondary stage of syphilis. Secondary Stage of Spyhilis mucous patches anal warts 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 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