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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. - PowerPoint PPT Presentation
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Mycobacterium
aerobic, non-endospore-forming rodsmyco = “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. tuberculosisattacking macrophages. When does the tubercleform? What happens when the macrophages die?Describe the process of liquefaction and its endresult. 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 urine-
contaminated 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