Download Outline made by: Caleb Richards Checked by: Roxy Godiwalla

Outline made by: Caleb Richards
Checked by: Roxy Godiwalla
NOTE: This outline was done pre-lecture due to time constraints.
For the Anaerobic and Atypical bacteria that follow, describe disease associations/clinical manifestations
and define aspects of epidemiology (mode of transmission, risk groups) and pathogenesis (sites of
infection, mechanisms of disease production, host interaction and response).
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Gram-positive bacillus include anaerobic clostridium and acid-fast mycobacterium
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Chlamlydia and treponema (spirochete) have weak or no gram stain
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Anaerobic Bacteria:
o
o
Clostridium tetani
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Motile, spore-forming, saphrophyte of soil/intestine
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Transmission: direct contact w/ spores (open wounds/rust nails)
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Tetanus symptoms
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Early: severe painful spasms, rigidity of voluntary muscles,
lockjaw.
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Progressive: rigidity, violent spasms of trunk, limb muscles
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Spasms of pharyngeal muscles  difficulty swallowing
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Respiratory spasms  death
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Pathogenesis: tetanospasmin binds to presynaptic membranes in motor
neurons; toxin degrades synaptobrevin (needed to dock
neurotransmitter vesicle on presynaptic membrane)  continuous
muscle contraction
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Briefly mentioned: closridium difficile (spore-forming, endogenous
infections, this is normal flora for 5% of population. Disease caused by
overgrowth from antibiotic use. Causes pseudomembrane colitis.
Clostridium botulinum
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Motile, spore forming, saphrophite of soil/intestine
–
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Transmission: ingesting toxin-contaminated foods (often canned) or
thru direct contact (spores in wound). Spores on food do not change
color/taste/odor.
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Foodborne botulism symptoms: weakness, nausea/vomiting, blurred
vision, inability to swallow, difficulty speaking, musculoskeletal
weakness, respiratory paralysis
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Pathogenesis: botulinum toxin is absorbed from gut, binds to
presynaptic receptors of motor neurons. Acetylcholine release is
inhibited  muscle contraction and paralysis
Atypical Bacteria:
o
o
Treponema pallidum
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Gram-negative spirilla that can’t be grown in vitro
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Transmission: STD, congenital (in utero)
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Not much antigen on the bacteria surface  limited immune host
response initially
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Outer membrane proteins have minimal expression, adhere to nearly all
body tissues, bind Ig and complement as “disguise”, and are coated with
fibrin so they can’t be phagocytosed.
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Hyaluronidase
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Syphilis symptoms:
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Primary: painless, ulcerative lesion
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Secondary: rash on trunk/hands/feet, flu-like illness
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Tertiary: multiple organs get inflammatory lesions (aka
gummas), arthritis, meningitis w/ hallucinations and psychosis)
Chlamydia trachomatis
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No gram stain
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Uses host cell ATP  energy parasite
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Transmission: directed contact w/ contaminated secretions (STD)
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EB, or elementary bodies, go into conjunctiva and urogenital tracts to
infect epithelial cells w/ endocytosis
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Endosome does not fuse with lysosome, but becomes inclusion body for
transformation of the EBs into RB (reticulate body)
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Trachoma symptoms:
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Follicular conjunctivitis: repeat infections, inflammation of
conjunctiva, person-person transmission
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Leading cause of blindness in world
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Corneal scarring
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Urogenital infection symptoms:
•
o
Eyelid turns inward, eyelashes become abrasive to
cornea (ouch!)  corneal ulcerations
Dysuria, thin urethral discharge, possible infertility
Mycobacterium tuberculosis
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Acid-fast (weak gram stain)
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Cell wall resists antimicrobials and is protected from drying by lipids in
cell wall
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3 species:
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M. tuberculosis (causes tuberculosis): 1/3 world infected
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M. leprae (causes leprosy)
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M. intracellulare (causes pneumonia in immunosuppressed)
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Transmission: contaminated respiratory droplets
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Tuberculosis symptoms
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Primary TB (aka clinical TB): 90% asymptomatic; fever, night
sweat, anorexia, weakness, productive bloody cough
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Secondary TB: immunosuppression triggers reactivation,
granulomas dissolve, clinical TB manifests
Pathogenesis: intracellular persistence – evades lysosomal fusion with
phagosome, catabolizes NO/ROS, activates macrophages to make IL-1,
TNF, IL-12 (formulation of granuloma) with reactivation possible from
contained bacteria.