Microbiology

Microbiology

1. ENTER

   • Entry portals
     • Examples
       • Skin
       • Nares, oropharynx, ear
       • Vagina, rectum
       • Conjunctiva
       • Umbilical cord
     • Access determinants
       • Host behaviors
         • Eating and drinking
           • Cholera
         • Contact with unwashed hands/mucosa
           • Influenza
         • Sexual practices
           • HIV, Siphilis
         • Scratching bites
           • Chagas
       • Motility
       • Sensing cues
         • Carbon Dioxide
           • Mosquitoes
           • Ticks
         • Temperature, vibration, shadows, odors

2. COLONIZE

   • Motility
     • Bacteria
       • Flagellar motility and chemotaxis
     • Viruses
       • Brownian motion
       • Flow
     • Fungi
       • Spore dispersal by random motion
       • Hyphal growth
     • Parasites
       • Protozoa
         • Cilia, amoeboid movement, gliding motion
       • Helminths and arthropotds
         • Muscle use
   • Avoiding mucosal clearance
     • Barriers
       • Tight junctions
       • Mucus barrier
       • Movement of secretions (e.g. cilia, peristalsis)
       • Secretion of bactericidal compounds
         • Acid (stomach)
         • Bile detergents (intestine)
         • IgA
         • Antimicrobial peptides and enzymes
     • Avoidance mechanisms
       • Changes in LPS to withstand detergents
       • Changes in cell wall to resist lysozyme, IgA proteases
   • Attachment
     • pili in uropathogenic E.coli
     • Cilia-binding adhesins in whooping cough
     • determines
       • Viral Tropism
         • Influenza and binding to species-specific sialic acid residues
     • Biofilms
       • catheter-related bloodstream infections
   • Crossing epithelial barrier
     • through
       • Skin defects
         • catheters, burns, wounds
       • Anatomic defects
         • tracheoesophageal fistula
       • Mucosal defects
         • mucositis in digestive tract as a result of chemotherapy
     • target cells
       • Dendritic cells in HIV
       • M cells (peyer's patches) in Salmonella
   • Invading cells
     • mechanisms
       • phagocytosis
         • macrophage TB
       • endocytosis
         • viral infections
       • active invasion
         • Toxoplasmosis

3. PERSIST

   • Avoiding detection & clearance
     • mechanisms
       • Intracellular invasion
       • capsules to avoid phagocytosis
       • antigenic variation
       • Immune modulation
         • production of mimics of immune proteins such as cytokines and cytokine receptors
       • residence in immune privileged sites
         • e.g. Varicella zoster virus residence in dorsal root ganglion
   • Stealing nutrients
     • in response to
       • sequestering of Fe by host
         • Lactoferrin
         • Transferrin
     • mechanisms
       • Fe binding siderophores
       • Lactoferrin receptor
       • Transferrin receptor

4. EXIT

   • mechanism
     • Vesicle rupture
       • Herpes simplex
     • Scaling
       • Dermatophytes
     • Eggs
       • Parasites
     • Vectors