bacterial diseases

bacterial diseases

1. acute

   • short term
   • influenza, ebola, gastroenteritis
   • particular set of (sometimes severe) symptomes

2. chronic

   • long term/entire life :(
   • HIV, Leprosy
   • slow/incomplete recovery

3. portal of entry: site at which microbes enter our body

   • urogenital tract
     • Escherichia coli
       • cystitis: an infection of the bladder
         • caused by GI tract bacteria infecting the UT
   • respiratory
     • Streptococcus pneumoniae
       • common commensal
       • pneumonia
   • gastrointestinal
     • Vibrio cholerae
       • watery diarrhea (few days)/death from extreme loss of water
   • skin breaks
     • Clostridium tetani
       • vaccines exist
       • bacteria found in soil, dust, etc.
       • tetanus (stiffness and spasms)

4. transmission: the spreading of microbes

   • person-to-person
     • touch
       • Staphylococcus aureus
         • live on skin
         • nosocomial (originating in a hospital)
         • causes scalded skin syndrome, impetigo, stye, etc.
     • air
       • Mycobacterium leprae
         • Leprosy
           • symptomless for 5-20 yrs
           • respiratory
           • causes skin lesion and sensory loss
     • saliva
       • Porphyromonas gingivalis
         • Periodontitis
           • causes gum to retreat from the teeth=tooth loss
           • inflammation of the gum
           • extremely common
     • contaminated blood/bodily fluids
       • Treponema pallidum
         • Syphilis
           • sometimes asymptomatic
           • ulcers/skin growths/rash
           • tertiary~15 yrs
   • food
     • Salmonella enterica
       • gastroenteritis
         • severe cases lead to hospitalization
       • cattle and poultry
   • water
     • V.cholerae
       • common in marine and freshwater
       • cholera
         • produces cholera toxin which causes water transfer from blood into intestine
   • fomites
     • C.tetani
       • tetanus
         • rigidity and convulsions of the skeletal muscles
       • ubiquitous
     • spores often infect wounds (e.g.rusty nail)
   • vectors
     • Yersinia pestis
       • infected rat fleas that bite humans
       • swollen lymph, nodes, necrosis

5. virulence: the ability of an organism to infect the host and cause disease

   • virulence factors: molecules that assist the bacterium in colonizing the host at cellular level
     • adhesins
       • adherence: the ability to adhere to target cell/location
       • anchor bacteria
       • tooth enamel
       • surface molecules on a pathogen which bind specifically to complementary surface receptors on cells of certain host tissues
     • capsules
       • surrounds and protects the bacterium
       • consists a slimy layer of polysaccharide
       • prevent phagocytosis, helps to adhere, antibiotic protection
     • endotoxins
       • part of the outer membrane of the cell wall of gram-ve bacteria
       • lipopolysaccharide
       • secreted by bacteria
       • Lipid A; most toxic region=fever, diarrhoea, toxic shock
     • exotoxins
       • a toxin released by a living bacterial cell into its surrounding
       • a toxin released by a living bacterial cell into its surroundings
       • highly specific targets
       • destroy cells or inhibit metabolism
       • tetanospasmin
         • produced by C.tetani
         • acts upon the CNS