Module 12: Pathogens

• E. coli pathogen properties:

  • non-spore forming
  • short rod to ovoid shape
• E. coli metabolism properties:

  • optimal growth at 37 degrees
  • facultative anaerobe
  • can ferment lactose to acid
• enterohemorrhagic E. coli disease course:

  • low microbial dose
  • 3-4 day incubation
  • ends in 4-10 days
• what are the symptoms of enterohemorrhhagic E. coli?

  • abdominal pain
  • short fever
  • vomiting
  • diarrhea/bloody diarrhea
• what is a possible complication of enterohemmorhagic e coli?

  hemolytic uremic syndrome
• what is the transmission route of enterohemorrhagic e. coli?

  fecal to oral
• what is the pathogensis of e. coli?

  • attachment through fimbriae
  • inject effectors into small intestine by type 3 secretion system
  • form pedestals where E. coli binds tightly to receptor
• e. coli shiga toxin properties:

  • AB toxin
  • B subunit binds GB3 in intestine and kidneys
  • A subunit cleaves rRNA and kills cells
• enterohemmeraghic e. coli diagnosis?

  culture stool sample, antigen test for shiga toxin
• enterohemmoragic e coli treatment?

  supportive care
• what is chlamydia pathogen?

  chlamydia trachomatis
• what are the properties of chlamydia trachomatis?

  • obligate intracellular parasite of eukaryoes
  • no cell wall peptidoglycan
  • extremely temperature sensitive
• what is a possible complication of chlamydia?

  pelvic inflammatory disease
• disease course of chlamydia:

  1. elementary body: small transmissible form
  2. differentiates into reticulate body: large replicative form
• transmission route of chlamydia?

  sexually transmitted
• chlamydia trachomatis pathogensis?

  • infect epithelial cells of cervix
  • bacteria enter endometrium and fallopian tubes
  • inflammatory response by neutrophils then adaptive response in submucoa
  • causes scarring and occlusion
• diagnosis of chlamydia?

  vaginal swab and culture
• treatment of chlamydia?

  doxycycline or azithromycine
• what pathogen causes skin infections?

  staphylococcus aureus
• what are the properties of s. aureus?

  • gram positive cocci
  • catalase and coagulase positive
• what is the s. aureus skin infection disease course?

  pus-forming infection

  • elevated temperature
  • swelling
  • abscess formation
• how is s. aureus causing skin infections transmitted?

  skin-to-skin or touching contaminated surfaces
• pathogensis of s. aureus:

  • surface proteins: promote colonization
  • invasins: promote bacterial spread
  • surface factors: inhibit phagocytosis
  • substances: enhance survival
  • immunological diseases
  • membrane damaging toxins: lyse eukaryotic cell membranes
• how is s. aureus causing skin infections diagnosed?

  culture
• how is s. aureus causing skin infections treated?

  antibiotics
• what pathogen causes lyme disease?

  borrelia burgdorferi
• what are the pathogen properties of borrelia burgdorferi?

  • corkscrew spirochete
  • linear chromosome
  • metabolically dependent on host
• what is the disease course of borrelia burgdorferi?

  stage 1:

  • 7-14 days after transmission
  • bullseye rash
  • fever and flu like symptoms

  stage 2: systemic infection after initial rash

  stage 3: further penetration and complications
• how is borrelia burgdorferi spread?

  vector: tick from genus ixodes

  • nymphs and larvae feed on mammals
  • adults prefer deer
• what is borrelia burgdorferi pathogenesis?

  • unique mobility, drills into tissues
  • adhesins bind to and invade tissues
  • degrade host and extracellular matrices
  • antigenic variation
• how is lyme disease diagnosed?

  blood test, confirm with western blot
• how is lyme disease treated?

  doxycycline
• what pathogen causes chronic wasting disease?

  prions
• what are the pathogenic properties of prions?

  • infectious protein folds differently
  • causes refolding in normal protein
• what animals are susceptible to cwd?

  mule and white-tailed deer, elk and moose
• what are the symptoms of cwd?

  • weight loss
  • isolation from herd
  • loss of coordination
  • hypersalivation
  • frequent urination and excessive thirs
• how are prions trnasmitted?

  oral ingestion of excrement and dead carcasses
• what is the pathogensis of prions?

  protein-protein interactions

  • abnormal protein binds to normal protein and changes conformation
  • accumulate in lysosomes and cause cell death
  • moves between cells using transport systems
• what is the treatment for chronic wasting disease?

  no treatment
• what pathogen causes antibiotic associated diarrhea and colitis?

  clostridium difficile