Lecture 10: Neisseria

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Lecture 10: Neisseria
2010-10-17 18:49:38
gonnorhea microbiology meningitis neisseria

lecture 10
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  1. Name the two human pathogens of neisseria
    N. gonnorhoeae and N. meningitidis
  2. What makes Neisseria an unusual specis of Gm- cocci?
    It is the only gram negative cocci that frequently causes disease
  3. Describe the physiology and structural characteristics of Neisseria:
    • aerobic
    • non-motile
    • does not form endospores
    • obligate human pathogen
    • oxidase positive
    • produces catalase
    • oxidizes carbs
    • Meningitidis and gonnorhoeae require iron
    • N. Meningitidis has variable growth on nutrient agar while N. gonnorhoeae is fastidious
  4. Describe the physical characteristics of Neisseria bacteria
    • Have a thin layer between the cell membrane and the outer membrane
    • Capsule is a major virulence factor
    • Its pili extends from the cellular membrane to the outer membrane
  5. Name the functions and characteristics of the pili in Neisseria
    • Functions: mediates attachment to host cells, mediates transfer of genetic material and is important for pathogenesis
    • Characteristics: has phase and antigenic variation
  6. Membrane proteins that mediate binding to epithelial and phagocytic cells. Are also important for cell to cell signaling
    • Opa proteins ( opacity proteins)
    • expression is associated with clinical disease
  7. this protein is responsible for most symptoms of gonnorhea. Is composed of Lipid A and has a core polysaccharide but lacks O-antigen
    LOS (lipooligosaccharide)
  8. ____ ____ may enhance endotoxin toxicity and protect the bacteria by binding antibodies
    Outermembrane blebs
  9. Stimulate antibodies that block antibodies against LOS
    Rmp proteins (reduction modifiable proteins)
  10. This protein cleaves IgA1, creates immunologically inactive Fc and Fab fragements and may inactivate IgA found at mucosal surface
    IgA protease
  11. How does N. gonnorhea encounter and enter human hosts?
    • Men and women often carry gonococci asymptomatically
    • Are transmitted through direct contact and enter through the vagina or urethral mucosa
    • They seek columnar epithelial cells of distal urethra or cervix and then attach to the surface of cells and multiply
  12. Describe the clinical characteristics of pelvic inflammatory disease
    • Caused when N. gonnorhea ascends into the upper reproductive tract and infects and inflames the uterus and fallopian tubes
    • can result in scarring of the upper reproductive tract & adjacent organ, as well as chronic pelvic pain
    • tubal scaring can lead to ectopic pregnancy or infertility
  13. Describe the clinical characteristics and symptoms of gonococcemia
    • disseminated infections with septicemia and infection of the skin and joints
    • occurs in 1-3% of infected women due to untreated asymptomatic infections
    • symptoms: fever, pain in joints, arthritis in wrists knees and ankles, pustular rash.
  14. How is Neissera Meningiditis spread?
    • through respiratory droplets among people in prolonged close contact
    • epidemics are common in developing countries
    • Humans are the only natural carriers
    • disease is common during dry, cold months
  15. Clinical Disease of Neisseria Meningitidis: Meningitis
    • begins abruptly with headache meningeal signs and fever
    • very young children have nonspecific signs (fever & vomiting)
    • Untreated: 100% mortality rate Treated: 10% with antibiotic therapy
    • Hearing deficits and arthritis can result
  16. Clinical Disease of Neisseria Meningitidis: Meningococcemia
    • Septicemia (presence of bacteria in the blood)
    • Thrombosis (blood clot) of small blood vessels and multiorgan involvement
    • Small, skin lesions on trunk and lower extremities, can form larger hemorrhagic lesions
    • Can lead to disseminated intravascular coagulation
    • Can persist for days or weeks with only low-grade fever, arthritis and skin lesions
  17. Disseminated intravascular coagulation involves
    •Formation of blood clots

    •Abnormal bleeding from skin

    •Can disrupt normal blood flow to organs

    •Can occur with shock and destruction of adrenal glands