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Name the two human pathogens of neisseria
N. gonnorhoeae and N. meningitidis
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What makes Neisseria an unusual specis of Gm- cocci?
It is the only gram negative cocci that frequently causes disease
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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
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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
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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
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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
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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)
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____ ____ may enhance endotoxin toxicity and protect the bacteria by binding antibodies
Outermembrane blebs
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Stimulate antibodies that block antibodies against LOS
Rmp proteins (reduction modifiable proteins)
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This protein cleaves IgA1, creates immunologically inactive Fc and Fab fragements and may inactivate IgA found at mucosal surface
IgA protease
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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
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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 tubescan 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
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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.
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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
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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
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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
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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
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