N.meningitidis Flashcards
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N.meningitidis
epidemic cerebrospinal meningitis. exists as normal flora in nasopharynx. infects only humans because it can not get iron from any other species-transferrin and lactofferrin.
morphology
non-motile with a polysaccharide capsule.
virulence factors
capsule-resists phagocytosis and promotes attachment. Adhesive pili-promotes attachment to human epithelium and slows phagocytosis. IgA protease-lyses secretory IgA. lipooligosacharide(endotoxin)-released from cell wall when the microbe lyses.Responsible for septic shock and hemorrhage due to destruction of red blood cells.
pathogenesis
Acquired through close contact with secretions or droplets. The meningococci enters through the nasopharynx amd attaches to the epithelium by pili leading to asymotomatic colonization.The bacteria is engulfed by epithelial cells of the mucosa and penetrate inti nearby blood vessels causing damage aling the way.Crosses the BBB and permeates the meninges causing fever,sore throat,headache. serious complications are associated with meningococcemia . The pathogen produces endotoxin into the generalized circulation amd stimulates specific white blood cells. Damage to vessles by cytokines leads to vascular collapse,hemorrhage and crops of lesions called PETECHIAE on the trunk and appendages. Meningococcemia can be a fulminant disease with a high mortlity rate.Has a suden onset,fever chills and ecchymoses,shock and coma.
clinical diagnosis
microscopy and culturing techniques. culturing on the chocolate agar plate. oxidase test of Neisseria shows a positive reaction. slide agglutination test is used to determine the serotype. zPCR test can detect gonoccocal DNA directly from a urine sample.
