326MbaSTD - Gonorrhea a Bacterial STD caused by Neisseria...

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Unformatted text preview: Gonorrhea- a Bacterial STD caused by Neisseria gonorrhoeae Neisseria gonorrhoeae • The gonococcus (GC) is never part of normal microbiota • Obligate human pathogen; not in the environment • No conventional animal model Encounter • Reservoir- many asymptomatic humans (many women with GC cervicitis are asymptomatic!) • Tropism for columnar epithelial cells of cervical os and distal urethra • Pili and surface proteins – attachment to these epithelial cells • Pilus Ag very variable because of antigenic variation- mutations and rearrangements in pilin genes- great diversity; makes them ineffective as vaccine candidates • PMN's engulf GC, and many survive! Multiplication and spread • Multiply rapidly in the epithelial cells, and shed in large numbers in genital secretions • May actually be transported by attaching to sperm • IgA protease- cleaves IgA; removes Fc end of molecules bound to GC- and thwarts effective opsonization • the IgA protease also may interfere with Ab mediated cytolysis • No exotoxins! • Very toxic endotoxin (LPS) important • Host inflammatory mediators cause many symptoms Fallopian tube organ culture model for gonorrhea: • GC attach to non-ciliated cells • The GC are internalized by non-ciliated cell microvilli by parasite directed endocytosis • Ciliated cells cease cilial motility and die- gonococcal LPS and/or peptidoglycan fragments effect this action • Vacuoles containing GC coalesce to form larger vacuoles where the protected GC multiply • Vacuoles fuse with basement membrane of cell and the vacuoles discharge (exocytose) the GC • Local inflammation or disseminated disease can occur DGI- a “sequela” seen in both men and women • Those strains that cause DGI often have altered LPS core- sialic acid added which is found on erythrocytes and therefore not immunogenic (seen as self!) • Pustular skin lesions (maculopapular) • Inflammation of tendons and joints (tenosynovitis)- subcellular fragments can cause this inflammation • Septic (suppurative) arthritis PID- a “sequela” seen only in women-ascends from cervix • Sometimes the first obvious symptom is pelvic pain •...
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This note was uploaded on 05/15/2010 for the course BIO 326M taught by Professor Field during the Spring '08 term at University of Texas.

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326MbaSTD - Gonorrhea a Bacterial STD caused by Neisseria...

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