Card Set Information

2011-11-25 20:39:00

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  1. General features
    • Gram negative cocci with kidney bean appearance
    • Oxidase positive
    • Ag variations: Pili, outer membrance proteins (OMPs)
    • OMPs contain short LPS called LOS
    • Lipid A and core oligosaccharide same
    • Differences: Meningococcus has polysaccharide capsule (can cause toxic shock), Gonococcus grows more slowly than meningococcus
  2. Meningitidis: organism
    • NP flora
    • Multiple serogroups; A, B, C, W-135, and Y are most important
    • Two classes of Pili, and multiple OMPs
  3. Meningitidis: Epi
    • NP flora of 10%
    • Inhalation of aerosolized droplets, close and prolonged contact
    • Higher attack rates in families
    • Disease in those that lack group specific Ab
    • Most cases in kids < 6
    • Group A - more severe
  4. Meningitidis: pathogenesis
    • Attachment/invasion: pili for initial attachment to nonciliated NP epi; pass through to submucosa via vesicles
    • Resisting Phagocytosis: Capsule prevents complement activated phagocytosis, LPS/LOS structure similar to sphongolipids -> ID as self, binds sialic acid to LOS side chains, which binds factor H
    • Injury: disseminated endotoxic injury via endotoxin blebs, hyperproduction of toxins
    • Immunity: group specific polysaccharide Ab, T-cell independent immune response in which IgG2 is predominant; Group B don't produce Ab
  5. Meningitidis: Clinical
    • Disease: Acute purulent meningitis with scattered skin petechiae; Disseminated intravascular coagulation syndrome (part of endotoxin shock); many progress to fulminant DIC and hsock with bilateral hemorrhage destruction of renal glands; some patients with low grade fever, arthritis
    • Tx: Penicillin still great
  6. Meningitidis: Prevention
    • Refampin for prophylaxis (pencillin has poor tissue penetration in NP)
    • quadrivalent vaccine
  7. Gonorrhoeae: Organism
    • Chocolate agar, CO2 supplementation
    • Outer membrane: LPS, LOS, phospholipids
    • OMPs: Porin A + B, Opa (adherence protein)
  8. Gonorrhoeae: Ag Variation
    • Pili: recombinational exchange between multiple pilin genes; results in silent pili or pili with changed antigenicity
    • Opas: controlled via pentameric sequence, changed of which are due to replicative slippage; each opa gene has on/off switch which can be activated at random for for each cell
  9. Gonorrhoeae: Epi
    • No effective means of control
    • Hard to detect asymptomatic cases
    • Major reservoir is asymptomatic patient
    • 95% of men show symptoms
    • 50% of women don't
  10. Gonorrhoeae: Pathogenesis
    • Attachment/invasion: Adherance ligands (pili) attach to nonciliated epi cells; microcolinies move across cells; Opas help in between cell adhesion and in cervical/urethral adhesion; microvilli pull bacteria into cell via parasite directed endocytosis; exit into submucosa
    • Survival: Scavenge iron; LOS sialyation binds factor H; pili/Opas prevent phagocytosis
    • Spread/dissemination: Localized via sticky clusters held together by Opas; injury to fallopian tub via LPS/LOS and cell wall fragments; can reach the blood stream
    • Immunity: Ag variations often degreats Abs
  11. Gonorrhoeae: clinical
    • Genital: men - 2-7 days post infection, purulent discharge, dysuria, local extension to epididymitis or prostatitis; endocervis primary site in women, increase vaginal discharge, urinary frequency, dysuria, abd pain, menstrual abnormalities
    • Other local infections: Rectal gonorrhea, pharyngeal gonorrhea
    • PID: 10-20% of women with gonorrhea; fever, lower abd pain,a dnexel tenderness, leukocytosis; can cause infertility, ectopic pregnancy
    • DGI: Fever, polyarthralgia, petechial, maculopapular rash
  12. Gonorrhoeae: diagnosis
    • Smear: Genital site smear with bean shapped gram negative cocci in neutrophil; 95% specific/sensitive in men, 50-70% in women
    • Culture: Men - urethral exudate; women - cervical/anal swabs
    • Must specify gonorrhea
    • Direct detection via nucleic amplification
  13. Gonorrhoeae: Treatment
    • Third generation cephalosporins - ceftriaxone
    • Prevention: safe sex