CLS03 - Gram negative cocci

  1. What are the general characteristics of Neisseria spp?
    • Gram negative
    • Diplococcus¬†
    • coffee bean shape
    • Aerobic, capnophilic (require CO2)
    • Non-motile
    • catalase positive
    • oxidase positive
  2. What Neisseria are commensal w/ location? Pathogenic?
    • Commensal: N. lactamica - nasopharynx of children (often mistaken for N. meningitids)
    • N. sicca - respiratory tract adults
    • N. elongata - upper respiratory tract
    • Pathogenic: N. gonorrhoeae
    • N. meningitides
    • Moraxella catarrhalis
  3. What makes collecting Neisseria specimens difficult sometimes?
    • sensitive to temp fluctuations and dry conditions
    • Dacron/rayon swabs are recommended
    • must be kept at room temp (cold sensitive)
    • Specs. should be kept moist until culture
    • *high CO2 needed for N. gonorrhoeae transport
  4. Chocolate II agar - use and ingredients
    • Isolation and cultivation of Neisseria and Haemophilus spp (and other fastidious bacteria)
    • Ingredients: Gonococci agar base
    • hemoglobin solution
    • supplement VX/IsoVitaleX
  5. Modified Theyer MArtin Agar - use and ingredients
    • Selective for N. gonorrheae: isolates from specimen contain mixed flora
    • Ingredients: chocolate agar base
    • enriched with hgb and supplement B
    • VCNT antibiotic soln added (gives the selectivity)
    • Vancomycin, Colistin, Nystatin, Trimethroprim lactate
  6. Martin-Lewis agar - use and ingredients
    • selective for N. gonorrhoeae: isolates from specimen contain mixed flora
    • ingredients: gonococci agar base
    • hemoglobin
    • Supplement solution/IsoVitaleX
    • VCAT inhibitor (Vancomycin, Colistin, Anisomycin, Trimethoprim)
  7. New York City agar - use and ingredients
    • isolation of pathogenic Neisseria
    • ingredients: NYC basal medium (agar, cornstarch)
    • horse or cow blood cells
    • Horse plasma, citrated
    • yeast dialysate
    • glucose soln
    • VCNT antibiotic soln
    • Vancomycin, colistin, nystatin, trimethoprim
  8. What are the diagnostic tests for Neisseria
    • Growth on special media: MTM, NYC, SBA, choc
    • Rapid fermentation: glucose, maltose, lactose
    • Cytochromse oxiadase test
    • Nitrate reduction
    • Superoxol test (30% peroxide)
    • Nucleic acid testing: PCR for specific genes (23S rRNA, 16S rRNA), probe assays
    • highly specific AND sensitive
    • *NOTE -almost every lab uses or sends out
  9. Neisseria gonorrhoeae - AKA, diseases
    • AKA Gonococcus (GC)
    • diseases: purlent urethrits (males)
    • cervicits (females)
    • pharyngitis and anorectal infections
    • conjuctivitis (mother -> bby)
    • disseminated infection to other sites including joints
  10. Neisseria gonorrhoeae - differences between men and women
    • Men: 95% show symptoms of acute infection (dysuria, urethral discharge)
    • Women: most infections asymptomatic
    • 40-60% may have urethral infection
    • Complications of vaginal accessory glands, pelvic inflammatory disease, Fitz-Hugh-Curtis syndrome, perihepatitis
    • Gonococcal opthalmia to newborns
  11. What are the virulence factors of Neisseria gonorrhoeae?
    • Receptors for human transferrin
    • capsule
    • pili
    • cell membrane proteins
    • lipooligosaccharide (LOS) or endotoxin
    • IgA protease
  12. Neisseria gonorrhoeae ID - microscopic appearance, plating, morphology
    • Gram stain (coffee-bean shaped diplococci)
    • gram neg inside PMNs is diagnostic for symptomatic males
    • not for females, because some Neisseria spp are normal flora
    • ALWAYS report presence of neutrophils (PMNs) because it indicates infection
    • Plating: sheep's blood agar, chocolate, MTM, ML, NYC
    • *culture media incubated at 35-37C in humid, 3-5% CO2 atmosphere
    • morphology: small grayish white convex shiny colonies
    • smoother or irregular margins
    • u to 5 different colony types on primary plate!
  13. Neisseria gonorrhoeae - antibiotic resistance
    • Cetriaxone or qunolones are usually effective
    • Macrolides are effect
    • B-lactimase is common (detect w/ spot test)
    • resistance to quinolones is emerging
  14. Neisseria gonorrhoeae - why is it important to public health
    • marker for increased transmission of other STDs
    • concomitant infection with C. trachomatis can occur
  15. Neisseria meningitidis - diseases
    • Meningitis: acute, purulent, associated w/ petichial rash
    • rapidly fatal
    • highly contagious
    • waterhouse-Friderichsen syndrome: bleeding into adrenal glands = inability to maintain blood pressure during septic shock (children)
    • Acute meningococcemia: in blood stream, not yet CSF
    • high mortality rate
    • Pneumonia
    • Conjunctivits, sinusitis, otitis media
    • hemmorhagic lesions
  16. Neisseria meningitids - transmission, virulence factors
    • transmission: person-to-person by contaminated resp. droplets (VERY CONTAGIOUS)
    • v factors: capsular polysaccharides prevent phago
    • lipooligosaccharadies play role in lysis of neutrophils and epithelial cells
    • pili and fimbriae enable binding to human cells
  17. bacterial meningitis serological group distribution
    • A: pandemics
    • B & C: predominantly in USA
    • G: community-aquired
    • Y: meningococcal pneumonia
    • W-135: invasive disease
    • *NOTE - vaccines available for A and B
  18. Neisseria meningitidis - specimen collection
    • CSF: centrifuge and use sediment for gram stain
    • USE TUBE #3
    • Blood cultures
    • N-P swabs: plated immediately or PROPER t.port media
    • (5-10% pop carry as normal flora 0.o)
  19. Neisseria meningitidis - plating and colony morphology
    • 5% SBA and chocolate
    • increased CO2 required for optimal growth
    • high humidty required
    • morphology: medium smooth round moist gray-to-white encapsulated strains (MUCOID)
  20. Neisseria meningitidis - gram stains
    • diplococci
    • bad news if found in CSF! Report immediately
    • fount intra and extra cellulary near PMNs in blood (and CSF?)
  21. Why is Neisseria meningitidis a public health issue?
    • Must be reported
    • All contacts must be traced and treated (aerosal transmission)
    • spreads quickly in crowded conditions
    • 5-10% of population are carriers
  22. Neisseria meningitids - biochem? acid from? isolated on?
    • oxidase positive
    • acid from glucose and maltose
    • isolated on sheep blood or chocolate agar
  23. Moraxella catarrhalis - AKA, microscopic appearance, presumptive ID
    • AKA: used to be N. catarrhalis
    • Micro: gram neg diplococci, INTRACELLULAR
    • presumptive: collected from eye/ear culture
    • gram neg diplococci
    • DNase positive
    • hydrolyzes tributryin
  24. Moraxella catarrhalis - disease
    • Respiratory infections: one of the "big three" for bacterial pneumonia in adults
    • otitis media
    • sinusitis
    • lower resp tract infections in elderly and COPD
    • rarely casues disseminated bacterermia, meningitis
  25. Moraxella catarrhalis - plating and morphology
    • Grows well on 5% SBA
    • morph: large, non-pigmented/gray, opaque, smooth
    • hockey puck: colony moves intact over agar surface
  26. Moraxella catarrhalis - biochem ID, antibiotic res, collection
    • biochemical ID: hydrolyzes tributyrin
    • reduces nitrate
    • cannot produce acid from carbs
    • resis: B-lactams effective with lactamase inhibitor
    • macrolides, cephalosporins, SXT, quinolones effective
Card Set
CLS03 - Gram negative cocci
CLS03 - Gram negative cocci