St. Louis Community College

Clinical Laboratory Technology



INTERNET LESSON PLAN NUMBER 4

TITLE OF LESSON: Aerobic Gram Negative Cocci

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LESSON OBJECTIVE: The student should be able to:

  1. Relate key characteristics and natural habitat of Neisseria, Branhamella, and Kingella.

  2. Differentiate the pathogenic Neisseria from the commensal Neisseria.

  3. Describe the clinical infections associated with Gram negative cocci.

  4. Describe the tests used to differentiate the species.

  5. Observe and accurately record the results of tests used to differentiate the species.

  6. Summarize the principle, purpose, and sources of error for each differential test used in the identification of the species.

  7. Relate the cellular and colonial morphology for each species listed in this lesson plan.

  8. Distinguish Neisseria, Branhamella, and Kingella.

  9. Identify the clinically significant Gram negative cocci.

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OVERVIEW:

The aerobic Gram negative cocci are one of the more fascinating groups of microorganisms. All but one species is considered part of our normal flora, but can cause disease in the right host. Two of the species are so delicate that they won't grow in culture unless we provide them with the desired environment. One of these will even commit suicide (autolyze) if unhappy. Our job, as laboratory professionals, is to examine isolates and distinguish the potentially pathogenic species from the normal residents.

MATERIALS:

Computer with Internet access

PROCEDURES:

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  1. Visit this site to read about the taxonomy of the Neisseria and related species.

    URL: http://www.cdc.gov/ncidod/dastlr/gcdir/NeIdent/NTax.html

  2. Visit this site to read about the habitat, taxon, pathogenicity, and prevalence of the Neisseria and related species. A table listing the Differential characteristics of human Neisseria sp., B. catarrhalis, and K. denitrificans, can also be viewed.

    URL: http://www.cdc.gov/ncidod/dastlr/gcdir/NeIdent/Index.html#IDENT

  3. Learn about the tests used for identification.
    (Note - There is an error in the biochemical chart. N. elongata is Dnase negative.)


    Biochemical Tests
    Acid Detection Tests
    URL: http://www.cdc.gov/ncidod/dastlr/gcdir/NeIdent/AcidDet.html
    Nitrate Reduction
    URL: http://www.cdc.gov/ncidod/dastlr/gcdir/NeIdent/Nitrate.html
    Polysaccharide from Sucrose
    URL: http://www.cdc.gov/ncidod/dastlr/gcdir/NeIdent/Polysacc.html
    DNase Test
    URL: http://www.cdc.gov/ncidod/dastlr/gcdir/NeIdent/DNa.html
    Enzyme Substrate Test
    URL: http://www.cdc.gov/ncidod/dastlr/gcdir/NeIdent/Enzsub.html


  4. Learn about the pathogenic Neisseria and their diseases by reading and viewing images on these pages.

    Pathogens and Their Disease
    N. gonorrhoeae
    URL: http://www.cdc.gov/ncidod/dastlr/gcdir/NeIdent/Ngon.html
    Gonorrhea
    URL: http://www.cdc.gov/ncidod/dastlr/gcdir/gono.html
    N. meningitidis
    URL: http://www.cdc.gov/ncidod/dastlr/gcdir/NeIdent/Nmen.html
    Meningococcal Disease
    URL: http://www.cdc.gov/ncidod/dbmd/diseaseinfo/meningococcal_g.htm


  5. A description of Branhamella catarrhalis is available at this site.

    URL: http://www.cdc.gov/ncidod/dastlr/gcdir/NeIdent/Bcat.html

  6. Read about and view images of commensal Neisseria, as you visit these sites.

    Commensal Neisseria
    N. lactamica
    URL: http://www.cdc.gov/ncidod/dastlr/gcdir/NeIdent/Nlac.html
    N. cinerea
    URL: http://www.cdc.gov/ncidod/dastlr/gcdir/NeIdent/Ncin.html
    N. flavescens
    URL: http://www.cdc.gov/ncidod/dastlr/gcdir/NeIdent/Nflavesc.html


  7. Information on Kingella denitrificans is on this page.

    URL: http://www.cdc.gov/ncidod/dastlr/gcdir/NeIdent/Kden.html

  8. Answer questions and participate in discussion.

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EXTRA SITES OF INTEREST

To learn more about the aerobic Gram negative cocci & their identification, go to the following sites.

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Objectives
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INTERACTION ITEMS:

  1. How would you distinguish K. denitrificans from N. gonorrhoeae?

  2. How would you distinguish N. meningitidis from a late lactose producing N. lactamica? From N. polysaccharea?

  3. How would you distinguish B. catarrhalis from N. cinerea, N. flavescens, and N. elongata?

CLASSROOM, LABORATORY, OR OTHER ACTIVITIES

  1. Play name that bug at: URL: http://www.stlcc.edu/fp/kiser/Name.bug.html

  2. Process the case presented at: URL: http://path.upmc.edu/cases/case53.html

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Objectives
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Evaluation

EVALUATION:

  1. Correctly identify mystery bugs #1 and 3.

  2. Correctly process the case study.

© Karen M. Kiser 1999


St. Louis Community College at Forest Park
Karen M. Kiser MA MT(ASCP)PBT
Emeritus Professor
Clinical Laboratory Technology/Phlebotomy
St. Louis, MO USA

Updated January 1, 2008

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