Bacteria

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Bacteria are single celled microorganisms, without a nucleus (prokaryotes), that can cause lots of morbidity and mortality. They are not infrequently seen by pathologists.

Actinobacteria

  • Previously known actinomycetes.

General

Notes:

  • Mycete = fungus; these organisms have a fungus-like appearance.

Gross

  • Yellow granules.[2]

Microscopic

Features:[3][2]

  • Branching rods.
  • Typically form pink/purple granules ("sulfur granule") that is surrounded by inflammatory cells (lymphocytes or neutrophils).

DDx:

  • Nocardia.

Notes:

  • Sulfur granule may be seen grossly - yellow.[2]

Images:

Stains

  • Gram +ve.
  • AFB -ve.
    • Nocardia +ve.

Helicobacter pylori

See Stomach.

Clostridium difficile

  • Commonly C. difficile.

General

  • Gram positive bacillus.

One virulent strain is:[4][5] BI/NAP1.

  • Deletion of tcdC locus.
  • Resistant to fluoroquinolones (gatifloxacin and moxifloxacin).

See also

References

  1. Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 446. ISBN 978-0781765275.
  2. 2.0 2.1 2.2 URL: http://pathmicro.med.sc.edu/mycology/mycology-2.htm. Accessed on: 14 September 2011.
  3. URL: http://pathology.class.kmu.edu.tw/ch05/Slide42.htm . Accessed on: 14 September 2011.
  4. URL: http://www.medpagetoday.com/InfectiousDisease/PublicHealth/2254. Accessed on: 15 August 2011.
  5. McDonald, LC.; Killgore, GE.; Thompson, A.; Owens, RC.; Kazakova, SV.; Sambol, SP.; Johnson, S.; Gerding, DN. (Dec 2005). "An epidemic, toxin gene-variant strain of Clostridium difficile.". N Engl J Med 353 (23): 2433-41. doi:10.1056/NEJMoa051590. PMID 16322603.