Gram-Positive Bacilli Part Four

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Gram-Positive BacilliPart Four

• MLAB 2434 Microbiology
• Keri Brophy-Martinez

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Non-Spore Formers Branching

• Gram positive rod
• Non-spore formers
• Pleomorphic morphology
• Branching
• Genera
• Actinomyces
• Nocardia
• Streptomyces

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Aerobic Actinomyces

• Member of the normal flora of mouth, head, and
  neck
• Pathogens
• Human bite wounds, eye cultures
• Cervicitis and endometritis in women
• Actinomycosis

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Aerobic Actinomyces

• Gram stain
• Gram positive rod
• Filamentous, branching
• Can be beaded
• Non acid-fast

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Aerobic Actinomyces

• Colony morphology
• Spider or granular center
• Branching filaments
• Takes up to 7-14 to develop
• Key Biochemicals
• Catalase negative
• Nonmotile
• Non-fermenters
• Produce H2S

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Aerobic Actinomycetes

• Nocardia
• Streptomyces
• Actinomadura
• Gordonia
• Rhodococcus
• Tsukamurella
• Nocardiopsis
• Dermatophilus

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NocardiaClinical Significance

• Pulmonary form
• Mostly in immunocompromised
• High fatality
• Starts as lung lesion
• Cutaneous
• Three forms
• Mycetoma
• Lymphocutaneous
• Superficial

Sulfur granules collected from draining sinus
tracts in mycetoma
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NocardiaLaboratory Diagnosis

• Microscopy
• Gram-positive branching filaments
• May show beading appearance
• Verify with acid fast stain
• Weakly Acid-fast

Gram-stained smear of sputum showing
Gram-positive branched beaded bacilli.
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NocardiaLaboratory Diagnosis

• Gram-positive filamentous bacilli
• Suspicious for actinomycetes

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NocardiaLaboratory Diagnosis

• Cultural characteristics
• Chalky, matte, dry, crumbly appearance
• May be pigmented
• Beta hemolytic
• Identification
• Urease positive
• Catalase positive
• Molecular testing

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Streptomyces

• Habitat
• Soil and decaying vegetation
• Disease states
• Mycetoma- a chronic, localized, painless,
  subcutaneous infection
• Sites head and neck
• Wound Skin infections

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StreptomycesLaboratory Diagnosis

• Microscopic Morphology
• Gram positive rod
• Branching
• Spider-like
• Non-acid-fast

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StreptomycesLaboratory Diagnosis

• Morphology Characteristics
• Aerobic growth in 3-30 days
• Waxy, bumpy or velvety rugose forms, yellow to
  orange
• Will grown on SBA, mycology media and LJ media
• GPR with extensive branching, chains and spores
• Identification
• Acid-fast negative

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References

• http//www.atsu.edu/faculty/chamberlain/golden2000
  /case5.htm
• http//chesschumpion.blogspot.com/2007/03/time-to-
  put-on-your-thinking-caps.html
• http//en.wikipedia.org/wiki/FileBacillus_subtili
  s_Gram.jpg
• https//labs.uhstx.com/clinical_int/dols/appb.html
  http//www.iccb.state.il.us/pt3/mod/science/mod_bi
  o111/mod10/p4.html
• http//www.flickr.com/photos/microbeworld/sets/721
  57625392265538/detail/http//www.uaz.edu.mx/histo/
  pathology/ed/ch_9b/c9b_clue.htm
• Kiser, K. M., Payne, W. C., Taff, T. A. (2011).
  Clinical Laboratory Microbiology A Practical
  Approach . Upper Saddle River, NJ Pearson
  Education.
• Mahon, C. R., Lehman, D. C., Manuselis, G.
  (2011). Textbook of Diagnostic Microbiology (4th
  ed.). Maryland Heights, MO Saunders.