1. Gram-Positive Bacilli Part Four
MLAB 2434: Microbiology
Keri Brophy-Martinez

2. Non-Spore Formers & Branching
Gram positive rod
Non-spore formers
Pleomorphic morphology
Branching
Genera
Actinomyces
Nocardia
Streptomyces

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

4. Aerobic Actinomyces Gram stain Non acid-fast Gram positive rod
Filamentous, branching
Can be beaded
Non acid-fast

5. 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

6. Aerobic Actinomycetes
Nocardia
Streptomyces
Actinomadura
Gordonia
Rhodococcus
Tsukamurella
Nocardiopsis
Dermatophilus

7. Nocardia: Clinical 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

8. Nocardia: Laboratory 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.

9. Nocardia: Laboratory Diagnosis
Gram-positive filamentous bacilli
Suspicious for actinomycetes

10. Nocardia: Laboratory Diagnosis
Cultural characteristics
Chalky, matte, dry, crumbly appearance
May be pigmented
Beta hemolytic
Identification
Urease positive
Catalase positive
Molecular testing

11. Streptomyces Habitat Disease states Soil and decaying vegetation
Mycetoma- a chronic, localized, painless, subcutaneous infection
Sites: head and neck
Wound & Skin infections

12. Streptomyces: Laboratory Diagnosis
Microscopic Morphology
Gram positive rod
Branching
Spider-like
Non-acid-fast

13. Streptomyces: Laboratory 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

14. References
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.