gram-positive bacilli part four
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Gram-Positive Bacilli Part Four. MLAB 2434: Microbiology Keri Brophy -Martinez. Non-Spore Formers & Branching. Gram positive rod Non-spore formers Pleomorphic morphology Branching Genera Actinomyces Nocardia Streptomyces. Aerobic Actinomyces. - PowerPoint PPT PresentationTRANSCRIPT
Gram-Positive BacilliPart Four
MLAB 2434: MicrobiologyKeri Brophy-Martinez
Non-Spore Formers & Branching
• Gram positive rod• Non-spore formers• Pleomorphic morphology
– Branching
• Genera– Actinomyces– Nocardia– Streptomyces
Aerobic Actinomyces• Member of the normal flora of
mouth, head, and neck
• Pathogens– Human bite wounds, eye cultures– Cervicitis and endometritis in women– Actinomycosis
Aerobic Actinomyces• Gram stain
– Gram positive rod– Filamentous,
branching– Can be beaded
• Non acid-fast
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
Aerobic Actinomycetes
• Nocardia• Streptomyces• Actinomadura• Gordonia• Rhodococcus• Tsukamurella• Nocardiopsis• Dermatophilus
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
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.
Nocardia:Laboratory Diagnosis
• Gram-positive filamentous bacilli
• Suspicious for actinomycetes
Nocardia:Laboratory Diagnosis
• Cultural characteristics– Chalky, matte, dry, crumbly
appearance– May be pigmented– Beta hemolytic
• Identification– Urease positive– Catalase positive– Molecular testing
Streptomyces
• Habitat– Soil and decaying vegetation
• Disease states– Mycetoma- a chronic, localized, painless,
subcutaneous infection• Sites: head and neck
– Wound & Skin infections
Streptomyces:Laboratory Diagnosis
• Microscopic Morphology– Gram positive rod– Branching– Spider-like– Non-acid-fast
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
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/File:Bacillus_subtilis_Gram.jpg• https://labs.uhstx.com/clinical_int/dols/appb.htmlhttp://
www.iccb.state.il.us/pt3/mod/science/mod_bio111/mod10/p4.html• http://www.flickr.com/photos/microbeworld/sets/72157625392265538/
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.