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Fungus-like Bacteria
Mod 3 Lec 3
Question | Answer |
---|---|
What genera are in the Actinomycetes? | Major: Actinomyces, Norcardia, Streptomyces Other: Rhodococcus, Actinomadura, Norcardiopsis |
What are Actinomycetes, and what were they thought to be? | They are higher bacteria; thought to be fungi for years; some form aerial mycelia; clinical manifestations similar to systemic fungal infection |
What Actinomycetes is anaerobic? | Actinomyces |
What Actinomycetes is aerobic? | Norcardia, Streptomyces |
What Actinomycetes is partially acid-fast? | Norcardia |
What Actinomycetes is not acid-fast? | Actinomyces, Streptomyces |
What can all genera of Actinomycetes produce? | Granules |
What does Actinomyces spp. look like on gram stain? | Gram-positive rods; obligate anaerobes |
What is seen in direct microscopy that is diagnostic for Actinomyces spp? | Yellow sulfer granules - bacterium and its waste |
Where are Nocardia spp. found? | Ubiquitous soil saprophytes |
Nocardia causes infection by | Inhalation or direct inoculation |
Most common Nocardia spp. | N. asteroides; N. brasiliensis is most important in tropical areas |
Gram stain characteristics or Nocardia spp. | Gram-variable/modified acid-fast bacilli; filamentous and branching; Gram-variable or "beaded" appearance; alternating gram-positive:gram-negative segements on a filament |
Are Nocardia spp. aerobic or anaerobic? | Strictly aerobic |
How can Nocardia spp. be isolated? | Routine media; w/in 4 days, can require 2-4 weeks; may be difficult - can be overgrown by faster growing organisms |
Nocardia spp. macro | Smooth and moist; or "mould like", grey-white, waxy or powdery; strong mildew odor |
Are Nocardia spp. acid-fast? | Acid-fast using modified Ziehl-Neelsen or Kinyoun acid-fast stain. |
How can Nocardia spp. and other aerobic actinomycetes be differentiated? | Tap Water Agar morphology; Nocardia spp. have recursively branching hyphae with aerial hyphae |
Biochemical characteristics of Nocardia spp. | Hydrolysis of casein, tyrosine, or xanthine |
Nocardia asteroides biochemical characteristics | Doesn't hydrolyze casein, xanthine or tyrosine |
Nocardia brasiliensis biochemical characteristics | Hydrolyzes casein and tyrosine |
Where is Rhodococcus equi found? | Soil saprophyte; associated w/domestic farm animals |
What does Rhodococcus equi cause? | Pulmonary infection that resembles TB |
Rhodococcus equi macro | Colony forms in 2-4 days; glistening, smooth, pink to red; reverse camp test positive |
Rhodococcus equi micro | Gram-positive coccobacillus; sometimes partially acid-fast |
Biochemical characteristics of Rhodococcus equi | Doesn't hydrolyze casein, xanthine, tyrosine |
Tap Water Agar morphology of Rhodococcus equi | No branching |
Where is Streptomyces spp. found | Soil (S. griseus); non-pathogenic; musty smell |
Streptomyces spp. macro | Colonies in 3-5 days at 35C; waxy, white powdery top |
Streptomyces spp. micro | Gram-positive filamentous bacilli; non-acid fast |
Streptomyces spp. morphology on Tap Water Agar | Aerial, tertiary branching on tapwater agar |
Biochemical characteristics of Streptomyces spp. | Hydrolyzes casein, xanthine and tyrosine |
Where are Actinomadura spp. found? | Only in tropics |
What does Actinomadura spp. cause? | Mycetoma |
Actinomadura spp. micro | Gram-positive filamentous bacilli; non acid-fast |
Actinomadura spp. morphology on Tap Water Agar | Aerial, tertiary branching |
Biochemical characteristics of Actinomadura spp | Hydrolyzes casein and tyrosine |
Where is Nocardiopsis spp found? | Soil saprophyte |
What is special about Nocardiopsis spp? | Thermotolerand, can grow at higher temperatures |