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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 |