Actinomycetes Flashcards
Identify the partially/modified acid-fast positive genera of Actinomycetes
- Nocardia
- Rhodococcus
Identify the partially/modified acid-fast NEGATIVE genera of Actinomycetes
- Streptomyces
- Actinomyces
Three aerobic actinomycetes
- Nocardia
- Rhodococcus
- Streptomyces
Anaerobic actinomycetes
Actinomyces
How do we differentiate Nocardia from Actinomyces and Streptomyces?
Acid-fast stains
- Pos: red
- Neg: blue
Nocardia causes infections primarily in what kind of patients?
Immunocompromised patients
Which organism causes pulmonary infection in the immunocompromised patients?
N. asteroides (80% of pulmonary infections)
The cutaneous infections which is usually from traumatic inoculation is caused by ____
N. brasiliensis
Cutaneous infections caused by traumatic inoculation may develop into ____
Actinomycotic mycetoma
List major illnesses observed in infections related to Nocardia
Immunocompromised patients
- Pulmonary
- Dissemination to the brain
- Cutaneous infections caused by traumatic inoculation
Which organism has high mortality?
Nocardia
Describe the microscopic appearance of Nocardia
Beaded, branching, filamentous GPRs
Describe the plate morphology of Nocardia
- Earthy smell
- Slow growing often resembles fungi (dry, heaped, white to orange aerial hyphae)
What is the preferred method used for identifying Nocardia?
High Performance Liquid Chromatography
Describe the methods for speciation in identifying Nocardia
- Speciation using hydrolysis of casein, xanthine, tyrosine, or hypoxanthine
- Look for hydrolysis (+) vs. no hydrolysis (-_
This organism has negative hydrolysis of casein, xanthine, tyrosine, or hypoxanthine
N. asteroides
This organism has positive hydrolysis of casein and tyrosine
N. brasiliensis
Can we differentiate Streptomyces from Nocardia using a Gram stain?
NO
Describe the microscopic appearance of Streptomyces
GPRs or filamentous, may be beaded
This organism is rare in human infections and commerical use of antibiotics, antifungals, and immunosuppresants
Streptomyces (primarily saprophytes)
Describe the microscopic appearance of Rhodococcus
Short, branching GPRs