BRANCHING/PARTIALLY ACID-FAST GRAM-POSITIVE BACILLI

Are normal inhabitants of soil and water; are primarily responsible for the decomposition of plant material; can occur in immunocompetent and immunocompromised individuals; grows slowly

• Nocardia
• Rhodococcus equi
• Thermophilic actinomycetes
• Actinomyces israelii

Are gram-positive (often with a beaded appearance); variably acid-fast, catalase positive, and strictly aerobic; Form branched filaments that extend along the agar surface (substrate hyphae), and into the air (aerial hyphae); are characterized by the presence of meso-diaminopinelic acid (DAP) and the sugars arabinose and galactose in the peptidoglycan of the cell wall

• Nocardia
• Rhodococcus equi
• Thermophilic actinomycetes
• Actinomyces israelii

A facultative intracellular organism that can persist and replicate within macrophages; MOT: inhalation of the organism from exposure to infected animal feces

• Nocardia
• Rhodococcus equi
• Thermophilic actinomycetes
• Actinomyces israelii

Responsible for hypersensitivity pneumonitis, an allergic reaction; an occupational disease that occurs in farmers, factory workers, and others who are repeatedly exposed to these agents; grows rapidly on TSA with 1% yeast extract; the ability to grow at 50℃ or greater is a characteristic

• Nocardia
• Rhodococcus equi
• Thermophilic actinomycetes
• Actinomyces israelii

Normal flora of the mouth; causes chronic granulomatous disease (CGD); wooden lumpy lesions that eventually drains pus

• Nocardia
• Rhodococcus equi
• Thermophilic actinomycetes
• Actinomyces israelii

Causes pulmonary infection and disseminated disease

• N. asteroides
• N. brasiliensis

Causes actinomycetoma

• N. asteroides
• N. brasiliensis

Nocardia MOT

• Traumatic inoculation
• Inhalation

Nocardia staining: gram-positive, branching/partially brranching beaded filaments

• Gram stain
• Acid fast stain
• Modified acid fast

Nocardia staining: rules out Mycobacteria

• Gram stain
• Acid fast stain
• Modified acid fast