Actinomycetes

Background

• Filamentous, mostly branching Gram-positive bacilli
• The order Actinomycetales includes the aerobic actinomycetes
  • Actinomycetales also include Corynebacterium (non-branching, non-acid-fast), Mycobacterium (non-branching, fully acid-fast), and Tropheryma whipplei
• Environmental organisms found in soil
• More commonly seen in fungal cultures
• Typically not acid-fast, though some are partially acid-fast

Organisms

Genus	Infections
Partially acid-fast (cell wall contains mycolic acid)
Nocardia	mycetoma, lymphocutaneous infections, skin abscesses; in immunocompromised hosts, invasive pulmonary and disseminated infections
Rhodococcus	pulmonary infections, bacteremia, skin and wound infections, UTIs, endophthalmitis, peritonitis, CLABSI, abscess in prostate, spleen, thyroid, kidney, or brain, osteomyelitis; associated with horses
Gordonia	skin infections, chronic pulmonary disease, CLABSI, wound infections, bacteremia
Tsukamurella	peritonitis, CLABSI, skin infection
Not partially acid-fast (cell wall does not contain mycolic acid)
Streptomyces	commonly contaminant; inoculation skin infection including mycetoma
Actinomadura	inoculation skin infection including mycetoma
Dermatophilus	inoculation skin infection from insects or thorns
Nodardiopsis
Oerskovia