-
Actinomycetes general characteristics - gram stain, ____robic, colony morph, habitat, transmission
- gram: elongated, gram +, form branching filamentous forms (look like fungi)
- __robic: aerobic, facultatively anaerobic, or obligately anaerobic
- morph: dry or mucoid colonies that are sometimes wrinkled
- may adhere to agar
- habitat: usually found in soil (aerobic)
- worldwide dstr, but prevalent in humid areas
- transmission: penetrating wounds, abrasions
- inhalation MAY transmit thermophilic actinomycetes
-
(brief) what are the two primary nocardia's and what disease do they cause?
- N. asteroides: majority of pulmonary/internal infections
- N. basiliensis: majority of skin infections
- mycetoma - chronic, localized, painless, subcutaneous
- lymphocutaneous infections
- skin abscesses
-
Nocardia asteroides - virulence factors, diseases
- Facultative intracellular pathogen in various cells
- Virulence factors: resistance to intracellular killing
- tropism for neuronal tissue (EEK)
- inhibit phogosome-lysosome fusion
- produces large amt catalse and hemolysins (much damage)
- diseases: chronic pulmonary infections
- lung lesion -> pneumonitis -> necrosis -> spread -> dissemination to brain, other organs
-
Nocardia basiliensis - diseases
- Cutaneous infections
- Nocardiosis
- Hands/feet mostly (rarely lungs/brain)
- innoculation from sliver/thorn
- subcutaneous abcess destroys tissues and bone (actinomycotic mycetomas)
- swelling, draining sinuses, sulfur granules
- *NOTE - organs teaming with sulfur granules ("popcorn")
-
Cultivation of Nocardia
- VERY DIFFICULT/PROBLEMATIC
- Slow growing on std media (normal flora may overtake)
- Special media: solid medium using paraffin (for isolation)
- Buffered charcoal-yeast etract medium
- martin lewis
- CNA (for optimal recovery)
- Sabourad dextrose agar
- *NOTE - Actinomycetes OTHER THAN Nocardia should be plated to routine and selective media and incubated for 2-3wks
-
Nocardia and acid-fastness?
- Nocardia considered PARTIALLY acid fast
- Unusual long-chain fatty acids in their cell walls
- retain carbolfuchsin dye during mild acid decolorization (show reddish-to-purple filaments)
-
Brief disease information about non-Nocardia Actinomycetes (Rhodococcus, Streptomyces, Gordonia, Tsukamurella, Tropheryma whipplei)
- Rhodococcus: catheter-related
- pulmonary infections, bacteremia, skin/wound infections
- Streptomyces: smelly
- Actinomycotic mycetoma
- Gordonia: usually a tag-along
- rarely skin infections, cathere-associated sepsis
- Tsukamurella: MOST SMELLY
- peritonitis, abscess, cutaneous lesions
- Tropheryma whipplei: often fatal
- Whipple disease
- diarrhea, weight loss, mal absorption, artharlgia, abdominal pain
- HAS NEVER BEEN CULTURED
|
|
