Gram-positive branching, filamentous rods. Includes N. asteroides (most common human pathogen), N. brasiliensis, N. cyriacigeorgica, N. farcinica, N. nova, N. otitidiscaviarum, N. pseudobrasiliensis, N. transvalensis. There are over 50 species.
Some species are partially acid-fast partially acid fast and can cause a positive (1-3)-β-D-glucan. I know. I had 3 transplant patients with a positive (1-3)-β-D-glucan brain and lung abscess I thought was fungal but grew Nocardia (Here is the case). There are two case reports on PubMed but I have now reported 3 cases on my PubMed blog. So I have 60% of the worlds literature. Ha!
Found in water and soil, it is usually acquired from trauma or inhalation. Some strains are found in the moth. Can occur in normal but more likely the immunoincompetent. High-dose steroids, history of Cytomegalovirus disease, and high levels of calcineurin inhibitors are risk factors for infection in organ transplant recipients (PubMed).
In transplant patients it increases mortality 10 fold (PubMed).
Ascending nodular lymphocutaneous disease, often after penetrating trauma from wood or other organic material.
Occasional disseminated disease in the immunoincompetent.
Nocardia cyriacigeorgica causes soft tissue infections:
"All patients reported having received injections of unknown substances described as “hydrogel,” “botulinum toxin,” “silicone,” “gel filler,” or “biogel.” Six patients indicated that they had received injections from an unlicensed person, either at home, in a hotel, or at a gathering where these injections were administered to multiple persons; these patients had been referred to this provider through friends or Internet sites (PubMed)."
Just let some random guy inject unknown material into your ass. Hard to believe.
In Mexico N. braziliensis is the most common cause mycetoma.
Susceptibility can be variable and, as best as can be determined, should be done. Tmp/sulfa (usually the treatment of choice) OR minocycline OR third generation cephalosporins OR imipenem OR amikacin. Often needs multiple drugs for CNS infections and surgical debridement for cure.
However, "93% of the N. farcinica isolates were resistant to sulfonamides. Also, during the course of our study, the resistance of N. farcinica to TMP-SMZ increased 24 percentage points (from 67% in the 1990s to 91% in the 2000s), and the resistance of N. nova to TMP-SMZ increased 24 percentage points (from 41% in the 1990s to 65% in the 2000s)(PubMed)."
For all species, "61% were resistant to sulfamethoxazole and 42% were resistant to trimethoprim-sulfamethoxazole (PubMed)."
N otitidiscaviarum is commonly resistant to TMP-SMX, and N nova and N farcinica are occasionally resistant.
Resistance to sulfa may be dependent of the lab, a 2012 review found only 2% were resistant to sulfa (PubMed).
Ironically, those with cardiac transplants have increased risk. (Get it? Those with no cardia get Nocardia? My son thinks it's a lame joke).
The CDC notes "Approximately 10% of cases with uncomplicated pneumonia are fatal." I don't know. Isn't the fact it was fatal make it complicated?
Nocardia is also a thrash metal band.
Relevant links to my Medscape blogFollow Ups
Last Update: 04/10/18.