Nocardia is a genus gram-positive, partially acid-fast, and strictly aerobic branching filamentous bacteria widely distributed in dust, soil, water, and vegetable matter. Because of their fungal‐like structure, Nocardia species have previously been mistaken for fungal organisms. To date, more than 50 species of pathogenic Nocardia have been identified. They cause lung, central nervous system and pus-forming skin infections. Infection by Nocardia asteroides complex (NAC) represents the most common cause of nocardiosis worldwide. Organs affected by Nocardia include the lungs, kidney, bone, muscle, and skin causing cellulitis, abscess, lymphocutaneous syndrome, or actinomycetoma and eye infections such as acute keratitis and endophthalmitis.4

CNS Nocardiosis

Central nervous system nocardiosis most frequently manifests as brain abscesses, however, in rare cases as meningitis or spinal cord infections. Their clinical course is typically over months, or even years, making early diagnosis and identification difficult. The mortality rate is 20-50%. Multiple abscesses are reported in 38% of the patients with CNS nocardiosis. These rates are higher than those associated with other bacterial brain abscesses. In case of multiple abscesses, the mortality rate rises to 66%.2

Nocardia infection in cat Source: BMC Vet Res. 2012; 8: 239. via PubMed central

Pulmonary Nocardiosis

Inhalation of Nocardia leads to pulmonary disease mimicking tuberculosis, fungal infection, or even malignancy.4 They can spread from lungs or skin to virtually any organ. Agricultural occupation is a risk factor for pulmonary nocardiosis. Systemic immunosuppression, corticosteroid therapy, lymphoma, sarcoidosis, systemic lupus erythematosus, chronic alcoholism, diabetes mellitus, and human immunodeficiency virus (HIV) infection are other predisposing factors. It can be fatal in patients with advanced HIV infection.3

Nocardiosis in Cats and Dogs

Nocardia infections cause draining skin lesions, pneumonia, or pyothorax in dogs and cats, and mastitis in cattle. Pyothorax is an accumulation of pus within the pleural space. It is a relatively uncommon but potentially life-threatening disease. The most frequently described routes of infection in dogs and cats include migrating foreign bodies such as plant awns, pulmonary tumor or abscess, penetrating wounds, and esophageal perforation. Cases of pulmonary infection with Nocardia species in dogs have occurred after chronic cyclosporine administration which results in increased susceptibility to infection. 2

Isolation and identification of the organism from a clinical specimen gives a definite diagnosis of nocardiosis. Sulfonamides have been considered as the standard for therapy.


  1. Vertebral Osteomyelitis and Multiple Cutaneous Lesions in a Dog Caused by Nocardia pseudobrasiliensis. J. Hilligas,corresponding author 1 E. Van Wie, 2 J. Barr, 2 K.E. Russell, 1 A.L. Perry, 1 B.R. Weeks, 1 and S. Zhang 1 J Vet Intern Med. 2014 Sep-Oct; 28(5): 1621–1625.
  2. Brain abscess caused by Nocardia asiatica. Atsuhito Uneda,* Kenta Suzuki, Shuichi Okubo, Koji Hirashita, Masatoshi Yunoki, and Kimihiro Yoshino Surg Neurol Int. 2016; 7: 74.
  3. Pulmonary Nocardiosis: Review of Cases and an Update. Malini Shariff * and Jayanthi Gunasekaran Can Respir Jv.2016; 2016
  4. Disseminated nocardiosis masquerading as metastatic malignancy. Rajalakshmi Arjun, Arjun Padmanabhan, Bhanu Prakash Reddy Attunuru, and Prerna Gupta Lung Indiav.33(4); Jul-Aug 2016



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