Opportunistic infections in immunosuppressed patients are common. However, as the life expectancy of patients with AIDS increases, the number of new or less common pathogens diagnosed has increased significantly. This is the case of a patient with AIDS who developed a pulmonary infection with Tsukamurella sp.
Patient is a 55 year old male with AIDS (CD4 count 116), on antiretroviral therapy, who presented with two weeks of fever, malaise and cough productive of white sputum.Past history significant for cutaneous T-cell lymphoma, no allergies, and 120 pack-year tobacco use.Physical exam: normal vital signs, weight 122lbs. Head and neck examination is normal. Chest exam significant for decreased breath sounds bilaterally. Abdominal and extremities examination unremarkable. Skin examination shows lesions compatible with cutaneous T-cell lymphoma.Chest CT scan shows “shotty” adenopathy in the aorto-pulmonary window and left hilum. There is a thick wall, irregular, right upper lobe cavitary lesion (Fig. 1). Similar lesions are seen with peripheral parenchymal opacities in the left upper lobe, left lower lobe, and middle lobe.Mild anemia (Hemoglobin 11.9) and MCV 108. Normal chemistry and liver function tests. Viral load 1,361 copies.Sputum examination 3 times for AFB was negative; gram stain showed normal respiratory flora.Bronchoscopy was normal. Bronchoalveolar lavage (BAL) showed normal respiratory flora. Transbronchial biopsies of the right upper lobe showed bronchial wall and lung parenchyma with mild chronic inflammation.Upon follow up, cultures grew Tsukamurella species. Repeat cultures were sent in sputum and Tsukamurella grew again.Patient was placed on Ciprofloxacin and Rifabutin (based on previously reported sensitivities). He had remission of symptoms and improvement of radiographic findings (Fig. 2). Sensitivities could not be confirmed in the laboratory, since the organism could not be re-grown.DISCUSSION: Initially, differential diagnosis included infections, such as Tuberculosis, Nocardiosis, Rhodococcus Equi, Actinomycosis, pulmonary mycoses, Sporotrichosis and parasitic. Non infectious possibilities included Wegener’s Granulomatosis, Lymphoma, Carcinoma, Rheumatoid Lung Disease, Sarcoidosis, and Langerhan’s Cell Histiocytosis.Tsukamurella, Nocardia, Gordona and Rhodococcus are mycolic acid-containing bacteria classified as Nocardioform Actinomycetes. Infections due to these organisms have been well reported, except for those due to Tsukamurella sp. T. paurometabola, T. pulmonis, inchonensis, T. wratislaviensis, and T. tyrosinosolvens have been described.These organisms were named after Tsukamura, a Japanese microbiologist who in 1971 described infection by Gordona aurantiaca in sputum of patients with chronic lung disease. In 1988, this organism was reclassified as Tsukamurella paurometabola. Infection has not been reported on immunosuppressed patients with HIV, most are related to malignancy.There are10 reported cases of Tsukamurella infections, only one in the lung. That case was due to Tsukamurella inchonensis, isolated from lung tissue of a patient with a necrotic tumor. These organisms are usually considered a contaminant, until they are isolated repeatedly.The natural habitat is unknown. Tsukamurella paurometabolum has been isolated from sputum, a mycetoma, and as pseudo-infection due to laboratory contamination.Repeated isolation and no evidence of contamination are most helpful in making the diagnosis, as well as lack of other pathogens, and good response to therapy. It is difficult to determine antimicrobial susceptibilities, since these are slow-growing organisms and do not give a smooth suspension of cells.Treatment is often based on previously reported susceptibilities. These organisms have been sensitive to Amikacin, Clarithromycin, Ciprofloxacin, Imipenem, and Sulfamethoxazole.CONCLUSIONS: Tsukamurella is an uncommon pulmonary pathogen in immunosuppressed patients. Repeated isolation is important for diagnosis. Treatment is based on previously reported sensitivities and in the response to it. This organism should be included in the differential diagnosis of lung infections in immunosuppressed patients.
J.P. Gomez, None.