Flexor tenosynovitis due to Mycobacterium asiaticum

Clinical significance of Mycobacterium asiaticum isolates in Queensland, Australia

Mycobacterium asiaticum was first reported as a cause of human disease in 1982, with only a few cases in the literature to date. This study aims to review the clinical significance of M. asiaticum isolates in Queensland, Australia. A retrospective review (1989 to 2008) of patients with M. asiaticum isolates was conducted. Data were collected through the Queensland TB Control Centre database. Disease was defined in accordance with the American Thoracic Society criteria. Twenty-four patients (13 female) had a positive culture of M. asiaticum, many residing around the Tropic of Capricorn. M. asiaticum was responsible for pulmonary disease (n = 2), childhood lymphadenitis (n = 1), olecranon bursitis (n = 1), 6 cases of possible pulmonary disease, and 2 possible wound infections. Chronic lung disease was a risk factor for pulmonary infection, and wounds/lacerations were a risk factor for extrapulmonary disease. Extrapulmonary disease responded to local measures. Pulmonary disease responded to ethambutol-isoniazid-rifampin plus pyrazinamide for the first 2 months in one patient, and amikacin-azithromycin-minocycline in another patient. While M. asiaticum is rare in Queensland, there appears to be an environmental niche. Although often a colonizer, it can be a cause of pulmonary and extrapulmonary disease. Treatment of pulmonary disease remains challenging. Extrapulmonary disease does not mandate specific nontuberculous mycobacterium (NTM) treatment.

Suppurative tenosynovitis and septic bursitis

Suppurative tenosynovitis and septic bursitis are closed space infections of the musculoskeletal system. Appropriate antibiotics in combination with incision and drainage are generally recommended. Aggressive surgical management is particularly important in tenosynovitis to prevent tendon necrosis. Empiric antibiotic coverage should be directed toward staphylococci and streptococci. Patient characteristics and epidemiologic exposures may provide clues to unusual causative organisms that are occasionally encountered, such as Neisseria gonorrhoeae, Pasteurella multocida, atypical mycobacteria, fungi, and protothecosis.

Pyogranuloma caused by Mycobacterium asiaticum infection in a steer

In 2003, a steer carcass was condemned at a Central Queensland abattoir because of metastatic tumors. In addition, a granulomatous lesion was found in the mediastinal lymph node. Histological examination showed this to be a pyogranuloma, typically associated with Rhodococcus or the Nocardia/Streptomyces group. However, in this case, the only etiological agent was an acid-fast bacillus, which would normally be associated with a more fibrous lesion. A number of nucleic acid-based techniques were used, and the isolate was identified as Mycobacterium asiaticum. This organism is a rarely encountered opportunistic pathogen of humans, associated with subtropical climates. This is the first report of this organism causing infection in cattle. The similarities between this case and cases of human disease are discussed.

Atypical mycobacterial flexor tenosynovitis presenting as carpal tunnel syndrome: Presentation of three cases and review

Three patients with carpal tunnel syndrome secondary to atypical mycobacteria flexor tenosynovitis are presented. Aggressive surgical debridement combined with long term antitubercular pharmacotherapy resulted in a good outcome, but the lag time to diagnosis and course of disease were long. Diagnosis of these infections requires a high suspicion index, adequate surgical biopsy and appropriate cultures. Atypical mycobacteria infections must be considered in the differential diagnosis in any patient with evolving chronic tenosynovitis, even if the patient has no history of immunosuppression, and especially if environmental risk factors are present.