PURPOSE: Rare species-induced nontuberculous mycobacteriosis cases encountered at our hospital were investigated to identify the clinical characteristics.
METHODS: The subjects were one patient each diagnosed with nontuberculous mycobacteriosis caused by rare species, M. abscessus, M. szulgai, M. gordonae, and M. xenopi (4 patients in total), at our hospital during an about 5-year period between 2006 and 2010. The imaging characteristics on chest CT, treatment methods, and outcomes were retrospectively investigated and compared with those in previously reported cases.
RESULTS: In our patients, no thin-walled cavity was noted in cases caused by M. szulgai and M. xenopi, unlike those in previous reports, but thick-wall cavities were present, and differentiation from pulmonary tuberculosis and lung cancer was difficult.The case caused by M. szulgai involved treatment with 4 drugs: RFP, INH, EB, and pyrazinamide (PZA), at the beginning, and therapy was then switched to 3-drug treatment with RFP, EB, and CAM. The case caused by M. gordonae involved treatment with 3 drugs: RFP, EB, and CAM, and the courses of these cases were favorable. In the 2 cases caused by M. abscessus and M. xenopi, respectively, the course was observed without treatment, but the disease did not aggravate, and spontaneously remitted.
CONCLUSIONS: In NTM caused by rare species, differentiation from pulmonary tuberculosis, lung cancer, and pneumonia on imaging is difficult in many cases. The disease remitted by early treatment or treatment was switched in some cases, but treatment was mostly effective. Some cases achieved remission without treatment.
CLINICAL IMPLICATIONS: For early diagnosis, not only sputum culture but also bronchial washing should be actively performed. Course observation may be necessary for some cases, avoiding hasting performing initial treatment, even though the condition tends to aggravate, showing difficulty in judging the necessity of treatment.
DISCLOSURE: The following authors have nothing to disclose: Yu Enomoto, Tadashi Takao, Hiroshi Igei
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