Pulmonary Infection Caused by Mycobacterium malmoense and the Difficulties in Distinguishing It From the Pulmonary Mycobacterium tuberculosis Infection.

Abstract

Mycobacteriummalmoenseis a rare species ofnon-tuberculosis mycobacteriadetected in Japan that causes pulmonary infection and cervical lymphadenitis. Here, we report a case of pulmonary infection caused byM. malmoense, which was difficult to distinguish fromMycobacterium tuberculosis(Mtb) infection. A 64-year-old Japanese woman with a history of pulmonarytuberculosishad bloody phlegm, a cough, and discomfort in her chest. Chest computed tomography revealed a cavity, infiltration, and a nodule. A smear test for acid-fast bacilli was positive, aMycobacteriumaviumcomplex transcription reverse-transcription concerted (TRC) test was negative, and an Mtb TRC test was withheld because the internal control was negative. After diluting the specimens, the internal control tested positive, and the sample tested negative. We diagnosed pulmonaryM. malmoenseinfection based on a culture test. In conclusion, attention should be paid to the concentration of bacteria in Mtb TRC test samples, ensuring that the internal control provides expected results.