Mycobacterium gordonae Pseudo-outbreak Cases That Affected the Determined Treatment Efficacy of Tuberculosis and Can Be Managed by Avoiding Tap Water Use

Abstract

The "criteria for discharge in Japan" for patients with TB include a negative smear test after treatment initiation, but contamination with nontuberculous Mycobacteria (NTM) can affect the determination of the effectiveness of treatment for TB. In 2020, we experienced a case in which a patient hospitalized for pulmonary TB underwent a persistently positive sputum smear test for determining treatment response that deviated from the clinical treatment response, making it difficult to determine discharge criteria. Mycobacterium gordonae was detected in culture samples, indicating the possibility of NTM contamination. The infection control team investigated 12 patients with a history of hospitalization in which M. gordonae was detected and 9 (75.0%) patients were smear-positive, and 6 (66.7%) received oral care using tap water. Suspecting the possibility of contamination from the water environment, environmental culture was performed, and M. gordonae was detected in tap water. Therefore, the faucet bubble cap was replaced, and bottled water was provided to patients for brushing their teeth and drinking water, in addition to a ban on the use of tap water during oral care. The number of M. gordonae cases decreased to 12 and 6 in 2021 and 2022, respectively, and a pseudo-outbreak of M. gordonae was suggested, and avoidance of tap water use was considered a useful measure to prevent NTM contamination.