Nationwide survey on nosocomial transmission of Mycobacterium abscessus in patients with tracheostomies in Japan

OBJECTIVES: Accumulating evidence supports the human-to-human bioaerosol transmission of non-tuberculosis mycobacteria. Patients with tracheostomies were particularly susceptible to Mycobacterium abscessus species (MABS) transmission within hospital settings; however, the nationwide prevalence remains unclear. This study aimed to identify the genetic characteristics and isolation rates of MABS in Japan, especially among patients with tracheostomies who were admitted to long-term healthcare facilities. METHODS: From November 1, 2023, to February 28, 2024, respiratory samples were collected nationwide from patients with tracheostomies who were hospitalised in long-term healthcare facilities due to neurodegenerative diseases. To identify their subspecies and phylogenetic clusters, whole-genome sequencing (WGS) was conducted on MABS isolates. RESULTS: This study included 1,118 screened patients across 47 facilities, of whom complete clinical data were available for 1,087 patients. Among 18 facilities (38.2%), MABS were isolated from 118 patients (10.6%). Of the tested 110 isolates available for WGS analysis, 84 (76.4%) were identified as M. abscessus subsp. massiliense and 26 (23.6%) as M. abscessus subsp. abscessus. Compared with patients without MABS isolation, those with MABS isolation were predominantly older and male and had a weakened cough reflex. The MABS isolates obtained from patients within the same facility were characterised based on genetic identity. CONCLUSIONS: MABS was detected in approximately 40% of long-term care facilities housing patients with tracheostomy. An investigation into the transmission routes of MABS within long-term care facilities is urgently warranted given the suspicion of nationwide nosocomial transmission.