A nosocomial outbreak of Mycobacterium Abscessus infection in a private hospital of Shanghai, China, 2021

Abstract Background: Mycobacterium abscessus i s a rapid-growing mycobacterium, and it is often present in the water supply of hospital. Here we describe an outbreak of M. Abscessus infection in a private hospital in Shanghai, the epidemiological investigation and control measures were also conducted. Methods: From September 27 th to October 1 st , 2021, four consecutive AFB-positive patients from same ward in a private hospital who were first suspected of MTB infection were reported to Putuo district Center for Disease Control. Bronchial lavage fluids were sampled from all inpatients for both Mycobacterium culture and metagenome sequencing analysis (mNGS). Epidemiological investigation and environmental examination were conducted during this outbreak. Findings : Three of the four index patients had positive culture result for M. abscessus , while mNGS showed positive sequencing results in all 4 patients. However, 32 environmental samples from different sources were negative for M. abscessus . A series of infection control measures were strictly performed, and no further cases were reported in one year follow up. Conclusions : This nosocomial outbreak was caused by M. abscessus but the accurate source remains uncertain. The unique pathogen was captured by mNGS, and this sequencing technique can play an important role in identifying nosocomial outbreak.