Helicobacter cinaedi is an emerging pathogen causing bacteraemia and cellulitis. Nosocomial transmission of this microbe has been described, but detailed molecular-epidemiological analyses have not been performed. Here, we describe the results of a multi-step genome-wide phylogenetic analysis of a suspected intra-hospital outbreak of H. cinaedi that occurred in a hospital in Japan. The outbreak was recognized by the infectious control team (ICT) of the hospital as a sudden increase in H. cinaedi bacteraemia. ICT defined this outbreak case based on 16S rRNA sequence data and epidemiological information, but were unable to determine the source and route of the infections. We therefore re-investigated this case using whole-genome sequencing (WGS). We first performed a species-wide analysis using publicly available genome sequences to understand the level of genomic diversity of this under-studied species. The clusters identified were then separately analysed using the genome sequence of a representative strain in each cluster as a reference. These analyses provided a high-level phylogenetic resolution of each cluster, identified a confident set of outbreak isolates, and discriminated them from other closely related but distinct clones, which were locally circulating and invaded the hospital during the same period. By considering the epidemiological data, possible strain transmission chains were inferred, which highlighted the role of asymptomatic carriers or environmental contamination. The emergence of a subclone with increased resistance to fluoroquinolones in the outbreak was also recognized. Our results demonstrate the impact of the use of a closely related genome as a reference to maximize the power of WGS.
Background: Pseudo-outbreaks of non-tuberculous mycobacteria (NTM) in association with the water supply system in hospitals have been previously reported. We found that the frequency of NTM isolation in clinical samples increased after the reconstruction and renovation of a hospital in Japan in 2014. Aim: To analyse NTM, their possible relationship with the hospital water supply system, and outcomes of preventive measures. Methods: Environmental samples obtained from the water supply in hospital wards were tested for NTM. On obtaining positive results, the bacteria were further analysed using polymerase chain reaction (PCR). Findings: The PCR products of NTM showed that most samples tested positive for Mycobacterium paragordonae. Because none of the analysed patients developed any disease due to these bacteria, this event was considered a pseudo-outbreak. Investigation of the water supply system revealed that samples obtained from the recently attached aerators/ rectifiers during hospital renovation tested positive for these bacteria. Therefore, measures to remove aerators/rectifiers and prevent patients from drinking tap water in the hospital were introduced. Thereafter, the frequency of NTM-positive samples significantly decreased in the hospital.
Conclusion:This study is one of the few reports which reveal the possibility of pseudooutbreaks of M. paragordonae in hospitals, hence raising the question whether aerators/rectifiers should be used in hospitals at all, because their mesh structure may promote NTM proliferation in supplied water. The importance of surveillance of bacteria derived from the environment, particularly after hospital reconstruction/renovation, is re-emphasized.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.