Fig. 2

The genetic relatedness based on single-nucleotide polymorphisms (SNPs) of carbapenem-resistant Klebsiella pneumoniae belonging to ST15 from the study hospital was illustrated in a phylogenetic tree. Included isolates consisted of 34 isolates from admission samples and 92 isolates from discharge samples collected in 2017 as well as clinical isolates collected from blood, bronchoalveolar lavage, nasopharynx and tracheal fluid from 2015 (n = 5), 2014 (n = 4), 2013 (n = 9) and 2012 (n = 1) at the same hospital. The specimen is denoted by shape and the collection year is denoted by colour. Due to the large difference in SNPs between the clusters, three horizontal axes were truncated (denoted by double pipe symbols). The closest distances between these clusters are denoted by the closest related inter-cluster relatives as indicated in the box. The maximum number of SNPs denoted in the hook parentheses indicate the largest distance between two isolates in the indicated cluster. Also denoted are the carbapenemases encoded by genes carried by the isolates within each cluster