LAUSR

Fifty-four unique clinical A. baumannii strains isolated from cerebrospinal fluid (CSF) together with 21 bloodstream isolates collected from 5 tertiary hospitals in East China between April 2013 and November 2016 were studied for susceptibility patterns, and the prevalence of resistance genes. The molecular epidemiological characteristics of CSF isolates and the phylogenetic relationships of isolates from different sources were assessed using multi-locus sequence typing (MLST) and core genome multi-locus sequence typing (cgMLST). A total of 94.4% (51/54) of CSF isolates were blaOXA-23-carrying carbapenem-resistant A. baumannii (CRAB). Their average resistance rate to different classes of antibiotics was extremely high (>90%), except for tigecycline and colistin. According to the Oxford MLST scheme, all of CSF isolates fell into 10 defined STs and 4 novel STs. ST195 and ST208 were the leading STs in isolates from either source. Fifty CSF isolates and 20 bloodstream isolates were assigned to clonal complex 92 (CC92), revealing a wild distribution of CC92 in the hospitals of East China. In combination with epidemiological data linked in time and space, the cgMLST results elucidated intra- and inter-hospital polyclonal dissemination of A. baumannii meningitis. Based on cgMLST, there was no correlation between phylogeny and the source of isolation in A. baumannii. These results emphasize that the genetic potential of this pathogen is vast enough to infect multiple human body sites.