Molecular features and transmission of NDM-producing Acinetobacter baumannii in Israeli Hospitals

NDM-producing Acinetobacter baumannii (NDMAb) were reported globally but little is known about the epidemiology and clinical features of NDMAb-infected patients. The goals of this study were to characterize 1) the epidemiology and clinical features of NDMAb–infected patients; 2) the microbiological and molecular features of NDMAb isolates and 3) the transmission networks of NDMAb within healthcare facilities. The study was conducted at the Tel-Aviv Sourasky, Rambam and Sha'are-Zedek Medical centers (TASMC, RMC and SZMC, respectively) in Israel. All cases detected between January 2018 and July 2019 were included. Phylogenetic analysis was based on core genome SNP distances. NDMAb cases were compared at a ratio of 1:2 with non-NDM carbapenem-resistant A. baumannii (CRAb) cases. The study included 54 NDMAb-positive out of 857 CRAb patients, including 6/179 (3.3%) in TASMC, 18/441 (4.0%) in SZMC and 30/237 (12.6%) in RMC. Patients infected by NDMAb had similar clinical features and risk factors as patients with non-NDM CRAb. Most isolates (41/54, 76%) were first detected from surveillance culture. The majority of isolates harbored the blaNDM-2 gene (n=33), followed by the blaNDM-1 (n=20) gene. The common ST's were the blaNDM-1 harboring ST-2 (n=3 4) and ST-107 (n=8) in SZMC and the blaNDM-2 harboring ST-103 in SZMC (n=6) and in RMC (n=27). All blaNDM alleles were located within a conserved mobile genetic environment flanked by the ISAb125 and IS91 family transposon. Clonal transmission was identified in most cases acquired in RMC and SZMC. NDMAb constitutes a minor part of CRAb cases and are clinically indistinguishable.