The Resistance Phenotype and Molecular Epidemiology of in Bloodstream Infections in Shanghai, China, 2012-2015.

(.pneumoniae) is a common nosocomial pathogen causing bloodstream infections. Antibiotic susceptibility surveillance and molecular characterization will facilitate prevention and management of bloodstream infections. isolates causing bloodstream infections were consecutively collected between January 2012 and December 2015 in Shanghai. Eighty isolates (20 per year) were randomly selected and enrolled in this study. Drug susceptibility were determined by the disk diffusion method. Polymerase chain reaction (PCR) was employed to detect extended-spectrum β-lactamases (ESBLs), carbapenemases, and seven housekeeping genes of . eBURST was used for multi-locus sequence typing (MLST). More than 50% isolates were resistant to cefuroxime, ampicillin-sulbactam, and piperacillin, while carbapenems had lower resistant rates than other antibiotics. Of the 80 isolates, 22 produced ESBLs, and 14 were carbapenemase producers. In the ESBL-producing isolates, the most common ESBL genes were and . Thirteen carbapenemase producers harbored and one other carried . ST11 (14/80) was the most frequent sequence type (ST), followed by ST15 (7/80) and ST29 (4/80). Our data revealed high prevalence of antibiotic resistant isolates from bloodstream infections but their genetic diversity suggested no clonal dissemination in the region. Also, one isolate harbored in this study, which was firstly reported in Shanghai.