Extensively Drug Resistant Acinetobacter baumannii ST369 Infection in Emergency Intensive Care Unit in Shandong Province, China

Abstract

Background: Acinetobacter baumannii is a significant nosocomial infectious pathogen worldwide. The aim of this study is to characterize the molecular epidemiology of Acinetobacter baumannii isolated from the clinical infection, providing the epidemiology data for prevention and control. Four patients hospitalized in EICU on January 31st, 2014, and then Acinetobacter baumannii infection was observed.Antimicrobial resistance and resistance genes were analyzed by antimicrobial susceptibility testing and PCR sequencing. Pulse field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were used to analyze these strains' clonal relatedness.Results: Sixteen strains were recovered, of which 4 strains were isolated from 4 patients, and others were from environment in EICU, such as air, phone and ventilator. All strains belonged to clonal pulsotype A and ST369. Sixteen antibiotics were used to perform the susceptibility testing, and all strains were extensively drug resistant (XDR) Acinetobacter baumannii, they were only susceptible to tigecycline and polymyxin B, but resistant to others, including carbapenems and aminoglycoside antibiotics. Furthermore, all strains carried blaOXA-23-like carbapenemases gene with ISAba1 insertion sequence in the upstream, aminoglycoside resistance genes ant(3″)-I, 16S rRNA methylase gene armA and disinfectant resistant gene qacE△1, which were mainly responsible for the spread of antimicrobial resistance. Fortunately, enhanced control measures were immediately implemented after this infection, and new strains were no longer detected for consecutive three months.Conclusions: molecular epidemiology of blaOXA-23-like carbapenemase-producing Acinetobacter baumannii ST369 in EICU of a hospital was characterized. Routine monitoring should be strengthen to prevent outbreaks of this disease.