Clinical isolates of Acinetobacter baumannii from bloodstream infections: PFGE characterization and virulence-associated factors

Abstract

Objective The epidemiology of Acinetobacter baumannii isolates from bloodstream infections, their antibiotic resistance profiles and virulence-associated factors were studied. Methods A total of 90 isolates from 17 hospitals were collected from the patients with bloodstream infections during July 2013 and July 2014.Vitek-2 Compact system was used for identification of the strains and antibiotic susceptibility testing. The epidemiology was studied by pulsed-field gelectrophoresis(PFGE). Drug-resistant genes and associated virulence genes were amplified by PCR. Results According to antimicrobial susceptibility testing, 75 isolates are multi-drug resistant Acinetobacter baumannii. PFGE results showed that 75 multi-drug resistant Acinetobacter baumannii isolates belonged to eight clone types(A to H), with the A (n=51)and B (n=14)clone being the dominant PFGE clone types. Different clone isolates spread in different hospitals. Most of the hospitals were given priority to with clone A. Clone A only maintaining high sensitive rate to cefoperazone/sulbactam、amikacin and tigecycline. Virulence gene abaI, cusE, ompA, bap, bfms detection rates are 93.3% (84/90), 92.2% (83/90), 100.0% (90/90), 84.4% (76/90), 92.2% (83/90), respectively. There were 7 mucoid isolates, which are all multi-drug resistant Acinetobacter baumannii, all belong to clone B and all associated virulence genes can be detected. Conclusions The dominant clone type of multi-drug resistant Acinetobacter baumannii from bloodstream infections is clone A. The abaI-, bap- and bfms-positive strains are associated with a higher incidence of antibiotic resistance in most types of antimicrobials. The acquisition of mucous type may indicate the emergence of virulent strains, which should be paid attention to during clinical treatment.(Chin J Lab Med, 2017, 40: 201-205) Key words: Acinetobacter baumannii; Virulence; Bacteremia