title: Risk factors and outcome for colistin-resistant Acinetobacter nosocomialis bacteraemia in patients without previous colistin exposure.
abstract: The clinical characteristics of patients with colistin-resistant Acinetobacter baumannii bacteraemia have been documented, but those of patients with bacteraemia caused by other Acinetobacter species remain unknown. Previous exposure to colistin has been shown to be associated with the emergence of colistin resistance, but may be not the only predisposing factor. In the current study, we highlight the risk and outcome of patients without previous exposure to colistin who acquired colistin-resistant Acinetobacter nosocomialis (ColRAN) bacteraemia. This 11-year single-centre retrospective study analysed 58 patients with ColRAN bacteraemia and 213 patients with colistin-susceptible A. nosocomialis (ColSAN) bacteraemia. Antimicrobial susceptibilities were determined with an agar dilution method. The clonal relationship of ColRAN isolates was determined with pulsed-field gel electrophoresis. A conjugation mating-out assay was conducted to delineate the potential transfer of colistin resistance genes. Multivariable analysis was performed to evaluate the risk factors for ColRAN bacteraemia. Chronic obstructive pulmonary disease (COPD) was independently associated with ColRAN bacteraemia (OR 3.04; 95% CI 1.45-6.37; p 0.003). Patients with ColRAN bacteraemia had higher APACHE II scores, but the two groups showed no significant differences in 14-day mortality (10.3% vs. 10.3%) or 28-day mortality (15.5% vs. 15.0%). ColRAN isolates had greater resistance than ColSAN isolates to all antimicrobial agents except for ciprofloxacin (0% vs. 6.6%). There were 16 different ColRAN pulsotypes, and two major clones were found. Colistin resistance did not transfer to colistin-susceptible A. baumannii or A. nosocomialis. These results show that COPD is an independent risk factor for acquisition of ColRAN bacteraemia. The mortality rates were similar between patients with ColRAN and ColSAN bacteraemia.
authors.affiliation: Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Centre, Taipei, Taiwan; Penghu Branch, Tri-Service General Hospital, National Defense Medical Centre, Penghu, Taiwan; Institute of Clinical Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Y-C
authors.initials: YC
authors.lastname: Wang
authors.affiliation: Institute of Clinical Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Emergency Department, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Y-T
authors.initials: YT
authors.lastname: Lee
authors.affiliation: Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Centre, Taipei, Taiwan.
authors.forename: Y-S
authors.initials: YS
authors.lastname: Yang
authors.affiliation: Institute of Clinical Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Emergency Department, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: C-T
authors.initials: CT
authors.lastname: Chen
authors.affiliation: Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Centre, Taipei, Taiwan; Institute of Clinical Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: C-H
authors.initials: CH
authors.lastname: Chiu
authors.affiliation: Songshan Branch, Tri-Service General Hospital, National Defense Medical Centre, Taipei, Taiwan.
authors.forename: T
authors.initials: T
authors.lastname: Yin
authors.affiliation: Institute of Clinical Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan; National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Miaoli County, Taiwan.
authors.forename: S-C
authors.initials: SC
authors.lastname: Kuo
authors.affiliation: Institute of Clinical Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Division of Infectious Diseases, Department of Medicine, Cheng-Hsin General Hospital, Taipei, Taiwan. Electronic address: tecklayyy@gmail.com.
authors.forename: T-L
authors.initials: TL
authors.lastname: Chen
authors.affiliation: Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Centre, Taipei, Taiwan.
authors.forename: J-C
authors.initials: JC
authors.lastname: Lin
authors.affiliation: Division of Infectious Diseases, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: F-D
authors.initials: FD
authors.lastname: Wang
authors.affiliation: Institute of Clinical Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Division of Infectious Diseases, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: C-P
authors.initials: CP
authors.lastname: Fung
authors.affiliation: Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Centre, Taipei, Taiwan.
authors.forename: F-Y
authors.initials: FY
authors.lastname: Chang
mesh_terms: D000150:Acinetobacter / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D000151:Acinetobacter Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000401:mortality; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use*; D016470:Bacteremia / Q000188:drug therapy / Q000453:epidemiology* / Q000401:mortality; D003091:Colistin / Q000494:pharmacology*; D003227:Conjugation, Genetic; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D022761:Gene Transfer, Horizontal; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D058889:Molecular Typing; D012189:Retrospective Studies; D012307:Risk Factors; D016019:Survival Analysis; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D003091:Colistin
keywords: Acinetobacter nosocomialis; chronic obstructive pulmonary disease; colistin resistant; mechanical ventilation; mortality