title: Acinetobacter baumannii nosocomial pneumonia: is the outcome more favorable in non-ventilated than ventilated patients?
abstract: BACKGROUND
  Acinetobacter baumannii hospital-acquired pneumonia (HAP) is associated with a high mortality worldwide. Non-ventilated patients with HAP (NVHAP) caused by nosocomial pathogens are reported to have a more favorable outcome than those with ventilator-associated pneumonia (VAP). The current study was designed to determine whether bacteremic patients with A. baumannii NVHAP also have a lower mortality than those receiving assisted ventilation.
  
  
  METHODS
  This retrospective 10-year study was conducted at a 2900-bed teaching hospital located in Northern Taiwan. The population consisted of 144 patients with A. baumannii bacteremia and HAP. Of these 96 had VAP and 48 had NVHAP. Charts were reviewed for demographic characteristics, comorbidities, clinical manifestations, antimicrobial susceptibility, and 14-day mortality. Clonal relationships were determined by molecular typing.
  
  
  RESULTS
  There were no significant differences between the two groups in comorbidities (Charlson scores). Patients with NVHAP were more likely to have developed bacteremia earlier, outside the ICU and undergone fewer invasive procedures. They had significantly lower APACHE II scores, fewer bilateral pneumonias and lower rates of antimicrobial resistance. No specific clones were identified in either group. The unadjusted (crude) 14-day mortality rates were not significantly different between the groups (NVHAP 43.8% vs. VAP 31.3%, p = 0.196). The adjusted 14-day mortality risk was significantly lower in ventilator-assisted patients (odds ratio = 0.201; 95% confidence interval = 0.075-0.538; p = 0.001).
  
  
  CONCLUSIONS
  Patients with bacteremic NVHAP and VAP caused by A. baumannii had similar crude mortality rates, but on logistic regression analysis those receiving ventilator assistance had a significantly lower mortality. This may have been due to better airway protection, more intensive monitoring with earlier diagnosis and treatment in patients with VAP, greater innate susceptibility to infection in those with NVHAP and differences in the virulence of A. baumannii.
authors.affiliation: Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Ya-Sung
authors.initials: YS
authors.lastname: Yang
authors.forename: Yi-Tzu
authors.initials: YT
authors.lastname: Lee
authors.forename: Tsai-Wang
authors.initials: TW
authors.lastname: Huang
authors.forename: Jun-Ren
authors.initials: JR
authors.lastname: Sun
authors.forename: Shu-Chen
authors.initials: SC
authors.lastname: Kuo
authors.forename: Chin-Hsuan
authors.initials: CH
authors.lastname: Yang
authors.forename: Te-Li
authors.initials: TL
authors.lastname: Chen
authors.forename: Jung-Chung
authors.initials: JC
authors.lastname: Lin
authors.forename: Chang-Phone
authors.initials: CP
authors.lastname: Fung
authors.forename: Feng-Yee
authors.initials: FY
authors.lastname: Chang
mesh_terms: D018806:APACHE; D000151:Acinetobacter Infections / Q000453:epidemiology* / Q000382:microbiology / Q000401:mortality; D040981:Acinetobacter baumannii / Q000235:genetics / Q000302:isolation & purification*; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015897:Comorbidity; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology / Q000401:mortality; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D016017:Odds Ratio; D010802:Phylogeny; D018410:Pneumonia, Bacterial / Q000453:epidemiology* / Q000382:microbiology / Q000401:mortality; D053717:Pneumonia, Ventilator-Associated / Q000453:epidemiology* / Q000382:microbiology / Q000401:mortality; D012121:Respiration, Artificial / Q000706:statistics & numerical data; D012189:Retrospective Studies; D013624:Taiwan / Q000453:epidemiology; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents