title: Epidemiology and outcome of Klebsiella species bloodstream infection: a population-based study.
abstract: OBJECTIVE
  To determine incidence rate, seasonal variation, and short- and long-term outcomes of Klebsiella species bloodstream infection (BSI) in a population-based setting.
  
  
  METHODS
  We identified 127 unique patients in Olmsted County, Minnesota, from January 1, 1998, to December 31, 2007, who had Klebsiella spp BSI. Multivariable Poisson regression was used to examine temporal change and seasonal variation in incidence rate, and Cox proportional hazards regression was used to determine predictors of mortality.
  
  
  RESULTS
  The age-adjusted incidence rate of Klebsiella spp BSI per 100,000 person-years was 15.4 (95% confidence interval [CI], 11.6-19.2) in men and 9.4 (95% CI, 7.0-11.8) in women. There was no linear increase in incidence rate of Klebsiella spp BSI during the study period (P=.55). The incidence rate of Klebsiella spp BSI increased at quadratic rate with age (P=.005). No significant difference was noted in incidence rate of Klebsiella spp BSI during the warmest 4 months compared to the rest of the year (incidence rate ratio, 0.97; 95% CI, 0.66-1.38; P=.95). The overall 28-day and 1-year all-cause mortality rates of Klebsiella spp BSI were 14% (95% CI, 9%-22%) and 35% (95% CI, 27%-44%), respectively. Respiratory source of BSI was associated with a higher 28-day mortality (hazard ratio, 4.90; 95% CI, 1.73-13.84; P=.003).
  
  
  CONCLUSIONS
  The incidence rate of Klebsiella spp BSI increased with age. There was no temporal change or seasonal variation in incidence rate of Klebsiella spp BSI during the past decade. The 28-day all-cause mortality rate of Klebsiella spp BSI was relatively low; however, a respiratory source of BSI was associated with a poorer outcome.
authors.affiliation: Department of Medicine, University of Kentucky Chandler Medical Center, 800 Rose St, Room MN 672, Lexington, KY 40536, USA. majdi.alhasan@uky.edu
authors.forename: Majdi N
authors.initials: MN
authors.lastname: Al-Hasan
authors.forename: Brian D
authors.initials: BD
authors.lastname: Lahr
authors.forename: Jeanette E
authors.initials: JE
authors.lastname: Eckel-Passow
authors.forename: Larry M
authors.initials: LM
authors.lastname: Baddour
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D016470:Bacteremia / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D002423:Cause of Death; D002648:Child; D002675:Child, Preschool; D017714:Community-Acquired Infections / Q000453:epidemiology; D003428:Cross Infection / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007223:Infant; D053208:Kaplan-Meier Estimate; D007710:Klebsiella Infections / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D008910:Minnesota / Q000453:epidemiology; D015999:Multivariate Analysis; D011159:Population Surveillance; D016016:Proportional Hazards Models; D012044:Regression Analysis; D012307:Risk Factors; D012621:Seasons; D017678:Sex Distribution; D016896:Treatment Outcome