title: Citrobacter peritoneal dialysis peritonitis: rare occurrence with poor outcomes.
abstract: BACKGROUND
  Non-Pseudomonas gram-negative bacteria are responsible for an increasing proportion of cases of peritoneal dialysis (PD)-related peritonitis. The role of Citrobacter species in the etiology of PD-related peritonitis is often underestimated. In the present study, we aimed to describe the clinical features, laboratory findings, and short- and long-term outcomes in PD-related peritonitis caused by Citrobacter.
  
  
  METHODS
  A retrospective review of all episodes of PD-related peritonitis caused by Citrobacter from a single center between 1990 and 2010 was performed. Clinical features, microbiological data, and outcomes of these episodes were analyzed.
  
  
  RESULTS
  Citrobacter species was responsible for 11 PD-related episodes (1.8% of all peritonitis episodes) in 8 patients. Citrobacter freundii was the most common etiologic species (73%), and mixed growth was found in the other 3 episodes (27%). Approximately half (46%) of the episodes were associated with constipation and/or diarrhea. Of the Citrobacter isolates from all episodes, 54% were resistant to cefazolin, and only 18% were susceptible to cefmetazole. All isolates were susceptible to ceftazidime, cefepime, carbapenem, and aminoglycosides. More than half of the patients (54%) were hospitalized for index peritonitis, and 27% of the episodes involved a change in antibiotic medication. One patient had relapsing peritonitis caused by C. koseri (9%). The mortality rate of PD-related peritonitis caused by Citrobacter was 18%, and 89% of surviving patients developed technique failure requiring a modality switch after an average of 12 months of follow-up (range 1.2-31.2 months).
  
  
  CONCLUSIONS
  PD-related peritonitis caused by Citrobacter is associated with poor outcomes, including high rates of antibiotic resistance, a high mortality rate, and a high rate of technique failure among survivors during the follow-up period.
authors.affiliation: Department of Traumatology, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Chia-Ter
authors.initials: CT
authors.lastname: Chao
authors.forename: Szu-Ying
authors.initials: SY
authors.lastname: Lee
authors.forename: Wei-Shun
authors.initials: WS
authors.lastname: Yang
authors.forename: Huei-Wen
authors.initials: HW
authors.lastname: Chen
authors.forename: Cheng-Chung
authors.initials: CC
authors.lastname: Fang
authors.forename: Chung-Jen
authors.initials: CJ
authors.lastname: Yen
authors.forename: Chih-Kang
authors.initials: CK
authors.lastname: Chiang
authors.forename: Kuan-Yu
authors.initials: KY
authors.lastname: Hung
authors.forename: Jenq-Wen
authors.initials: JW
authors.lastname: Huang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002954:Citrobacter / Q000472:pathogenicity*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010530:Peritoneal Dialysis / Q000009:adverse effects*; D010538:Peritonitis / Q000209:etiology* / Q000382:microbiology* / Q000473:pathology; D012189:Retrospective Studies; D055815:Young Adult
keywords: Citrobacter; end-stage renal disease; gram-negative bacteria; peritoneal dialysis; peritonitis.