title: A multicenter case-case control study for risk factors and outcomes of extensively drug-resistant Acinetobacter baumannii bacteremia.
abstract: OBJECTIVE
  Extensively drug resistant (XDR) Acinetobacter baumannii infections are increasing. Knowledge of risk factors can help to prevent these infections.
  
  
  METHODS
  We designed a 1∶1∶1 case-case-control study to identify risk factors for XDR A. baumannii bacteremia in Singapore and Thailand. Case group 1 was defined as having infection due to XDR A. baumannii, and case group 2 was defined as having infection due to non-XDR A. baumannii. The control group comprised patients with blood cultures obtained to determine possible infection.
  
  
  RESULTS
  There were 93 patients in each group. Pitt bacteremia score (adjusted odds ratio [aOR], 2.570 [95% confidence interval (CI), 1.528-4.322]), central venous catheters (CVCs; aOR, 12.644 [95% CI, 2.143-74.620]), use of carbapenems (aOR, 54.391 [95% CI, 3.869-764.674]), and piperacillin-tazobactam (aOR, 55.035 [95% CI, 4.803-630.613]) were independently associated with XDR A. baumannii bacteremia. In case group 2, Pitt bacteremia score (aOR, 1.667 [95% CI, 1.265-2.196]) and third-generation cephalosporins (aOR, 2.965 [95% CI, 1.224-7.182]) were independently associated with non-XDR A. baumannii bacteremia. Concurrent infections (aOR, 3.527 [95% CI, 1.479-8.411]), cancer (aOR, 3.172 [95% CI, 1.135-8.865]), and respiratory source (aOR, 2.690 [95% CI, 1.160-6.239]) were associated with an increased risk of 30-day mortality. Survivors received more active empirical therapy (16.7% vs 9.6%; P = .157), had fewer cases of XDR bacteremia (45.8% vs 52.6%; P = .452), and received higher median definitive polymyxin B doses (840,000 units vs 700,000 units; P = .339) CONCLUSIONS: Use of CVC and broad spectrum antibiotics were unique risk factors of XDR A. baumannii bacteremia. Effective antimicrobial stewardship together with use of a CVC bundle may reduce the incidence of these infections. Risk factors of acquisition and mortality may help identify patients for early initiation of polymyxin B therapy.
authors: Department of Pharmacy, Tan Tock Seng Hospital, Singapore.
authors: Tat Ming
authors: TM
authors: Ng
authors: Christine B
authors: CB
authors: Teng
authors: David C
authors: DC
authors: Lye
authors: Anucha
authors: A
authors: Apisarnthanarak
mesh_terms: D000151:Acinetobacter Infections / Q000188:drug therapy* / Q000401:mortality; D040981:Acinetobacter baumannii; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D016470:Bacteremia / Q000188:drug therapy* / Q000401:mortality; D015780:Carbapenems / Q000627:therapeutic use; D016022:Case-Control Studies; D062905:Central Venous Catheters; D002511:Cephalosporins / Q000627:therapeutic use; D060085:Coinfection / Q000401:mortality; D024881:Drug Resistance, Bacterial; D005260:Female; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D009369:Neoplasms / Q000401:mortality; D010397:Penicillanic Acid / Q000031:analogs & derivatives / Q000627:therapeutic use; D010878:Piperacillin / Q000627:therapeutic use; D000077725:Piperacillin, Tazobactam Drug Combination; D011112:Polymyxin B / Q000627:therapeutic use; D012141:Respiratory Tract Infections / Q000401:mortality; D012307:Risk Factors; D012720:Severity of Illness Index; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents; D015780:Carbapenems; D002511:Cephalosporins; D000077725:Piperacillin, Tazobactam Drug Combination; D010397:Penicillanic Acid; D011112:Polymyxin B; D010878:Piperacillin