title: Association of ertapenem and antipseudomonal carbapenem usage and carbapenem resistance in Pseudomonas aeruginosa among 12 hospitals in Queensland, Australia.
abstract: OBJECTIVE
  The objective of this study was to determine the association between ertapenem and antipseudomonal carbapenem use and carbapenem resistance in Pseudomonas aeruginosa in 12 hospitals in Queensland, Australia.
  
  
  METHODS
  Data on usage of ertapenem and other antipseudomonal carbapenems, measured in defined daily doses per 1000 occupied bed-days, were collated using statewide pharmacy dispensing and distribution software from January 2007 until June 2011. The prevalence of unique carbapenem-resistant P. aeruginosa isolates derived from statewide laboratory information systems was collected for the same time period. Mixed-effects models were used to determine any relationship between ertapenem and antipseudomonal carbapenem usage and carbapenem resistance among P. aeruginosa isolates in the 12 hospitals analysed.
  
  
  RESULTS
  No relationship between ertapenem usage and P. aeruginosa carbapenem resistance was observed. The introduction of ertapenem did not replace antipseudomonal carbapenem prescribing to any significant extent. However, an association between greater usage of antipseudomonal carbapenems and greater P. aeruginosa carbapenem resistance was demonstrated.
  
  
  CONCLUSIONS
  It is likely that the only mechanism by which ertapenem can improve P. aeruginosa resistance patterns is by being used as a substitute for, rather than in addition to, antipseudomonal carbapenems.
authors.affiliation: Pharmacy Department, Princess Alexandra Hospital, Queensland, Australia. david_mcdougall@health.qld.gov.au
authors.forename: David A J
authors.initials: DA
authors.lastname: McDougall
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Morton
authors.forename: E Geoffrey
authors.initials: EG
authors.lastname: Playford
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D015780:Carbapenems / Q000627:therapeutic use*; D004363:Drug Utilization / Q000706:statistics & numerical data; D000077727:Ertapenem; D006761:Hospitals; D006801:Humans; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000302:isolation & purification; D011793:Queensland; D018440:beta-Lactam Resistance; D047090:beta-Lactams / Q000627:therapeutic use*
chemical_list: D000900:Anti-Bacterial Agents; D015780:Carbapenems; D047090:beta-Lactams; D000077727:Ertapenem