Background Patients colonized with carbapenem-susceptible Pseudomonas aeruginosa (CSPA) strains upon admission to the intensive care unit (ICU) tend to be quickly followed by detected carbapenem-resistant P. aeruginosa strains after admission. Objective To assess the risk factors associated with the quick loss of carbapenem susceptibility and to identify time threshold of prior antimicrobial exposure for the loss during ICU stay. Setting A tertiary-care teaching hospital with 2560 beds located in the northwest region of China. Method A retrospective observational study was conducted between January 2013 and April 2016 at ICUs. Logistic regression analysis was used to assess risk factors, and receiver operating characteristic (ROC) analyses were constructed to identify the time threshold. Main outcome measure The time threshold and risk factors for the quick loss of carbapenem susceptibility. Results Among the 84 patients with CSPA initially, 32 (38.1%) patients were observed to have a loss of carbapenem susceptibility during ICU stay. Logistic regression analyses showed that previous carbapenem exposure was only independently associated with the loss of carbapenem susceptibility (odds ratio 13.16; 95% CI 3.13-55.24; p < 0.001). The optimal cut-off was 3.5 days on ROC curve, indicating the high risk for loss of susceptibility. Conclusion In order to alleviate selective pressure caused by antipseudomonal carbapenems exposure, continued research is needed to determine the most appropriate carbapenems treatment strategies.
Keywords: Antibiotics resistance; Carbapenem; China; Intensive care; Time threshold; Treatment strategy.