P330 Antibiotic combination therapy and clinical outcome for multidrug-resistant Pseudomonas aeruginosa infections

Abstract

globally, tigecyclinewas consideredas the last resort to treat pandrugresistant bacteria. Though tigecycline non-susceptible K. pneumoniae isolates have been identified increasingly in recent years, the clinical information regarding bloodstream infection due to tigecycline nonsusceptible K. pneumoniae has never been reported. Objectives: The aim of this cohort study is to investigate the clinical and microbiological characteristics of tigecycline non-susceptible Klebsiella pneumoniae bacteremia in adult patients from a medical center in Taiwan. Methods: Patients with tigecycline non-susceptible K. pneumoniae bacteremia identified by E-test using FDA criteria were analyzed at a medical center in Taiwan between January 2010 and December 2012. Data on clinical features, therapy and outcomes of patients were collected from medical records. Genes for cabapenemases, plasmidic ampC -type, and extended-spectrum b-lactamases (EBSLs) were analyzed by polymerase chain reaction. Antimicrobial susceptibilities and pulsed-field gel electrophoresis (PFGE) results were determined among all the isolates. Results: A total of 36 patients with tigecycline non-susceptible K. pneumoniae bacteremia were identified. 29 patients had nosocomial bacteremia and 4patients had healthcare-associated bacteremia. Only 13 patients had the exposure to tigecycline in the past 30 days. The overall 28-day mortality rate was 36.1%. The MIC50 and MIC90 of tigecycline were 6 and 8mg/L, respectively. 8 isolates were ertapenem non-susceptible K. pneumoniae , including 2 isolates not susceptible to imipenem. 19 isolates were ESBL producers, and DHA-1 was detected in 18 isolates. No carbapenemase was detected among the 36 isolates. PFGE demonstrated that most isolates were epidemiologically unrelated. Conclusion: This study for the first time showed the distinct features of tigecycline non-susceptible K. pneumoniae causing bacteremia and the associated poor prognosis. More studies focusing on the risk factor and the resistance mechanisms of tigecycline non-susceptible K. pneumoniae bacteremia are necessary in Taiwan.