181. Antimicrobial Susceptibility Trends and Risk Factors for Antibiotic Resistance in Pseudomonas aeruginosa Bacteremia: A 10-Year Experience at a Korean Tertiary Hospital

BACKGROUND: Bacteremia due to Pseudomonas aeruginosa is associated with high mortality and inappropriate initial antimicrobial therapy leads to worse outcomes. We aimed to analyze clinical characteristics of P. aeruginosa bacteremia and risk factors for antibiotic resistance and investigate their antimicrobial susceptibility trends. METHODS: We retrospectively reviewed the medical records of patients with P. aeruginosa bacteremia admitted to a tertiary hospital between January 2009 and March 2019. RESULTS: A total of 242 patients were identified and the median age was 70 years [interquartile range (IQR) 57.6–75.4]. Hepatobiliary tract (28.5%) was most common primary site of infection, followed by respiratory tract (20.2%) and urinary tract (15.7%). Out of 197 (81.4%) patients treated with susceptible antibiotics and the median duration of active antibiotic therapy was 10 days (IQR 4–15.5). The percentages of susceptible P. aeruginosa to amikacin, aztreonam, cefepime, ceftazidime, ciprofloxacin, colistin, gentamicin, imipenem, meropenem, piperacillin–tazobactam, and ticarcillin-clavulanate were 90.1%, 57.9%, 77.3%, 74.8%, 74.4%, 99.2%, 91.3%, 76.0%, 76.0%, 69.4%, and 51.2%. There were 24.8% carbapenem-resistant P. aeruginosa (CRPA), 36.4% multidrug-resistant P. aeruginosa (MDRPA), and 15.3% extensively drug-resistant P. aeruginosa (XDRPA). Susceptible P. aeruginosa to gentamycin and ticarcillin-clavulanate were significantly decreased in 2014–2019 than that in 2009–2013 (both; P < 0.001). Resistance rates to carbapenems and fluoroquinolones tended to increase over time. CRPA, MDRPA, and XDRPA were significantly associated with delayed active therapy (>48 h) (all; P < 0.001). Independent risk factors for CRPA were urinary tract infection (adjusted odds ratio [aOR], 3.4; 95% confidence interval [CI], 1.5–7.8), underlying hematologic malignancy (aOR, 3.0; 95% CI, 1.1–8.3) and cerebrovascular accident (aOR, 2.6; 95% CI, 1.1–5.9), hospital-acquired infection (aOR, 2.5; 95% CI, 1.0–6.1), and co-colonization with multidrug-resistant organisms (aOR, 2.2; 95% CI, 1.1–4.4). CONCLUSION: The identification of risk factors for antibiotic resistance and analysis of antibiotics susceptibility are useful for early initiation of appropriate antibiotics in patients with P. aeruginosa bacteremia. DISCLOSURES: All authors: No reported disclosures.