Clinical characteristics and risk factors for carbapenem-resistant Pseudomonas aeruginosa infection

BACKGROUND: Pseudomonas aeruginosa (PA) is a major opportunistic pathogen responsible for nosocomial infections, particularly those affecting the lower respiratory tract. The emergence of carbapenem-resistant PA (CRPA) poses a significant global therapeutic challenge, as increasing resistance rates complicate clinical management. OBJECTIVES: To investigate the clinical characteristics and antimicrobial resistance profiles of CRPA infections, identify associated risk factors among patients at The Affiliated Hospital of North Sichuan Medical College, and provide evidence for the development of effective prevention and control strategies. MATERIAL AND METHODS: A retrospective case-control study was conducted involving 94 patients with CRPA infection (study group) and 50 patients with CSPA infection (control group) between January 2021 and December 2022. Clinical characteristics and risk factors were analyzed using univariate analyses and multivariable logistic regression. Variable selection for the primary model was performed using best-subset selection based on the Bayesian information criterion (BIC). RESULTS: Carbapenem-resistant PA isolates were primarily recovered from lower respiratory tract secretions (77.66%) and were most frequently identified in the intensive care unit (ICU) (41.49%). Compared with CSPA strains, CRPA exhibited significantly higher resistance rates to aztreonam, ciprofloxacin, levofloxacin, and cephalosporins (p < 0.05). Multivariable logistic regression using best-subset selection identified prior exposure to carbapenems (adjusted odds ratio (aOR) = 6.914, 95% confidence interval (95% CI): 2.765-17.290, p < 0.001) and aminoglycosides (aOR = 6.209, 95% CI: 1.701-22.668, p = 0.006) as independent risk factors for CRPA infection. CONCLUSIONS: Carbapenem-resistant PA infection imposes a considerable burden in our hospital, particularly among ICU patients. Prior exposure to carbapenems and aminoglycosides significantly increases the risk of CRPA infection. The BIC-selected model identified the same main risk factors as the fully adjusted sensitivity analysis, supporting the consistency of the findings. Strengthening antimicrobial stewardship and tailoring empirical therapy according to local antimicrobial susceptibility patterns are essential to curb resistance and improve clinical outcomes.