Incidence and resistance rates of Pseudomonas aeruginosa bloodstream infections in Switzerland: a nationwide surveillance study (2010-2022).

PURPOSE

Bloodstream infections (BSIs) cause significant morbidity and mortality worldwide. Pseudomonas aeruginosa is an important microorganism in BSIs. The aim of this study was to analyze recent trends in the incidence and resistance rates of P. aeruginosa BSIs in Switzerland and its different linguistic regions.

METHODS

This retrospective, nationwide observational study analyzed the incidence (using Poisson regression models) and antimicrobial resistance (using logistic regression models) of P. aeruginosa BSIs in Switzerland from 2010 to 2022.

RESULTS

The annual incidence of P. aeruginosa BSIs in Switzerland increased from 5.5 BSIs per 100,000 inhabitants in 2010 to 7.6 BSIs per 100,000 inhabitants in 2022 (p < 0.001). The incidence was higher in the French-speaking region than in the German-speaking region. The resistance rates increased significantly for cefepime (2.4% in 2010, 8.8% in 2022; p < 0.001), ceftazidime (5.6% in 2010, 9.4% in 2022; p = 0.014), ciprofloxacin (3.3% in 2010, 6.5% in 2022; p = 0.014), and piperacillin-tazobactam (6.4% in 2010, 11.2% in 2022; p = 0.002). No significant trends were observed for carbapenem-, aminoglycoside-, or multidrug-resistant P. aeruginosa. A high incidence was observed in patients ≥ 80 years, whereas resistance rates were high in young patients.

CONCLUSION

The increase in the incidence of P. aeruginosa BSIs emphasizes the importance of monitoring resistant and susceptible P. aeruginosa BSIs. Compared to the population-weighted mean resistance rates in Europe in 2022, those in Switzerland were lower, but an increase was observed for most antibiotics. The high resistance rates in young patients require further investigation.