Abstract
BACKGROUND: P. aeruginosa is a major cause of hospital-acquired infections, particularly in healthcare settings in the UK and Europe. In 2017, the number of patients with P. aeruginosa bacteraemia in a London teaching hospital was increasing and demographic studies had attempted to identify the cause. A case–control study was undertaken with the aim to determine the pre-existing risk factors for developing P. aeruginosa bacteraemia among hospital inpatients, many of whom were immunocompromised. METHODS: Multivariable, matched, case-control analysis using conditional logistic regression was performed to determine the risk factors associated with acquisition of P. aeruginosa bacteraemia at a tertiary care teaching hospital (800 patient beds; 98 beds for haematology patients) in London, UK. The cases were 137 patients with hospital-onset P. aeruginosa detected in blood and two control groups comprising a total of 845 patients (treated between April 2015 – July 2018). The analysis included the following predictor variables: admission method, blood test results, known viral infection, presence of central lines, surgical history, urinary tract infection and P. aeruginosa detected in urine, wound, or respiratory system. SPSS and R were used for the statistical analysis. RESULTS: Of 135 patients with bacteraemia due to Pseudomonas aeruginosa, 23 (17%) died within 30 days compared with 20 (4.1%) of 488 matched patients with no bacteraemia and 24 (6.7%) of 357 patients with other causes of bacteraemia. Analysis showed white cell count ≤ 2 × 10(9)/L was associated with increased risk of pseudomonas bacteraemia (Adj. OR = 3.3 (1.6–6.6 ; p < 0.001) vs. patients with other causes of bacteraemia. Presence of P aeruginosa in urine or respiratory secretions and number of central venous catheters were associated with Adj. OR 19.3 (95% CI: 3.0-122 ; p = 0.02), 23.0 (95% CI: 2.3-226.3 ; p = 0.007 and 2.0 (95% CI: 1.17–3.37 ; p = 0.01) respectively. CONCLUSIONS: This study showed leucopenia, having more than one central-venous catheter, P. aeruginosa urinary and respiratory infection, non-elective admission to hospital, and presence of virus were risk factors for P. aeruginosa bacteraemia. In healthcare settings where P. aeruginosa bacteraemia is prevalent, additional screening for carriage and treatment of bacteriuria with P. aeruginosa should be considered during hospital admission with an aim to prevent bacteraemia. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13756-025-01628-0.