Clinical and treatment-related risk factors for nosocomial colonisation with extensively drug-resistant Pseudomonas aeruginosa in a haematological patient population: a matched case control study

Matthias Willmann, Anna M Klimek, Wichard Vogel, Jan Liese, Matthias Marschal, Ingo B Autenrieth, Silke Peter, Michael Buhl

BackgroundThis study aimed to investigate risk factors for colonisation with extensively drug-resistant P. aeruginosa (XDR-PA) in immunocompromised patients and to build a clinical risk score (CRS) based on these results.MethodsWe conducted a matched case¿control study with 31 cases and 93 controls (1:3). Cases were colonised with XDR-PA during hospitalisation. Independent risk factors were determined using a three step conditional logistic regression procedure. A CRS was built with respect to the corresponding risk fraction of each risk factor, and its discriminatory power was estimated by receiver operating characteristic (ROC) analysis.ResultsThe presence of a central venous catheter (OR 7.41, P¿=¿0.0008), the presence of a urinary catheter (OR 21.04, P¿<¿0.0001), CRP¿>¿10 mg/dl (OR 7.36, P¿=¿0.0015), and ciprofloxacin administration (OR 5.53, P¿=¿0.025) were independent risk factors. The CRS exhibited a high discriminatory power, defining a high risk population with an approximately fourteen times greater risk for XDR-PA colonisation.ConclusionsUnnecessary use of antibiotics, particularly ciprofloxacin should be avoided, and a high standard of infection control measures must be achieved when using medical devices. A CRS can be used for adaptation of the active screening culture policy to the local setting.