Risk of acquiring multidrug-resistant Gram-negative bacilli from prior room occupants in the intensive care unit

The objective of this prospective cohort study was to determine whether admission to an intensive care unit (ICU) room previously occupied by a patient with multidrug-resistant (MDR) Gram-negative bacilli (GNB) increases the risk of acquiring these bacteria by subsequent patients. All patients hospitalized for >48 h were eligible. Patients with MDR GNB at ICU admission were excluded. The MDR GNB were defined as MDR Pseudomonas aeruginosa, Acinetobacter baumannii and extended spectrum β-lactamase (ESBL) -producing GNB. All patients were hospitalized in single rooms. Cleaning of ICU rooms between two patients was performed using quaternary ammonium disinfectant. Risk factors for MDR P. aeruginosa, A. baumannii and ESBL-producing GNB were determined using univariate and multivariate analysis. Five hundred and eleven consecutive patients were included; ICU-acquired MDR P. aeruginosa was diagnosed in 82 (16%) patients, A. baumannii in 57 (11%) patients, and ESBL-producing GNB in 50 (9%) patients. Independent risk factors for ICU-acquired MDR P. aeruginosa were prior occupant with MDR P. aeruginosa (OR 2.3, 95% CI 1.2–4.3, p 0.012), surgery (OR 1.9, 95% CI 1.1–3.6, p 0.024), and prior piperacillin/tazobactam use (OR 1.2, 95% CI 1.1–1.3, p 0.040). Independent risk factors for ICU-acquired A. baumannii were prior occupant with A. baumannii (OR 4.2, 95% CI 2–8.8, p <0.001), and mechanical ventilation (OR 9.3, 95% CI 1.1– 83, p 0.045). Independent risk factors for ICU-acquired ESBL-producing GNB were tracheostomy (OR 2.6, 95% CI 1.1–6.5, p 0.049), and sedation (OR 6.6, 95% CI 1.1–40, p 0.041). We conclude that admission to an ICU room previously occupied by a patient with MDR P. aeruginosa or A. baumannii is an independent risk factor for acquisition of these bacteria by subsequent room occupants. This relationship was not identified for ESBL-producing GNB.