Risk factors for infection/colonization caused by resistant Gram negative bacilli in critically ill patients (An observational study of 1633 critically ill patients)

ObjectiveThe objective of this study is to identify risk factors associated with multi-resistant Gram negative (RGNB) infection and colonization among critically ill patients.MethodsA prospective cohort study of all patients aged 21–90 admitted for more than 24 hours in Medical and Surgical intensive care units (ICU) at a large teaching hospital in Singapore for the period of Aug '07–Dec '09 was conducted. Patient demographics, comorbidities, antibiotics, invasive devices, and culture results were collected. Forward stepwise logistic regression analyses were done to identify risk factors associated with RGNB infection and colonization.ResultsOf the 1373 patients included in the analysis, 13.5% developed RGNB infection. A logistic regression analysis including variables with a p value of < 0.2 in the univariate analysis showed that recent surgery (OR 2.1, 95% CI 1.2–3.6), renal impairment (OR 2.9, 95% CI 1.5–5.4), liver disease (OR: 3.8, 95% CI 1.7–8.8), central line (OR 1.8, 95% CI 1.01–3.4) were independently associated with RGNB infection in the ICU. Surgery (OR 3.9, 95% CI 2.7–5.7), third-line antibiotics (carbapenem, vancomycin, linezolid) (OR 1.8, 95% CI 1.2–2.9) were independently associated with RGNB infection during their hospitalization.ConclusionThe major risk factors identified for RGNB infection and colonization in the ICU were mainly patient dependent. However, broad spectrum initial antibiotic treatment remains an important independent modifiable risk factor. Interventions aimed at reducing initial broad spectrum antibiotics are clearly needed to help control the spread of these difficult to treat infections.

► A prospective study of 1633 patients admitted to the intensive care unit (ICU)
► 185 (13.5%) of these patients acquired a resistant Gram negative (RGNB) infection.
► Broad spectrum initial antibiotics were an independent risk factor for RGNB.
► There is an urgent need for strategies to reduce broad spectrum antibiotic use.