Predictors and outcome associated with an Enterococcus positive isolate during intensive care unit admission

Abstract

This study reports the incidence, risk factors and mortality associated with a positive Enterococcus spp. isolate during admission to two tertiary intensive care units participating in an antibiotic cycling study. Incidence was low, with only 4.2% of admissions (36/852) at Royal Brisbane and Women's Hospital and 2.8% (31/1104) at Westmead Hospital developing a positive Enterococcus spp. isolate (P=0.087). A positive enterococcal isolate, while not an independent predictor of mortality (odds ratio [OR]=1.6, 95% confidence interval [CI] 0.80 to 3.2, P=0.18), may be a marker of the underlying severity of illness with higher unadjusted in-hospital mortality (26% or 17/66 vs 14% or 250/1855, P=0.007). Independent risk factors for a positive isolate were use of meropenem/imipenem (OR=5.7, 95% CI 2.4 to 14, P <0.001) and cefepime (OR=2.5, 95% CI 1.2 to 5.3, P=0.017) within 48 hours of intensive care unit admission, the presence of a nasogastric tube (OR=4.1, 95% CI 1.3 to 14, P=0.018), renal replacement therapy (OR=2.2, 95% CI 1.0 to 4.7, P=0.046), operative intervention (OR=1.8, 95% CI 1.0 to 3.2, P=0.035) and age (OR=1.2, 95% CI 1.1 to 1.5, P=0.009). None of these factors, except for the need for renal replacement therapy (OR=6.2, 95% CI 1.4 to 27, P=0.015), was associated with increased mortality. Enterococci-directed empiric therapy in the treatment of sepsis remains of unproven value, although this negative finding must be evaluated against other higher powered studies.