Clinical outcome in ICU patients with Enterobacter bacteremia

Purpose and methods

To investigate the clinical impact of Enterobacter bacteremia in ICU patients, a retrospective (January 1992–December 2000), matched cohort study was performed. All ICU patients with Enterobacter bacteremia were defined as cases (n = 67). Matching of the controls (1:2–ratio) (n = 134) was based on the APACHE II system: an equal APACHE II score (± 1 point) and admission diagnosis.

Results

There was a high rate of appropriate antibiotic therapy in patients with Enterobacter bacteremia (96%). The mean delay in the start of antibiotic therapy was short (0.5 ± 0.9 days). Following the matching procedure cases and controls had nearly equal APACHE II scores (23 ± 8.3 vs 23 ± 8.3; P = 0.890) and related expected mortality rates (41 ± 24.1% vs 40 ± 24.1%; P = 0.805). Patients with Enterobacter bacteremia had more hemodynamic instability (78% vs 60%; P = 0.015). They also had a longer ICU stay (36 ± 32.1 vs 15 ± 18.7 days; P < 0.001) and a longer ventilator dependence (32 ± 26.8 vs 12 ± 17.0 days; P < 0.001). There was no difference between cases and controls in age (52 ± 19.8 vs 53 ± 19.3 years; P = 0.831), acute respiratory failure (93% vs 84%; P = 0.079) and acute renal failure (16.4% vs 15.8%; P = 0.892). Hospital mortality was not different between cases and control patients (34.3% vs 38.8%; P = 0.536). A multivariate survival analysis showed the APACHE II related expected mortality as the only independent predictor of mortality (HR, 3.7; 95% CI, 2.0–6.7; P < 0.001).

Conclusion

After accurate adjustment for severity of underlying disease and acute illness, no difference in mortality was found between ICU patients with Enterobacter bacteremia (34.3%) and their matched cohort subjects (38.8%). In the presence of accurate and prompt antibiotic therapy, bacteremia involving Enterobacter species does not adversely affect the outcome in ICU patients.