ICU-acquired nosocomial infection: impact of delay in adequate antibiotic treatment

Objective

To evaluate the impact of the delay in adequate antibiotic treatment (AAT) on outcome in ICU patients with nosocomial pneumonia (NP) or bloodstream infection (NBSI).

Design

Retrospective cohort study.

Setting

A 6-bed medical ICU in a university hospital.

Methods

Patients with first NP (bronchoalveolar lavage culture ≥ 10⁴ CFU/ml or protected specimen brush culture ≥ 10³ CFU/ml) or first NBSI (CDC definition) were included between May 1998 and September 1999. The organ failure score (Fagon criteria) at the time of sampling (day 0) and the interval between sampling and the start of AAT were recorded. Antibiotic treatment was considered to be adequate when all etiologic organisms isolated from the culture specimen were found to be sensitive to the initial empiric antibiotics. Mortality was compared according to the time of AAT and the organ failure score on day 0.

Results

A total of 25 patients (mean SAPSII = 44) were included in the study. Seventeen of them presented with a first NP and eight with a first NBSI. The infection occurred 6.5 ± 4.6 days after ICU admission, 23 patients were receiving mechanical ventilation on day 0. The ICU mortality was 48% (12/25) and was not different between NP patients and NBSI patients: 9/17 vs 3/8 (P = 0.47). Mortality increased with the duration without AAT (P = 0.011) and was reduced when AAT was started on day 0 (P = 0.016) or day 1 (P = 0.036). A subsequent change from inadequate to adequate antibiotic treatment had no impact on survival. Mortality was also associated with the number of organ failures on day 0 (P = 0.017).

Conclusions

The mortality rate in patients developing NP or NBSI can be reduced when AAT is started before day 2. When the results of the bronchoscopy specimen and blood cultures are obtained early, they can therefore be helpful to start AAT and influence survival.