Comparative analysis of patients with early-onset versus late-onset nosocomial lower respiratory tract infections in medical ICU

Objective

To compare risk factors and pathogens between early-onset (occurring 48–96 hours after ICU admission) nosocomial lower respiratory tract infections (NLRTI) and late-onset (occurring after 96 hours of ICU admission) NLRTI.

Patients and methods

From March 1993 to September 1999, all patients admitted in our 30-bed medical ICU were included in this study, their characteristics were prospectively collected. CDC criteria were employed to define nosocomial pneumonia and tracheobronchitis.

Patients with early-onset NLRTI and those with late-onset NLRTI were compared to patients without NLRTI by univariate and multivariate analysis.

Results

Three thousand six hundred and eighty-one patients were hospitalized (age 58 ± 18 years, SAPS II 37 ± 17, length of ICU stay 12 ± 15 days, mechanical ventilation [MV] 85%, duration of MV 11 ± 13 days, ICU mortality 36%, secondary hospitalization 82%, antimicrobial therapy before ICU admission 49%).

Five hundred and seventeen (14%) patients developed at least one episode of NLRTI, late-onset NLRTI were more frequent than early-onset NLRTI (87% and 13% respectively).

Multidrug resistant bacteria were isolated in the major part of NLRTI (respectively for early-onset and late-onset NLRTI): Pseudomonas aeruginosa (21%, 24%), Staphylococcus aureus (16%, 12%) and Acinetobacter baumannii (12%, 30%).

Conclusion

The risk factors associated with either early-onset or late-onset NLRTI are similar to those identified by other studies. In our population, length of ICU stay before NLRTI occurrence does not seem to have an impact on the nature of causing organism; these data could be helpful to improve initial empiric antimicrobial therapy in our ICU.

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