Risk factors for treatment failure in patients with ventilator-associated pneumonia receiving appropriate antibiotic therapy

Introduction

Treatment failure (TF) can be anticipated in 30–40% of patients developing ventilator-associated pneumonia (VAP). Little information about lack of response of VAP to treatment is available. The aim of the study is to evaluate potential risk factors for TF in patients with VAP receiving appropriate antibiotic therapy.

Methods

A prospective observational cohort study. Microbiologically confirmed (>10⁵ colony-forming units/ml) clinical findings (CPIS > 6) were necessary for the diagnosis of VAP. TF was defined as a lack of clinical (in first 3 days of the therapy) and microbiological (in first 7 days of the therapy) response to therapy. All patients had surveillance cultures for endotracheal aspirate (every second day), urine and blood (weekly). Student's t tests, chi-square tests and logistic regression analyses were used for statistical analyses.

Results

Eighty-one patients enrolled into the study; 40% of them were female and the mean age was 71 ± 14. Fifty-one of the patients had TF. When the groups were compared (TF and treatment success), patients with TF were older, had more comorbidities, higher admission and VAP APACHE II scores, Acinetobacter baumanni pneumonia, higher initial bacterial load (colony-forming units/ml) and lower daily carbohydrate intake. Transfusions, bacteremia, infection with multidrug-resistant microorganismis and steroid therapy were similar across the groups. Among the significant parameters, age and comorbidity were not entered into the logistic regression since the APACHE II score covers these two parameters. VAP with A. baumanni (OR 4.4, 95% CI 1.2–16, P = 0.027), higher VAP APACHE II scores (OR 12, 95% CI, 3–45, P = 0.0001) and lower daily carbohydrate intake (OR 4.4, 95% CI 1.3–15, P = 0.016) were independent predictors for TF in logistic regression analyses.

Conclusion

These results suggest that patients with higher VAP APACHE II scores and pneumonia with A. baumanni and lower carbohydrate intake were at risk for TF.