Study objectives: To asses the impact of locally developed antimicrobial treatment guidelines in the initial empiric treatment of ICU patients with severe hospital-acquired pneumonia (HAP).
Design: Observational cohort study with pre-guideline and post-guideline data collection.
Patients: A total of 48 pre-guideline patients with 56 episodes of severe HAP defined by the National Nosocomial Infections Surveillance (NNIS) compared with 58 guideline-treated (GUIDE) patients with 61 episodes of severe HAP.
Results: The two groups were similar in terms of mean (+/- SD) age (NNIS group, 67.7 +/- 9.6 years; GUIDE group, 68.0 +/- 11.5 years) and simplified acute physiology score (NNIS group, 12.9 +/- 3.9; GUIDE group, 12.6 +/- 3.1) at the HAP diagnosis, and the proportion of the most frequent isolates (ie, Pseudomonas and methicillin-resistant Staphylococcus aureus). There was wide variation in initial antibiotic use in NNIS-treated patients, with cefotaxime, ceftazidime, and piperacillin being the most common agents compared with all of the GUIDE patients who received an imipenem-cilastin-based regimen. Vancomycin use was similar in both groups. The GUIDE patients had a higher percentage of adequately treated patients (81% vs 46%, respectively; p < 0.01) with a lower mortality rate at 14 days (8% vs 23%, respectively; p = 0.03). A lower mortality rate was also noted at the end of 30 days and the end of hospitalization but was not statistically significant. Appropriate imipenem use (as defined by the guidelines) occurred in 74% of the cases, and there was no increase in the number of imipenem-resistant organisms isolated during the course of the study.
Conclusions: These guidelines represent a successful implementation of a "deescalation" approach, because the recommended empiric therapy with broad-spectrum antibiotics was switched to therapy with narrower spectrum agents after 3 days. Based on our experience, this approach improves the adequacy of antibiotic treatment, with improvement in short-term survival and without increasing the emergence of resistant organisms.