Impact of a rotating empiric antibiotic schedule on infectious mortality in an intensive care unit

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Abstract
Objective The development of antibiotic-resistant bacteria is associated with significant morbidity and mortality in critically ill patients. We postulated that quarterly rotation of empirical antibiotics could decrease infectious complications from resistant organisms in an intensive care unit (ICU). Design Prospective cohort study. Setting An ICU at a university medical center. Subjects All patients admitted to the general, transplant, or trauma surgery services who developed pneumonia, peritonitis, or sepsis of unknown origin. Interventions A 2-yr study consisting of 1 yr of nonprotocol-driven antibiotic use and 1 yr of rotating empirical antibiotic assignment. Measurements and Main Results Over 100 variables were recorded for each infectious episode, including patient characteristics (e.g., Acute Physiology and Chronic Health Evaluation [APACHE] II score, age, comorbidities), infection characteristics (e.g., site, organism), treatment characteristics (e.g., antibiotic, treatment duration) and outcome measures (e.g., mortality, length of stay, antibiotic cost). Of 1456 consecutive admissions to the ICU, 540 episodes of infection were treated. No differences were noted in age, APACHE II score, race, overall antibiotic utilization or duration of therapy between the 2 yrs of study. Outcome analysis revealed significant reductions in the incidence of antibiotic-resistant Gram-positive coccal infections (7.8 infections/100 admissions vs. 14.6 infections/100 admissions, p < .0001), antibiotic-resistant Gram-negative bacillary infections (2.5 infections/100 admissions vs. 7.7 infections/100 admissions, p < .0001), and mortality associated with infection (2.9 deaths/100 admissions vs. 9.6 deaths/100 admissions, p < .0001) during rotation. Logistic regression identified age (odds ratio [OR], 1.03; 95% confidence interval [CI], 1.01–1.06), APACHE II score (OR, 1.06; 95% CI, 1.01–1.13), solid organ transplantation (OR, 9.50; 95% CI, 2.01–52.21), and malignancy (OR, 10.16; 95% CI, 4.11–26.96) as independent predictors of mortality. Antibiotic rotation was an independent predictor of survival (OR 6.27, 95% CI 2.78–14.16). Conclusion Rotation of empirical antibiotic therapy seems to be a promising method to reduce infectious mortality in an ICU.