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Appropriateness of antibiotic use and its influence on outcome of patients admitted to an intensive care unit


To evaluate the appropriateness of antibiotic use in patients hospitalized in our intensive care unit and to describe its effect on clinical outcomes.


Medical-surgical intensive care unit of Hospital Moinhos de Vento, a private hospital with an open medical service.


Between March 2000 and October 2000, antibiotic prescription made for adult patients hospitalized in the ICU were reviewed according to an institutional protocol from the Infectious Control Service (ICS). This protocol specified that for all cases a written justification is provided by the responsible physician, although no direct intervention is expected on the medical order. Appropriateness was established by the investigators through prospective collection of clinical data and chart review. Antibiotic prescription was evaluated regarding its indication, empirical use, pharmacokinetics and duration of treatment. Clinical outcomes evaluated were infection worsening or cure and mortality.


A total of 137 antibiotic prescriptions were studied, from 90 patients. Sixty-six per cent were male, age ranged from 17 to 98 years, 61% were older than 61 years, and 61 (68%) medical and 29 (32%) were surgical cases. Among these patients, 81 infections were observed, predominantly respiratory infections (48 [59%] episodes) and sepsis (28 [34%] episodes), and less frequently other infections (abdominal, endocardites, gaseous gangrene, urinary tract, phlebitis). Nosocomial infection occurred in 61 (75.3%) episodes, and in 13 (16.7%) cases immunodeficiency was associated. One or more etiologic agent was only identified in 44 (54%) episodes, 54% Gram-negative bacilli and 43% Gram-positive cocci. Antibiotic use was empirical in 54.4%, etiology guided in 27.8% and in 2.2% no infection was observed. According to criteria defined by ICS, appropriate antibiotic use was observed in only 39% of prescriptions, and the majority were considered inappropriate (61%). Prescriptions were considered inappropriate because of inadequate choice of the drug (44 episodes); errors in doses, intervals or duration (five episodes); choice of combined drugs (one episode); and no adjustment after antibiogram release (two episodes). There was no statistical difference in the appropriateness between empirical (57%) and nonempirical (44%) antibiotic use. Treatment of community-acquired infections were more inappropriate than nosoco-mial infections (73% versus 54%; P < 0.05). However, empirical or appropriate use was not associated with clinical outcomes. Empirical treatment had similar rates of cure (54.5% versus 45.5%) or worsening (58.3% versus 41.6%) to nonempirical treatment, respectively. Although not statistically significant, appropriate use had a cure rate lower than inappropriate use (40% versus 60%), probably due to other clinical factors besides antibiotic use.


Antibiotic use in an ICU setting is empirical in majority of the cases, probably due to the lack of an etiologic agent identified in half of the episodes, and high complexity of patients. In the present study, empirical or inappropriate use did not seem to influence clinical outcome. Appropriateness of antibiotic use for ICU patients may need to consider other criteria than those used for regular patients.

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Silva, N., Polanczyk, C. & Behar, P. Appropriateness of antibiotic use and its influence on outcome of patients admitted to an intensive care unit. Crit Care 5 (Suppl 3), P68 (2001).

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  • Intensive Care Unit
  • Nosocomial Infection
  • Etiologic Agent
  • Antibiotic Prescription
  • Phlebitis