ANTIBIOTIC RESTRICTION DOES NOT ALTER ENDEMIC COLONIZATION WITH RESISTANT GRAM-NEGATIVE RODS IN A PEDIATRIC INTENSIVE-CARE UNIT

Objective: To test whether a ceftazidime restriction policy in a pedia tric intensive care unit (ICU) could decrease the endemic rate of colo nization with ceftazidime-resistant Gram-negative bacilli. Design: Pro spective, pre- vs, postintervention study. Setting: University hospita l pediatric ICU. Patients: Consecutive children admitted to the pediat ric ICU over a 19-mo period. Interventions: After an observation perio d in which antibiotic use was not controlled, ceftazidime was prohibit ed unless the patient's microbiological results indicated that the dru g was necessary for cure. Aminoglycoside use was not regulated. The si ze of the endemic reservoir of ceftazidime- and tobramycin-resistant o rganisms was determined by daily nasopharyngeal and rectal swab specim ens obtained on all admissions to the ICU. Measurements and Main Resul ts: Despite a 96% reduction in ceftazidime use, the incidence density (number of isolates/100 patient-days) of ceftazidime-resistant organis ms increased through the course of the study, from 1,57 to 2.16, The i ncidence density of tobramycin-resistant organisms was unchanged. Ceft azidime restriction resulted in a small but nonsignificant decrease in the proportion of ceftazidime-resistant organisms acquired late (beyo nd 72 hrs) in the patients' ICU course (56.5% vs. 45.9%), However, the re was a more substantial decrease in the proportion of ceftazidime-re sistant organisms derived from species known to harbor derepressible a mp C beta-lactamases (68.2% vs. 45.9%, p < .05). Conclusions: These da ta indicate that antibiotic restriction policies in an ICU fail to dim inish the size of the endemic reservoir of antibiotic-resistant Gram-n egative rods, and suggest that such policies in the absence of broader efforts to limit antibiotic use will have little impact.