Comparative Efficacy of Two Doses of Nebulized Colistimethate for the Eradication ofPseudomonas Aeruginosain Children with Cystic Fibrosis

Abstract

BACKGROUND: Cystic fibrosis (CF) affects the respiratory and digestive systems. It evolves toward deterioration of pulmonary function through colonization withPseudomonas aeruginosa. There is no consensus with respect to its eradication. Nebulized colistimethate is used for eradication treatment, but the optimal dose and duration is yet to be determined.OBJECTIVES: To compare the efficacy of two doses of nebulized colistimethate (30 mg versus 75 mg twice daily) for the eradication ofP aeruginosain children with CF and intermittent colonization.METHODS: A cohort study with both historical (30 mg) and prospective (75 mg) arms was conducted from 1999 to 2003. Medical records were used to collect data.RESULTS: Eighty-one patients were recruited in the retrospective group, for a total of 111 treatment courses. Twenty patients were recruited in the prospective group, for a total of 20 events. There was no statistically significant difference in the rate of eradication ofP aeruginosaat days 28 and 90, neither when comparing the doses of colistimethate nor duration of treatment. There was a statistically significant difference (P=0.004) between days 1 and 90 in all analyzed subgroups (regardless of dose or duration of treatment) for forced vital capacity only. In the group of patients in whom eradication was achieved at day 28 (after receiving a three-week treatment course of colistimethate), 50% of patients developed a new infection 5.75 months later, on average, regardless of the dose administered. In the group of patients who achieved eradication at day 90 (after receiving a 15-week treatment course of colistimethate), 50% of the 14 patients developed a new infection after an average period of 7.3 months (P=0.28).CONCLUSIONS: There is no difference in the efficacy between a 30 mg dose and a 75 mg dose of colistimethate forP aeruginosaeradication in children with CF and intermittent colonization.