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Antibiotic strategies comparable for P aeruginosa in kids with CF

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – Children with cystic fibrosis and recently acquired Pseudomonas aeruginosa infection fare as well with either cycled or culture-based tobramycin inhalation therapy, results of a multicenter trial indicate.

Furthermore, there’s no benefit in adding ciprofloxacin to the regimen, the researchers report in their paper in the September issue of the Archives of Pediatrics and Adolescent Medicine.

“Administering TIS (tobramycin inhalation solution) at the time of recently documented isolation of P aeruginosa in the respiratory tract of children with CF resulted in similar success in maintaining participants free from PEs (pulmonary exacerbations) over an 18-month period, compared with a prophylactic antipseudomonal treatment strategy,” they conclude. “Therefore, providing treatment based on a cycled, quarterly schedule is not supported by the results of this trial.”

Dr. Miriam M. Treggiari, at Seattle Children’s Hospital, Washington, and colleagues hypothesized that early and more intensive antibiotic therapy would reduce rates of pulmonary exacerbations and the frequency of P aeruginosa-positive respiratory cultures in children with CF and newly identified P aeruginosa infection.

To test this, they conducted a trial over 18 months (six quarters) involving 304 such children aged 1 to 12 years. They were randomized to receive cycled antibiotic treatment every quarter, or culture-based therapy in which antibiotics were given only in the quarters when cultures were positive for P aeruginosa.

Treatment was the same in each arm, with tobramycin inhalation solution BID given for 28 days, along with either ciprofloxacin BID or placebo for 14 days, per quarter.

Outcomes were virtually the same in all groups, the investigators found.

Specifically, pulmonary exacerbations requiring IV antibiotics or hospitalization occurred in 16% of the cycled therapy group and 17% of the culture-based group (hazard ratio 0.95; p=0.86), and in 19% of the ciprofloxacin group versus 14% of the placebo group (hazard ratio 1.45; p=0.20).

During the study period, less than 20% of cultures were positive for P aeruginosa, according to the report, with no difference in rates between treatment groups.

“Young children recently acquiring P aeruginosa have a high likelihood of eradication with antibiotic therapy and a prolonged period until reemergence of the pathogen,” Dr. Treggiari and colleagues comment.

Overall, they conclude, “Based on these findings, judicious use of TIS with close microbiologic monitoring of airway cultures in young patients with CF recently infected with P aeruginosa is recommended.”

Nonetheless, they add that additional studies are needed to understand the long-term clinical impact and safety of early antibiotic treatment. In fact, most of the participants in the current trial have been enrolled in a 10-year observational study to collect long-term information on microbiologic outcomes, pulmonary function data, growth statistics, and hospitalization rates.

Arch Pediatr Adolesc Med 2011;165:847-856.