Effect of continuous antistaphylococcal therapy on the rate of P-aeruginosa acquisition in patients with cystic fibrosis

Continuous therapy with antistaphylococcal antibiotics is advocated by some cystic fibrosis (CF) centers. but it is unclear whether this strategy favo rs early colonization with P. aeruginosa. We used the data base for the Ger man Centers of the European Registry for Cystic Fibrosis (ERCF) to assess t he effect of continuous antistaphyloccocal therapy on the rate of P. aerugi nosa acquisition in CF patients. Patients included in this analysis had to be < 18 years of age, P. aeruginosa-negative prior to entry in the ERCF, an d to have had at least 2 additional P. aeruginosa-negative respiratory cult ures while followed in the ERCF. Of the 639 patients fulfilling these criteria, 48.2% received continuous an tistaphyloccocal therapy. 40.4% intermittent antibiotic therapy, and 11.4% no antibiotic therapy. There were no differences between the groups in body mass index, as well as forced vital capacity (FVC) and forced expired volu me in 1 sec (FEV1) at baseline. The rate at which patients acquired positiv e respiratory cultures for Staph. aureus was significantly lower in the gro up receiving continuous antistaphyloccocal antibiotic therapy than in those not receiving such therapy, Patients receiving continuous antistaphyloccoc al antibiotic therapy had a significantly higher rate of P. aeruginosa acqu isition compared to patients receiving only intermittent or no antibiotic t herapy. This difference was especially apparent for children younger than a ge 6 years. We conclude that continuous therapy with antistapyloccocal antibiotics dire cted against Staph. aureus increases the risk of colonization with P, aerug inosa. How this affects the clinical outcome of these patients remains to b e determined. (C);2001 Wiley-Liss. Inc.