Investigation of early antibiotic use in pediatric patients with acute respiratory infections by high‐performance liquid chromatography

In this study, we developed and validated two reliable high‐performance liquid chromatography (HPLC) methods for the qualitative detection of six oral β‐lactams, which are commonly used in pediatric patients with acute respiratory infections (ARIs). Two distinct reverse‐phase chromatographic separations of six β‐lactams were obtained. Four β‐lactams (cefadroxil, cephalexin, cefaclor and cefixime) in urine were separated using a gradient program with a mobile phase consisting of K(2)HPO(4) buffer (20 mm, pH 2.8) and acetonitrile on a LichroCART 250 × 4.6 mm, Purospher STAR C(18) end‐capped (5 μm) column. Two remained β‐lactams (amoxicillin and cefuroxime) were analyzed using a gradient elution with the mobile phase containing K(2)HPO(4) buffer (20 mm, pH 3.0) and acetonitrile on a LichroCart(®) Purospher Star C(8) end‐capped column (5 μm, 125 × 4.6 mm). Good linearity within the range of 0.3–30 μg/ml for cefadroxil, cephalexin, cefaclor and cefixime, and 0.2–20 μg/ml for amoxicillin and cefuroxime, was attained. The precisions were <14%. The accuracies ranged from 85.87 to 102.8%. The two validated methods were then applied to determine these six antibiotics in 553 urine samples of pediatric patients with ARIs. As a result, 32.2% were positive with one or more of six tested β‐lactams. Cefixime was the most commonly detected agent, accounting for 9.8% of enrolled patients.