Initial Antibiotic Selection Based on Microbiologic History in Pediatric Cystic Fibrosis-Related Pulmonary...

The Cystic Fibrosis (CF) Foundation guideline for the treatment of pulmonary exacerbations (PEx) does not address empiric antibiotic selection. The primary objective of this study is to characterize how patient-specific microbiological histories are utilized in initial antibiotic selection for CF-related PEx at a pediatric institution. The secondary outcome was to characterize why changes were made to empiric antibiotic regimens.

This single-center, retrospective study evaluated individuals aged 1-21 years hospitalized for CF-related PEx at Children's Medical Center Dallas between August 1, 2016 and July 31, 2018.

Among 285 screened hospital encounters, 156 encounters met inclusion criteria. Median age was 12.9 years with a median baseline forced expiratory volume (FEV₁) of 84% predicted. Staphylococcus aureus, Pseudomonas aeruginosa, and Stenotrophomonas maltophilia were the organisms most targeted by empiric antibiotics with median months since last growth of 1.5, 9.2, and 5.5, respectively. A difference was observed in median time since last growth for targeted organisms versus those not targeted by the initial antibiotics, but wide overlapping timeframes were noted. Organisms isolated on admission cultures were sensitive to the initial antibiotics regimen in 78.2% of encounters.

While variable, patient-specific microbiologic history and time since last growth of historical organisms are taken into consideration when selecting initial antibiotics for the treatment of PEx in children with CF. Expanding initial antibiotic coverage to target microbiological growth histories beyond 1 year prior to a hospital admission did not appear to increase the likelihood of providing coverage for organism(s) isolated on the admission sputum culture in children hospitalized for CF-related PEx.